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Birds in cities : a study of populations, foraging ecology and nest-sites of urban birds Weber, Wayne Carson 1972

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BIRDS IN CITIES: A STUDY OF POPULATIONS, FORAGING ECOLOGY AND NEST-SITES OF URBAN BIRDS by WAYNE C. WEBER B.Sc, U n i v e r s i t y of B r i t i s h Columbia, 1967 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n the Department of Zoology We accept t h i s thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA September, 1972 In presenting t h i s thesis i n p a r t i a l f u l f i l m e n t of the requirements for an advanced degree at the University of B r i t i s h Columbia, I agree that the Library s h a l l make i t f r e e l y available for reference and study. I further agree that permission fo r extensive copying of t h i s thesis for scholarly purposes may be granted by the Head of my Department or by h i s representatives. It i s understood that copying or publication of t h i s thesis for f i n a n c i a l gain s h a l l not be allowed without my written permission. Department of Zoolop c The University of B r i t i s h Columbia Vancouver 8, Canada Date A f n l 3 \<T73 ABSTRACT The ecology of urban birds—populations, foraging ecology, and nest-sites—was studied between 1968 and 1970, mostly in Vancouver, British Columbia. Four census plots in Vancouver, each in a different habitat type, were studied year-round.. Additional winter studies were made on two plots each in Sacramento, California and Ottawa, Ontario and on two additional Vancouver plots. Breeding bird densities on the Vancouver plots were lower than those in some other urban areas, but comparable to those in most non-urban habitats. Densities decreased with increasing urbanization. In winter, densities were generally higher than in the breeding season,.and were much higher than those in non-urban habitats. Winter densities, unlike breeding densities, increased with greater urbanization. The availability of food is probably a major cause of the high winter den-s i t i e s . Sacramento and Ottawa both had lower winter densities than Vancouver. The species diversity of the urban plots was low at a l l seasons. This results both from a small number of species and a low equitability ( i . e . , dominance of the population by a very few species). On the Vancouver plots, species diversity was highest in the breeding season, owing to a higher equitability then. The latter probably results from t e r r i t o r i a l behaviour, which makes i t less likely that one or two "sp^l^es w i l l dominate the community. i i i i i The urban bird populations were dominated—especially on the most urbanized plots—by House Sparrows, Starlings, and Rock Doves. An attempt is made to explain how the biological features of these three species make them especially well suited to the urban environment. Two types of observations—stopwatch observations and spotcheck6 —were used, in studies of foraging ecology. This phase of the study was confined to the Vancouver plots. An analysis of the stopwatch observa-tions revealed that nearly every species had a distinctive foraging pattern. The only pair of species which had closely similar patterns were the Starling and the Robin. However, these two had quite different foraging methods and utilized different foods. The spotchecks, being discrete, .were amenable to s t a t i s t i c a l testing. Tests were carried out to see whether the use of different microhabitats corresponded to their availability , and to check for dif-ferences between species. In both cases, only tests involving the Crested Mynah failed to show significant differences. This lack of s i g -nificance is believed to be merely the result of a small sample size. Nest-sites were also studied. Interspecific differences in nest 'height and placement were demonstrated. A conspicuous feature was the almost total absence of nests near the ground. Cat predation and human disturbance are probably responsible for this. In closing, some general features of urban bird ecology are dis-cussed. The importance of studying the foraging ecology of unrelated species, as well as of related ones, is stressed. While two related species with similar foraging ecology usually occupy different habitats, iv ,the same,.,is .probably true of unrelated species to a lesser degree. The foraging patterns of urban birds may be expected to overlap more than those of non-urban birds, and nest-site availability may be particularly crucial to birds in c i t i e s . TABLE OF CONTENTS Section Page A. INTRODUCTION . . . . . . 1 B. BIRD POPULATIONS . . . . . . 4 METHODS 4 STUDIES IN VANCOUVER, BRITISH COLUMBIA 8 The urban habitat in Vancouver: general features, . . 8 Climatic considerations . . . , 10 Description of study plots . . . . 11 Vegetation surveys . . . 16 STUDIES IN SACRAMENTO, CALIFORNIA . . . . . . . . 18 The urban habitat in Sacramento: general features . . 18 Climatic considerations . 18 Description of study plots 19 Vegetation surveys . . . . 20 STUDIES IN OTTAWA, ONTARIO . . . 21 The urban habitat in Ottawa: general features . . . 21 Climatic considerations . . . . . . . . . . . 23 Description of study plots 23 Vegetation surveys . . . . . . 25 RESULTS OF BIRD CENSUSES 25 Density 37 Diversity . 54 Species composition . . . . 59 v v i Section Page DISCUSSION 61 Density . . . . . • • • • • 61 Diversity . . • . . . . . . . . . . • • • 65 Species composition . . . . . . 69 C. FORAGING ECOLOGY 75 METHODS . . . . . • • • • • 75 MICROHABITAT COMPOSITION OF STUDY PLOTS 77 RESULTS 82 Stopwatch observations . . 82 Species accounts • 92 Importance of individual microhabitats to terre s t r i a l foragers . . • 135 Spotchecks , . . . . . . . . . . . .... . • • 148 Comparison of foraging patterns with microhabitat availability . . . . . . • • •.... 152 Comparison between foraging patterns of different species ( a l l macrohabitants) . . . . 153 DISCUSSION . t . . . . . . . . . . . . . . 156 D. NEST-SITES . . . . . . . . 163 METHODS 163 RESULTS . . . . . . . . . . . . . . . . . 163 DISCUSSION 166 E. GENERAL DISCUSSION . . . . . . 169 F. SUMMARY 173 LITERATURE CITED 181 v i i Appendix Page I. Symbols used for bird species recorded during censuses of Vancouver study plots, 1968-1970 26 II. Plants present on Vancouver study plots 191 III. Census of trees present on Vancouver study plots . . . . 197 IV. Heights of trees on Vancouver study plots . . , 200 V. Results of bird censuses on Vancouver study plots . . . . 202 VI. Numbers of trees on Shepard's study plots,. . 218 VII. Results of censuses on Shepard's study plots 220 VIII. Times and weather conditions during censuses of Vancouver study plots, 1968-1970 222 IX. Temperatures during study period, compared to Normals . . 228 X. Precipitation during study period, compared to Normals . 230 XI. Plants present on Sacramento study plots . . . . . . . . 232 XII. Census of trees present on Sacramento study plots (33% sample) 236 XIII. Heights of 33% sample of trees on Sacramento study plots. 238 XIV. Results of Bird Censuses on Sacramento study plots . . . 240 XV. Times and weather conditions during censuses of Sacramento plots, 1970 242 XVI. Plants present on Ottawa study plots . . . . . 244 XVIIi Census of.trees present on Ottawa study plots . ... . . . 246 XVIII. Heights of sample of trees on Ottawa study plots . . . . 248 XIX. Results of bird censuses on Ottawa study plots . . . . . 250 XX. Times and weather conditions during censuses of Ottawa plots, 1970 '. . 252 XXI. Microhabitat composition of study plots - total area of plots, including trees . . . . . 254 v i i i Appendix Page XXII. Microhabitat composition of study plots - area not covered by buildings, ignoring trees . . 256 XXIII. Breakdown.of stopwatch observations on top 18 species according to location, season, and time of day 258 XXIV. Nests discovered in 1968 262 XXV. Nests discovered in 1969 . 265 LIST OF TABLES Table Page 1. Mean Densities of Breeding-Season Birds on Vancouver Study Plots, 27 2. Mean Numbers and Densities of Breeding-Season Birds on 19th & Yukon plot 29 3. Mean Numbers and Densities of Breeding-Season Birds on 14th & Spruce plot . . . . . . . . . . . . 30 4. Mean Numbers and Densities of Breeding-Season Birds on 43rd & Churchill plot . . . • . . . . . . . . 31 5. Breeding Bird Populations on Vancouver Study Plots, 1968-1969 . . . . . . • . . 34 6. Breeding Bird Populations on Vancouver Study Plots, 1968 35 7. Breeding Bird Populations on Vancouver Study Plots, 1969 36 8. Mean Densities of Winter Birds on Vancouver Study Plots 39 9. Mean Numbers and Densities of Winter Birds on 19th & Yukon plot 41 10. Mean Numbers and Densities of Winter Birds on 14th & Spruce plot 42 11. Mean Numbers and Densities of Winter Birds on 43rd & Churchill plot . . . . . . . 43 12. Mean Numbers and Densities of Winter Birds on Ferguson Road plot 44 13. Index to Abundance of Migrant Birds on Vancouver Study Plots in Spring . . . . . . . . . . . . 46 14. Index to Abundance of Migrant Birds on Vancouver Study Plots in Fall 47 15. Mean Densities of Winter Birds on Shepard's Vancouver Study Plots 49 ix Table x Page 16. Mean Densities of Birds on Sacramento Study Plots, . . . 50 17. Mean Densities of Birds on Ottawa Study Plots . . . . . 51 18. Mean.Density, Number of Species, and Percentage Introduced Species in Different Habitats in North America in the Breeding Season 52 19. Mean Density, Number of Species, and Percentage Introduced, Species in Different Habitats in North America in Winter . . . . . . . . . . . 53 20. Number of Species, Bird Species Diversity, and Equitability, on Vancouver, Sacramento, and Ottawa Census Plots 56 21. Trophic Structure of Urban Bird Communities 73 22. Microhabitat Composition of Study Plots 73 23. Distribution of Foraging Time for Species with largest number of observations 83 24. Distribution of Foraging Time for Species with 20 or more observations 86 25. Distribution of Foraging Time for Species with largest number of observations (as Table 23, but observations on plots, only) 87 26. Summary of Food,observations . . . . . . . . . . 88 27a. Distribution of Foraging Time for American Robin according to Season (All Macrohabitats combined) . . . 93 27b. Distribution of Foraging Time for American Robin according to Plot (All Seasons combined) 93 28a. Distribution of Foraging Time for Starling accord-ing to Season (All Macrohabitats combined) 97 28b. Distribution of Foraging Time for Starling accord-ing to Plot (All Seasons combined) . . . . . . . 97 29a. Distribution of Foraging Time for Rock Dove (Common Pigeon) according to Season (All Macrohabitats combined) . . . . . 101 x i Table Page 29b . Distribution of Foraging Time for Rock Dove .(Common Pigeon) according to Plot (All Seasons combined) . . . . 101 30a. Distribution of Foraging Time for House Sparrow according to Season (All Macrohabitats combined) . . . 104 30b. Distribution of Foraging Time for House Sparrow according to Plot (All Seasons combined) . . . . . . . 104 31a. Distribution of-Foraging Time for Crested Mynah according to Season (All Macrohabitats combined) . . . 107 31b. Distribution of Foraging Time for Crested Mynah according to Plot (All Seasons, combined) 107 32a. Distribution of Foraging Time for Black-capped Chickadee according to.Season (All Macro-habitats combined) . . . . . . . . . . . . . . . H I 32b. Distribution of.Foraging Time for Black-capped Chickadee according to Plot (All Seasons combined) . I l l 33. Utilization of Individual Microhabitats by Terrestrial-foraging birds: (a) Loose Earth . . . . • . . . . . . . . . . . . 1 3 6 (b) Hard Earth . . . . . . . . . . . . . . . 1 3 7 (c) Gravel i 3 8 (d) Roads . . . . . . . . . 138 (e) Sidewalks . . . . . . . 139 (f) Lawns 139 (g) Tall Grass 140 (h) Sparse Grass . . . . . 141 34. Distribution of Foraging Time for Species with largest number of observations, as indicated, by spotchecks , . . . . . 150 35. Results of x2 tests on Randomness of Foragings . . . . 154 36. Results of x2 tests for Interspecific Differences in Foraging Patterns. - A l l Plots combined 154 37. Height distribution of Nests, 1968-1969 . 164 38. Location of Nests, 19.68-1969 165 x i i LIST OF ILLUSTRATIONS Figure Page 1. Map of Vancouver, showing locations of study plots . . . 11a 2. 19th and Yukon plot, Vancouver l i b 3. 19th and Yukon plot, Vancouver . l i b 4. 14th and Spruce plot, Vancouver , 12a 5. 14th and Spruce plot, Vancouver „ 12a 6. 43rd and Churchill plot, Vancouver 13a 7. 43rd and Churchill plot, Vancouver 13a 8. Ferguson Road plot, Vancouver 14a 9. Ferguson Road plot, Vancouver 14a 10. 22nd and Dunbar plot, Vancouver . . „ 15a 11. 22nd and Dunbar plot, Vancouver , 15a 12. 33rd and Dunbar plot, Vancouver . . . . . . . . . 16a 13. 33rd and Dunbar plot, Vancouver 16a 14. Map of Sacramento, showing locations of study plots . . 19a 15. S and 24th plot, Sacramento . . . . . . . . . . 20a 16. S and 24th plot, Sacramento 20a 17. F and 21st plot, Sacramento . . . . 20b 18. F and 21st plot, Sacramento 20b 19. Map of Ottawa, showing locations of study plots . . . . 23a 20. Rockcliffe Park plot, Ottawa , . 24a 21. Rockcliffe Park plot, Ottawa. 24a 22. Alta Vista plot, Ottawa . . . . . 24b 23. Alta Vista plot, Ottawa . . . . . 24b x i i i ACKNOWLEDGMENT I wish to express my gratitude to Dr. Rudolf H. Drent, under whose supervision the study was carried out., Dr. Drent provided patient guidance both during the field work and during the preparation of the manuscript. Dr. Peter A. Larkin directed the study during i t s i n i t i a l phases and made numerous helpful comments and criticisms throughout the study. Dr. Ian McTaggart Cowan, Dr. Robin Harger, and Dr. Frank Tompa also gave helpful suggestions at various times. I would also like to thank Mr. Steve Borden and especially Mrs. Dolores Lauriente of the Biology Data Centre at The University of British Columbia for assistance in processing the foraging ecology data. Mrs. W. Morris of Vancouver aided me by identifying many of the ornamental plants on my study plots. When I was in Sacramento, Dr. Miklos D. F. Udvardy of Sacramento State College helped me in many ways. Steven Speich and Mrs. Betty Kimball suggested possible locations for study plots. Mr. Gordon Grieve of the Department of Botany, Sacramento State College, assisted me greatly in identifying cultivated plants. I want to thank Dr. Anthony J . Erskine, of the Canadian Wildlife Service, and Mrs. Erskine for their kindness when I was in Ottawa. Dr. Erskine's advice on location of the study.plots and on other matters was very much appreciated. Dr. W. J . Cody, of the Plant Research Institute, Dejpartp4atr-ef^4gRjvcu.1 ture, spent an afternoon identifying trees and shrubs with me. xiv Financial support for the study was provided by scholarships from the National Research Council for the years 1967 to 1970. Travel funds to and from Sacramento and Ottawa were generously provided by Dr. C. S. Holling from a Ford Foundation grant. Finally, I would like to thank Michael G. Shepard, who kindly allowed me to use the data from his Vancouver census plots. A. INTRODUCTION The study of bird populations has in recent years attracted the interest of a rapidly-increasing number of professional and amateur ornithologists. . Attention in such studies has been focused on the density, diversity, and species composition of breeding and wintering bird populations in different habitat types, and on the effects of various environmental factors on these parameters. Bird population studies have provided much valuable information about such fundamental ecological concepts as interspecific competition, competitive exclusion, niche segregation and species diversity (Odum, 1950). , In addition, bird censuses are important in studies of ecosystem dynamics; before one can,understand the functioning of any ecosystem, i t is essential to know something about the abundance of birds and other animals and plants which are component parts of the system. Most bird censuses have been conducted in forested habitats (see Udvardy, 1957). Man-made habitats such as croplands have received less attention, and urban habitats (here defined as those in which buildings of one kind or another constitute a major feature of the environment) have been.virtually ignored. The area occupied by urban habitats is rapidly increasing throughout,the world, and no comprehensive survey of bird populations can afford to neglect such areas. There have been sug-gestions that bird populations in urban areas are characterized by high density (Pitelka, 1942), low diversity (Woolfenden and Rohwer, 1969) 1 2 and, at least in North America, by a high proportion of introduced species. With the intention of further exploring questions like these, I began censuses, in 1968, of four study plots in and near the city of Vancouver, British Columbia, each representing a different major type of habitat (macrohabitat). Previous studies of bird populations on a plot have usually been confined to either the breeding season or the winter; few areas have been censused throughout the year. I carried out censuses year-round since this is essential to complete the overall picture of habitat u t i l -ization; i t also permits observations on habitat utilization by transient birds, another much-neglected topic (Parnell, 1969; Recher, 1966). The final part of the population study was a comparison of win-tering bird populations in Vancouver with those in Sacramento, California and Ottawa, Ontario. I wanted to find out whether the patterns of high density, low diversity, and dominance of introduced species evident in Vancouver urban areas were the same elsewhere. In particular, I wanted to compare wintering bird populations in three areas with very different winter climates. Since comparable census figures, for other urban areas did not exist, I myself made v i s i t s to Sacramento in January 1970, and to Ottawa in February 1970, and censused two plots in each city. The structure of an avian community can be described by summar-izing the results of a series of bird censuses. Other kinds of observations are necessary, however, to gain insight into the functioning of the community, that i s , the patterns of resource utilization by the various species. One of the most fundamental ecological factors is food, 3 and perhaps the most obvious aspect of resource u t i l i z a t i o n is food-niche u t i l i z a t i o n (Salt, 1953). To determine feeding niches in the present study, foraging observations (described in detail under methods) were made on most of the species inhabiting the four main study plots, to dis-cover where they searched for food. It seems reasonable to assume that birds looking for food in different places must be obtaining different foods (MacArthur, 1958). Collection of birds on or near the study plots to determine stomach contents was neither advisable nor feasible, but whenever possible, observations were made on the actual food items being obtained by birds. No foraging observations were made in either Sacramento or Ottawa. Another aspect of resource u t i l i z a t i o n is nest-location. The abundance of many species of birds is affected by the availability of suitable nest-sites. During the course of the study, the locations of a l l nests found on or near the census plots was recorded. The time spent in nest-searches was small, however, in comparison with that spent on censuses and foraging observations, and the great bulk of effort in the study was devoted to the latter two acti v i t i e s . B. BIRD POPULATIONS 1. Methods The object of my counts i n Vancouver was to explore some general e c o l o g i c a l features of avian communities i n urban habitats, as w e l l as to compare the b i r d populations of d i f f e r e n t habitat types within the c i t y . I began preliminary censuses of several p l o t s i n January and February, 1968. Three of these, which I have c a l l e d the 19th and Yukon, 14th and Spruce, and 43rd and C h u r c h i l l p l o t s , were selected as permanent study areas. The other pl o t s which were censused at that time were re-jected as permanent study areas for several reasons, e s p e c i a l l y hetero-geneity of habitat within the p l o t s . I began regular censuses at semi-monthly i n t e r v a l s on my three permanent plots i n May, 1968. A fourth p l o t , the Ferguson Road p l o t , was added i n October, 1968 and was censused with the same frequency as the other p l o t s . From 1 A p r i l to 15 August, 1969, a l l plots were cen-sused once a week i n order to more accurately determine breeding popu-l a t i o n s . Censuses were continued at bi-weekly i n t e r v a l s thereafter u n t i l the conclusion of the program i n February, 1970. A t o t a l of 207 censuses were c a r r i e d out; 56 each on the 19th and Yukon and 14th and Spruce p l o t s , 54 on the 43rd and C h u r c h i l l p l o t , and 41 on the Ferguson Road p l o t . Michael G. Shepard (MS) conducted censuses on two other plots i n Vancouver between December, 1969 and March, 1970, and has kindly 4 5 allowed me to include h i s data. I have c a l l e d h i s pl o t s the 33rd and Dunbar and 22nd and Dunbar p l o t s . Each was censused a t o t a l of eight times. Shepard's p l o t s were selected i n consultation with me, and h i s counts have provided some i n t e r e s t i n g comparisons with my own. I spent the period 16 to 29 January 1970 i n Sacramento, C a l i f -ornia, to carry out b i r d censuses i n urban areas for comparison with my Vancouver counts. I selected two census p l o t s , as described below, and censused each pl o t f i v e times. I desired counts from at l e a s t two d i f f e r e n t habitat types; however, the l i m i t e d time a v a i l a b l e did not permit adequate coverage of more than two p l o t s . From 16 to 28 February 1970, I v i s i t e d Ottawa, Ontario, and con-ducted censuses on two pl o t s i n a s i m i l a r fashion to my Vancouver and Sacramento counts. Four censuses were made on each p l o t , one i n the v i l l a g e of R o c k c l i f f e Park and the other i n the A l t a V i s t a d i s t r i c t of Ottawa. Descriptions of these pl o t s are given below. I was fortunate i n that Dr. Anthony J . Erskine of the Canadian W i l d l i f e Service, Ottawa, was also engaged i n urban b i r d census work at the time of.my v i s i t . The two pl o t s I chose were suggested by Erskine as possible census areas. The r e s u l t s of my counts o f f e r i n s t r u c t i v e comparisons with Erskine's own censuses of a huge area (275 acres) i n a rather new, very open r e s i d e n t i a l area (Erskine, 1970a). Further winter counts of a d d i t i o n a l p l o t s i n Ottawa are being c a r r i e d out by Erskine and should bring the 1969-1970 counts into better perspective. The procedure followed in.making a census was to begin at one. corner of a p l o t , walk down the f i r s t s t r e e t to the end of the p l o t , walk back i n the opposite d i r e c t i o n along the f i r s t lane, walk along the next s t r e e t i n the o r i g i n a l d i r e c t i o n , and so f o r t h u n t i l the p l o t had been completely covered. Plots were covered i n the same d i r e c t i o n each time. This should increase the comparability of successive counts. To obtain accurate population f i g u r e s , i t might have been better to a l t e r -nate the d i r e c t i o n of coverage. However, th i s source of error should be n e g l i g i b l e i n a census which takes only one or two hours to complete. I t could be more serious i f the census required three or four hours (see remarks below). Censuses were generally not c a r r i e d out during poor weather (continuous r a i n or strong winds). The low b i r d counts which are often obtained i n such weather conditions are probably more a r e s u l t of the observer's impaired a b i l i t y to detect birds than of actual changes i n b i r d numbers. Time of day can make an important difference i n the number of b i r d s recorded on a census (Davis, 1965). During the summer, most passerine birds show a considerable decrease i n song and other a c t i v i t y by four or f i v e hours a f t e r sunrise (Robbins and Van Velzen, 1967). In winter, however, no such decrease i s evident. In the present study, 57 of 62 censuses during the May to July period were begun before 07:00, and 44 of these were begun before 06:30 ( a l l times are P a c i f i c Standard Time). Sunrise during t h i s period occurred between 04:08 and 04:52. Since the counts took between one and two hours to complete, they were nearly always f i n i s h e d within four hours of sunrise. Even i n winter (November to February), only two counts were begun i n the afternoon and 7 most (45 out of 72) were begun before 09:30. The duration of the counts varied between plots and between counts on any one p l o t . I considered i t more important to achieve com-ple t e coverage of a plo t than to standardize the time spent conducting each census. The 43rd and C h u r c h i l l p l o t , for example, took longer to census than the 14th and Spruce p l o t , which was nearly i d e n t i c a l i n s i z e , owing to the thicker vegetation and the presence of several inconspicuous species of birds on the former p l o t . There was also a seasonal d i f f e r -ence; summer counts took longer than winter ones. (On the 43rd and C h u r c h i l l p l o t , 22 summer counts (May to August) averaged 100.5 minutes i n duration, while 16 winter counts (November to February) averaged 89 . 4 minutes; on the 14th and Spruce p l o t , 20 summer counts averaged 73.8 minutes, while 18 winter counts averaged 63.8 minutes.) This difference i s l a r g e l y due to the f l o c k i n g habits of most birds i n the winter, which r e s u l t s i n sections of a plot being almost devoid of bir d s ; most of the birds concentrate i n a few spots. A l l b irds seen or heard on a plo t were recorded during a census. Birds i n f l i g h t over a p l o t were recorded but were not included i n the to t a l s except when they were foraging (as was often the case with swallows and birds of prey). During a census, observations were recorded i n a notebook and the approximate l o c a t i o n of each b i r d was noted. The method of spot-mapping singing males, developed by Williams (1936) and recommended by Kendeigh (1944), was not used, since t h i s method has l i m i t e d a p p l i c a -b i l i t y to urban areas. The commonest urban birds (House Sparrows, 8 S t a r l i n g s , Rock Doves) either do not sing or else sing frequently i n non-t e r r i t o r i a l contexts. The number of nests and the t o t a l number of birds recorded probably give a,better i n d i c a t i o n of the numbers of these species. The study of Snow (1965) demonstrates that r e l i a n c e on counts of singing males alone may r e s u l t i n many breeding birds being missed. 2. Studies i n Vancouver, B r i t i s h Columbia (a) The Urban Habitat i n Vancouver: General Features The o r i g i n a l vegetation over most of the area now occupied by Vancouver was a heavy coniferous forest dominated by Douglas f i r (Pseudotsuga menziesii), western red cedar (Thuja plioata)3 and western hemlock (Tsuga heterophylla). This area f a l l s within the wet subzone of the Coastal Douglas F i r Zone as defined by K r a j i n a (1965). Urbanization of t h i s habitat has generally involved almost complete removal of the native tree cover; of the Vancouver census p l o t s , only the 33rd and Dunbar p l o t had large numbers of mature native c o n i f e r s . I a r b i t r a r i l y c l a s s i f i e d the r e s i d e n t i a l d i s t r i c t s of Vancouver into three types, and picked my three i n i t i a l census plo t s to each repre-sent one of these. The " t y p i c a l r e s i d e n t i a l " type, of which the 19th and Yukon p l o t i s an example, covers perhaps 75% of the r e s i d e n t i a l area. It includes single-dwelling areas with one-storey and (sometimes) two-storey frame houses, often on.small (33-foot) l o t s , and with r e l a t i v e l y few trees which are mostly le s s than 30 feet t a l l . T a l l t e l e v i s i o n a e r i a l s are numerous and are used as song perches by some species of 9 b i r d s . Well-mowed and often extensive lawns are t y p i c a l . This type con-s i s t s mostly of lower- and middle-income,areas of the c i t y . The "well-wooded r e s i d e n t i a l " type, which includes the 43rd and C h u r c h i l l p l o t , occupies probably no more than 15% of the r e s i d e n t i a l areas. I t comprises single-dwelling areas with large one- and two-storey frame houses, frequently on 75-foot or larger l o t s , and with numerous large trees, often including many c o n i f e r s . This type consists c h i e f l y of high-income areas, most of which l i e i n the western h a l f of the c i t y . The "apartment" type, of which the 14th and Spruce p l o t i s t y p i c a l , i s the l e a s t extensive of the three r e s i d e n t i a l types (about 10%). It comprises multiple-dwelling areas which often include old two-storey houses as well as low-rise and h i g h - r i s e apartment blocks; trees are generally very few and buildings cover a large percentage of such areas. This can be regarded as the most highly urbanized of the three r e s i d e n t i a l types, while the "well-wooded r e s i d e n t i a l " type i s l e a s t urbanized. Of Shepard's study p l o t s , the 33rd and Dunbar p l o t f a l l s into the "well-wooded r e s i d e n t i a l " category and i s rather s i m i l a r to the 43rd and C h u r c h i l l p l o t . The 22nd and Dunbar pl o t i s somewhat intermediate between the " t y p i c a l r e s i d e n t i a l " and "well-wooded r e s i d e n t i a l " types, although perhaps closer to the l a t t e r . The Fraser Delta south of Vancouver once supported vegetation inc l u d i n g black Cottonwood (Populus trichocarpa) forests along the r i v e r channels and shore pine (Pinus aontorta) bogs farther inland. It i s now a d a i r y i n g and mixed-farming area which i s r a p i d l y being urbanized as 10 new housing subdivisions are b u i l t . The Ferguson Road pl o t on Sea Island i s perhaps t y p i c a l of t h i s very heterogeneous habitat; i t includes a row of houses as w e l l as a large area of pasture (the p r e v a i l i n g habitat type i n the d e l t a ) . The sprawling Vancouver International A i r p o r t now occupies most of Sea Island. Commercial and i n d u s t r i a l areas o f f e r habitats very d i f f e r e n t from those of r e s i d e n t i a l areas, and probably have quite d i f f e r e n t b i r d populations. However, I did not consider such areas f o r census plots be-cause of the problems posed by height of b u i l d i n g s , d i f f i c u l t y of access, and intensive human a c t i v i t y . (b) Climatic Considerations Vancouver.city has a cool humid mesothermal climate (Cfb i n the Koppen system as given by Trewartha, 1954). This c l i m a t i c type i s char-a c t e r i s t i c of most of northwestern Europe, southern Chile, and much of New Zealand and Tasmania, as we l l as the northwest coast of North America. Vancouver's climate i s a t y p i c a l of th i s type, however, i n that i t has t r a n s i t i o n a l c h a r a c t e r i s t i c s toward a Mediterranean (Csb) climate, most notably a d i s t i n c t summer dry season.. The Vancouver International A i r p o r t , i n f a c t , f a l l s within the Mediterranean type as defined by Kbppen, on account of i t s low summer p r e c i p i t a t i o n . The climate can be described as one of cloudy, wet, and mild winters and sunny, dry, and warm (but not hot) summers. Normal monthly temperatures and p r e c i p i t a -t i o n , as w e l l as those f o r each month during the study period, are given i n Appendices IX and X. The July mean temperature at the Vancouver 11 International A i r p o r t i s 63.8°F.; the January mean, 37.2°F.; and the mean annual p r e c i p i t a t i o n , 41.1 inches, including 17.8 inches of snow. Temperatures are no longer taken at the downtown Vancouver weather o f f i c e , but when both stations operated simultaneously, i t was found that there was no s i g n i f i c a n t difference i n temperatures. P r e c i p i t a t i o n , however, i s much greater i n the c i t y owing to the proximity of the North Shore mountains; the annual mean i s 60.2 inches, including 23.1 inches of snow. Humidity i s high throughout the year (averaging 81%), and annual c l o u d i -ness averages 56% (83% i n December, 37% i n J u l y ) ; because of t h i s , d a i l y range i n temperature i s low (mean range 9°F. i n January, 17°F. i n J u l y ) . Comparison of 1968 to 1970 temperatures and p r e c i p i t a t i o n with normal (Appendices IX and X) w i l l reveal several s i g n i f i c a n t departures. Most of these had l i t t l e obvious e f f e c t on birds i n the study p l o t s , except f o r the severe cold, accompanied by heavy snow, of December, 1968 and January, 1969. On 30 December 1968, the thermometer registered an al l - t i m e record low of -0.3°F. at the Vancouver International A i r p o r t , and from 19 to 31.January, 1969, temperatures remained continuously below freezing. The mean temperature for January, 1969 was more than ten degrees below normal. This cold snap, as well as k i l l i n g much ever-green shrubbery, had notable e f f e c t s on birds which are described in.the Results section. (c) Description of Study Plots The locations of the s i x Vancouver study plots are indicated on Fi g . 1. The general descriptions presented below are supplemented by 11A Vancouver International Airport . \ *• \ C**^ F i g . 1 Map of Vancouver, showing locations of study p l o t s (1) 19th & Yukon pl o t (2) 14th & Spruce p l o t (3) 43rd & C h u r c h i l l p l o t (4) Ferguson Road p l o t (5) 22nd & Dunbar p l o t (6) 33rd & Dunbar pl o t l i b . 3. 19th & Yukon p l o t , Vancouver. T y p i c a l back lane. Note s c a r c i t y of trees; tree at r i g h t i s a blossoming Japanese cherry (Prunu.8 serrulata). A p r i l 1970. 12 two photographs of each p l o t (Figs. 2 to 13). The 19th and Yukon plo t consisted of nine c i t y blocks, covering 44.03 acres, and bounded by 19th Avenue on the north; Ontario Street on the east; 22nd Avenue on the south; and Yukon Street on the west. Judging by the dates on sidewalks, most of i t was b u i l t up between 1929 and 1931. The houses are mostly single-storey and most l o t s are only 33 feet wide; small garages are also present on most l o t s . A l l streets are paved; some.are separated from boulevard lawns by s t r i p s of gravel, others by concrete curbs. Lanes are present throughout and are gravelled. Street trees, mostly small maples (Acer sp.) and oaks (Querous sp.) have been planted along 20th, 21st, and 22nd Avenues and part of,Columbia Street. Garden trees are generally few and small, and comprise c h i e f l y ornamental cedars (Chamaeoyparis lawsoniana and others) i n front yards, and apples (Malus sylvestris) and cherries (Prunus serrulata) i n back-yards. The habitat i s not quite uniform; the houses i n the southern, part of the p l o t are mostly newer than those i n the northern part, and most of the few older two-storey houses are on 19th Avenue. Similar habitat surrounds the p l o t on a l l sides, although the density, age, and height of houses.is greater to the east, the number of trees i s smaller to the south, and a commercial s t r i p e x i s t s along Cambie Street, a block to the west. The 14th and Spruce p l o t covered nine blocks and measured 39.84 acres. I t was bounded by 11th Avenue on the north, Spruce Street on the east, 14th Avenue on the south, and Hemlock Street on the west. This area was b u i l t up between 1911 and 1913. The o r i g i n a l buildings were 12a F i g . 4. 14th & Spruce p l o t , Vancouver. Note the large old two-storey houses as w e l l as the newer apartment blocks. Trees are maples, (Acer sp., i n foreground) and h o l l y (Ilex aquifolium). Shrub at l e f t i s f o r s y t h i a (Forsythia sp.). A p r i l 1970. F i g . 5. 14th & Spruce p l o t , Vancouver - back lane. Vegetation i s almost non-existent; concrete and asphalt dominate the scene. A p r i l 1970. 13 large two- or three-storey frame houses, most of which have been replaced by apartment blocks over a period of time. The apartments are mostly medium-sized (10 to 20 suites) and two or three storeys i n height. . Two hi g h - r i s e apartments about 100 feet t a l l are on the p l o t ; one of these, as w e l l as a smaller apartment, was completed during the study period. A l l s t r e e t s are paved, most with concrete curbs; most lanes are gravelled, some o i l e d . Street trees have been planted only on 13th Avenue, Spruce Street, and part of Birch Street; these include birches (Betula pendula), maples, hawthorns (Crataegus oxyacantha)> oaks and elms (Ulmus amerieana). Garden trees are few except for ornamental cedars. A large area of lawn and blacktop surrounds the newest h i g h - r i s e . Other habitats nearby i n -clude a schoolyard immediately adjacent to the,southeast corner of the plo t ; the heavily-treed, high-income Shaughnessy Heights d i s t r i c t one block south of the plot; and the commercial d i s t r i c t of G r a n v i l l e Street one block to the west. The 43rd and C h u r c h i l l p l o t included seven blocks and was 39.26 acres i n area. I t was delimited by 43rd Avenue on the north; C h u r c h i l l Street on the east; 47th Avenue on the south; and Angus Drive, 45th Avenue^ and W i l t s h i r e Street on the west. I t was b u i l t up between 1927 and 1930. A l l l o t s are 75 feet wide, and large two-storey houses are the ru l e . Nearly a l l houses also have garages or carports. A l l streets are paved, with concrete curbs, and gravelled lanes are present throughout. Large s t r e e t trees l i n e a l l s t r e e t s , and form a dense canopy i n many places; there are also many large garden,trees. Maples have been planted a l o n g . a l l the east-west s t r e e t s ; of the north-south s t r e e t s , C h u r c h i l l F i g . 6. 43rd & C h u r c h i l l p l o t , Vancouver. Adera St. near 43rd Ave., showing large two-storey houses and l o f t y b i r c h trees (Betula pendula). A large Douglas f i r (Pseudotsuga menziesii) can be seen i n the background. A p r i l 1970. Fi g . 7. 43rd & C h u r c h i l l p l o t , Vancouver - back lane, showing dense vegetation. Trees include Lombardy poplar (Populus nigra) i n l e f t f o r e -ground and background. Douglas f i r (Pseudot-suga menziesii) at l e f t , and mountain ash (Sorbus auouparia) at r i g h t . September 1970. LO 14 and Marguerite are bordered by elms, Adera and Angus by birches, and W i l t s h i r e by maples. Garden trees include apples, ch e r r i e s , Port Orford cedars (Chamaecyparis lawsoniana)3 western red cedars, mountain ashes (Sorbus aucupavia)3 and P a c i f i c dogwoods (Cornus nuttallii). The habitat i n t h i s p l o t was notably nonuniform i n that garden trees became fewer and smaller i n the western part of the p l o t . Only 121 trees were counted i n the southwesternmost block of the p l o t , compared with 293 i n the north-, easternmost (although the l a t t e r were l a r g e r ) . In p a r t i c u l a r , many of the large c o n i f e r s , which gave the p l o t much of i t s d i s t i n c t i v e character, were concentrated along the easternmost lane i n the p l o t . D i s s i m i l a r habitats adjacent to the 43rd and C h u r c h i l l p l o t included a schoolyard one block to the west and a more open area along G r a n v i l l e Street, one block to the east. The Ferguson Road pl o t consisted of a 200-foot wide s t r i p along a road rather than a more-or-less square area l i k e my Vancouver study p l o t s . I t extended for nearly a mile along Ferguson Road, from Macdonald Road to Shannon Road, and covered 24.03 acres. The eastern quarter of the s t r i p included ten houses and a v a r i e t y of ornamental trees along the north side of,Ferguson Road. The remainder of the p l o t consisted l a r g e l y of pasture, but also included s i x houses. Three large barns were located on or immediately adjacent to the p l o t . Ferguson Road i s paved and i s bordered by gravel and weeds. Two long.rows of small choke-cherry trees (Primus virginiana) border sections of the road, and comprise nearly h a l f the trees on the p l o t . A badly-neglected pear orchard (Pyrus communis) l i e s opposite part of the r e s i d e n t i a l d i s t r i c t . 14a Fi g . 9. Ferguson Road p l o t , Vancouver. R e s i d e n t i a l area near the east end of the p l o t . Numerous small trees border both sides of the road. September 1970. 15 Pasture extends f o r several hundred yards north and south of Ferguson Road. East of Macdonald Road there i s a low-density r e s i d e n t i a l area with numerous trees; west of Shannon Road l i e a sandy, grass-covered area, a small freshwater marsh, and a large f i e l d used for truck-farming. The Fraser River and i n t e r t i d a l marshes and mudflats are nearby. A l -though the Ferguson Road pl o t includes more than one habitat type, I believe that i t makes a v a l i d census area, since much of the Fraser Delta has a s i m i l a r combination of habitat types. One might say that the d e l t a e x h i b i t s a large-scale patchiness i n habitat as opposed to the smaller-scale patchiness i n the c i t y proper. More,detailed information on the plants occurring i n the four p l o t s described above i s given i n Appendices II to IV. Shepard's plo t s were les s i n t e n s i v e l y studied, but w i l l be b r i e f l y described here. The 33rd and Dunbar p l o t was rather s i m i l a r to the 43rd and C h u r c h i l l p l o t . I t covered nine blocks and measured 48.02 acres i n area. However, many more large conifers ( e s p e c i a l l y Douglas f i r ) are present than on the 43rd and C h u r c h i l l p l o t . Despite t h i s , the general aspect of the 33rd and Dunbar pl o t i s more open, p a r t l y owing to the lack of s t r e e t trees on the north-south s t r e e t s . Most of the st r e e t trees are birches, elms, and maples. Lots are large (mostly 50-foot, some 66-foot) but most of the houses are single-storey rather than two-storey. Edge e f f e c t s may r e s u l t from the proximity of Dunbar Street, a main t r a f f i c artery which borders the p l o t on the east; Memorial Park West, a partly-wooded, partly-open area which extends between 31st and 33rd; and the dense second-growth mixed forest of the U n i v e r s i t y of F i g . 10. 22nd & Dunbar p l o t , Vancouver. Looking east on 24th Avenue. Trees are mainly elms (Ulrnus amerioana). A p r i l 1970. F i g . 11. 22nd & Dunbar p l o t , Vancouver. Back lane near 24th and Dunbar. Trees and large shrubs are scarce, as i n the 19th & Yukon p l o t . A p r i l 1970. 16 B r i t i s h Columbia Endowment Lands, one block to the west of the p l o t . The 22nd and Dunbar p l o t , which covers nine blocks (47.26 acres), contains mostly single^storey houses on small l o t s (mostly 33-foot, some 50-foot) but i s well-treed. Large deciduous trees, mainly maples, elms, and horsechestnuts (Aesaulus hippocastanum) l i n e most of the st r e e t s . . However, r e l a t i v e l y few. large conifers are present, and most of these are ornamental cedars. Common deciduous garden, trees i n both t h i s and the 33rd and Dunbar pl o t include c h e r r i e s , P a c i f i c dogwoods, and mountain ashes. This p l o t i s bordered by the broad thoroughfares of Dunbar Street on the east and 25th (King Edward) Avenue on the south, and by a shore pine bog on the Univ e r s i t y Endowment Lands to the west. The 22nd and Dunbar p l o t i s more or less intermediate between the " t y p i c a l " open Vancouver r e s i d e n t i a l areas l i k e the 19th and Yukon p l o t and heavily-treed areas l i k e the 43rd and C h u r c h i l l or 33rd and Dunbar p l o t s . (d) Vegetation Surveys During 1970, vegetation surveys of my four main Vancouver study p l o t s were c a r r i e d out. Since the object.of my census work was to com-pare b i r d populations i n d i f f e r e n t h a b i t a t s , I wanted f a i r l y d e t a i l e d information about the habitat. Many published b i r d census studies contain very l i t t l e information on the habitat, and few contain adequate d e t a i l . I began by l i s t i n g a l l the plants I could i d e n t i f y on,each p l o t . These are l i s t e d i n Appendix I I . I s u b j e c t i v e l y categorized each species as common or not common according to the ,following rough c r i t e r i a : 16a Fi g . 12. 33rd & Dunbar p l o t , Vancouver, Looking south along Wallace Street. Note the numerous large Douglas f i r s (Pseudotsuga menziesii); also note the absence of st r e e t trees along Wallace. A p r i l 1970. Fi g . 13. 33rd & Dunbar p l o t , Vancouver. T y p i c a l back lane; note the density of trees and shrubs. A p r i l 1970. 17 trees, common i f an average of one or more per block present; shrubs, i f an average of " s e v e r a l " (3 to 10) per block present; herbs, i f an average of "many" (10 plus) per block present. Woody plants 15 feet or more i n height were classed as trees, while those less than 15 feet t a l l were classed as shrubs. Botanical names have been taken mainly from Bailey (1949). In the case of trees, I mapped, i d e n t i f i e d , and estimated the height of each i n d i v i d u a l present i n the p l o t s , and also measured the DBH (diameter at breast height) of st r e e t trees. The exception to t h i s was the 43rd and C h u r c h i l l p l o t , where the large number of trees made th i s i m p r a c t i c a l . Instead I mapped the trees on three out of the seven blocks on t h i s p l o t , so chosen as to obtain what should be a represen-t a t i v e sample (the southwesternmost block, the northeasternmost block, and one-half of each of the two c e n t r a l blocks). The species composition of trees on each pl o t i s given i n Appendix I I I , and the d i s t r i b u t i o n of i n d i v i d u a l s i n various height classes i n Appendix IV. I did not do vegetation surveys on.Shepard's census p l o t s . However, Shepard made a count of trees on h i s pl o t s (Appendix VI), although he did not estimate heights or attempt to i d e n t i f y some of the l e s s common species. I t would seem superfluous to do a d e t a i l e d vegeta-t i o n survey for a p l o t on which only eight b i r d censuses were taken (as compared with about 50 censuses on each of my p l o t s ) . 18 3. Studies i n Sacramento, C a l i f o r n i a (a) The Urban Habitat i n Sacramento: General Features The urban habitat i n Sacramento i s very d i f f e r e n t from that i n Vancouver. The older parts of the c i t y , p a r t i c u l a r l y the r e s i d e n t i a l areas north and west of Interstate Highway 80 (see F i g . 14), which included my study p l o t s , are more heavily wooded than most Vancouver r e s i d e n t i a l areas. This i s not s u r p r i s i n g , since summer temperatures i n Sacramento frequently exceed 100°F., and trees are valued for t h e i r shade. Also, the broad lawns c h a r a c t e r i s t i c of Vancouver are not evident; the houses are situated much closer to the s t r e e t . The older area of Sacramento de-l i m i t e d above was the only section of the c i t y which had lanes; since I considered lanes necessary for good census coverage, I confined my attention to t h i s area. Many of the newer subdivisions are much more open and more l i k e Vancouver habita t s , but these areas would have been d i f f i c u l t to census. The two p l o t s I picked i n Sacramento were unavoid-ably rather s i m i l a r to one another, at l e a s t more so than were my three Vancouver c i t y p l o t s , but the d i f f e r e n c e i n both the habitat (vegetation and buildings) and i t s associated b i r d populations were s u b s t a n t i a l . (b) Climatic Considerations Sacramento has a rather t y p i c a l inland Mediterranean climate (Csa i n the Koppen system), with mild winters, hot summers, a large d a i l y range of temperature, and a summer-drought, winter-rain p r e c i p i t a t i o n 19 regime. The July mean temperature i s 75.4°F.; the January mean, 45.2°F.; and the annual mean p r e c i p i t a t i o n , 16.3 inches (figures from the United States Weather Bureau o f f i c e at the Sacramento A i r p o r t ) . January temper-atures i n Sacramento average a maximum of 53°F. and a minimum of 37°F.; f r o s t occurs on 20 days per winter, on average (9 days i n January), but severe f r o s t s (below 25°F.) are very rare. January p r e c i p i t a t i o n averages 3.2 inches. When I ar r i v e d i n Sacramento, about 8.7 inches of r a i n had f a l l e n during the preceding s i x weeks, compared to a normal of 4.8 inches i n the same period, and the Sacramento River was near flood stage, although serious flooding did not take place. A succession of storms from the southwest produced unusually warm and wet conditions during the f i r s t ten days of my stay; minimum temperatures averaged about 50° and maxima about 60°. On the l a s t two days, however, temperatures were lower and over-night ground f r o s t s occurred. I do not know what e f f e c t , i f any, t h i s unusual weather may have had on the urban b i r d populations. (c) Description of Study Plots The two plot s were located as follows (see F i g . 14): (1), bounded by F Street on the north, 24th Street on the east, I Street on the south, and 21st Street on the west; and (2), bounded by S Street on the north, 27th Street on the east, V Street on the south, and 24th Street on the west. I s h a l l r e f e r to these pl o t s r e s p e c t i v e l y as the "F and 21st" and "S and 24th" p l o t s . Both pl o t s covered nine c i t y blocks and measured 34.7 acres i n area, and both occupied f l a t ground with an elevation of. 20 less than 100 feet above sea l e v e l . The F and 21st p l o t i s i n one of the oldest sections of Sacramento, and was probably b u i l t up about 1910 or 1920 (Gordon Grieve, pers. comm.). The buildings are nearly a l l multi-storeyed. Large houses of two or three storeys and small apartment blocks, containing 4 to 20 s u i t e s , pre-dominate. Most of the buildings are about 30 to 35 feet i n height. A l l s t r e e t s are paved from curb to curb, and most of the back lanes are also paved. The area i s very well-treed, and rows of l o f t y elms, 70 to 80 feet t a l l , along the streets are c h a r a c t e r i s t i c . Two blocks i n the north-western part of the p l o t d i f f e r from the others i n having large, grassy courtyard-like areas in.the centre. The S and 24th p l o t i s i n a newer part of the c i t y , and was probably b u i l t up less than 40 years ago. Small, one-storey, single-r family dwellings predominate and there are r e l a t i v e l y few apartment blocks. As i n the other p l o t , a l l the st r e e t s and most of the lanes are paved from curb to curb. Instead of massive elms, however, the s t r e e t trees consist l a r g e l y of medium-sized sycamores, and the general aspect of the habitat i s much more open ( F i g . 15). (d) Vegetation Surveys Vegetation surveys s i m i l a r to those on my Vancouver plo t s were c a r r i e d out on the two Sacramento census areas. An attempt was made f i r s t to i d e n t i f y a l l the plant species ( e s p e c i a l l y trees and shrubs) occurring on the plots (Appendix XI). Plants were l i s t e d as e i t h e r com-mon or not common on each p l o t according to the same c r i t e r i a used i n Vancouver. 20a F i g . 15. S & 24th p l o t , Sacramento. Looking north on 25th Avenue near T Street. The trees i n the foreground are sycamores (Tlatanua oaoidentalis). A fan palm (Washingtonia robusta) can be seen i n the background. January 1970. 20b Fi g . 17. F & 21st p l o t , Sacramento; i n t e r s e c t i o n of G Street and 21st Avenue. Large trees, from l e f t , are elm (Ulmus sp.); a second elm; Canary Island date, palm (Phoenix oanariensis); redwood (Sequoia sempervirens); European white b i r c h (Betula pendula); camphor-tree (Cinnamomum aamphora); and a t h i r d elm. Note the large multi-storeyed houses. January 1970. Fig . 18. F & 21st p l o t , Sacramento. Back lane. Note that surface i s paved. Trees and large shrubs are numerous. January 1970. 21 In addition, on three of the nine blocks i n each p l o t , a l l trees were mapped and t h e i r i d e n t i t y and height determined (see Appendices XI and XIII). On each pl o t the blocks chosen were the northwesternmost block, the c e n t r a l block, and the southeasternmost block. Choice of the blocks for analysis i n t h i s way should eliminate any possible bias owing to progressive changes i n the habitat i n e i t h e r a north-south or east-west d i r e c t i o n . The time a v a i l a b l e did not allow coverage of more than t h i s 33% sample of the trees, but a complete analysis would probably have been superfluous i n view of the l i m i t e d amount of data on b i r d populations which could be gathered. Lawn grasses and weeds have not been included i n Appendix X i . Common lawn grasses i n Sacramento include Poa pratensis (Kentucky blue-grass) , Poa annua, Poa trivialis, Agrostis tenua, Agrostis palustris, Festuca elatior (Meadow fescue), and Festuoa rubra (red fescue). Common weeds include the English daisy (Bellis perennis)t p l a n t a i n (Plantago lanceolata), and of course the ubiquitous dandelion, Taraxacum officinale (Gordon Grieve, pers. comm.). The s c i e n t i f i c and common names of plants l i s t e d have been c h i e f l y those used by Bailey (1949). Other h e l p f u l sources were V i e r t e l (1970) and Van Rensselaer (1948). 4. Studies i n Ottawa, Ontario (a) The Urban Habitat i n Ottawa: General Features Ottawa i s a considerably older c i t y than e i t h e r Vancouver or Sacramento. Thus a considerable v a r i e t y of urban habitats e x i s t s , owing 22 to s p a t i a l d i v e r s i t y i n both the types of buildings and the d i f f e r i n g density and composition of tree cover, both connected to some degree with the age of the area ( i . e . , the number of years since i t was b u i l t up). At one extreme, i n r e s i d e n t i a l d i s t r i c t s , i s the R o c k c l i f f e Park area, which i s r e l a t i v e l y old and heavily-wooded. Erskine's census area i n B e l - A i r Heights and Copeland Park represents something close to the other extreme. The downtown core of Ottawa i s s t i l l another extreme, but as i n other large c i t i e s , such an area would be d i f f i c u l t to census accur-ately because of the numerous t a l l buildings and intensive human a c t i v i t y . The v i r t u a l absence,of laneways i n Ottawa (perhaps because of problems i n snow removal) posed a problem i n censusing. Some birds were undoubtedly missed i n my counts because of the d i f f i c u l t y of seeing i n t o backyards, and the Ottawa counts are probably more conservative ,than the Vancouver and Sacramento counts. The problem was l e s s serious then I a n t i c i p a t e d , however, on account of the rather low d e n s i t i e s of birds and the prevalence of cold, c l e a r , s t i l l a i r through which the c a l l s of bi r d s could be heard for long distances. The absence of lanes also made i t p ossible to census a larger area i n the,same time, a desirable s i t u a -t i o n i n view of the low b i r d d e n s i t i e s i n Ottawa. A conspicuous d i f f e r e n c e between Ottawa and both Vancouver and Sacramento was the predominance of b r i c k rather than frame houses. This may have considerable importance i n the e f f e c t s i t has on the nesting-s i t e s offered to b i r d s , but i t appears to have les s influence on winter b i r d populations. 23 (b) Climatic Considerations The c l i m a t i c differences between Ottawa and Vancouver, at l e a s t i n winter, are much greater than those between Sacramento and Vancouver.. Ottawa has a strongly continental climate with warm summers, severe winters, and moderate p r e c i p i t a t i o n at a l l seasons with no dry,period (cool humid microthermal, or Dfb, according to the KSppen c l a s s i f i c a t i o n ) . The July mean temperature i s 69.7°F.; the January mean, 13.1°F.; and the mean annual p r e c i p i t a t i o n , 33.6 inches, including 86.1 inches of snow. (Temperature data are from the weather o f f i c e at the National Research Council i n Ottawa; p r e c i p i t a t i o n data, from the Ottawa Airport.) Feb^ ruary temperatures average 15.3°F. (mean maximum 22.9°F., mean minimum 7.7°F.), and February p r e c i p i t a t i o n averages 2.3 inches, nearly a l l (19.2 inches) i n the form of snow. Temperatures as low as -20°F. are not unusual, and there i s a snow cover, often heavy, of several months' duration. Weather conditions were about normal during my v i s i t i n February, although no major snowstorms occurred during the period. Temperatures ranged from 40°F. on 22 February to -17°F. on 27 February, but were be-tween 0° and 20° most of the time. Snow cover was about two or three f e e t , and winds were generally l i g h t . (c) Description of Study Plots The R o c k c l i f f e Park p l o t was bounded by Minto Place on the west; C o l t r i n Road on the north; Acadia Road, Crescent Road, Buena V i s t a Road, 23A F i g . 19. Map of Ottawa, showing locations of study p l o t s . (1) R o c k c l i f f e Park p l o t (2) A l t a V i s t a p l o t 24 and S p r i n g f i e l d Road on the east; and Mariposa Road on the south (see F i g . 19). It measured 68.6 acres i n area. The p l o t l i e s atop a h i l l overlooking the Ottawa River. This i s a high-income r e s i d e n t i a l area which appears to have been superimposed on a native elm-maple forest with a minimum of c l e a r i n g . Most of the trees on the p l o t are native species, although many exotic spruces, pines, and other species have been planted. The houses are large, usually two-storeyed, and l o t s are wide. The area was probably b u i l t up at least 50 years ago. The R o c k c l i f f e Park p l o t i s very s i m i l a r i n general aspect to the 43rd and C h u r c h i l l p l o t i n Vancouver. The A l t a V i s t a p l o t was 103.5 acres i n area and was bounded by A l t a V i s t a Drive on the west; Roger Road on the noth,, Highridge, B i l l i n g s , and Fairbanks Roads on the east; and Summit Avenue on the south. This area was b u i l t up mainly between 1951 and 1955 (A. J . Erskine, pers. comm.), although there are a number of older houses along Pleasant Park Road, which runs through the centre of the p l o t . This p l o t has f a r fewer trees than the R o c k c l i f f e Park p l o t , although more than Erskine's census area. The habitat i s not quite uniform; there are more trees i n the south h a l f of the p l o t , , i n c l u d i n g numerous large elms, although these are much more scattered than i n Rockcliffe.Park. There are also large tr e e l e s s areas along Pleasant Park Road. Lots are smaller i n A l t a V i s t a than i n R o c k c l i f f e Park, though larger than i n most Vancouver areas. One-storey, single-family houses predominate. 24a F i g . 20. R o c k c l i f f e Park p l o t , Ottawa, showing large houses and heavy tree cover. Trees are mainly elms (Ulmus amerioana), sugar maples (Acer saooharvm), and Norway spruces (Pioea abies). February 1970. Fi g . 21. R o c k c l i f f e Park p l o t , Ottawa—bird-feeder on Kinzua Road. Several Evening Grosbeaks and at l e a s t one Common Redpoll (at extreme upper r i g h t ) can be seen. February 1970. 24b F i g . 23. A l t a V i s t a p l o t , Ottawa. Open area along Pleasant Park Road, near Fairbanks Road. Feeding f l o c k s of S t a r l i n g s and Rock Doves concentrated i n t h i s area. February 1970. (d) Vegetation Surveys The vegetation surveys on my Ottawa plots were very much less complete than the Vancouver or Sacramento surveys f o r several reasons, inc l u d i n g the large s i z e of the p l o t s and the absence of lanes. I was l i m i t e d i n my tree analysis to mapping, i d e n t i f y i n g , and estimating heights of trees along streets i n what appeared to be t y p i c a l portions, of each p l o t . Thus the tree sample i s representative only of trees along the s t r e e t s , and the nature of the tree cover i n backyards may have been d i f f e r e n t . Furthermore, a l l the herbaceous plants and low shrubs had been buried by the deep snow cover, although such plants are obviously of no importance to winter b i r d populations. Results of the vegetation surveys are given,in Appendices XVI, XVII, and XVIII. C r i t e r i a f o r "common" and "not common" plants were the same as i n Vancouver. In addition, I added a "very common" category for trees of which numerous i n d i v i d u a l s per block were present on the area. 5. Results of Bird Censuses The dates of the censuses on the four main Vancouver p l o t s are l i s t e d i n Appendix VIII, together with times and attendant weather con-d i t i o n s . The birds recorded on each of these 207 censuses are l i s t e d i n Appendix V. The information contained i n Appendix V has been summar-ized and compared i n various ways i n Tables 1 through 14. The r e s u l t s of Shepard's counts are given,in Appendix VII, and they are summarized and compared i n Table 15. To conserve space, I have used a system of symbols for b i r d 26 Appendix I Symbols used f o r b i r d species recorded during censuses of Vancouver study p l o t s , 1968-1970 ACT - American Coot MGW - MacGillivray's Warbler AG - American Goldfinch MH - Marsh Hawk AP - Water P i p i t MW - Myrtle Warbler AR - American Robin NS - Northern Shrike AW - Audubon's Warbler NWC - Northwestern Crow BB - Brewer's Blackbird OCW - Orange-crowned Warbler BC - Brown Creeper OJ - Oregon Junco BCC - Black-capped Chickadee OSF - Olive-sided Flycatcher BE - Bald Eagle Bonaparte's G u l l PF - Purple Finch BG - PGF - Peregrine Falcon BHG - Black-headed Grosbeak PH - Pigeon Hawk BK - Belted Kingfisher PSK - Pine S i s k i n BS - Barn Swallow PT - P i n t a i l BSW - Black Swift RBN - Red-breasted Nuthatch BT - Common Bushtit RC - Red C r o s s b i l l BTGW - Black-throated Gray Warbler RCK - Ruby-crowned Kinglet BTP - Band-tailed Pigeon RHB - Rufous Hummingbird BWR - Bewick's Wren RLH - Rough-legged Hawk CBC - Chestnut-backed Chickadee RNP - Ring-necked Pheasant CC - Brown-headed Cowbird RSF - Red-shafted F l i c k e r CG - Canada Goose RWB - Red-winged Blackbird CH - Cooper's Hawk RWS - Rough-winged Swallow CM - Crested Mynah S - S t a r l i n g CNH - Common Nighthawk SB - Snow Bunting CP - Rock Dove or Common Pigeon SEO - Short-eared Owl CRP - Common Redpoll SH - Sparrow Hawk CS - C l i f f Swallow SJ - S t e l l e r ' s Jay CSN - Common Snipe SS - Song Sparrow CSR - Chipping Sparrow ST - Rufous-sided Towhee CTR - Common. Tern SVS - Savannah Sparrow CW - Cedar Waxwing TS - Townsend's S o l i t a i r e DCC - Double-crested Cormorant TSL - Tree Swallow DW - Downy Woodpecker TW - Townsend's Warbler EG - Evening Grosbeak VGS - Violet-green Swallow FS - Fox Sparrow VSW - Vaux's Swift GBH - Great Blue Heron VT - Varied Thrush GCK - Golden-crowned Kinglet WCS - White-crowned Sparrow GCS - Golden-crowned Sparrow WF - Western Flycatcher GWG - Glaucous-winged G u l l WM - Western Meadowlark GWT - Green-winged Teal WT - Western Tanager GYL - Greater Yellowlegs WV - Warbling Vireo Wilson's Warbler HF - House Finch WW -HG - Herring G u l l WWC - White-winged C r o s s b i l l HS - House Sparrow WWP - Western Wood Pewee HT - Hermit Thrush WWR - Winter Wren K - K i l l d e e r YBS - Yellow-bellied Sapsucker LSP - Least Sandpiper YHB - Yellow-headed Blackbird MDK - Mallard YT - Yellowthroat MG - Mew G u l l YW - Yellow Warbler Table 1. Mean densities of breeding-season b i r d s on Vancouver study plots (means for 1968 and 1969) expressed as b i r d s per 100 acres Species 19 th & 14th & 43rd & Ferguson Species 19 th & 14th & 43rd & Ferguson code Yukon Spruce C h u r c h i l l Road code Yukon Spruce C h u r c h i l l Road HS 159.5 105.4 39.7 90.9 BTP (2.7) 2.9 AR 77.9 24.9 173.1 62.4 RCK 2.6 S 72.0 50.7 45.6 106.3 GCK 2.3 CP 24.0 90.7 (0.9) (9.3) GCS 2.3 3.5 BS 22.6 7.1 19.3 107.6 EG (1.7) VGS 16.6 12.1 12.4 (14.1) WT (1.5) (0.6) HF 13.5 5.8 39.7 (41.9) MW 1.4 CM 11.9 11.3 7.3 4.2 PF (1.2) BCC (6.4) (2.0) 37.2 (2.6) FS 1.1 AG 4.0 ( l . D 13.0 (5.8) WWP 0.5 CC 1.6 6.0 33.3 WF 0.5 WW 0.9 0,3 4.3 1.0 OJ 0.3 cw (0.6) (2.0) (0.6) TW 0.3 0.3 ocw . 0.6 0.2 2.6 0.6 RSF (0.2) YW 0.6 0.2 1.1 1.0 BC (0.2) MGW 0.6 0.2 0.5 BWR (0.2) CSR (0.4) 0.2 ( l . D SJ (0.2) WCS. 0.4 3.8 (4.5) RWS 0.2 AW 0.3 0.2 13.9 1.6 BTGW 0.2 RHB 0.3 1.5 DW (0.2) NWC (0.1) (2.0) 7.0 SEO 0.2 CS 0.1 (0.2) (0.6) (31.1) BB 89.6 RBN (0.1) 0.9 RWB (11-8) SVS 0.1 0.3 30.4 LSP 1.9 HT 0.1 0.9 0.3 K (1.3) OSF 0.1 0.2 CSN 1.0 GWG (0.3) RNP (1.0) SS 7.9 6.4 MDK (0.6) BT 6.4 MH (0.3) PSK (5.2) YHB (0.3) WV 2.7 BHG (0.3) TOTAL INDIVIDUALS 411.2 313.6 439.4 655.0 SPECIES PER CENSUS 10.1 9.0 16.4 13.9 TOTAL CENSUSES 16 16 17 13 Figs, i n i t a l i c s : migrants (not i n c l , i n t o t a l s ) ; f i g s , i n brackets: non-breeding v i s i t o r s ( i n c l . i n t o t a l s ) 28 species i n a l l the tables and appendices r e l a t i n g to the Vancouver work. For the convenience of the reader, these symbols are explained i n Appendix I, a foldout sheet immediately preceding Table 1, so that the l i s t of symbols can be consulted simultaneously with the relevant tables and appendices. The nomenclature used by the American O r n i t h o l o g i s t s ' Union (1957) has been followed for both English and s c i e n t i f i c names of b i r d s . In Appendix V, a l l b i r d species recorded on a,census have been l i s t e d , but those seen i n f l i g h t overhead or seen outside the p l o t have been indicated separately, and have not been included i n the t o t a l s . Tables 1 through 4 summarize the numbers of b i r d s recorded on the p l o t s during the breeding season (1 May to 31 J u l y ) . These figures do not represent the numbers of breeding adults, since they also include independent young and ( e s p e c i a l l y i n the case of some species on the Ferguson Road plo t ) post-breeding concentrations of species not breeding on the p l o t . Non-breeding birds c o n s i s t e n t l y or oc c a s i o n a l l y present on the p l o t s ( v i s i t o r s ) are also included i n the t o t a l s , but species judged to be migrants have been omitted. The s i t u a t i o n i s complex, since some species may be migrants on one p l o t , but non-breeding summer v i s i t o r s or even breeders on another p l o t . Table 1 compares breeding-season b i r d populations on each of the p l o t s , averaged over two seasons (mean number of birds per census and mean number per 100 acres). Tables 2 through 4 compare populations i n 1968 and 1969 on three of the p l o t s . (The Ferguson Road pl o t was not censused i n the summer of 1968.) The 1968 figures are much l e s s accurate because of the small number of censuses. 29 Table 2. Mean Numbers and Densities of Breeding-Season Birds on 19th & Yukon p l o t , 1968-1969 Species 1968 1969 Mean for a l l censuses** Mean no. Mean no. Mean no. Density/IOOA HS 68.5(4) 70.8(12) 70.3(16) 159.5 AR 41.8(4) 31.8(12) 34.3(16) 77.9 S 30.3(4) 32.2(12) 31.7(16) 72.0 CP 8.0(4) 11.4(12) 10.6(16) 24.0 BS 11.5(4) 9.4(12) 9.9(16) 22.6 VGS 7.3(4) 7.3(11) 7.3(15) 16.6 HF 10.5(4) 4.4(11) 5.9(15) 13.5 CM 7.3(4) 4.6(12) 5.3(16) 11.9 BCCt 2.3(3) 3.0(10) 2.8(13) 6.4 AG 3.8(4) 1.1 (6) 1.8(10) 4.0 CC 0.8(2) 0.7 (6) 0.7 (8) 1.6 WW* 0.5(1) 0.3 (2) 0.4 (3) 0.-9 cwt 0.5(1) 0.2 0.3 (2) 0.6 ocw* 0.3 (3) 0.3 (3) 0. 6 YW* 0.3(1) 0.3 (1) 0.3 (2) 0. 6 MGW* 0.5(1) 0.2 (1) 0.3 (2) 0.6 CSRt 0.8(1) 0.2 .(1) 0.4 WCS* 0.3 (1) 0. 2l (1) . 0.4 AW* 0.2 (1) 0.1 (1) 0.3 RHB* 0.2 (1) 0.1 (1) 0.3 NWCt 0.1 (1) 0.1 < 1> 0.1 CS* 0.1 (1) 0.1 (1) 0.1 RBNt 0.3(1) o.il (1) 0.1 SVS* 0.1 (1) 0.1 (1) 0.1 RT* 0.1 (1) 0.1 (1) 0.1 OSF* 0.1 (1) 0.1 (1) 0.1 Species per census T o t a l i n d i v i d u a l s No. of counts 11.0 193.2 4 9.8 176.8 12 10.1 181.3 16 411.2 Mean weighted according to number of censuses taken i n each winter. Migrants: not included i n t o t a l (figures i n i t a l i c s ) . Non-breeding v i s i t o r s . ( i n c l u d e d i n t o t a l s ) . Numbers i n parentheses i n "Mean no." column are numbers of counts on which each species was recorded.. 30 Table 3. Mean Numbers and Densities of Breeding-Season Birds on 14th & Spruce p l o t , 1968-1969 Species 1968 1969 Mean for a l l censuses** Mean no. Mean no, Mean no. Density/IOOA HS 44.0(4) 41.3(12) 42.0(16) 105.4 CP 35.5(4) 36.3(12) 36.1(16) 90.7 S 20.5(4) 20.1(12) 20.2(16) 50.7 AR 11.5(4) 9.4(12) 9.9(16) 24.9 VGS 3.5(4) 5.3(H) 4.8(15) 12.1 CM 5.0(4) 4.3(12) 4.5(16) 11.3 BS 2.3(4) 3.0(12) 2.8(16) 7.1 HF 2.3(3) 2.3 (9) 2.3(12) 5.8 BCCt 0.5(1) 0.9 (6) 0.8 (7) 2.0 NWCt 1.0(3) 0.8 (4) 0.8 (7) 2.0 AGt 1.3(2) 0.2 (2) 0.4 (4) 1.1 GWGt 0.2 (2) 0.1 (2) 0.3 WW* 0.2 (2) 0.1 (2) 0.3 est 0.1 (1) 0.1 (1) 0.2 OCW* 0.1 (1) 0.1 (1) 0.1 MGW* 0.3(1) 0.1 (1) 0.2 YW* 0.1 (1) 0.1 (1) 0.2 CSR* 0.1 (1) 0.1 (1) 0.2 AW* 0.1 (1) 0.1 (1) 0.2 Species per census 9.3 8.9 9.0 Tota l i n d i v i d u a l s 127.3 124.1 124.8 313.6 No. of counts 4 12 16 Mean weighted according to number of censuses taken i n each winter. *Migrants: not.included i n t o t a l (figures i n i t a l i c s ) . tNon-breeding v i s i t o r s (included i n t o t a l s ) . Numbers i n parentheses i n "Mean no." column are numbers of counts on which each species was recorded. 31 Table 4. Mean Numbers and Densities of Breeding-Season Birds on 43rd & C h u r c h i l l p l o t , 1968-1969 Species 1968 1969 Mean f o r a l l censuses** Mean no. Mean no. Mean No. Density/100A AR 77.8(4) 64.9(13) 67.9(17) 173.1 S 33.0(4) 13.2(13) 17.9(17) 45.6 HF 16.8(4) 15.2(13) 15,6(17) 39.7 HS 18.3(4) 14.8(13) 15.6(17) 39.7 BCC 17.8(4) 13,6(13) 14.6(17) 37.2 BS 4,3(4) 8.6(13) . 7.6(17) 19.3 AW* 7,2 (2) 5.5 (2) 13.,9 AG 4.8(4) 5.2(13) 5,1(17) 13.0 VGS 4,8(4) 4.9(13) 4.9(17) 12.4 SS 5 . 6(4) 2,5(13) 3.1(17) 7.9 CM 2.3(4) 3,1(13) 2.9(17) 7.3 NWC 1.0(2) 3.3(11) 2.8(13) 7.0 BT 0.5(2) 3.2 (7) 2.5 (9) 6.4 CC 2.8(3) 2.2(11) 2.4(14) 6.0 PSKt 4,5(4) 1,3 (7) 2.1(11) 5.2 WW* 2,2 (4) 1,7 (4) 4.3 WCS* 1.9 (2) 1. 5 (2) 3.8 WV 1.0(3) 1.1 (7) 1.1(10) 2.7 BTPt 1,0(3) 1,1 (5) 1.1 (8) 2.7 OCW* 1.3 (6) 1.0 (6) 2.6 RCK* 1.3 (2) 1.0 (2) 2,6 GCK 1.2 (6) 0.9 (6) 2.3 GCS* 1.2 (2) 0.9 (2) 2.3 CW+ 2,8(1) 0.2 (1) 0.8 (2) 2.0 EG+ 2.3(1) 0.2 (1) 0.6 (2) 1.7 WTf 0.5(1) 0.6 (5) 0.6 (6) 1.5 RHB* 0.8 (2) 0. 6 (2) 1.5 MW* 0. 7 (1) 0.5 (1) 1.4 PFf '. 0,6 (4) 0.5 (4) 1.2 ^CSRT 0.8(2) 0.3 (4) 0.4 (6) 1.1 YW* 0,5 (3) 0.4 (3) 1,1 FS* 0. 5 (1) 0.4 (1) 1.1 RBN 0.5 (5) 0.4 (5) 0.9 CPt 0.8(2) 0.2 (2) 0.4 (4) 0.9 HT* 0.5 (2) 0,4 (2) 0.9 est 0.5(1) 0.2 (2) 0.2 (3) 0.6 WWP* 0.3(1) 0.2 (2) 0,2 (3) 0.5 32 (Table 4 - concluded) Species 1968 1969 Mean for a l l censuses** Mean no. Mean no. Mean no. Density/IOOA MGW* ••0.2 (3) 0.2 (3) 0.5 WF* 0.2 (2) 0.2 (2) 0.5 OJ* 0,2 (1) 0.1 (1) 0.3 SVS* 0. 2 (1) 0.1 (1) 0.3 TW* 0.2 (1) 0.1 (1) 0.3 RSFf 0.1 (1) 0,1 (1) - 0.2 -BCt 0.1 (1) 0.1 (1) 0.2 BWRt 0.3(1) 0.1 (1) 0.2 SJt 0.3(1) 0.1 (1) 0.2 RWS* 0.1 (1) 0,1 (1) 0.2 BTGW* 0.1 (1) OA (1) 0.2 DWt 0.1 (1) 0.1 (1) 0.2 OSF* 0,1 (1) Oo 1 (1) 0.2 SEO* 0.1 (1) 0.1 (1) 0.2 Species per census 16.8 16.2 16.4 T o t a l i n d i v i d u a l s 203.2 162.1 172.5 439.4 No, of counts 4 13 17 Mean weighted according to number of censuses taken i n each winter. *Migrants: not included i n t o t a l (figures i n i t a l i c s ) . •^Non-breeding v i s i t o r s (included i n t o t a l s ) . Numbers i n parentheses i n "Mean no." column are numbers of counts on which each species was recorded. 33 Tables 5, 6, and 7 compare estimated numbers of t e r r i t o r i a l males (most of which represent breeding pai r s ) on the four plots i n both seasons, i n 1968, and i n 1969, r e s p e c t i v e l y . Non-breeders are excluded. These figures were arrived at from the t o t a l number of b i r d s recorded, the numbers of singing males, and the numbers of nests located. These are the figures usually quoted i n the l i t e r a t u r e as "breeding d e n s i t i e s . " It i s necessary to explain why breeding populations and breeding-season populations on the pl o t s have been computed separately. This i s because o r n i t h o l o g i s t s have usually presented r e s u l t s of breeding b i r d censuses and winter b i r d censuses i n fundamentally d i f f e r e n t ways. The breeding populations are needed for comparison with the r e s u l t s of other studies i n North America, Europe, and elsewhere. But breeding-season populations ( i . e . , i n c l u d i n g non-breeding v i s i t o r s as well as breeders) are needed to make a f a i r comparison of breeding and winter b i r d popula-t i o n s ; that i s , we need a measure of breeding populations which i s c a l c u -lated i n p r e c i s e l y the same way as are wintering populations. Tables 8 through 12 give mean numbers and d e n s i t i e s of wintering b i r d s on the pl o t s i n the same way that Tables 1 through 4 do for breeding-season b i r d s . The winter season i s considered to be from 1 November to 28 (29) February. It seems poin t l e s s to d i s t i n g u i s h winter "residents" on the pl o t s from winter " v i s i t o r s , " since no wintering b i r d i s attached to a p a r t i c u l a r area i n the way that a . t e r r i t o r i a l breeding b i r d i s . Tables 13 and 14 summarize the occurrence of transient birds on the pl o t s i n spring and autumn migration, r e s p e c t i v e l y . To a r r i v e at 34 Table 5. Breeding b i r d populations on Vancouver study p l o t s , means for 1968-1969 combined, expressed as pairs per 100 acres Species 19th & 14th & 43rd & ... , Ferguson code Yukon Spruce C h u r c h i l l Road HS 50.0 43.9 16.6 33.3 AR 42.0 18.8 71o3 33.3 S 35.2 40.2 28.0 33,3 CP 15.9 42.7 BS 11.4 3.8 10.2 41.6 CM 7.9 7.5 2.5 present VGS 7.9 7.5 7.6 HF 4.5 2.5 22.9 AG 1.1 7.6 CC** 1.8 6.4 15.0 BCC 14.0 SS 7.6 8.3 WV 2.5 NWC 1„3 GCK 1.3 RBN present BB 25.0 SVS 20.8 BT 1.3 To t a l pairs 176.0 166.9 194.9 195.5 Breeding species (mean f o r 2 seasons) 9.5 8 14 9 Mean number of b i r d s , not breeding p a i r s , per census; not included i n t o t a l . Ferguson Road was censused i n 1969 only. 35 Table 6. Breeding b i r d populations on Vancouver study plo t s i n 1968, expressed as pairs per p l o t Species code 19 th & Yukon 14 th & Spruce 43rd & C h u r c h i l l HS 21 18 7 AR 21 8 31 S 15 16 12 CP 7 17 BS 5 1 3 CM 4 3 1 VGS 3 2 3 HF 2 1 10 AG 1 3 CC** 0.8 2.8 BCC 6 SS 4 WV 1 BT 1 T o t a l p a i r s 79 66 82 Breeding species 10 8 13 ** Mean number of b i r d s , not breeding pa i r s , per census; not included i n t o t a l . 36 Table 7. Breeding b i r d populations on Vancouver study p l o t s . i n 1969, expressed as pai r s per plo t Species code 19 th & Yukon 14 th & Spruce 43rd & C h u r c h i l l Ferguson Road HS ,-23 17 6 8 AR 16 7 25 8 S 16 16 10 8 CP 7 17 BS 5 2 5 10 CM 3 3 1 present VGS 4 4 3 HF 2 1 8 AG 3 CC** 0.7 2.2 3.6 BCC 5 SS 2 2 WV 1 NWC 1 GCK 1 RBN present BB 6 SVS 5 T o t a l p a i r s 76 67 71 47 Breeding species 9 8 15 9 ** Mean number of b i r d s , not breeding p a i r s , per census; not included i n t o t a l . 37 these f i g u r e s , I have simply used the migration periods for a l l b i r d species (spring migration, 16 March to 7 Junes; autumn migration, 11 August to 30 November) and divided the t o t a l recorded number of migrants of each species by the number of censuses during the migration period. Densities per 100 acres are also given. In f a c t , most species have mig-r a t i o n periods much shorter than those given above, and the numbers of birds to be expected during t h e i r migration periods are much higher than those shown i n Tables 13 and 14. Since nearly a l l the species i n these tables e i t h e r breed or winter somewhere i n the Vancouver area, the , decision as to which species are migrants has been rather a r b i t r a r y . I have included only those species which occurred on the study plots c h i e f l y o r , e x c l u s i v e l y during the migration periods outlined above. The dates of the Sacramento b i r d censuses, with times and associated weather conditions, are l i s t e d i n Appendix XV. The census re s u l t s themselves are given i n Appendix XIV, and are summarized i n Table 16. In a s i m i l a r way, data for the Ottawa censuses are given,in Appendix XX, Appendix XIX, and Table 17, r e s p e c t i v e l y . (a) Density The four Vancouver p l o t s . d i f f e r e d l i t t l e among themselves i n the t o t a l density of breeding b i r d s (see Table 5). The range of densities was only from 167 to 196 males per 100 acres. The highest density was on the Ferguson Road p l o t , but the.figures on t h i s p l o t are probably exagger-ated because of the s t r i p - l i k e shape of the p l o t . Ignoring the.Ferguson Road p l o t , the highest density (195 males per 100 acres) was on the 43rd 38 and C h u r c h i l l p l o t , the p l o t which most resembled a f o r e s t . The lowest density (167 males per 100 acres) was on the most urbanized p l o t , the 14th and Spruce p l o t . My observations i n commercial d i s t r i c t s of Vancouver suggest that breeding b i r d d e n s i t i e s there are lower s t i l l . Breeding-season densities on.the Vancouver plots (Table 1) show greater divergence than breeding d e n s i t i e s . The 14th and Spruce pl o t had a much lower density (314 birds per 100 acres) than the,other three; and the Ferguson Road plot had much the highest density (657 birds per 100 acres). The high density on the Ferguson Road pl o t was la r g e l y the re s u l t of post-breeding concentrations (in l a t e June and July) of House Sparrows, House Finches, S t a r l i n g s , Brewer's Blackbirds, Barn Swallows, C l i f f Swallows, Brown-headed Cowbirds, Red-winged Blackbirds, and Violet-green Swallows (see Appendix V). The differences among the Vancouver plots i n density of winter birds are much more s t r i k i n g than those of breeding birds (see Tables 8 and 15). The three plots with most t r e e s — 4 3 r d and C h u r c h i l l , 33rd and Dunbar, and 22nd and Dunbar—had the lowest de n s i t i e s (319, 303, and 186 birds per 100 acres, r e s p e c t i v e l y ) . This i s the reverse of the pattern i n summer, when the well-wooded pl o t had the highest density. The very low d e n s i t i e s of b i r d s , p a r t i c u l a r l y of House Sparrows, on the 22nd and Dunbar p l o t were somewhat anomalous, since t h i s p l o t i s the le a s t w e l l -wooded of the three. The high winter density on the 19th and Yukon p l o t (501 birds per 100 acres) was mainly due to large S t a r l i n g f l o c k s , while the even higher density on the Ferguson Road pl o t (1021 birds per 100 acres) was c h i e f l y because of flocks of both S t a r l i n g s and Brewer's Table 8. Mean densities of winter birds on Vancouver study p l o t s , 1968-1970 (means for three winters combined) expressed as bi r d s per 100 acres Species 19 th & 14 th & 43rd & Ferguson Species 19 th & 14th & 43rd & Ferguson code , Yukon Spruce C h u r c h i l l Road code Yukon Spruce C h u r c h i l l Road S 249.0 96.2 31.5 464.0 SJ 1.2 HS 146.7 133.8 26.8 128.2 BC 1.1 OJ 27.4 16.4 102.8 1.0 FS 0.3 0.3 CP 26.8 69.0 1.1 11.4 EG 0.2 0.8 CM 17.3 17.3 1.2 55.1 CH 0.2 0.3 HF 7.7 8.9 32.4 13.3 SSH 0.2 0.3 GWG 6.9 15.5 2.9 NS 0.2 0.8 SS 6.7 4.4 16.8 21.1 WWRt 0.2 AR* 5.2 2.2 15.1 41.9 MG 60.1 BCC 4.1 1,2 34.2 1.8 WCS 24.4 NWC 1.6 3.6 2.1 RWB 21.1 RSF 1.1 0.1 3.2 RNP 1.6 BTPt 0.3 0.2 CSN 1.3 BBt 0.3 148.2 GCS 1.0 PSK 0.8 3.5 RLH 0.8 CRP 0.3 5.4 GBH 0.8 AG 0.1 1.2 HG 0.5 DW 0.1 0.2 BWR 0.5 BT 14.8 MH 0.3 GCK 6.9 PH 0.3 PF 6.3 14.8 BE 0.3 VT 3.6 ACT 0.3 RCK 2.4 AWt 0.3 CBC 1.8 ST 1.5 1.8 RBN 1.4 SPECIES PER CENSUS 9.9 9.2 13.6 11.8 TOTAL INDIVIDUALS 500.5 369.7 319.0 1021.0 NUMBER OF CENSUSES 20 19 17 16 * Robin counts a f t e r 14 February have not been included, since migrants begin a r r i v i n g then (except for Ferguson Road—see text), t Migrants: not included i n t o t a l s (except f o r Brewer's Blackbirds on Ferguson Road). 40 Blackbirds. The density on the l a t t e r p l o t , however, was c e r t a i n l y i n -f l a t e d , since large S t a r l i n g and blackbird flocks would often perch on the telephone wires along the road whenever they were frightened up from the , f i e l d s . Winter b i r d populations i n Ottawa (Table 17) were much lower than i n Vancouver. The well-wooded R o c k c l i f f e Park p l o t had a density of 141 birds per 100 acres, while Erskine's study area i n B e l - A i r Heights and Copeland Park had a density of only 119 birds per 100 acres. The high density of b i r d s on the A l t a V i s t a p l o t (344 b i r d s per 100 acres) was probably not t y p i c a l of the habitat; an u n i d e n t i f i e d (but undoubtedly a r t i f i c i a l ) food source consistently attracted large flocks of S t a r l i n g s and Rock Doves to one part of the p l o t . The dependence of b i r d s on bird-feeders i n Ottawa was very con-spicuous (see also Erskine, 1970a); most b i r d s , e s p e c i a l l y Evening Gros-. beaks and Common Redpolls, were concentrated around feeders. In contrast, the only species notably concentrated around feeders i n Vancouver was the House Finch. However, the p o t e n t i a l importance of feeders i n hard weather was emphasized by the cold snap and snow of December 1968 and January 1969 i n Vancouver. Flocks of 40 or 50 S t a r l i n g s , which had not been seen i n the area previously, began using the feeders at my home i n North Vancouver, and numbers of other birds at the feeders increased sharply. The same pattern was evident on the census p l o t s , and persisted u n t i l the snow began to melt i n early February. The d e n s i t i e s of winter birds i n Sacramento were unexpectedly low: 203 b i r d s per 100 acres on the F and.21st p l o t , and 159 birds per 41 Table 9. Mean Numbers and Densities of Winter Birds on 19th & Yukon p l o t , 1968-1970 Species Jan-Feb 1968 1968-1969 1969-1970 Mean for a l l censuses Mean no. Mean no. Mean no. Mean no. Density/IOOA s 144.3(3) 128.5(8) 81.3(9) 109.7(20) 249.0 HS 43.7(3) 75.9(8) 61.6(9) 64.6(20) 146.7 OJ 7.7(3) 14.4(8) 11.4(9) 12.1(20) 27.4 CP 17.3(3) 9.1(8) 12.3(9) 11.8(20) 26.8 CM 19.0(3) 6.4(8) 4.9(7) 7.6(18) 17.3 HF 4.3(3) 4.8(5) 1,9(6) 3.4(14) 7.7 GWG 2.7(3) 3.6(8) 2.7(7) 3.1(18) 6.9 SS 4.7(3) 1.8(8) 3,4(9) 3.0(20) 6.7 AR* 5.0(3) 3.6(8) 0.7(4) 2.3(15) 5.2 BCC 1.0(2) 1.5(5) 2.3(9) 1.8(16) 4.1 NWC 0.3(1) 1.3(5) 0.3(1) 0.7 (7) 1.6 RSF 0.7(2) 0.6(4) 0.3(2) 0.5 (8) 1.1 BTPt 0.3(1) 0.2 (1) 0.3 BBt 0.3(1) 0.2 (1) 0.3 Species per census 10.7 10.4 9.2 9.9 T o t a l i n d i v i d u a l s 250.7 251.3 183.9 220.3 500.5 Number of censuses 3 8 9 20 Numbers i n p "which each arentheses i n species was "Mean no," recorded. column are numbers of counts on Robin counts a f t e r 14 February have not been included, since migrants begin a r r i v i n g then. Migrants: not included i n t o t a l s . 42 Table 10. Mean Numbers and Densities of Winter Birds on 14th & Spruce p l o t , 1968-1970 Species Jan-Feb 1968 1968-1969 1969-1970 Mean for a l l censuses Mean no. Mean no. Mean no. Mean no. Density/IOOA HS 36.0(2) 46.3(8) 63.4(9) 53.3(19) 133.8 S 18.5(2) 45.8(8) 36.1(9) 38.3(19) 96.2 CP 28.0(2) 21.9(8) 32.3(9) 27.5(19) 69.0 CM 1.0(1) 8.9(8) 6.4(9) 6.9(18) 17.3 OJ 2.0(1) 7.4(7) 6.8(9) 6.5(17) 16.4 GWG 8.5(2) 6.3(8) 5.6(9) 6.2(19) 15.5 HF 2.5(2) 4.0(6) 3.3(6) 3.5(14) 8.9 SS 2.5(2) 1.0(6) 2.2(9) 1.7(17) 4.4 NWC 1.4(4) 1.8(6) 1.4(10) 3.6 AR* 1.5(2) 1.6(6) 0.2(2) 1.0(10) 2.2 BCC 1.0(7) 0.5 (7) 1.2 PSK 0.7(1) 0.3 (1) 0.8 CRP 0.2(1) 0.1 (1) 0.3 RSF 0.5(1) 0.1 (1) 0.1 AG 0.1(1) 0.1 (1) 0.1 DW o . K D 0.1 (1) 0.1 Species per census 8.5 8.8 9.7 9.2 To t a l i n d i v i d u a l s 101.0 144.5 160.2 147.4 369.7 Number of censuses 2 8 9 19 Numbers i n parentheses i n "Mean no." column are numbers of counts on which each species was recorded. Robin counts a f t e r 14 February have not been included, since migrants begin a r r i v i n g then. 43 Table 11. Mean numbers and densities of winter birds on 43rd & C h u r c h i l l p l o t , 1968-1970 Species Feb. 1968 1968-1969 1969-1970 Mean for a l l censuses Mean no. Mean no. Mean no. Mean no. Density/IOOA OJ 53 46.3(7) 34,3(9) 40.4(17) 102.8 BCC 8 11.7(7) 15.3(9) 13.4(17) 34.2 HF 18 11.7(6) 12,9(9) 12.7(16) 32.4 S 53 15.9(5) 5.1(7) 12.4(13) 31.5 HS 8 6.0(7) 14.3(9) 10.5(17) 26.8 SS 7 4.9(7) 7.9(9) 6.6(17) 16.8 AR* (17) 6.7(7) 5.4(9) 5.9(17) 15.1 BT 12 3.7(2) 6.8(4) 5.8 (7) 14.8 GCK 6 5.7(6) 2.7 (7) 6.9 PF 4 2.3(4) 2.4(6) 2.5(11) 6.3 CRP 5.0(2) 0.1(1) 2.1 (3) 5.4 VT 13 1.1(5) 0.3(2) 1.4 (8) 3.6 PSK 0.9(3) 1,9(3) 1.4 (6) 3.5 RSF 3 1,4(6) 0.9(7) 1,2(14) 3.2 RCK 1.3(6) 0.8(6) 0.9(12) 2.4 NWC 1.3(2) 0.6(2) 0.8 (4) 2.1 CBC 1.3(7) 0.7 (7) 1.8 ST 0.4(2) 0.8(4) 0.6 (6) 1.5 RBN 1,0(5) 0,5 (5) 1.4 SJ 1 0.8(4) 0.5 (5) 1.2 CM 0.9(3) 0.2(1) 0.5 (4) 1.2 AG 1.1(2) 0.5 (2) 1,2 BC 0.8(5) 0.4 (5) 1.1 CP 0.6(2) 0,3(1) 0.4 (3) 1.1 FS , 2 0.1 (1) 0.3 EG 0.1(1) 0.1 (1) 0.2 pw 0.1(1) 0.1 (1) 0.2 CH 0.1(1) 0.1 (1) 0.2 SSH 0.1(1) o;i (1) 0.2 NS 0.1(1) 0.1 (1) 0.2 BTPt 0.1(1) 0.1 (1) 0.2 WWRt 0.1(1) 0.1 (1) 0.2 Species per census 14 13.4 13.7 13.6 To t a l i n d i v i d u a l s (205) 129.1 114.8 125.1 319.0 Number of censuses 1 7 9 17 Numbers i n parentheses i n "Mean no." column are numbers of counts on which each species was recorded.. Robin counts a f t e r 14 February have not been included, since migrants begin a r r i v i n g then. Migrants: not included i n t o t a l s . 44 Table 12. Mean numbers and den s i t i e s " o f winter birds on Ferguson Road p l o t , 1968-1970 Species 1968-1969 1969-1970 Mean for a l l censuses Mean no, Mean no. Mean no. Density/IOOA s 90.0(6) 124.4(10) 111.5(16) 464.0 BB 32.5(6) 37,5 (9) 35.6(15) 148.2 HS 37.5(6) 26,8(10) 30.8(16) 128.2 MG 23.1 (3) 14.4 (3) 60.1 CM 10.0(6) 15.2 (8) 13.3(14) 55.1 AR 15.7(5) 6.7 (8) 10.1(13) 41.9 WCS 3.3(5) 7.4 (9) 5.9(14) 24.4 SS 4.0(6) 5.7(10) 5.1(16) 21.1 RWB 1.2(3) 7.4 (5) 5.1 (8) 21.1 PF 7.8(3) 1.0 (5) 3.6 (8) 14.8 HF 5.0(5) 2.1 (6) 3.2(11) 13.3 CP 1.5(3) 3.5 (8) 2.8(11) 11.4 GWG 0,3(1) 0.9 (7) 0.7 (8) 2.9 BCC 0.2(1) 0.6 (4) 0.4 (5) 1.8 ST 0.7 (3) 0.4 (3) 1.8 RNP 0.7(1) 0.2 (1) 0.4 (2) 1.6 CSN 0.5 (2) 0.3 (2) 1.3 GCS 0.4 (4) 0.3 (4) 1.0 OJ 0.4 (4) 0.3 (1) 1.0 NS 0.2(1) 0,2 (2) 0,2 (3) 0.8 RLH 0.2(1) 0.2 (1) 0,2 (2) 0.8 GBH 0.2(1) 0.2 (1) 0.2 (2) 0.8 EG 0.3 (1) 0.2 (1) 0.8 HG 0.2 (1) 0.1 (1) 0.5 BWR 0.3(2) 0.1 (1) 0.5 FS 0,1 (1) 0.1 (1) 0,3 CH 0.1 (1) 0,1 (1) 0.3 SSH 0.1 (1) 0,1 (1) 0.3 MH 0.2(1) 0.1 (1) 0.3 PH 0.1 (1) 0.1 (1) 0.3 BE 0.1 (1) 0.1 (1) 0.3 ACT 0.2(1) 0.1 (1) 0.3 AWt 0.2(1) 0.1 (1) 0.3 Species per census 10.8 12.4 11.8 T o t a l i n d i v i d u a l s 210.8 266,1 245.3 1021.0 Number of censuses 6 10 16 Numbers i n parentheses i n "Mean no." column are numbers of counts on which each species was recorded. Migrants: not included i n t o t a l s . 45 100 acres on the S and 24th p l o t . Nevertheless, observations by the wri t e r , as w e l l as Christmas B i r d Counts (Audubon F i e l d Notes 24:452-453, 23:422, etc.) ind i c a t e that numbers of many b i r d species present i n the c i t y (e.g., S t a r l i n g s , White-crowned Sparrows, and Oregon Juncos) were very high i n the a g r i c u l t u r a l lands around the c i t y . The low dens i t i e s of House Sparrows and Starl i n g s i n Sacramento were p a r t i c u l a r l y sur-p r i s i n g . A comparison of wintering populations with breeding-season pop-ulations i s possible only f o r the Vancouver p l o t s . Noteworthy i s the fa c t that three of the four plots had higher populations i n winter than i n summer (19th and Yukon p l o t , 501 versus 411 birds per 100 acres; 14th and Spruce p l o t , 370 vs. 314; and Ferguson Road p l o t , 1021 vs. 657). The only exception was the 43rd and C h u r c h i l l p l o t (319 vs. 438 birds per 100 acres). The higher winter de n s i t i e s are accounted for la r g e l y by the huge i n f l u x of St a r l i n g s into the Vancouver area i n winter. There were large differences among the plot s i n the de n s i t i e s of migrant b i r d s , both spring and autumn. In spring (16 March to 7 June), the mean density of migrants was 127 birds per 100 acres on the Ferguson Road p l o t ; 110 per 100 acres on the 43rd and C h u r c h i l l p l o t ; 26 per 100 acres on the 19th and Yukon p l o t ; and 8 per 100 acres on the 14th and Spruce p l o t . Migrants made up 23.9% of the t o t a l b i r d population during the spring migration season on the Ferguson Road p l o t , and 21.8% on the 43rd and C h u r c h i l l p l o t , but only 2.5% on the 14th and Spruce p l o t . In autumn, migrants were less abundant. The mean density of autumn migrants was 40 per 100 acres on the 19th and Yukon p l o t ; 35 per 46 Table 13. Index to abundance of migrant b i r d s on Vancouver study plots i n spring (.16 March-7 June) expressed as birds per 100 acres Species 19 th & 14th & 43rd & Ferguson code Yukon Spruce C h u r c h i l l Road SH 0.2. LSP 2.5 BTP 26.8 3.7 SEO 0.2 RHB 1.9 0.4 3.5 0.8 WF 0.6 WWP 0.6 OSF 0.2 0.2 VGS 26,2 TSL 2.1 RWS 0.2 CS 0.2 0.4 VT 1.1 0,2 3,3 HT 0.9 2.0 0.4 TS 0,2 GCK 0.2 0,2 8,4 0.4 RCK 4.9 1.4 10.0 0.8 wv 2.2 ocw 0.8 0.4 4.7 0.4 YW 0.8 0.2 1.4 1.2 MW 3.3 AW 1.5 0.4 18,6 2.5 BTGW 0.2 TW 0.4 0.4 MGW 0,8 0,2 0.6 WW 1.1 0.4 5.7 1.2 WT 1.0 0.4 PF 0.2 SVS 0.4 0.4 53.2 CSR 0.2 1,2 WCS 10.4 3,3 5.9 23.3 GCS 0.8 5.7 7.1 FS 2,4 WWR 0.2 Number of censuses 12 13 13 10 47 Table 14. Index to abundance of migrant birds on Vancouver study pl o t s i n f a l l (11 August-30 November) ex-pressed as birds per 100 acres Species 19 th & 14th & 43rd & Ferguson code Yukon Spruce C h u r c h i l l Road PH 0.2 BTP 15.9 4.1 CNH 0.2 VSW 0.3 RHB 0.5 YBS 0.2 WF 0.2 WWP 0.8 OSF 0.3 VGS 0.4 CS 0.3 VT 0.8 0.2 1.7 HT 0.3 0.2 GCK 1.2 0.2 9.0 RCK 0.2 0.2 2.4 AP 0.2 WV 0.2 0.8 OCW 5.0 1.2 2.9 0.8 YW 1.1 0.7 2.0 1.1 MW 0.2 0.2 AW 3.2 1.3 1.5 0.8 BTGW 0.3 0.2 0.5 MGW 0.2 0.3 YT 0.2 0.4 WW 0.3 0.2 1.2 WT 0.1 2.0 BHG 0.2 SVS 0.3 0.3 16.6 CSR 0.2 WCS 7.3 2.0 1.5 12.9 GCS 2.0 0.5 0.5 FS 0.2 0.5 0.4 RBN 0.3 0.4 WWR 0.5 BB 0.5 Number of censuses 15 15 15 11 48 100 acres on the 43rd and C h u r c h i l l p l o t ; 34 per 100 acres on the Ferguson Road p l o t ; and 7 per 100 acres on the 14th and Spruce p l o t . Migrants comprised 9.0% of the t o t a l b i r d population during the autumn migration on the 43rd and C h u r c h i l l p l o t , and 8.1% on the 19th and Yukon p l o t , but only 1.7% on the 14th and Spruce p l o t . Contrary to the impression given by the data, migrants are probably more numerous, not scarcer, i n autumn than i n spring, since young of the year are also migrating i n autumn. This apparent discrep-ancy i s probably a r e s u l t of the censusing schedule. Censuses were conducted weekly during the spring, but only biweekly i n autumn. Migra-t i o n tends to occur i n waves, with sharp day-to-day fl u c t u a t i o n s i n the number of migrants present i n any one area. Numerous migration waves occurred during the spring censuses: examples are the 70 Band-tailed Pigeons,on the 43rd and C h u r c h i l l p l o t , 8 A p r i l 1969; the 47 V i o l e t -green Swallows on the Ferguson Road p l o t , 10 A p r i l 1969; the 49 White-crowned Sparrows on the 19th and Yukon p l o t , 28 A p r i l 1969; and the 92 Audubon's Warblers on the 43rd and C h u r c h i l l p l o t , 1 May 1969 (see Appendix V). In autumn, most such waves probably occurred between censuses, and the numbers of migrants were thus underestimated. On the Ferguson Road p l o t , the commonest migrants were open-country species l i k e Savannah Sparrows and Violet-green Swallows. However, i n the three census p l o t s i n th e , c i t y of Vancouver, most,of the common migrants were forest or forest-edge species, and they appeared to prefer well-wooded areas even i n migration. This seems to be the chief reason for the d i f f e r e n c e between the 43rd and C h u r c h i l l p l o t , where 49 Table 15. Mean densities of winter birds on Shepard's Vancouver study p l o t s , expressed as birds per 100 acres Species code 22nd & Dunbar 33rd & Dunbar OJ 43.6 89.8 HS 40.2 59.9 HF 10.6 56.2 BCC 10.6 37.0 S 32.0 6.2 AR** 2.1 5.8 SS 13.2 12.0 ST 10.6 1.6 PSK 1.6 10.4 CP 10.3 0.5 PF 4.2 3.1 BT 0.3 5.2 RC 3.9 SJ 3.4 CBC 3.4 RSF 1.6 1.3 GWG 1.8 0.5 CRP 1.3 WCS 1.1 DW 0.5 0.3 CM 0.8 EG 0.3 0.5 RBN 0.5 GCK 0.5 RCK 0.3 Total i n d i v i d u a l s 185.6 303.3 Species per census (mean) 10.6 10.6 Number of censuses 8 8 Robin counts a f t e r 14 February have not been included since migrants begin a r r i v i n g then. 50 Table 16. Mean dens i t i e s of birds on Sacramento study plots (winter 1970), expressed as birds per 100 acres Species F & 21st S & 24th House Sparrow 69.1 35.7 American Goldfinch 42.1 16.1 S t a r l i n g 31.7 24.2 Oregon Junco 18.4 16.7 Scrub Jay 10.4 12.7 White-crowned Sparrow 9.8 14.4 Common Crow 9.8 1.7 American Robin 2.9 4.0 Pine S i s k i n 2.9 Red-shafted F l i c k e r 1.7 1.2 Audubon's Warbler 1.7 1.7 Red-breasted Nuthatch 1.7 Mockingbird 1.2 3.5 Rock Dove 24.8 Sparrow Hawk 1.2 Rufous-sided Towhee 0.6 Tota l i n d i v i d u a l s 203.4 158.5 Species per census (mean) 9.0 9.2 Number of censuses 5 5 51 Table 17. Mean dens i t i e s of birds on Ottawa study plots (winter 1970), expressed as birds per 100 acres Species R o c k c l i f f e Park A l t a V i s t a B e l - A i r Heights, Copeland Park (Erskine,1970) Evening Grosbeak 66.3 70.3 9.4 Common Redpoll 24.0 33.6 13.3 House Sparrow 21.9 56.3 81.4 Black-capped Chickadee 12.0 1.2 0.2 Rock Dove 8.4 45.6 0.4 White-breasted Nuthatch 2.2 0.2 Boreal Chickadee 1.5 Downy Woodpecker 1.1 Red-breasted Nuthatch 1.1 Common Crow 0.7 1.0 0.1 Pine Grosbeak 0.7 S t a r l i n g 0.4 112.3 14.3 Black-backed three-toed Woodpecker 0.4 Bohemian Waxwing 10.4 Blue Jay 0.7 Ring-necked Pheasant 0.5 Gray Partridge 0.2 Northern Shrike 0.1 T o t a l i n d i v i d u a l s 140.6 332.1 119.2 Species per census (mean) 8.8 7.8 4.7 Number of censuses 4 4 several 52 Table 18. Mean density, number of species, and percentage introduced species i n d i f f e r e n t habitats i n North America i n the breeding season (Based on breeding b i r d census, Audubon F i e l d Notes volumes 22-24, supplemented by Erskine, 1971) Habitat Sample Density: s i z e males per 100 acres Number of species % introduced birds deciduous forest n=42 258 (110-907) v .;.24,j6 (10-46) 0.3 coniferous forest n=58 193 (34-562) 19.2 (9-34) 0 mixed forest n-18 207 (114-364) 21.9 (13-39) 0 bog n=4 64 (8-122) 12.0 (8-19) 0 woodland n=5 152 (60-195) 18.0 (12-23) 0 deciduous shrubbery n=ll 196 (50-395) 20.2 (12-38) 0 desert n=3 85 (39-120) 16.7 (14-22) 0 grassland, crops n=25 81 (15-168) 5.3 (3-9) 0 tundra n = l l 13 (1-24) not given 0 marsh n=8 350 (106-832) 12.0 (8-22) 0 urban n=l 218 8.0 43.5 edge n=59 245 (12-624) 23.7 (7-58) 5.7 In each case the mean i s given followed by extremes i n brackets. 53 Table 19. Mean density, number of species, and percentage introduced species i n d i f f e r e n t habitats i n North America i n winter (Based .on,.winter>b-lr'd^..population study, Audubon Field-Notes=s»vplumes 22-24) Sample Density: Number of % introduced Habitat i n d i v i d u a l s species birds per 100 acres deciduous f o r e s t n=13 151 (18-377) 19.3 (4-33) 1.1 (0-8.0) coniferous forest n=6 188 (56-390) 15.8 (10-25) 0 mixed forest n=6 340 (50-1616) 20.7 (10-43) 0 woodland n=6 340 (42-630) 34.0 (12-46) 0.1 (0-0.3) deciduous shrubbery n=4 229 (111-370) 21.8 (18-31) 2.5 (0-9.8) desert n=3 218 (63-438) 15.3 (14-17) 0 grassland, crops n=9 240 (16-670) 14.9 (5-33) 32.3 (0-87.5) urban n=3 182 (92-336) 8.3 (7-9) 80.4 (73.8-87.0) edge n=39 254 (9-843) 22.3 (5-46) 12.5 (0-48.2) In each case the mean i s given followed by the extremes i n brackets. 54 migrants were con s i s t e n t l y common, and the 14th and Spruce p l o t , where they were consistently scarce. F i n a l l y , noteworthy e f f e c t s on density of birds resulted from unusual weather conditions i n at l e a s t two cases,. In the f i r s t case, the aforementioned cold snap of l a t e January, 1969, i n f l u x e s of House Finches into the 19th and Yukon and 43rd and C h u r c h i l l p l o t s , and of S t a r l i n g s into the 14th and Spruce and 43rd and C h u r c h i l l p l o t s , were observed. An apparent exodus of Rock Doves from the 14th and Spruce p l o t also occurred. In the second case, the cool, wet spring i n 1969 caused a delay i n the occupation of Robin t e r r i t o r i e s i n the three c i t y p l o t s ; breeding d e n s i t i e s were not reached u n t i l mid-April, and large numbers of Robins remained well into A p r i l on the Ferguson Road p l o t , a favourable feeding area. (b) D i v e r s i t y The d i v e r s i t y of avian communities can be quantified i n several ways. Species r i c h n e s s — t h e number of species present i n an area (or the number of breeding species, i n the case of a breeding c e n s u s ) — i s the simplest way of expressing d i v e r s i t y . A more useful measure, which takes into account the r e l a t i v e abundance of species as well as the number of species, i s the information-theory index of d i v e r s i t y (Shannon and Weaver, 1949) which has been applied to birds by MacArthur and co-workers (MacArthur and MacArthur, 1961; MacArthur, 1964, 1965; MacArthur, Recher, and Cody, 1966). The r e l a t i v e abundance of species, or equita-b i l i t y , can be measured separately i n several ways (Sheldon, 1969). 55 In the four Vancouver p l o t s , the number of breeding b i r d species was low (Tables 5 to 7). An increase i n the number of species i s e v i -dent i n moving from more urbanized to les s urbanized h a b i t a t s ; only 8 species bred on the 14th and Spruce p l o t , both i n 1968 and 1969, but 13 species bred on the 43rd and C h u r c h i l l p l o t i n 1968, and 15 i n 1969. Bird species d i v e r s i t y (H) can be calculated by the formula H = -^ p ^ l n p^, where p^ i s the proportion of the t o t a l i n d i v i d u a l birds i n the population belonging to the i t h species (MacArthur and MacArthur, 1961). The species d i v e r s i t y for each census p l o t i n the present study i s given i n Table 20. Among the Vancouver p l o t s , the pattern i n breeding d i v e r s i t y i s the same as that f o r species richness; the lowest d i v e r s i t y (1.717) was on the 14th and Spruce p l o t , and the highest (2.031) on the 43rd and C h u r c h i l l p l o t . The index of e q u i t a b i l i t y used i n Table 20 i s J , which equals H/H , where H i s the maximum possible d i v e r s i t y for the number of max max r ' species (Tramer, 1969). H m a x * s simply the natural logarithm of the number of species. According to Sheldon (1969), J i s a better index of e q u i t a b i l i t y than e, the index used by Lloyd and Ghelardi (1964), since e v a r i e s considerably with the number of species when the number of species i s small. In the Vancouver p l o t s , e q u i t a b i l i t y of breeding populations was greatest on the Ferguson Road p l o t (.890), suggesting that perhaps equi-t a b i l i t y i s lower i n urban habitats than elsewhere (see Discussion). The lowest e q u i t a b i l i t y value (.733) was on the.43rd and C h u r c h i l l p l o t ; t h i s low value was l a r g e l y a r e s u l t of the dominance of Robins i n the breeding avifauna. 56 Table 20. Number of Species, B i r d Species D i v e r s i t y , and E q u i t a b i l i t y on Vancouver, Sacramento, and Ottawa Census Plots Plot Number of Species Breeding^ •: Breeding-Season Winter 19th & Yukon 10 15 12 14th & Spruce 8 13 16 43rd & C h u r c h i l l 16 30 30 Ferguson Road 9 25 32 22nd & Dunbar 19 33rd & Dunbar 22 F & 21st 13 S & 24th 14 R o c k c l i f f e Park 13 A l t a V i s t a 11 Be l - A i r Heights-Copeland Park 9 Pl o t B i r d Species D i v e r s i t y Breeding Breeding-Season Winter 19th & Yukon 1.843 1.809 1.446 14th & Spruce 1.717 1.722 1.718 43rd & C h u r c h i l l 2.031 2.210 2.373 Ferguson Road 1.956 2.416 1.869 22nd & Dunbar 2.167 33rd & Dunbar 2.055 F & 21st 1.912 S & 24th 2.160 R o c k c l i f f e Park 1.602 A l t a V i s t a 1.673 Be l - A i r Heights-Copeland Park 1.012.. Pl o t E q u i t a b i l i t y Breeding Breeding-Season Winter 19th & Yukon .800 .668 .582 14th & Spruce .826 .671 .620 43rd & C h u r c h i l l .733 .650 .698 Ferguson Road .890 .751 .539 22nd & Dunbar .736 33rd & Dunbar .665 F & 21st .745 S & 24th .818 R o c k c l i f f e Park .625 A l t a V i s t a .698 Be l - A i r Heights-Copeland Park .461 57 Turning to breeding-season populations, the number of species on the Vancouver plo t s followed the same trend as i n breeding populations. The lowest number of species (12) was on the 14th and Spruce p l o t , and the highest (30) on the 43rd and C h u r c h i l l p l o t . . The breeding-season d i v e r s i t i e s i n Vancouver did not exactly p a r a l l e l the breeding d i v e r s i t i e s ; the lowest breeding-season d i v e r s i t y (1.722) was again on the 14th and Spruce p l o t , but the highest (2.416) was on the Ferguson Road p l o t rather than 43rd and C h u r c h i l l . On the 19th and Yukon and 14th and Spruce p l o t s , breeding-season d i v e r s i t i e s were very close to breeding d i v e r s i t i e s ; but on the 43rd and C h u r c h i l l p l o t , and p a r t i c u l a r l y on the Ferguson Road p l o t , breeding-season d i v e r s i t i e s were higher (2.416 vs. 1.956 on Ferguson Road), owing to the presence i n considerable numbers of several non-breeding v i s i t o r s . The previously-mentioned post-breeding concentrations of several species on the Ferguson Road p l o t were l a r g e l y responsible for the high breeding-season d i v e r s i t y there. The e q u i t a b i l i t y of breeding-season populations presents a s i m i l a r p i c t u r e to that of breeding populations; that i s , highest on the Ferguson Road plo t (.751) and lowest on the 43rd and C h u r c h i l l p l o t (.650). Breeding-season e q u i t a b i l i t i e s were uniformly lower than breed-ing e q u i t a b i l i t i e s , however, because of the i n c l u s i o n of a number of rare non-breeding v i s i t o r s . i n the former. The number of wintering b i r d species i n the Vancouver study areas varied i n the same way as the number of breeding and breeding-season species; that i s , with fewest species i n the most urbanized areas., 58 Excluding counts from the 1967-68.^winter, which are based on at most three censuses, the Vancouver wintering b i r d avifaunas ranged from 11 species on the 14th and Spruce pl o t (1968-69) to 26 species on the 43rd and C h u r c h i l l p l o t (1969-70) and 29 species on the Ferguson Road pl o t (1969-70). The number of species on Shepard's pl o t s was intermediate. Species richness i n Ottawa and Sacramento was comparable to that on the more urbanized Vancouver p l o t s ; the Ottawa pl o t s had 11 and 13 species, and the Sacramento p l o t s , 13 and 14 (Table 20). Although H has not usually been applied to wintering populations, I have calculated values for the winter b i r d populations on my p l o t s . Winter d i v e r s i t i e s are best compared with breeding-season d i v e r s i t i e s , since non-breeding v i s i t o r s are ignored i n breeding d i v e r s i t i e s . Of the Vancouver p l o t s , the 14th and Spruce p l o t had nearly i d e n t i c a l H values f o r the winter and the breeding season; the 43rd and C h u r c h i l l p l o t had a somewhat higher d i v e r s i t y i n winter; and the 19th and Yukon and Ferguson Road plo t s had much lower d i v e r s i t i e s i n winter. The mean H value for the four.plots i n winter was 1.852, as opposed to 2.039 i n the breeding season. Since the number of species varied l i t t l e between summer and winter, seasonal differences i n d i v e r s i t y indices were l a r g e l y due to differences i n e q u i t a b i l i t y . (The mean breeding d i v e r s i t y for the four p l o t s , however, was 1.877, or nearly the.same as the mean winter d i v e r s i t y . ) Wintering d i v e r s i t i e s i n Sacramento were s i m i l a r to those,in Vancouver. Those i n Ottawa, however, were markedly lower, as one might expect. The highest d i v e r s i t y i n winter was again i n well-wooded areas, 59 with the 43rd and C h u r c h i l l p l o t having the highest (2.373). The mean e q u i t a b i l i t y value for the,four,main Vancouver pl o t s i n . winter was .610, somewhat lower than the breeding-season mean of .685. , The 43rd and C h u r c h i l l p l o t had a higher e q u i t a b i l i t y i n winter, but the others were a l l lower. The e q u i t a b i l i t y on the 19th and Yukon and Ferguson Road p l o t s was e s p e c i a l l y low because of the dominance of S t a r l i n g s i n t h e i r winter b i r d populations. The highest J Values were i n the three well-wooded plo t s (43rd and C h u r c h i l l , 22nd and Dunbar, and 33rd and Dunbar). E q u i t a b i l i t y values i n Sacramento were decidedly higher than i n Vancouver, while those i n Ottawa were about the same. (c) Species Composition On the Vancouver census p l o t s , i t i s evident that the most t y p i c a l urban species—House Sparrows, S t a r l i n g s , and Rock Doves—are le a s t abundant, during the breeding season, i n the well-wooded area (43rd and C h u r c h i l l ) . This i s countered by the greater abundance there of f o r e s t and forest-edge.species (Robin, Black-capped Chickadee, Song. Sparrow, American Goldfinch, Brown-headed Cowbird, Warbling Vireo, North-western Crow, Golden-crowned K i n g l e t , and Red-breasted Nuthatch). Swallows show less d i f f e r e n c e i n numbers among the p l o t s . Birds charac-t e r i s t i c of open f i e l d s (Brewer's Blackbirds, Savannah Sparrows) make a s i z a b l e contribution to the population of the Ferguson Road p l o t . Of a l l the p l o t s , the 19th and Yukon and the 14th and Spruce p l o t s show the greatest s i m i l a r i t i e s ; t h e i r . d i f f e r e n c e s are more quantitative than q u a l i t a t i v e . The larges t differences were i n the abundance of Rock 60 Doves (commoner on 14th and Spruce) and Robins (commoner on 19th and Yukon). The trends i n abundance of Robins and Rock Doves are p a r t i c u l a r l y c l e a r . The more urbanized the habitat, the commoner Rock Doves become; and the better-wooded, the commoner Robins become. Winter b i r d populations show a pattern s i m i l a r to breeding popu-r l a t i o n s . However, the t y p i c a l urban species are even scarcer i n the well-wooded area than i n summer. This may be p a r t l y a r e s u l t of the more r e s t r i c t e d opportunities for feeding i n that habitat as compared with more bui l t - u p habitats. On the other hand, the Oregon J u n c o — commonest of the s t r i c t l y w i n t e r - v i s i t a n t species—was most abundant i n the well-wooded area. The species composition on the Sacramento pl o t s showed much s i m i l a r i t y to that on the Vancouver p l o t s , except for the presence of Scrub Jays and the abundance of Goldfinches. The presence of Scrub Jays may r e f l e c t physiognomic s i m i l a r i t i e s between urban habitats and the species' normal oak-woodland habitat. In Ottawa, the greater abundance of S t a r l i n g s , Rock Doves, and House Sparrows on the A l t a V i s t a p l o t , as compared to the better-wooded R o c k c l i f f e Park p l o t , was very conspicuous. The high numbers of Evening Grosbeaks and Common Redpolls i n Ottawa were probably not t y p i c a l , since numbers of these birds may fl u c t u a t e greatly from winter to winter and from time to time during one winter (A. J . Erskine, pers. comm.). 61 6. Discussion (a) Density Since P i t e l k a (1942) found a breeding b i r d density of 1200 pairs per 100 acres on a small study pl o t i n the v i l l a g e of D i l l o n Beach, C a l i f o r n i a , a number of authors have found that urban areas.often have higher densities of breeding birds than other hab i t a t s . Speirs, Markle, and Tozer (1970), i n a comprehensive study of b i r d populations i n Ontario County, Ontario, found that urban b i r d d e n s i t i e s averaged nearly twice those i n forests and more than four times those i n f i e l d s . (Ten or, eleven p l o t s were censused i n each of these three habitat types.) Erskine, censusing birds i n several habitats i n the Clay Belt region of c e n t r a l Ontario and Quebec, found that of seven pl o t s studied, the highest density was i n an urban area (see Audubon F i e l d Notes 24.(6), 1970). In South A f r i c a , S i e g f r i e d (1968) estimated.that the density of b i r d s i n "fynbos" (Mediterranean scrub vegetation) around the town of Stellenbosch was about h a l f that i n the urban area. To f a c i l i t a t e comparison of breeding b i r d d e n s i t i e s i n d i f f e r e n t h a b i t a t s , I summarized the r e s u l t s of breeding b i r d censuses conducted on 124 plots throughout North America i n the years 1968 to 1970 (Audubon F i e l d Notes 22 (6), 1968; 23 (6), 1969; and 24 (6), 1970), plus 120 a d d i t i o n a l plots l i s t e d by Erskine (1971). The r e s u l t s of t h i s compila-t i o n are shown i n Table 18. (Although Udvardy (1957) presented,a s i m i l a r a n a l y s i s , he did not give mean densities for d i f f e r e n t h a b i t a t s , but only the highest and lowest densities.) A comparison such as t h i s i s 62 admittedly a crude one, when one takes into account the huge geographic area included and the varying a b i l i t i e s and techniques of the observers, who made the censuses. Nevertheless, some of the differences i n density are c l e a r enough that a number of generalizations are warranted. The d e n s i t i e s of breeding birds on the Vancouver plots (167 to 196 males per 100 acres) are only s l i g h t l y less than those,in most North American f o r e s t s . They are lower than those,in some other urban areas, e.g., 272 males per 100 acres i n London, England (Simms, 1962); 364 males per 100 acres i n Ithaca, New York (Simmers, 1965); an average of 407 males per 100 acres i n ten plots i n Ontario urban areas (Speirs, Markle, and Tozer^ 1970); and 526 and 607 males per 100 acres i n two plots i n St. Petersburg-Gulfport, F l o r i d a (Woolfenden and Rohwer, 1969). Other urban areas have breeding b i r d d e n s i t i e s closer to those i n Vancouver: 175 males per 100 acres i n Stellenbosch, Cape Province, South A f r i c a ( S i e g f r i e d , 1968); 203 males per 100 acres on a plo t i n St. Petersburg, F l o r i d a (Woolfenden and Rohwer, 1969); and 218 males per 100 acres i n Senneterre, Quebec (Erskine, 1970b). A number,of possible reasons f o r the high de n s i t i e s of breeding b i r d s i n urban areas may be suggested. One i s the abundance of nesting s i t e s , mainly in-the form of holes or crevices i n bu i l d i n g s . A large percentage of urban birds belong to species which are l a r g e l y or exclu-s i v e l y hole-nesters (e.g., House Sparrow, S t a r l i n g , Rock Dove, Crested Mynah). Another contributory factor i s the abundance of food, e s p e c i a l l y of scraps and garbage, although t h i s i s c e r t a i n l y less important i n summer than i n winter. A f i n a l point i s that urban r e s i d e n t i a l areas, 63 with t h e i r complex mosaic of trees, lawns, gardens, b u i l d i n g s , and roads, can be regarded as ecotones. High densities of organisms are often c h a r a c t e r i s t i c of ecotones (Odum, 1959, p. 278; Clarke, 1965, p. 412). Wintering b i r d populations i n urban areas tend to be even higher, i n r e l a t i o n to non-urban habitats, than breeding populations. The densi t i e s of winter,birds on 84 North American plo t s i n various habitats (taken from Audubon F i e l d Notes 22 (3), 1968; 23 (3), 1969; and 24 (3), 1970) have been summarized i n Table 19. (The data of Webster (1966) have not been used, since he included repeat censuses on a si n g l e p l o t on the same basis as censuses on d i f f e r e n t plots.) The s i x Vancouver plot s censused i n winter had a mean density of 450 birds per 100 acres, and only one had fewer than 300 birds per 100 acres; t h i s i s a higher density than i n any of the habitats l i s t e d i n Table 19. (Of the three urban p l o t s included i n the table, two had very low d e n s i t i e s , one be-cause i t was located i n an area of very cold winter climate, and the other because i t was i n a commercial d i s t r i c t with very l i t t l e vegeta-t i o n . ) The high winter densities of birds i n c i t i e s are probably con-nected with the a v a i l a b i l i t y of food ( S i e g f r i e d , 1968). In colder, climates, at l e a s t , most wintering birds depend l a r g e l y on food provided i n t e n t i o n a l l y or inadvertently by man. Regularly-supplied b i r d feeders are p a r t i c u l a r l y important to several seed-eating species (House Finches and Oregon Juncos i n Vancouver; Evening Grosbeaks and Common Redpolls i n Ottawa). Many people who do not maintain b i r d feeders throw out bread crumbs or other scraps at i r r e g u l a r i n t e r v a l s . Household garbage i s also 64 an important food source for several species. In Vancouver, t h i s i s u t i l i z e d e s p e c i a l l y by S t a r l i n g s , Rock Doves, Crested Mynahs, and House Sparrows, and also by Glaucous-winged Gulls and Northwestern Crows. Dogs may also be an important factor i n the ecology of urban b i r d s , since by knocking over garbage cans and s c a t t e r i n g the contents, they increase the food supply for several species of b i r d s . The lower winter b i r d populations i n Ottawa as compared with Vancouver are c l e a r l y r e l a t e d to the cold winter temperatures and deep snow which p r e v a i l i n Ottawa. Salt (1953) found that ground-foraging birds disappeared completely i n winter from a study p l o t i n the S i e r r a Nevada which had deep snow cover. Thus, ground-foraging birds i n Ottawa must be r e s t r i c t e d to foods provided by man, while those i n Vancouver are not, since the ground i s r a r e l y snow-covered. The reasons for the low de n s i t i e s of winter birds i n Sacramento are not c l e a r . Perhaps the a v a i l a b i l i t y of food i n urban habitats was less than in.the surrounding farmland. The fact that no b i r d feeders were seen on the study pl o t s may also be s i g n i f i c a n t . The pattern of wintering populations which exceed breeding-season populations, which was followed on three of the four Vancouver study p l o t s , appears to be c h a r a c t e r i s t i c only of areas with mild winter climates (cf. Woolfenden et a l . , 1968; Woolfenden; 1970). In Audubon F i e l d Notes, Vols. 22 to 24 (1968 to 1970), 25 pl o t s were censused both summer and winter. Of the eight plots i n t h i s group which had higher d e n s i t i e s i n winter than i n summer, seven were i n F l o r i d a and one was i n Texas. (It should be noted that these comparisons involve breeding 65 populations, and that breeding-season populations, when non-breeding v i s i t o r s are included, would be higher.) In what appears to be the only other year-round study of urban b i r d populations, that of S i e g f r i e d (1968) i n South A f r i c a , winter d e n s i t i e s also exceeded breeding-season d e n s i t i e s . Few attempts have been made to determine the abundance of migrant birds i n several habitats simultaneously. Among the rare excep-tions are the studies of Recher (1966) and P a r n e l l (1969). Furthermore, I know of no other study i n which the abundance of migrants has been measured i n r e l a t i o n to the t o t a l abundance of a l l b i r d species. This seems l i k e a promising f i e l d f o r future study; however, i n view of the rapid f l u c t u a t i o n s i n populations of migrants, i t would be advisable to make d a i l y censuses i n any s p e c i f i c attempt to study the ecology.of migrant b i r d s , rather than weekly or biweekly censuses as i n the present study. But many more studies of migrant b i r d populations w i l l be needed before the findings of the present study i n regard to migrants can be placed i n perspective. (b) D i v e r s i t y The number of breeding b i r d species i n urban h a b i t a t s , compared with other h a b i t a t s , i s cons i s t e n t l y low. The values of .8 to 15 species found i n Vancouver are t y p i c a l . Erskine (1970b) found only 8 breeding species on h i s p l o t i n Senneterre, Quebec; Woolfenden and Rohwer (1969) found 11, 8, and 6 species on t h e i r three p l o t s i n F l o r i d a . , (The high number of species l i s t e d by Speirs, Markle, and Tozer (1970) i n Ontario 66 urban areas—between 20 and 30 species on 9 out of 10 p l o t s — i s suspect, . since they apparently included non-breeding v i s i t o r s and transients as well as breeding birds.) The low number of species i n c i t i e s compares with averages of between 16 and 25 species on breeding censuses, i n other North American habitats (Table 18), usually with p l o t s smaller than those i n the present study. The only non-urban habitats with low numbers of species were bogs (average 12.0 species), marshes (12.0 species), and f i e l d s (5.3 species). Some ad d i t i o n a l figures on the number of b i r d species i n d i f f e r e n t habitats are given by Tramer (1969), based on censuses from Audubon F i e l d Notes and other sources. The only large discrepancies between numbers of species i n Tramer's l i s t and mine are i n shrublands (Tramer, mean of 14.1 species; present study, 20.2 species) and marshes (Tramer, 6.3 species; present study, 12.0 species). These differences may be due to differences i n our methods of c l a s s i f y i n g habitats. Of course, i t must be conceded that comparisons of species r i c h -ness l i k e the present .one or that of Tramer (op. c i t . ) are l i m i t e d i n value because of differences i n the s i z e of the census plots used. The number of species w i l l increase as the p l o t s i z e increases (Oelke, 1966); the same i s also true of species d i v e r s i t y (MacArthur and MacArthur, 1961), but to a much le s s e r degree. However, the differences i n numbers of species are probably even,greater than the data suggest, since observers usually choose l a r g e r census pl o t s i n habitats l i k e tundra, grassland, and desert; which are characterized by low numbers of species and low d e n s i t i e s . 67 Tramer (1969) also gives figures for mean breeding d i v e r s i t y of birds i n d i f f e r e n t habitats. . The mean d i v e r s i t y of the four Vancouver plot s (1.887) i s about equal to Trainer's values for marshes and grassland, and much lower than those f o r a l l other habitats. H values given by Tramer f or forests are mostly between 3.5 and 4.0. Even on fiv e - a c r e p l o t s , MacArthur and Mac Arthur (1961) found a mean d i v e r s i t y of 2.296 on seven deciduous forest p l o t s — a p p r e c i a b l y higher than the Vancouver d i v e r s i t i e s . Thus, a very low species d i v e r s i t y appears to be character-i s t i c of urban b i r d populations. . I t i s probably no coincidence that, of the Vancouver p l o t s , the highest breeding d i v e r s i t y was i n the 43rd and C h u r c h i l l p l o t , the one most resembling a f o r e s t . The only figures a v a i l a b l e on e q u i t a b i l i t y of b i r d populations i n d i f f e r e n t habitats are again those of Tramer (1969). He found mean breeding e q u i t a b i l i t i e s ranging from 0.718 i n marshes to 0.921 i n t r o p i c a l woodlands. The mean e q u i t a b i l i t y f o r the four Vancouver plots (.812) i s considerably lower than those f o r a l l other habitats except marshes. Therefore, the low species d i v e r s i t y of urban avifaunas seems to r e s u l t both from a small number of species and a low e q u i t a b i l i t y ( i . e . , domi-nance of the population by a very few species). The number of wintering b i r d species i n urban habita t s , unlike the number of breeding species, does not seem to be.lower than i n other h a b i t a t s . Species l i s t s f o r the plo t s studied i n winter range from 9 to 29 species, and average 16.6 species. These figures compare with averages of 15 to 20 wintering species i n various other North American ha b i t a t s , on plo t s ranging i n mean s i z e from 20 to 50 acres (Table 19). 68 The only other study i n which wintering and breeding-season d i v e r -s i t i e s have been compared appears to be that of Anderson (1970). Anderson's figures are means from f i v e stands of oak woodland i n the Willamette Valley of Oregon.. The b i r d populations he studied had a d i v e r -s i t y index of 2.56 i n winter (2 November to 1 March) and 3.13 i n the breeding season (2 June to. 15 J u l y ) . This compares with respective values of 1.852 and 2.039 i n the present study. Anderson's d i v e r s i t y indices, are much higher, which i s to be expected i n a woodland. Furthermore, the d i f f e r e n c e between breeding-season.and winter d i v e r s i t i e s i s much greater i n Anderson's study areas than i n mine. Evidently, t h i s i s accounted for by the fact that urban b i r d populations have a much higher percentage of permanent-resident birds than do forest populations. The figures f or e q u i t a b i l i t y of winter b i r d populations i n Vancouver, which indi c a t e a lower e q u i t a b i l i t y than i n the breeding season, support the suggestion of Tramer (1969) that J values for avian communities w i l l probably be lower i n winter. I agree with Tramer's contention that t h i s i s due at l e a s t i n part to the e f f e c t of t e r r i t o r i a l behaviour during the breeding season, which makes i t les s l i k e l y that a community w i l l be numerically dominated by one or two species at that season. A number of authors (MacArthur and MacArthur, 1961; MacArthur, MacArthur, and Preer, 1962; Cody, 1966, 1970; Karr, 1968; Austin, 1970) have attempted to r e l a t e b i r d species d i v e r s i t y to the vegetation p r o f i l e . Since no measurements of vegetation p r o f i l e were taken during the present study, no such comparisons.can be made here. 69 (c) Species Composition House Sparrows and S t a r l i n g s appear to be the dominant b i r d species i n urban r e s i d e n t i a l areas both i n North America and i n Europe. They are joined by Rock Doves i n more heavily built-up areas and ( i n summer) by Robins i n well-treed areas. The Robin i s replaced by the Blackbird (Turdus merula) i n Europe. In South A f r i c a , though the assemblage of urban b i r d species i s quite d i f f e r e n t , some of the major species are c l o s e l y r e l a t e d to species important i n North America (see S i e g f r i e d , 1968). For example, two of the commoner species i n Si e g f r i e d ' s study area were the Larger Striped Swallow (Hirundo ououllata)3 a congener of the Barn Swallow, and the Olive Thrush (Turdus ol-ivaaeus), a congener of the Robin. The Cape Sparrow (Passer melanura) i s the dominant urban b i r d i n South A f r i c a ; but i t has been replaced i n some areas by the congeneric House Sparrow, which has been introduced i n South A f r i c a and i s s t i l l increasing i t s range there. The high proportion of i n d i v i d u a l s belonging to introduced (exotic) species i s one of the most s t r i k i n g features or urban avifaunas i n North America. The three species which I have considered most t y p i c a l of urban h a b i t a t s — t h e House Sparrow, S t a r l i n g , and Rock Dove^— happen to be the only species of exotic birds (excluding gamebirds) which have become established over most of the continent. In Vancouver, these three are joined by a fourth exotic species, the Crested Mynah (Mackay and Hughes, 1963). The percentage of introduced birds found i n various North Ameri-can habita t s , as indicated by breeding b i r d censuses published i n 70 Audubon F i e l d Notes, Vols. 22 to 24, i s given i n Table 18. (Nearly a l l of these introduced birds were S t a r l i n g s , House Sparrows, or Ring-necked Pheasants.) Other than urban habitats, edge habitats were the only ones which supported s i g n i f i c a n t numbers of introduced b i r d s . Many of the "edge" p l o t s included woodland-field edge (used by nesting St a r l i n g s ) or urban edge; In winter (Table 19), i t i s seen that f i e l d s also harbour many introduced birds (mainly S t a r l i n g s ) . The lack of introduced birds on breeding censuses i n f i e l d s can be explained by the absence of s u i t -able n e s t - s i t e s . A l l of the introduced birds prominent i n North American c i t i e s are also c h a r a c t e r i s t i c of urban areas i n t h e i r o r i g i n a l Old World ranges (see Cramp and Tomlins, 1966, for House Sparrows, S t a r l i n g s , and Rock Doves; and Vaughan and Jones, 1913, for Crested Mynahs). While urban habitats are of very recent advent i n North America, they have existed for centuries or even m i l l e n n i a i n the Old World. Thus Eurasian birds have had much longer to adapt to urban habitats than North American b i r d s , and i t i s not s u r p r i s i n g that the former should be more successful i n New World c i t i e s . Some of the reasons why these birds may have become successful i n urban habitats i n the f i r s t place are suggested below. Hole nesters make up a disproportionately high percentage of urban b i r d s . S t a r l i n g s , Crested Mynahs, Tree Swallows, and Violet-green Swallows are obligatory hole-nesters; House Sparrows and Rock Doves may b u i l d nests i n the open, but usually do so i n a crevice i n a b u i l d i n g . Hole-nesters enjoy a.certain amount of protection from predation and from accidental disturbance of the nest. Very few urban birds nest on 71 or near the ground (Simms, 1962); i n Vancouver, the only such species i s the Song Sparrow. Predation by cats probably has much to do with the s c a r c i t y of ground nesters. This may be a serious problem even for arboreal nesters; Evenden (1957), i n a study of House Finch breeding success i n Sacramento, C a l i f o r n i a , reported that cats were responsible for nearly a l l of the 29% loss of young from the nest. The majority of urban birds are non-migratory, with the exception of the S t a r l i n g . However, even some S t a r l i n g populations (e.g., that breeding i n B r i t a i n ) are non-migratory (Bent, 1950, p. 187). There i s l i t t l e doubt that there i s less seasonal f l u c t u a t i o n i n the a v a i l a b i l i t y of food i n c i t i e s than i n other habitats such as f o r e s t s , thus permitting large wintering b i r d populations. Permanent residence i n an area i s an advantage to a hole-nesting species i n competition for n e s t - s i t e s with a migratory species. For example, House Sparrows often take over Purple Martin nest boxes before the Martins a r r i v e i n the spring (Bent, 1942, p. 492). Ground-foraging species constitute the great majority of urban b i r d s , as documented by t h i s study. Even.tree-nesters (e.g., the Robin) are usually ground-foragers. The only p r i m a r i l y arboreal-foraging b i r d common i n Vancouver i s the Black-capped Chickadee. The s c a r c i t y of trees i n many urban areas leaves l i t t l e room f or arboreal foragers. Salt (1953; 1957) set up a system of ten foraging-trophic cate-gories and used them to compare the structures of d i f f e r e n t avifaunas. Each category included birds of s i m i l a r food.type and foraging l o c a t i o n (or method). These categories, or modifications thereof, have also been 72 used by other authors,(e.g., Bock and Lynch, 1970; Anderson, 1970). Since foraging locations of the birds i n t h i s study are treated elsewhere, only the trophic structure w i l l be discussed here. I c l a s s i f i e d birds into trophic groups according to the descrip-tions of food habits given i n Bent et a l . (1942 to 1968) and Martin, Zim and Nelson (1951). A species was considered omnivorous i f plant and animal foods were both important; graminivorous i f the d i e t consisted mainly of seeds; herbivorous,if i t was mainly plant material other than seeds; insectivorous i f i t was mainly i n s e c t s ; and carnivorous i f i t was mainly animals other than i n s e c t s . The high proportion of omnivorous birds i n urban habitats i s evident at once from Table 21. It approaches or exceeds 90% both summer and winter on the 19th and Yukon and 14th and Spruce p l o t s . In winter, the l e s s e r importance of omnivorous birds i n well-treed habitats i s obvious. In none of the three well-wooded Vancouver plo t s does the per-centage of,omnivores reach 50%. In the R o c k c l i f f e Park p l o t , Ottawa, i t i s only 22%, compared with 65% i n the A l t a V i s t a p l o t . The high percen-tages of omnivorous birds r e f l e c t the nature of winter food sources a v a i l a b l e to urban b i r d s . Looking at other groups, i n s e c t i v o r e s are generally much scarcer i n winter than i n summer, and are important,in winter only in-well-wooded habitats (titmice, nuthatches, woodpeckers, e t c . ) . Graminivorous species are more important i n winter, e s p e c i a l l y i n the well-wooded areas (various f i n c h e s ) . Carnivores, although few i n number i n any avian community, are almost non-existent i n urban habitats except for a,few a c c i p i t r i n e hawks i n winter (the Ferguson Road pl o t i s an exception). 73 Table 21. Trophic structure of urban b i r d communities: Percentages of i n d i v i d u a l s belonging to d i f f e r e n t trophic groups on Vancouver, Sacramento and Ottawa plo t s Plot Omnivores Graminivores Herbivores Insectivores Carnivores Breeding 19th & Yukon 85.4 3.7 10.9 14th & Spruce 91.7 1.5 6.8 43rd & C h u r c h i l l 60.4 21.0 18.6 Ferguson Road 59.4 20.0 20.6 Winter 19th & Yukon 90.8 8.4 0.8 14th & Spruce 91.3 8.3 0.4 43rd & C h u r c h i l l 26.8 51.0 2.5 19.5 0.2 Ferguson Road 75.0 22.7 1.6 0.2 0.4 22nd & Dunbar 47.9 37.9 8.0 6.3 33rd & Dunbar 25.6 57.3 1.6 15.5 F & 21st 62.3 36.0 1.7 S & 24th 68.0 29.8 0.4 1.8 R o c k c l i f f e Park 22.3 64.0 0.5 13.1 A l t a V i s t a 65.1 31.3 3.1 0.4 Table 22. Microhabitat composition of study pl o t s Microhabitat Plot name code ^ ^ d e s c r i p t i o n 14th & 19 th & 43rd & Ferguson Spruce Yukon C h u r c h i l l Road 01,02 bare earth 2.9 4.3 10.0 5.2 03 gravel 12.8 7.7 5.7 3.6 04 roads (& parking) 35.3 20.4 14.5 11.0 05 sidewalks 12.7 6.7 4.9 06,07,08 grass 36.3 61.0 65.0 80.3 NOTE: Figures give percentage of area, excluding that part covered by b u i l d i n g s , and ignoring the presence of trees. 74 S i e g f r i e d (1968) noted that i n number of species, insectivores were dominant i n South A f r i c a n urban areas, although omnivores were more important than i n other habitats. In number of i n d i v i d u a l s , graminivores were dominant. However, S i e g f r i e d thought that the Cape Sparrow might be better classed as an omnivore.than as a graminivore, i n which case the omnivores would make up 67% of the urban b i r d s . Biomass, rather than the number of i n d i v i d u a l s , has been used as a basis for studying the trophic structure of b i r d communities by a number of authors (e.g., Turcek, 1956; S a l t , 1957; Speirs, Markle, and Tozer, 1970; Bock and Lynch, 1970). The paucity of weight data on b i r d species involved i n the present study has precluded an analysis based on biomass here. To summarize, the most successful urban birds are hole-nesting, non-migratory, ground-foraging, omnivorous b i r d s . The S t a r l i n g , House Sparrow, and Rock Dove come closest to meeting t h i s d e s c r i p t i o n . In the case of the two former species, t h e i r aggressiveness i n f o r c i n g other birds from t h e i r n e s t i n g - s i t e s must also be a decisive factor i n deter-mining t h e i r success i n urban habitats. Although t h i s t r a i t has been mentioned by numerous authors (e.g., Bergtold, 1913; Kalmbach and Gabrielson, 1921), i t appears that no quantitative study of the e f f e c t s of S t a r l i n g s and House Sparrows on the numbers of other species has yet been made. C. FORAGING ECOLOGY 1. Methods In previous studies of avian foraging ecology, two main types of observations have been used. Both were used i n the present study. In the f i r s t type, used by MacArthur (1958), Stallcup (1968), and Willson (1970), a bird's foraging a c t i v i t y i s followed with a stopwatch f o r as long as possible a f t e r the.bird i s f i r s t seen, and the number of seconds spent in,each of a number of a r b i t r a r i l y - d e f i n e d foraging zones, or micro-h a b i t a t s , i s recorded. In the second type, used by many authors i n c l u d i n g Gibb (1954, 1960), Dixon (1954), Balda (1969), and Morse (1967a, 1967b), only the microhabitat i n which the b i r d was foraging when f i r s t seen i s recorded. These two types of observations are ref e r r e d to hereafter as stopwatch observations,and spotchecks, r e s p e c t i v e l y . As pointed out by Stallcup (1968), simple tests of the s t a t i s t i c a l s i g n i f i c a n c e of d i f f e r -ences between species, or between a species' use of d i f f e r e n t micro-habitats and t h e i r a v a i l a b i l i t y , can be made only on spotchecks; however, I agree both with Stallcup and with MacArthur (1958), that stopwatch observations probably give a better picture of the d i s t r i b u t i o n of a bird's foraging time, since i n making spotchecks, one,probably tends to overestimate the amount of time spent i n the more open microhabitats. In the present study, 29 microhabitats were recognized (8 t e r -r e s t r i a l microhabitats, 15 i n trees and shrubs, and 6 miscellaneous types); these are described below. The microhabitats should not be 75 76 confused with the macrohabitats, or major habitat types which the study plots were designed to represent: most microhabitats were present i n a l l the macrohabitats. Whenever e i t h e r a stopwatch or a spotcheck was taken, the date, time of day, macrohabitat, l o c a t i o n on or o f f the study p l o t , and the weather were noted. A stopwatch observation could be made on only one b i r d at a time, but spotchecks were sometimes made simultaneously on:a f l o c k of b i r d s . An attempt was made to spend an equal amount of time making f o r -aging observations i n each season and i n each macrohabitat. This did not re s u l t i n the same number of observations being made, however. The seasonal d i s t r i b u t i o n of the 1866 stopwatch observations was as follows: winter, 333; spring, 387; summer, 597; and autumn, 549. More than h a l f the observations (941) were made before 10:00; 487 were made i n midday (10:00 to 14:00) and 438 a f t e r 14:00. The majority of observations were made i n good weather (no r a i n , no strong wind); so few were made i n poor weather that the data were not analyzed separately according to weather type. When foraging observations were being made, a p l o t was traversed i n a s i m i l a r fashion to that described for censusing. When a foraging b i r d was located, a spotcheck was usually made f i r s t , then a stopwatch observation was made i f possible. In the stopwatch observations, time spent handling food was included as w e l l as the time spent searching; for most species studied, the handling-time was n e g l i g i b l e compared to the searching-time. Heights of birds foraging above ground l e v e l were v i s u a l l y estimated to the nearest foot. An observation was terminated 77 when the b i r d flew away, was l o s t to view, or turned to some a c t i v i t y other than foraging. As a r u l e , multiple observations were not made on the same b i r d . In the ana l y s i s , spotchecks made on i n d i v i d u a l s on which stopwatch observations were subsequently made were disregarded, so that the spotchecks would be a t r u l y independent method of measuring the.dis-t r i b u t i o n of foraging-time. This i s d i f f e r e n t from the s i t u a t i o n i n other studies where both types of observations have been made on the same i n d i v i d u a l s (e.g., MacArthur, 1958; Root, 1967; St a l l c u p , 1968), i n which figures given for the two methods are merely two d i f f e r e n t ways of measuring the same thing. The foraging observations were begun i n June, 1968, and continued through March, 1970. An attempt was made to observe a l l species occur-r i n g r e g u l a r l y on the p l o t s , but eight or ten species accounted for the great majority of observation. Fourteen hundred and t h i r t y - n i n e of 1866 stopwatch observations (77.1%), and a s i m i l a r percentage of spotchecks, were made on the four main study p l o t s ; but when bi r d s could not be found on the p l o t s , observations were made o f f the p l o t s . i n adjacent, s i m i l a r habitat. No foraging observations were made on Shepard's census p l o t s . 2. Microhabitat Composition of Study Plots The environment within the four main Vancouver study plots was divided into 29 microhabitats, equivalent to the "foraging zones" of MacArthur (1958), for the purpose of making foraging observations. A l i s t of these, with d e s c r i p t i o n s , i s as follows: 78 01 to 08 - T e r r e s t r i a l Microhabitats 01 - Loose earth - bare earth c u l t i v a t e d or softened i n some. other way ( c h i e f l y gardens); usually beneath trees or shrubs. Also included were barnyards on Ferguson Road p l o t . 02 - Hard earth - bare, hard-packed earth: most observations, from a hard-packed schoolyard adjacent to the 14th and Spruce p l o t . 03 - Gravel - mainly gravelled lanes and s t r i p s along the edges of roads lacking curbs. 04 - Roads - paved streets (including curbs) and s i m i l a r exten-sive paved areas (parking areas, driveways). 05 - Sidewalks - paved sidewalks, d i f f e r i n g from roads c h i e f l y i n dimensions ( e s p e c i a l l y narrowness). 06 - Lawns - areas of grass kept short (less than 6 inches t a l l ) by repeated mowing (or grazing); also included were pas-tures along Ferguson Road. 07 - T a l l grass - grass more than 6 inches t a l l ( i . e . , over the heads of most foraging passerines), mainly along the edges of lanes and roads; also along fencelines on the Ferguson Road p l o t . . 08 - Sparse grass - short grass and low herbaceous weeds, usually patchy and interspersed with loose,earth, hard earth, or gravel. Found mainly along the edges of lanes and of roads lacking curbs; also around the,edges of barn-yards on the Ferguson Road p l o t . 79 09 to 14 - Deciduous Trees - (Trees - woody plants 15 feet or more i n height). 09 - Deciduous Trees, 0 to 5 feet above ground l e v e l 10 - " " , 5 to 10 feet " 11 - " " , 10 to 20 feet " 12 - " " , 20 to 30 feet 11 13 - " " , 30 to 40 feet " 14 - " " , more than 40 feet 15 to 20 - Evergreen Trees (mainly c o n i f e r s , also broad-leaved ever-greens such as h o l l y , arbutus, etc.) 15 - Evergreen Trees, 0 to 5 feet above ground l e v e l 16 - " " , 5 to 10 feet " 17 - " " , 10 to 20 feet " 18 - " " , 20 to 30 feet " 19 - " " , 30 to 40 feet 20 - 11 , more than 40 feet 21 to 23 - Shrubs (Shrubs - woody plants l e s s than 15 feet i n height), 21 - Shrubs, 0 to 5 feet above ground l e v e l 22 - " , 5 to 10 feet " " 23 - " , 10 to 15 feet " " " 24 to 29 - Miscellaneous Microhabitats 24 - Feeders - a l l types of elevated bird-feeders 25 - Garbage cans 26 - Miscellaneous ground - sawdust p i l e s , s a l t blocks, wooden steps, wooden bridges, rocks, etc. 80 27 - Miscellaneous above ground - roofs, fencetops, rock w a l l s , telephone.poles, telephone wires, etc. 28 - Shallow water - water shallow enough for a b i r d to wade i n ; usually next to lawn, sparse.grass or loose earth. 29 - Herbs - mostly t h i s t l e s and other t a l l weedy plants,on Sea Island. In the tables and figures which follow, the percentage of t o t a l foraging time ( i n the case of stopwatch observations) or the percentage of the t o t a l number of observations ( i n the case of spotchecks) i n each of the 29 microhabitats i s given for various species. In some of the tables, these 29 microhabitats have been lumped into broader categories, to f a c i l i t a t e comparisons. In most studies of foraging ecology, with the notable exception of Balda (1969), the d i s t r i b u t i o n of foraging-time by birds among d i f f e r e n t microhabitats has not been compared with the a v a i l a b i l i t y or extent of those microhabitats. In the present study, d e t a i l e d a e r i a l photographs of the study plots,made such comparisons possible, at l e a s t f o r the p r i -marily ground-foraging species (14 of the 18 species on which 20 or more observations were made, and 5 of the 6 on which 100 or more observations, were made). These photographs were obtained from the Lockwood Survey Cor^ poration of Vancouver, and were taken i n May 1968, during the i n i t i a l phase of the study. The extent of d i f f e r e n t microhabitats on each of the four study pl o t s was assessed by means of an area dot g r i d with 100 dots to the square inch. The number of dots f a l l i n g on each of the types of 81 microhabitat was counted. Not a l l of the microhabitats could be d i s t i n -guished from one another on the a e r i a l photographs; those which could be are l i s t e d i n Appendix XXII. These nine categories are further lumped into the f i v e l i s t e d i n Table 22. The correspondence of the categories i n Table 22 to the eight t e r r e s t r i a l microhabitats recognized w i l l be c l e a r by reference to the code designations. For each species, the data i n Table 22 provide a basis f o r c h i -square tests between the number of spotchecks i n d i f f e r e n t microhabitats and the extent of those microhabitats, to discover whether or not foraging was at random and whether any microhabitats were p a r t i c u l a r l y favored. In these t e s t s , only t e r r e s t r i a l foraging was considered. The i n i t i a l r e s u l t s of the assessment of microhabitat composition of the study p l o t s are shown i n Appendix XXI. These figures were con-verted i n t o those i n Appendix XXII by considering only the area not covered by b u i l d i n g s , and by ignoring the trees ( i . e . , by making an educated guess at what microhabitat lay beneath each t r e e ) . In most cases t h i s was simple, since i t was obvious that i f the tree were not there, the dot would f a l l on road, sidewalk, lawn, etc. In other cases i t was hard to determine what lay beneath the tree. Other d i f f i c u l t i e s were encountered: since the area encompassed i n an a e r i a l photograph was considerable, most of the buildings were viewed from s l i g h t l y to one side, and sections of ground near the buildings were hidden. Also, shadows cast by buildings and trees often made i t hard to i d e n t i f y micro-hab i t a t s . The extent of gardens (loose earth) was p a r t i c u l a r l y d i f f i c u l t , to measure; t h i s was p r e c i s e l y the microhabitat which was most l i k e l y to 82 occur beneath trees or beneath edges.of b u i l d i n g s . The extent of bu i l d i n g s , roads, and sidewalks, on the other hand, was probably measured with much greater accuracy. Despite these problems, the figures i n Appendices XXI and XXII should give a reasonable p i c t u r e of the extent of the d i f f e r e n t t e r r e s t r i a l microhabitats, and should point out p a r t i c -u l a r l y w e l l the differ e n c e i n microhabitat composition among the four p l o t s . The figures i n Appendix XXII are, of course, those which should be most relevant to a ground-foraging b i r d . The figures for coverage of trees and of various types of buildings given i n Appendix XXI, however, aid i n quantitative d e s c r i p t i o n of the study p l o t s , and i n understanding some of.the reasons f o r i n t e r p l o t differences i n b i r d populations. In Table 22, the plots have been arranged i n a l i n e a r fashion from the most urbanized (14th and Spruce) to the le a s t urbanized (Ferguson Road). As one moves away from the heavily urbanized areas, i t can be seen that the area covered by pavement (roads, parking areas, driveways, and sidewalks) tends to decrease sharply; so does the area of gravel; while the area of bare earth and of.lawn, p a r t i c u l a r l y the l a t t e r , tends to increase. 3. Results (a) Stopwatch Observations Urban habitats are dominated by birds which forage c h i e f l y on the ground, and the foraging observations were o r i g i n a l l y intended to examine Table 23. D i s t r i b u t i o n of foraging time for species with l a r g e s t number of observations, expressed as percentage of time per microhabitat Microhabitat American S t a r l i n g Common House Crested Black-capped White-crowned code de s c r i p t i o n Robin Pigeon Sparrow Mynah Chickadee Sparrow 01 loose earth 8.5 2.6 0.9 11.6 0.9 0.5 14.8 02 hard earth 0.1 T 5.7 1.8 0.6 03 gravel 3.5 2.0 12.4 6.5 5.2 1.9 04 road 3.1 4,5 23.1 9.7 8.5 1.3 05 sidewalk 5.4 2.9 16.3 10.1 12.3 12.6 06 lawn 74.7 81.0 35.9 48.3 64.4 0.3 21.0 07 t a l l grass 1.1 1.3 0.1 0.9 3.4 2.2 08 sparse grass 0.9 3.2 5.3 9.2 2.7 45.0 09 deciduous tree , 0- 5' 4.2 10 it it 5-10* 0.2 14.8 11 i i it 10-20' 1.1 1.3 0.2 30.6 12 II i i 20-30' 1.0 0.5 0.2 17.6 13 ti II 30-40' T 0.1 4.9 14 II II 40' + T 1.6 15 evergreen tree , 0- 5' 1.2 16 II it 5-10' 2.2 17 i i it 10-20' 0.2 7.0 18 i i i i 20-30' 0.1 3.3 19 II n 30-40' 0.5 20 II II 40' + 21 shrub, 0-5' 5.1 22 II 5-10' 0.3 23 II 10-15* 0.3 1.0 24 feeder 1.2 1.9 0.3 25 garbage can 0.5 0.3 26 mis cellaneous, ground 0.2 T 1.0 0.5 27 miscellaneous, above ground 0.2 0.6 3.0 28 shallow water 29 herbs 0.4 T o t a l seconds of observation: 23400 14222 13039 10073 7457 1840 3438 Number of observations: 245 210 128 272 123 160 58 (Table 23 - concluded) North- Golden-House Oregon Song Brewer's western Savannah Brown-headed Pine Common crowned Audubon's Code Finch Junco Sparrow Blackbird Crow Sparrow Cowbird S i s k i n Bushtit Kinglet Warbler 01 4o9 29.8 24.8 7.6 02 1.8 2.3 03 3.5 11.3 8.3 04 0.7 2.9 4.5 0.6 05 0.4 8.9 1.7 06 32.0 7.8 37.4 43.8 07 4.8 1.7 2.1 08 19.4 18.4 16.6 34.0 09 10 11 9.8 1.1 12 12.0 12.4 13 0.7 14 15 16 17 18 19 20 21 22 0.1 23 0.4 24 8.1 6.6 25 26 2.6 0.3 0.1. 0.8 27 2.3 28 0.5 29 10.0 t.s. 3275 2993 2984 2395 n.o. 35 79 46 34 14.8 1.0 14.7 1.7 8.4 13.9 3.7 0.7 10.1 7.5 57.5 51.0 69.8 23.6 3.7 10.7 7.3 1935 1573 1452 22 22 21 0.6 17.8 31.2 1.4 3.1 2.0 5.9 41.9 29.1 8.5 30.3 14.6 6.3 19.0 14.4 .4.4 -4.9 14.3 17.1 12.8 1.8 6.0 9.3 1.2 34.5 1.2 2.1 10.8 3.4 1.2 1.8 3.2 0.4 22.9 15.7 5.3 1318 680 400 340 36 47 30 25 85 only t e r r e s t r i a l foraging. For the f i r s t few months of the study, no s p e c i a l e f f o r t was made to obtain observations on b i r d s foraging i n trees or shrubs. Furthermore, a b i r d foraging on the ground i s generally much easier to see than one foraging i n a tree. For these reasons, therefore, the extent of arboreal foraging has probably been greatly underestimated for those species which forage both on the ground and i n trees. Both Robins and S t a r l i n g s , for example, undoubtedly forage i n trees much more frequently than the data i n d i c a t e . However, the actual patterns of f o r -aging on the ground are probably very close to those suggested by the data. There i s probably a s l i g h t bias against observing birds on loose earth, owing to the density of shrubbery i n some gardens, but t h i s i s much less serious than the bias against observing birds i n trees. The use of bird-feeders i s also probably much greater than the data suggest. In the early part of the study, I d e l i b e r a t e l y avoided making observations of birds at feeders; i t was only a f t e r observing the greatly increased use of feeders during the December 1968 to January 1969 cold s p e l l and snowfall that I r e a l i z e d the importance of feeders, and began to take observations on birds using them. The o v e r a l l d i s t r i b u t i o n of foraging time among the 29 micro-habitats f o r each of the 18 species on which 20 or more stopwatch obser-vations were obtained i s shown i n Table 23. This includes a l l observa-t i o n s , regardless of season, macrohabitat, l o c a t i o n on or o f f the study p l o t s , time of day, and weather. For the s i x species on which more than 100 observations were obtained, separate breakdowns are given for the foraging patterns according to.the season and the macrohabitat (Tables 27 to -p-I to VO 0 H-CO O CD r-1 CD O c co to O o o O r-1 1 Ul I VO 1 c* i M 1 N5 to o o O o OO O oo Ui 00 at cr co CD OP *o cr CO o cr •< CO n fa to OQ H CD n 01 < H o 01 C H CO CO CD I-J cr cr OQ co •B H - H -cn n « CD OQ CO r t CD r t 0 H co Oi CD H r t O rt 3 CD c co es nd h-1 O o to ON 00 to o • a o © o to CO M -vj Ul 00 o 1—' Ul -J 4^ • • o o Ul vo Ui ON J> CO M o h-1 vo VO • o e » to Co 4> o Ul H M to o O 00 VO 00 • e o • • o 00 U) ON -> op I—1 »-j to o o o o » • o 00 Ui 00 vo o ON CO o o • • e • CO • VO -P- to Ul ON M M o oo Co • o » • to vo CO to N) Ul o o I—1 M 4>-• • e » o © 00 4>- I-1 VO CO 1—' CO VO O CO • • • O « © to to o 00 Co Ul Co o V ON • • e • K> VO r-J i H 1 I-1 vo 'o 00 • e • • O J vo ON to ON to I-1 I—* e o • to o oo oo I—' Ul CO o a e CO l - 1 »o M oo • © 0 I—1 to M ON Ui - J o e ft * ON M oo ON 4^ M 4> CO to CO • • • VO -P-Ul 4> ON Co e O Ui Ul ON Co I—1 • • • N5 ON to American Robin S t a r l i n g Common Pigeon House Sparrow Crested Mynah Black-capped Chickadee White-crowned Sparrow House .Finch Oregon Junco Song.Sparrow Brewer's Blackbird Northwestern Crow Savannah Sparrow Brown-headed Cowbird Pine S i s k i n Common Bushtit Golden-crowned Kinglet Audubon's Warbler 87 Table 25. D i s t r i b u t i o n of foraging time f o r species with l a r g e s t number of observations (as Table 23, but observations on plo t s only), expressed as percentage of time per microhabitat Microhabitat American S t a r l i n g Common House Crested Black-capped code Robin Pigeon Sparrow Mynah Chickadee 01 9.0 3.3 1.6 13.9 0.2 0.6 02 0.1 T 0.7 03 3.5 2.7 17.6 6.2 2.0 04 3.0 5.3 18.3 11.9 9.6 05 5.6 3.2 20.0 9.3 13.8 06 74.0 77.1 38.8 45.3 69.8 0.3 07 1.1 1.8 0.1 2.7 08 0.7 4.6 2.5 9.1 1.1 09 5.0 10 0.2 17.4 11 1.2 0.3 0.2 33.6 12 1.0 0.7 0.3 16.8 13 T 0.2 5.6 14 T 1.6 15 1.5 16 2.2 17 0.2 1.4 18 0.1 0.7 19 0.3 20 21 6.1 22 0.3 23 0.4 0.5 24 1.5 2.3 25 0.7 26 0.3 T 0.8 0.8 27 0.4 0.8 3.7 28 29 T o t a l seconds of observation: 21565 10100 7362 8052 5087 1514 Number of observations: 227 160 83 223 86 134 Table 26. Summary of food observations Species Total Total Food Number of: observ- birds item Observ- Birds ations ations American Robin 45 45 earthworms 20%** 20%** mountain ash berries 17 17 holly berries 2%** 2%** cherries 3 3 apples 2 2 House Sparrow 30 68 bread 22 57 apples 2 2 mites 1 4 ice cream cone 1 1 hot dog bun 1 1 maple seeds 1 1 birch seeds 1 1 insects 1 ' 1 Starling 13 29 earthworms 3 3 mountain ash berries 3 3 dogwood berries 3 3 cherries 2 3 meat 1 15 garbage 1 2 House Finch 11 18 birch seeds 4 4 seeds (feeder) 3 4 weed seeds 1 7 broom seeds 1 1 mountain ash berries 1 1 apples 1 1 Oregon Junco 9 10 birch seeds 4 4 seeds (feeder) 3 4 grass seed 1 1 maple seeds 1 1 Common Pigeon 7 16 bread 5 12 grass seeds 1 3 grain 1 1 Purple Finch 7 8 berries 7 8 Pine Siskin 7 39 birch seeds 3 8 maple buds 2 24 alder seeds 2 7 Common Redpoll 4 24 birch seeds 4 24 American Goldfinch 4 4 thistle seeds 3 3 birch seeds 1 1 (Table 26 - concluded) Species T o t a l T o t a l Food Number of: observ- bi r d s Item Observ- Birds ations ations Crested Mynah 2 3 garbage 1 2 meat 1 1 White-crowned Sparrow 2 2 t h i s t l e seeds 1 1 grain 1 1 Northwestern Crow 2 2 garbage 1 1 amer. robin n e s t l i n g 1 1 Orange-crowned Warbler 2 2 insects 2 2 Black-capped Chickadee 1 1 insects 1 1 Red-shafted F l i c k e r 1 1 pear 1 1 Golden-crowned Sparrow 1 1 mountain ash b e r r i e s 1 1 Glaucous-winged G u l l 1 1 lunch bag 1 1 Rufous Hummingbird 1 1 flower nectar 1 1 F r a c t i o n a l numbers since both earthworms and b e r r i e s were taken during one observation. 90 to 32). No separate breakdown'according to time of day i s shown, since most such differences i n foraging patterns were small, inconsistent, and of uncertain s i g n i f i c a n c e (except possibly for Rock Doves). Table 25 presents the foraging patterns of'the . s i x top species i n s i d e the study pl o t s only, when observations made outside the plots have been excluded. F i n a l l y , i n Table 24, the 29 microhabitats l i s t e d i n Table 23 are combined into 7 larger categories, to point out more c l e a r l y the differences among the 18 major species. The small amount of data obtained on the actual food items used by birds i n the study i s l i s t e d i n Table 26. Despite the small sample s i z e s , these data form a valuable supplement to those from food-habits studies based on stomach analyses, which are almost i n v a r i a b l y of birds c o l l e c t e d i n non-urban habitats and usually i n geographical areas remote from Vancouver. The only food-habits study from the Vancouver area of which I am aware i s that of Scheffer and Cottam (1935) on Crested Mynahs. In the species accounts which follow, a summary i s given of each species'.foraging pattern, and comparisons are made with those of other species. For the s i x species with the l a r g e s t sample s i z e s , comparisons are made of foraging patterns i n d i f f e r e n t seasons and i n d i f f e r e n t macro-ha b i t a t s , and of the o v e r a l l patterns versus those i n the study plots proper. The r e s u l t s of published food-habits studied are then summarized, together with f i e l d observations of food items taken i n Vancouver; and i n most cases, an attempt i s made to r e l a t e the d i e t to the foraging pattern observed i n the present study. The f i r s t paragraph i n each species account summarizes the 91 conditions under which the stopwatch observations were made, i . e . , the number of observations made i n each of the four study p l o t s , i n each season, and i n each of the three time-periods of the day. F u l l d e t a i l s concerning these points are given i n Appendix XXIII. In almost no species were the observations evenly d i s t r i b u t e d among the p l o t s , seasons, and time-rperiods; t h i s resulted from differences i n the seasonal and numerical status of the species on the four pl o t s as well as from i r r e g u -l a r i t i e s i n the sampling schedule. The importance of Appendix XXIII cannot be overemphasized, since the sample sizes ( i n d i f f e r e n t p l o t s and seasons) d i c t a t e what can be said i n the species accounts. An explanation i s necessary concerning the food-habits studies c i t e d i n the species accounts. Most of these are based on stomach analyses of birds c o l l e c t e d i n the early years of the 20th century by the U.S. B u i l o g i c a l Survey, the forerunner of the present U.S. Fis h and W i l d l i f e Service. Many papers on food habits were published by such authors as Beal (1900, 1907, 1910, 1915, 1948), Judd (1901), and Kalmbach (1914, 1918, 1922, 1940). These papers give volumetric analyses of the di e t s of large samples of b i r d s , but unfortunately the data from d i f -ferent geographic.areas and d i f f e r e n t habitats are r a r e l y presented separately. Furthermore, since the purpose of such investigations was usually to assess the e f f e c t of birds on a g r i c u l t u r a l crops, the samples, are obviously biased towards the diets of birds i n a g r i c u l t u r a l areas. In addition, these papers s u f f e r from the usual d i f f i c u l t i e s encountered i n studies of animal d i e t s ( d i f f e r e n t i a l d e t e c t a b i l i t y of food items i n the,gut, d i f f e r e n t i a l c a l o r i c value of d i f f e r e n t kinds of food, e t c . ) ; 92 these d i f f i c u l t i e s have been thoroughly reviewed by Hartley (1948). The compilation of Martin, Zim and Nelson (1951), i s apparently based p r i m a r i l y on the same material as the early food-habits studies, but t h e i r method of - analysis i s quite d i f f e r e n t . The percentage of plant versus animal material i n the d i e t of each b i r d species i s given separ-a t e l y for each season.. Their d e f i n i t i o n s of the seasons are d i f f e r e n t from the usual (summer, June through August; autumn, September and October; winter, November through March; and spring, A p r i l and May). The animal foods are not analyzed q u a n t i t a t i v e l y , but the plant foods are analyzed separately for d i f f e r e n t parts of the United States, depending on the sample s i z e . Exact percentages of d i f f e r e n t plant items i n the d i e t are not given, but a "star r a t i n g system" i s used, where one.star, means that an item makes up between 2% and 5% of the d i e t , two stars means between 5% and 10%, and so f o r t h . When th i s information i s con-sidered together with the reports of Beal, Judd, Kalmbach, and others, a much better p i c t u r e of each species' d i e t can be pieced together. Despite the shortcomings of the food-habits studies, the items of major i n t e r e s t , that i s , the o v e r a l l differences, among species, are f a i r l y obvious i n most instances. Together with the differences i n f o r -aging ecology noted i n the present study, they should give a,clear i n d i c a t i o n of how birds make use of the feeding niches a v a i l a b l e i n an urban habitat. ( i ) Species Accounts Robin - Most observations were on the 43rd and C h u r c h i l l and 19th and Yukon p l o t s . Spring, summer, and autumn were each represented by at 93 Table 27a. D i s t r i b u t i o n of foraging time f o r American Robin according to season ( a l l macrohabitats combined), expressed as percen-tage of time per microhabitat Microhabitat code winter spring summer f a l l 01 11.7 13.4 6.2 3.9 02 0.2 03 2.6 3.6 6.5 04 3.3 3.7 0.6 05 4.6 5.7 7.2 06 70.7 73.7 76.4 71.7 07 2.2 0.2 1.3 08 0.2 1.4 0.6 11 1.2 3.7 12 0.7 4.4 13 0.1 14 0.1 17 9.7 18 7.9 26 0.1 0.4 t o t a l seconds: 443 8200 11610 3147 t o t a l observations: 7 72 116 50 Table 27b. D i s t r i b u t i o n of foraging time f o r American Robin according to p l o t ( a l l seasons combined), expressed as percentage of time per microhabitat Microhabitat code t y p i c a l well-wooded apartment pasture-r e s i d e n t i a l r e s i d e n t i a l r e s i d e n t i a l 01 8.7 7.7 11.1 10.3 02 0.3 03 2.1 8.1 0.9 0.1 04 4.4 3.2 0.2 2.0 05 5.4 9.6 3.1 06 76.4 66.0 81.9 76.5 07 0.8 5.7 08 0.2 0.6 3.2 11 1.3 0.9 0.7 2.2 12 1.0 1.1 1.9 13 0.1 14 0.1 17 0.6 18 0.5 26 0.2 0.5 0.2 t o t a l seconds: 8140 6850 3419 3156 t o t a l observations: 83 85 28 31 94 l e a s t 50 observations, but only seven were made i n winter. Nearly h a l f the observations were made before 10:00. In i t s o v e r a l l foraging pattern, the Robin showed a greater con-centration of a c t i v i t y on lawns (74.7% of t o t a l foraging time) than any other species except the S t a r l i n g (see Table 23). If a l l categories of grass are combined (Table 24), three a d d i t i o n a l species exceed the Robin i n use of grass: the Brewer's Blackbird, Savannah Sparrow, and Brown-headed Cowbird. A l l three of these occurred c h i e f l y on the Ferguson Road p l o t , which had the largest area of grass (80.3%). The o v e r a l l foraging patterns of Robins and S t a r l i n g s were quite s i m i l a r . Both species foraged about 8% of the time on paved surfaces; however, Robins made much greater use of loose earth (8.5% vs. 2.6%). Both foraged i n trees to some extent, the Robin perhaps more than the S t a r l i n g , although both c e r t a i n l y used trees much more than the data suggest. The exclusion of observations made outside the plots made no appreciable d i f f e r e n c e i n the foraging pattern of Robins. Seasonal differences i n the foraging patterns of Robins were not pronounced (Table 27a), although the sample for winter was much too small to be representative; more than 70% of foraging time (was spent on lawns i n a l l seasons. , Foraging i n trees was heaviest i n f a l l and winter, the seasons when f r u i t was most.readily a v a i l a b l e . The aboreal foraging i n autumn was mainly for mountain ash b e r r i e s while that i n winter was mainly for h o l l y b e r r i e s . Seasonal differences i n the proportional use of other microhabitats, i f r e a l , are small and of uncertain s i g n i f i c a n c e . 95 A small but notable difference exists i n the foraging patterns of Robins i n d i f f e r e n t macrohabitats; due to. the large sample s i z e , i t i s u n l i k e l y to be spurious. In the well-wooded r e s i d e n t i a l habitat, only 66.7% of the foraging time was spent on lawns, but 13.2% on paved sur-faces; while i n the apartment habitat, 81.9% of the time was spent on lawns, and only 3.3% on pavement. The u t i l i z a t i o n of these microhabitats on the two pl o t s i s thus i n reverse proportion to t h e i r a v a i l a b i l i t y , a pattern which was shown by no other species. Possible reasons f o r t h i s are suggested i n the Discussion. Martin, Zim and Nelson (1951), basing t h e i r analysis on 1423 Robin stomachs, indi c a t e that the Robin's food i s mainly vegetable, with the percentage ranging from 21% i n spring to 81% i n autumn. Animal foods are mainly insects ( e s p e c i a l l y Lepidoptera and Coleoptera; also Hemiptera, Diptera, and Isoptera) and earthworms. In the northeastern United States, (770 stomachs), the most important plant foods are cherries (10% to 25% of t o t a l food, by volume); and dogwood, sumac, and tupelo f r u i t s (each 5% to 10%). Other comprehensive studies of Robin foods include those of Beal (1907, 1915), Brooks (1939), Hamilton (1940, 1943), and Kalmbach (1914). F o r t y - f i v e observations, each on a d i f f e r e n t i n d i v i d u a l , were made i n the present study on.the actual food items taken by Robins. The main items were earthworms (20-1/2 observations) and mountain ash b e r r i e s (17 observations); c h e r r i e s , h o l l y b e r r i e s , and apple pulp were also eaten (Table 26). The importance of earthworms suggested by figures from the present 96 study i s greater than that indicated by other reports. Kalmbach (1914), studying the diet of Utah Robins from A p r i l through July, found that earthworms made up only 8.7% by volume of the food (although nearly 20% i n J u l y ) ; Howell (1942) found that earthworms comprised 15% by weight of. the stomach contents of 15 nesting Robins at Ithaca, N.Y. Of course one mountain ash berry i s much smaller and weighs much l e s s , than an average-s i z e d worm; however, a s i n g l e observation of a Robin taking a worm may mean much less than one of a Robin taking b e r r i e s . Data from Heppner (1965) indi c a t e that a Robin hunting worms averages only about one capture every f i v e minutes, while a very considerable quantity of b e r r i e s could be consumed i n the same time. I t should also be pointed out that the importance of earthworms may be underestimated by examination of stomach contents, since they lack hard body parts and may therefore be d i f f i c u l t to d i s t i n g u i s h i f digestion i s advanced (see van Koersveld, 1950). Heppner (1965) c a r r i e d out experiments on the foraging behaviour of Robins, and concluded that they locate earthworms v i s u a l l y . He observed that Robins hunted for worms more i n t e n s i v e l y under lawn sprink-l e r s or during rainstorms, and found that when the lawn was wet, the worms often crawled to.within 1/4" or 1/8" of the ground surface i n t h e i r burrows, so that Robins could presumably see them more e a s i l y . Although no quantitative observations were made, i t was also noted during the , present study that Robins foraged on lawns more i n t e n s i v e l y on rainy days, or i n the v i c i n i t y of lawn s p r i n k l e r s on sunny days. S t a r l i n g - Nearly h a l f the S t a r l i n g observations were made on the 19th and Yukon p l o t ; about h a l f were made before 10:00; and the observations 97 Table 28a. D i s t r i b u t i o n of foraging time f or S t a r l i n g according to season ( a l l macrohabitats combined), expressed as percentage of time per microhabitat Microhabitat code winter spring summer f a l l 01 23.2 0.2 02 T 03 2.0 6.9 0.9 2.6 04 4.5 0.1 3.0 13.5 05 4.0 3.2 2.8 2.1 06 83.8 65.6 85.5 71.9 07 5.1 3.4 08 0.6 0.6 5.2 11 1.7 1.5 12 0.4 1.6 13 0.2 25 3.3 26 0.3 t o t a l seconds: 1998 1542 8447 2235 t o t a l observations: 47 28 87 48 Table 28b. D i s t r i b u t i o n of foraging time f or S t a r l i n g according to p l o t ( a l l seasons combined), expressed as percentage of time per microhabitat Microhabitat code t y p i c a l well-wooded apartment pasture-r e s i d e n t i a l r e s i d e n t i a l r e s i d e n t i a l 01 6.6 02 0.1 03 2.5 7.3 04 7.3 12.6 1.0 05 4.7 0.6 3.7 06 76.2 78.6 77.1 78.8 07 1.5 5.3 08 0.4 7.1 15.8 11 3.1 12 0.7 3.4 13 1.7 25 3.8 26 0.1 t o t a l seconds: 5119 1114 1966 1901 t o t a l observations: 85 14 39 22 98 were w e l l - d i s t r i b u t e d seasonally, although there were fewer i n spring and more i n summer. Sta r l i n g s made heavier use of lawn, o v e r a l l , than any other species (81.0% of t o t a l foraging time); the same was true f o r a l l cate-gories of grass combined (85.5%). The s i m i l a r i t y of the S t a r l i n g ' s over-a l l foraging pattern to that of the Robin has already been noted; both species made much less use of paved surfaces than most of the other common species. Next to the Robin, the species most s i m i l a r to the S t a r l i n g i n foraging was probably the Crested Mynah. Mynahs, however, spent much less time on lawns than S t a r l i n g s (64.4% vs. 81.0%) and much more time on paved surfaces (20.8% vs. 7.4%). Although no timed observations of arboreal foraging by Mynahs were made during the study, some foraging i n trees was observed. A e r i a l foraging f o r insects by S t a r l i n g s , i n swallow fashion, has been noted by several authors (e.g., Kalmbach and Gabrielson, 1921) and was observed on numerous occasions i n the Vancouver area, but not on the study plots during 1968 to 1970. Despite the f a c t that nearly 25% of the observations were made outside the p l o t s , the foraging pattern of S t a r l i n g s within the p l o t s was nearly i d e n t i c a l to the o v e r a l l pattern. Neither was there any c l e a r i n d i c a t i o n that foraging patterns were d i f f e r e n t i n d i f f e r e n t macro-hab i t a t s . Seasonal differences on foraging patterns were not large (Table 28a); the low percentage f o r use of lawns i n spring, and high per-centage for loose earth, was probably due l a r g e l y to the small sample s i z e . Foraging i n trees was observed only i n summer and autumn. 99 Food items eaten by S t a r l i n g s were recorded on only 13 occasions (29 i n d i v i d u a l s ) , and included earthworms, mountain ash b e r r i e s , dogwood b e r r i e s , c h e r r i e s , and garbage (Table 26). Garbage was taken on only 2 occasions, but 18 i n d i v i d u a l s were involved. The most thorough study of S t a r l i n g foods i s that of Kalmbach and Gabrielson (1921), who analyzed 2301 stomachs. The year-round d i e t was 57% animal, 43% vegetable; the animal f r a c t i o n ranged from 20% i n February to 95% i n May. Forty-two per cent of the year-round d i e t was insects (nearly h a l f Coleoptera; also Orthoptera, Lepidoptera, and other orders). Plant food was mainly f r u i t ; cherries reached a maximum importance of 17% i n June (compared with 25% for Robins). Garbage was eaten only i n small q u a n t i t i e s , but most of the birds i n t h i s sample were probably shot i n farmland, and urban S t a r l i n g s unquestionably eat much more garbage. Dunnet (1955) found that the food brought to n e s t l i n g S t a r l i n g s i n a r u r a l area near Aberdeen, Scotland, consisted of 85% (by weight) cranefly (Tipula sp.) larvae; 15% earthworms; and smaller quantities of beetles, f l i e s , c a t e r p i l l a r s , and chicken feed. Winter foods i n the, Aberdeen area (Dunnet, 1956), were not analyzed g r a v i m e t r i c a l l y , but the main items were cranefly larvae and oats (obtained mainly from stubble-f i e l d s and l i v e s t o c k feeders), and beetles were also important. Other studies of S t a r l i n g food habits include those of Kalmbach (1922), Lindsey (1939), Martin, Zim and Nelson (1951), and Shadowen (1969). The concentration of S t a r l i n g s at b i r d feeders i n the Vancouver area during severe winter weather, noted i n the present study, i s p a r a l -l e l e d by the change i n foraging habits noted by Dunnet (1956) during a 100 period of deep snow cover i n Scotland i n January, 1952. S t a r l i n g f l o c k s , which normally fed mainly in,pastures, instead were found i n farmyards at l i v e s t o c k feeders, or i n v i l l a g e s feeding on scraps. Dunnet made the observation, which can be extended to many other b i r d species, that severe winter weather caused S t a r l i n g s to become almost e n t i r e l y dependent on man. Rock Dove.- Out of 128 observations on Rock Doves, 83 were made on the study p l o t s , nearly a l l on the 14th and Spruce or 19th and Yukon p l o t s ; nearly h a l f were made before 10:00. The observations were w e l l -d i s t r i b u t e d seasonally (Appendix XXIII). Rock Doves spent nearly twice as much time (39.4%) foraging on pavement as any of the other common species. Use of roads (23.1%) was p a r t i c u l a r l y heavy, but sidewalks (16.3%) were also used more than by any other species. Lawns were used correspondingly,less (35.9%). When observations made outside the p l o t s are excluded, some small differences are evident. Use of pavement (38.3%) and of lawn (38.8%) are nearly the same; however, the importance,of roads versus sidewalks i s reversed, use of gravel i s greater, and use of hard earth and sparse , grass i s much l e s s . Most of the observations on hard earth and sparse grass were made i n a schoolyard adjacent to the 14th and Spruce p l o t ; these microhabitats were rare in s i d e the p l o t s . Few birds other than Rock Doves used t h i s schoolyard for foraging. There i s a suggestion that Rock Doves may forage more on grass i n spring (47.6%) and summer (43.7%) than i n autumn (37.2%) and winter (32.6%), but these differences are d i f f i c u l t to d i s s o c i a t e from those 101 Table 29a. Distribution of foraging time for Rock Dove (Common Pigeon) according to season ( a l l macrohabitats combined), expressed as percentage of time per microhabitat Microhabitat code winter spring summer f a l l 01 12.4 02 0.4 12.6 0.1 03 29.2 9.8 8.9 14.6 04 18.3 17.8 17.4 34.6 05 7.1 24.8 17.6 12.8 06 30.8 47.6 32.8 35.9 07 0.3 08 1.8 10.6 1.3 27 0.7 total seconds: 968 1990 5817 4264 total observations: 21 21 36 50 Table 29b. Distribution of foraging time for Rock Dove (Common Pigeon) according to plot ( a l l seasons combined), expressed as percentage of time per microhabitat Microhabitat code typical well-wooded apartment pasture-residential residential residential 01 1.5 1.8 02 1.4 03 18.7 17.5 04 18.9 11.6 18.0 05 14.8 0.5 26.9 06 45.0 87.8 29.3 07 08 1.1 4.3 27 0.8 seconds: 3743 189 3430 observations 39 2 42 102 caused by sampling error. The data suggest a heavier use of lawn i n t y p i c a l r e s i d e n t i a l habitats than i n apartment habitats; t h i s may be due simply to the greater extent of lawns i n the former, since Rock Doves seem more adaptable i n foraging than most other species. A heavier use of lawns i n the morning and l a t e afternoon, and of roads and gravel road-edges i n midday, i s also suggested. Only one comprehensive study of Rock Dove foods appears to have been made: the very thorough report of Murton and Westwood (1966), based on work i n Yorkshire, England. This paper i s one of few i n which the d i e t s of b i r d s l i v i n g i n d i f f e r e n t habitats have been compared, and per-haps the only one which includes a d e t a i l e d study of the d i e t of a b i r d i n an urban area. Two Rock Dove populations were studied: one of c l i f f -nesting coastal b i r d s which foraged mainly i n farmland, and one of birds i n the c i t y of Leeds, which foraged mainly within the c i t y . One hundred and two stomachs from the former population and 267 from the l a t t e r , both w e l l - d i s t r i b u t e d seasonally, were analyzed. The c l i f f - n e s t i n g birds subsisted mainly on barley (90% to ,100% of the food, by weight, i n December through February); wheat (65% i n September); and weed seeds (about 65% i n June). The urban b i r d s , i n con-t r a s t , subsisted mainly on bread (and cake) i n a l l seasons except autumn; other important foods were grains (barley, wheat, maize), weed seeds, "exotic seeds" (peanuts, m i l l e t , canary seed, e t c . ) , and garbage. Most of the bread and much of the grain was thought to be d e l i b e r a t e l y fed to the birds by people. Murton and Westwood concluded that the urban Rock 103 Doves were d i r e c t l y dependent on man, e s p e c i a l l y i n winter. Only 7 observations (16 in d i v i d u a l s ) of Rock Dove,food items were made during the present study; i n 5 observations (12 i n d i v i d u a l s ) , the food was bread, and other items were grass seed and grain (Table 26). Even t h i s t i n y sample shows a close resemblance to Murton and Westwood's data. The deliberate feeding of Rock Doves by people i s probably much more prevalent i n England than i n Vancouver, and I suspect that bread may be les s important, and household garbage more important, i n the die t of Vancouver birds than i n that of Leeds b i r d s . Furthermore, a large part of the Vancouver Rock Dove population l i v e s near the waterfront grain elevators and eats s p i l l e d grain, while Murton and Westwood (1966) point out that there are no stored-grain f a c i l i t i e s i n Leeds which could be used by the b i r d s . Nevertheless, many of the Leeds birds fed i n grain-f i e l d s outside the c i t y , so that o v e r a l l d i e t s of Vancouver and Leeds b i r d s may be s i m i l a r even though the places where they obtain food are not. House Sparrow - Most of the 272 observations on House Sparrows (see Appendix XXIII) were made on the 19th and Yukon and 14th and Spruce p l o t s ; most were made i n summer and autumn; and more than h a l f were made before 10:00. House Sparrows made less use of lawns (48.3% of t o t a l foraging time) than any other of the commoner species, except for Rock Doves. Their use of pavement (19.8%) was exceeded only by Rock Doves, North-western Crows, and (very s l i g h t l y ) by Crested Mynahs. They also made heavy use of loose earth (11.6%) and sparse grass (9.2%), e s p e c i a l l y i n 104 Table 30a. D i s t r i b u t i o n of foraging time f o r House Sparrow according to season ( a l l macrohabitats combined), expressed as percentage of time per microhabitat Microhabitat code winter spring summer f a l l 01 23.5 14.0 7.6 15.4 03 0.2 5.5 10.0 04 1.2 14.7 5.5 05 7.8 25.8 9.7 7.6 06 9.7 58.8 55.9 39.9 07 1.5 0.2 08 4.1 19.5 10 4.2 11 0.4 12 0.7 23 0.9 24 28.2 0.3 26 11.2 1.1 27 15.0 t o t a l seconds: 421 765 5203 3684 t o t a l observations: 19 35 139 79 Table 30b. D i s t r i b u t i o n of foraging time for House Sparrow according to p l o t ( a l l seasons combined), expressed as percentage of time per microhabitat Microhabitat code t y p i c a l well-wooded apartment pasture-r e s i d e n t i a l r e s i d e n t i a l r e s i d e n t i a l 01 4.4 6.2 87.4 03 2.3 13.6 04 12.7 14.7 11.9 6.9 05 .8.3 10.2 13.2 06 54.9 70.6 42.4 2.8 07 0.1 0.3 08 13.6 6.5 2.8 10 4.6 11 0.4 12 0.8 23 0.9 24 0.7 3.1 26 1.6 27 2.1 t o t a l seconds: 3762 394 3016 880 t o t a l observations: 109 21 75 18 105 view of the s c a r c i t y of sparse grass on the study p l o t s . This may be re-lated to the importance of seeds i n the House Sparrow's di e t (see below), since "sparse grass" consists l a r g e l y of weed patches. Four species of f r i n g i l l i d s , however, made much heavier use of loose earth and sparse grass than did House Sparrows. The elimination of observations made outside the plots made very l i t t l e d i f f e r e n c e i n the House Sparrow's foraging pattern. The observa-tions treated here thus appear to be representative i n a more general sense. Some of the seasonal differences suggested by the data are probably r e a l ones. Feeders were used only i n winter, although the 28.2% of foraging time they accounted, for i s based on only 19 observations, and i s undoubtedly an exaggeration of t h e i r true importance. The heavy use of sparse grass i n autumn (19.5%) probably r e f l e c t s the a v a i l a b i l i t y of weed seeds at that season. The use of lawn, on the other hand, i s highest i n spring and summer. The foraging pattern on the Ferguson Road p l o t was quite d i f f e r e n t from that on the Vancouver c i t y p l o t s ; on the former, 87.4% of the time was spent on loose earth (although only 18 observations were made). This i s mainly because most of the Ferguson Road sparrows l i v e d around barns and fed on s p i l l e d grain i n n e a r b y areas of loose earth, although these occupied only a small percentage of the p l o t ' s area. In the c i t y , l e s s time was spent on lawn and more,on gravel and pavement on the 14th and Spruce pl o t than on the other p l o t s , corresponding with the a v a i l a b i l i t y of these microhabitats. 106 T h i r t y observations, including 68 i n d i v i d u a l s , were made on House Sparrow food items. Bread and s i m i l a r items (hot dog bun, ice-cream cone) accounted for 24 observations (59 i n d i v i d u a l s ) , and the other items were tree seeds, i n s e c t s , mites, and apple pulp (Table 26). According to Martin, Zim and Nelson (1951), plant materials pre-dominate at a l l seasons i n the d i e t of the House Sparrow (minimum 91% i n spring, maximum 99% i n winter). The animal foods are c h i e f l y insects (Coleoptera, Orthoptera, Lepidoptera, Diptera, Hemiptera, Hymenoptera, e t c . ) . Grains dominate the plant food; Judd (1901) reported that grains comprised 74% of the annual d i e t , while Kalmbach (1940) found that they made up 55% of the food i n a sample of 8004 stomachs. In the eastern United States, Martin, Zim and Nelson (1951) give the major foods as corn (between 25% and 50% of the t o t a l ) , oats and wheat (each 10% to 25%) and sorghum and crabgrass seeds (each 5% to 10%). Sunflower seeds and barley were important i n other areas. A very d e t a i l e d and comprehensive account of the House Sparrow's di e t i s given by Kalmbach (1940). The d i e t of House Sparrows along Ferguson Road i s probably s i m i l a r to that indicated i n the studies mentioned above. In the c i t y , however, bread (and garbage) i s evidently of much greater.importance to House Sparrows, as i t was to the Rock Doves of Leeds. |;Grested Mynah - More than h a l f the observations were on the. 19th and Yukon p l o t , and most were made before 410:00. Sample si z e s f or summer and autumn were much larger than those for winter and spring (Appendix XXIII). The o v e r a l l foraging pattern of Mynahs was intermediate between that of Rock Doves and House Sparrows, on the one hand, which spent much 107 Table 31a. D i s t r i b u t i o n of foraging time f o r Crested Mynah according to season ( a l l macrohabitats combined), expressed as percentage of time per microhabitat Microhabitat code winter spring summer f a l l 01 2.2 0.3 02 5.1 03 20.9 6.7 1.9 04 2.3 22.6 5.8 9.8 05 5.3 4.6 12.1 14.6 06 44.5 72.7 60.2 69.9 07 17.3 4.3 0.8 08 6.6 3.7 1.5 25 3.0 26 1.1 t o t a l seconds: 640 477 2694 3646 t o t a l observations: 14 10 40 59 Table 31b. D i s t r i b u t i o n of foraging time f o r Crested Mynah according to p l o t ( a l l seasons combined), expressed as percentage of time per microhabitat Microhabitat code t y p i c a l well-wooded apartment pasture-r e s i d e n t i a l r e s i d e n t i a l r e s i d e n t i a l 01 5.8 02 03 1.8 3.0 04 11.5 18.6 5.4 05 6.4 51.2 36.5 06 77.5 30.2 53.6 35.4 07 0.5 0.9 58.7 08 1.5 25 26 0.9 0.7 t o t a l seconds: 3630 43 1225 189 t o t a l observations: 62 1 17 6 108 le s s time on lawns; and S t a r l i n g s and Robins, on the other hand, which spent much more time there. Mynahs spent about h a l f as much time on paved surfaces as Rock,Doves, but a c t u a l l y a l i t t l e more,than House Sparrows (Mynahs 20.8%, House Sparrows 19.8%); however, House Sparrows spent much more time on loose earth (11.6% vs. 0.9%). Robins and S t a r l i n g s foraged on pavement les s than 10% of the time. The exclusion of observations taken outside the p l o t s makes no great d i f f e r e n c e i n Mynah foraging patterns. The percentage for lawn i s greater (69.8% vs. 64.4%), while those for hard earth, gravel, and sparse grass are appreciably l e s s . The evidence for large seasonal differences i n Mynah foraging patterns i s unconvincing. Summer and autumn foraging patterns are s i m i l a r to one another and to the year-round pattern. Winter,and spring sample s i z e s are much smaller; the apparent decrease i n usage of lawn i n winter i s l a r g e l y compensated for by usage of t a l l grass. Mynahs appear, however, to spend more time on lawns i n the t y p i c a l . r e s i d e n t i a l habitat than i n the apartment ha b i t a t , i n keeping with the greater extent of lawn i n - t h e former. Apart from some,data on the food of n e s t l i n g Mynahs c o l l e c t e d by, Steve R. Johnson, which i s not yet a v a i l a b l e , the only d e t a i l e d study of food i s that of Scheffer and Cottam (1935). Their report i s based on, the stomach contents of -137 birds c o l l e c t e d i n the Vancouver area between May and December, 1932. The o v e r a l l d i e t was 61% vegetable and 39% animal, and i n d i c a t i o n s were that Mynahs are le s s insectivorous,and more frugivorous,than S t a r l i n g s . Insects (mostly Diptera and Lepidoptera) 109 amounted to 22% of the food, and earthworms 5%. F r u i t made up 32%, mostly w i l d f r u i t s (28%) but also i n c l u d i n g c u l t i v a t e d cherries, strawberries, raspberries, etc. Grain made up 3%, l e a f y vegetables (cabbage, lettuce) 9%, and garbage a s i g n i f i c a n t 15%. Most of these birds were probably c o l l e c t e d on Sea and Lulu Islands, and garbage i s surely much more impor-tant to c i t y Mynahs; two observations (3 birds) of Mynah foods i n the present study were both of household garbage. During the winter, Crested Mynahs are often c l o s e l y associated with foraging flocks of S t a r l i n g s . A group of 20 to 30 S t a r l i n g s accom-panied by 3 or 4 Mynahs i s t y p i c a l . I f a p a r t i c u l a r l y a t t r a c t i v e food source has been located, such flocks w i l l often by joined by groups of House Sparrows and Rock Doves, and occasionally by one or two Northwestern Crows and Glaucous-winged G u l l s . S t a r l i n g s and Mynahs, however, appear to form the nucleus of such f l o c k s . Most aggressive acts i n S t a r l i n g -Mynah flocks are i n t r a s p e c i f i c ; but Mynahs are often dominant i n i n t e r -s p e c i f i c attacks. The reasons f o r t h i s include both the Mynah's greater s i z e and i t s p e c u l i a r habit of taking a s e r i e s of long hops toward a desired food,item, which appears to f r i g h t e n the S t a r l i n g s . Both,species usually walk when foraging, but S t a r l i n g s appear to be incapable of making these long hops. Despite the close association of Mynahs with foraging f l o c k s . o f S t a r l i n g s , differences i n foraging locations are noticeable, Mynahs spending more time on paved and gravelled surfaces. In mixed flocks of several species, i t i s .obvious that S t a r l i n g s concentrate on lawns, while Glaucous-winged G u l l s , Northwestern Crows, and Rock Doves spend much time 110 on roads and road-edges. These flocks usually appear wherever household garbage has been scattered; however, Crested Mynahs and S t a r l i n g s were the only species seen feeding d i r e c t l y from garbage cans. Black-capped Chickadee - This was the only arboreal-foraging species on which more than 50 stopwatch observations were obtained. Of the 160 observations, 80 were made on the 43rd and C h u r c h i l l p l o t , and most were made before 10:00; the seasonal d i s t r i b u t i o n was rather even, though there were more observations i n summer and f a l l . Black-capped Chickadees spent 0.8% of t h e i r foraging time on the ground, 87.9% i n trees, 6.4% i n shrubs, 1.9% at feeders, and 3.0% i n miscellaneous locations (telephone poles, telephone wires, fences, e t c . ) . (The use of feeders i s probably much greater than the data suggests since observations at feeders were made only during the l a s t few months of the study.) Two other species of insectivorous arboreal-foraging birds were common on the 43rd and C h u r c h i l l p l o t : Common Bushtits and Golden-crowned Ki n g l e t s . Bushtits spent f ar more time i n shrubs than Chickadees (43.9% vs. 6.4%); Golden-crowned Kinglets spent 100% of t h e i r time i n trees, but 56.5% i n conifers (cf. 14.2% for Black-capped Chickadees). Audubon's Warblers, l i k e Black-caps, foraged mainly i n deciduous trees, but were present i n numbers only f o r b r i e f periods during migration. They tended to forage at s l i g h t l y greater heights than the Chickadees (17.1% of time at heights of more than 30 feet, versus 6.5% for Chickadees); they also spent much time on lawns (31.2%). The only notable d i f f e r e n c e i n Black-capped Chickadee foraging patterns caused by the exclusion of observations outside the plo t s was I l l Table 32a. D i s t r i b u t i o n of foraging time for Black-capped Chickadee according to season ( a l l macrohabitats combined), expressed as percentage of.time per microhabitat Microhabitat code winter spring summer f a l l 01 1.1 2.2 06 0.7 09 10.7 10 19.8 13.5 13.6 14.7 11 41.8 29.1 21.6 37.3 12 19.4 12.7 13.2 24.6 13 21.1 1.0 4.5 14 8.7 0.8 15 3.1 16 8.8 2.2 17 1.5 2.5 15.2 1.4 18 7.4 1.4 19 1.8 0.6 21 0.7 7.1 7.0 22 0.4 0.3 23 1.5 1.2 24 7.7 5.0 27 2.5 0.8 7.5 t o t a l seconds: 273 275 719 573 t o t a l observations: 23 26 59 52 Table 32b. D i s t r i b u t i o n of foraging time for Black-capped Chickadee according to p l o t ( a l l seasons combined), expressed as percentage of ,time per microhabitat Microhabitat code t y p i c a l well-wooded apartment pasture-r e s i d e n t i a l r e s i d e n t i a l r e s i d e n t i a l 01 0.8 0.9 06 0.7 09 34.7 10 17.5 11.4 11.7 45.9 11 38.3 31.1 46.0 19.4 12 33.3 13 19.9 3.4 5.6 14 3.1 15 3.0 16 4.5 17 2.4 2.1 18 1.3 19 0.7 21 1.8 24.4 22 1.5 0.6 23 2.2 24 1.5 1.4 6.5 27 18.9 1.3 2.1 t o t a l seconds: 206 762 324 222 t o t a l observations: 21 80 26 7 112 the lower use of conifers (6.1% vs. 14.2%). Foraging patterns were simi -l a r i n d i f f e r e n t macrohabitats, except that shrubs were used heavily only i n the apartment habitat (perhaps owing p a r t l y to the s c a r c i t y of trees?). Seasonal v a r i a t i o n s , however, were notable. Feeders were used only i n winter (7.7% of foraging time) and spring (5.0%). Shrubs were apparently used more i n summer (9.0%) and autumn (8.5%) than i n winter and spring (less than 1%). Nevertheless, the 10-to-20 foot l e v e l i n deciduous trees was the most-used microhabitat i n a l l seasons (21.6% i n summer, increas-ing to 41.8% i n winter). According to Martin, Zim and Nelson (1951), the percentage of plant material i n the Black-capped Chickadee's d i e t ranges from 9% i n summer to 53% i n winter. The animal food consists mainly of insects (Lepidoptera, Coleoptera, Hemiptera, e t c . ) ; spiders are also important. Tree seeds are the main plant food; pine seeds make up between 5% and 10% of the o v e r a l l d i e t , while hemlock seeds, b i r c h seeds, and poison-ivy b e r r i e s each contribute 2% to 5%. Other studies of chickadee d i e t include those of McAtee (1926) and Weed (1898). No us e f u l information on chickadee foods was gathered during the present study, but the use of seeds at bird-feeders during the winter agrees with the pattern of increased u t i l i z a t i o n of plant foods at that season. The foraging ecology of the Paridae (titmice and chickadees) has been studied more than that of any other group of birds (e.g., Hartley, 1953; Gibb, 1954, 1960; Dixon, 1954, 1955; Haftorn, 1956; Root, 1964, 1967; Balda, 1969; Morse, 1967a, 1970). 113 Of p a r t i c u l a r i n t e r e s t are the observations of Brewer (1963), who studied the foraging ecology of Black-capped Chickadees i n I l l i n o i s f l o o d -p l a i n f o r e s t s . The foraging patterns of I l l i n o i s chickadees were gener-a l l y s i m i l a r to those i n Vancouver, although t h e , I l l i n o i s birds foraged more,often on the ground, i n herbaceous vegetation, and i n woody vines (rare i n Vancouver), and less often i n trees and shrubs. The use of trees showed a seasonal v a r i a t i o n (91.4% of time i n winter but only 67.6% i n summer), while no such v a r i a t i o n was evident i n Vancouver. The I l l i n o i s chickadees foraged over a greater range of heights than Vancouver chickadees, but concentrated t h e i r a c t i v i t y more at heights of le s s than 10 feet (46.0% of time during October to March). Morse (1970), i n a thorough, comprehensive study of the behaviour, and ecology of mixed-species foraging f l o c k s , also provides data on the foraging stations and foraging methods of Black-capped Chickadees i n three d i f f e r e n t habitats i n Maine. Two studies have been made of the comparative foraging ecology of Black-capped and Chestnut-backed Chickadees; one i n the breeding season (Sturman, 1968) and one i n winter (Smith, 1967). In her study, c a r r i e d out i n a mixed forest (about 50% coniferous and 50% deciduous) near the Un i v e r s i t y of B r i t i s h Columbia campus i n Vancouver, Smith found that Black-caps foraged 76% of the time i n deciduous trees (598 spot-checks), while Chestnut-backs foraged 84% of the time i n conifers (327 spotchecks). Black-caps foraged at much lower mean heights than Chestnut-backs, and spent more time on tree trunks and large limbs. Sturman con-curred with these fin d i n g s , and also showed that Chestnut-backs foraged - 114 more i n the forest canopy, while Black-caps foraged more i n the sub-canopy; that Chestnut-backs fed more from f o l i a g e and cones, while Black-caps fed more from bark; and that Chestnut-backs used a hanging posture and fed from the underside of branches and twigs more often than Black-caps. In the present study, only 14 observations (146 seconds) were made on Chestnut-backed Chickadees, of which 10 (116 sec.) were on the 43rd and C h u r c h i l l p l o t ; 10 observations (68 sec.) were i n autumn. A l l foraging was i n trees, 71.2% i n deciduous trees and 28.8% i n con i f e r s . The use of conifers was probably much higher than the data suggest, and clo s e r to that found by Smith (1967); h a l f the t o t a l foraging time (72 sec.) was accounted for by two observations i n deciduous trees. Nonethe-l e s s , the r e s u l t s corroborate those of Smith and Sturman i n that Chestnut-backs used conifers much more than Black-caps (29% of foraging time vs. 14%), and also foraged at greater heights (20.5% of time above 30 feet, compared with 7.1% for Black-caps). Several studies of parid foraging and feeding ecology i n Europe (e.g., Gibb, 1954, 1960; Palmgren, 1932; Haftorn, 1956) have included observations on the Willow T i t , which has t r a d i t i o n a l l y been considered co n s p e c i f i c with the Black-capped Chickadee. However, differences i n plumage and behaviour, inc l u d i n g rather d i f f e r e n t foraging ecology, sug-gest to me that these two forms should not be considered consp e c i f i c . For example, food-caching i s very common i n the.Willow T i t (Haftorn, 1956) but not i n the Black-capped Chickadee. Snow (1967) has recently elevated the.Willow T i t to the rank of a f u l l species. White-crowned Sparrow - Most observations were made on.the Ferguson Road p l o t ; observations were w e l l - d i s t r i b u t e d through autumn, winter, and spring (none i n summer) and through d i f f e r e n t times of day. Most or a l l of these observations r e f e r to the Gambel's White-crown.(Zonotriahia leucophrys gambelii)3 which migrated i n flo c k s through a l l the plot s and wintered on the Ferguson Road plot;,no observations referred c e r t a i n l y to the Puget Sound White-crown (Z. L. pugetensis)3 which breeds commonly in-the Vancouver area but not on the study p l o t s . White-crowned Sparrows made heavier use of sparse grass, i . e . , weed patches (45.0% of t o t a l foraging time) than any other of the commoner species; loose earth (14.8%) was also heavily u t i l i z e d . Use of sidewalks was also considerable (12.6% o v e r a l l , but 38.1% on the 43rd and C h u r c h i l l p l o t ) . According to Martin, Zim, and Nelson (1951), plant materials make up 96% of the d i e t i n f a l l and 99% i n winter, but only 64% i n summer. In a sample of 540 White-crown stomachs from the P a c i f i c States (mostly C a l i f o r n i a ) , 464 of which were taken i n autumn and winter, the major plant foods were pigweed (10% to 25% of t o t a l food volume) and oats (5% to 10%). Berries of nightshade and, blackberry and the seeds of.annual bluegrass and 6 species of weeds each made up 2% to 5%. The animal foods were . mainly insects (Hymenoptera, Lepidoptera, Coleoptera, etc.) and spiders. De Wolfe ( i n Bent, 1968), describing the food of 90 White-crowns taken i n C a l i f o r n i a , reported that 68 contained 100% plant material, while only 22 contained any in s e c t s ; no insects at a l l were found i n the stomachs of the 30 birds taken from September through A p r i l . 116 White-crowns'usually remain close to shrubbery when foraging (although le s s so than Song Sparrows), which may p a r t l y explain the importance of loose earth. The birds foraging on sidewalks on the 43rd and C h u r c h i l l p l o t were apparently picking up b i r c h seeds, which must, have been more.easily v i s i b l e there. The heavy use of sparse grass by White-crowns i s c l e a r l y connected with the importance i n t h e i r d i e t of seeds, as indicated by the food-habits studies. The Golden-crowned Sparrow, l i k e the Gambel's White-crown, was a migrant on a l l four,plots and a winter resident on the Ferguson Road p l o t . Fourteen stopwatch observations (1415 sec.) of Golden-crowns were obtained, 9 of them (1144 sec.) on the Ferguson Road p l o t ; most were i n winter (5 observations, 580 sec.) or spring (6 observations, 515 s e c ) . Their f o r -aging patterns were nearly i d e n t i c a l to those of White-crowns,on both the Ferguson Road and 43rd and C h u r c h i l l p l o t s , and the two species usually foraged together i n mixed f l o c k s . F i f t y - n i n e per cent of the. Golden-crown's o v e r a l l foraging time was i n sparse grass, 16% on loose, earth, and most of the remainder on lawn. House Finch - The 35 House Finch observations were d i s t r i b u t e d f a i r l y evenly among the four macrohabitats (although most were made outside the plots) and among the four seasons (Appendix XXIII); most observations were made before 10:00. House Finches foraged on the ground, above ground i n herbaceous vegetation, and i n trees. Ground foraging accounted f o r 60.0% of the o v e r a l l foraging time. As for thetother finches studied, use of sparse grass was heavy (19.4%), even i n the t y p i c a l r e s i d e n t i a l habitat where 117 t h i s microhabitat was scarce (49.4% of 1044 seconds of observation). Nearly a l l the rest of the ground foraging was on lawns. Most of the tree foraging was during the winter at medium heights (10 to 30 feet) i n birches, whose seeds the birds ate. The observations i n herbaceous plants (10.0% of foraging time) were a l l i n patches of t a l l weeds near the Ferguson Road p l o t . Feeders were used only i n winter and spring, but accounted for 8.1% of foraging time, more than for any other species; even so, t h i s figure i s probably a gross underestimate. House Finches were c l e a r l y very dependent on feeders i n winter, and the large numbers noted by Shepard on the 33rd and Dunbar pl o t occurred mainly i n one block which had several feeders. In t h i s connection, i t should be noted that the House Finch has only recently extended i t s range into south-western B r i t i s h Columbia (reviewed by Edwards and S t i r l i n g , 1961), and the presence of b i r d feeders may be very important to i t s survival,over the winter, as appears to be the case f o r the introduced House Finch population i n the eastern United States ( E l l i o t t and Arbib, 1953). Beal (1907) made a de t a i l e d study of the foods of House Finches i n southern C a l i f o r n i a , based on the contents of 1206 stomachs. Weed seeds made up 86% of the t o t a l , f r u i t 11%, animal food 2%, and miscel-laneous items 1%. The main animal foods were Homoptera, Lepidoptera, and Coleoptera. Martin, Zim and Nelson (1951) give the percentage of plant food in.1163 stomachs as ranging from 92% i n spring to v i r t u a l l y 100% i n autumn and 99% i n winter. In 849 stomachs from C a l i f o r n i a , w e l l -d i s t r i b u t e d throughout the year, the major plant foods were seeds of f i l a r e e (25% to 50% of the t o t a l ) and of turkey-mullein and mustard (each 118 10% to 25%). Figs and prunes and the seeds of 6 other weed species were also important. Several other c u l t i v a t e d f r u i t s are also eaten (Bent et a l . , 1968). In Denver, Colorado, however, Bergtold (1913) noted that domestic garbage (bread, apples, oranges, etc.) and even,suet from b i r d -feeders was often eaten. Eleven,observations of House Finch foods, i n v o l v i n g 18 b i r d s , were made during the present study (Table 26). The most important items were b i r d seeds (4 observations, 4 b i r d s ) ; bird-seed from feeders (3 observations, 4 b i r d s ) ; and weed seeds (1 observation, 7 b i r d s ) . The fondness of House Finches for f r u i t s i s suggested by the observation of several dozen young bi r d s eating Saskatoon b e r r i e s (Amelanchier sp.) i n Queen Eliz a b e t h Park, a mile south of the 19th and Yukon p l o t , i n the early summer of 1968. The c l o s e l y - r e l a t e d Purple Finch appears to spend much less time foraging on the ground than the House Finch. Sixteen observations (694 sec.) were obtained on Purple Finches, of which 13 (597 sec.) were on the 43rd and C h u r c h i l l p l o t and the rest on the Ferguson Road p l o t . Twelve observations (566 sec.) were i n winter. Only 17.9% of the t o t a l foraging time was on the ground, about h a l f on lawn and h a l f on loose earth. Shrubs accounted f or 67.1%, and deciduous trees for 14.0%. Of 8 i n d i v i d u a l s (70 observations) whose food could be i d e n t i f i e d , 2 were feeding on choke-cherries and the remainder on the f r u i t of various,deciduous shrubs. Purple Finches seem to be much more highly frugivorous than House Finches during the winter. 119 Oregon Junco - The great majority of the 79 observations were made on the 19th and Yukon and 43rd and C h u r c h i l l p l o t s ; a l l but 10 were made i n autumn and winter; and a l l but 10 were made before 14:00. Ground foraging accounted for 76.4% of the t o t a l foraging time of Juncos; loose earth was used 29.8% of the time, a figu r e exceeded by no other species and approached only by Song Sparrows. Sparse grass (10.4%) was also favoured; both loose earth and sparse grass must be good sources of seeds, since most of the ground-foraging finches concentrate t h e i r foraging there. Arboreal foraging accounted for 14.2% of t h e . t o t a l f o r -aging time; feeders accounted for 6.6% (17.7% i n winter), second only to the House Finch. Nine observations, including 10 b i r d s , were made of Junco foods during the study. In every instance the food was seeds, mainly b i r c h seeds (4 observations, 4 birds) and seeds at b i r d feeders (3 observations, 4 b i r d s ) . Beal (1910), i n an analysis of 269 Oregon Junco stomachs taken mostly i n autumn and winter, reported that 24% of the food was of animal o r i g i n , and 76% of plant o r i g i n . Weed seeds made up 62% of the annual d i e t (95% i n September). According to Martin, Zim, and Nelson (1951), the percentage of plant material i n the food of C a l i f o r n i a birds ranged from 52% i n summer to 95% i n autumn. The animal food was mainly insects (Coleoptera, Hymenoptera, Orthoptera, etc.) and spiders. Major plant foods were oats and chickweed (each comprising 10% to 25% of the t o t a l food); and barley, pigweed, redmaids, and miner 1s l e t t u c e (each 5% to 10%) . - 120 Gashwiler and Ward (1968), studying the d i e t of 262 juncos c o l -l e c t e d i n partly-logged co n i f e r forests i n western Oregon, found that the annual d i e t was 51% plant and 49% animal. Animal foods made up only 5% i n February, but 90% i n June. Nearly a l l the animal food was insects (46% of the t o t a l ) , mainly Coleoptera (19%) and Hymenoptera (16%). Conifer seeds (mainly Douglas f i r ) were important i n the d i e t , i n contrast to the s i t u a t i o n i n C a l i f o r n i a a g r i c u l t u r a l areas; they t o t a l l e d 14% of the yearly d i e t . F r u i t s and seeds of shrubs (mainly Rubus spp.) made up 9 % o f the food, grass seed 10%, and weed seeds 17%. The above data i n d i c a t e that Juncos r e l y heavily on insect food during the summer, perhaps more than other ground-foraging finches; but i n winter they are almost e n t i r e l y seed-eaters, which agrees with the heavy e x p l o i t a t i o n of loose earth, sparse grass, trees, and feeders observed i n the present study. Song Sparrow - The majority of Song Sparrow observations were made on the 43rd and C h u r c h i l l and Ferguson Road p l o t s ; i n autumn and winter; and before 10:00 or a f t e r 14:00 (Table 25). Song Sparrows foraged on bare ground more (37.9% of t o t a l foraging time) than any other species; most of t h i s was loose earth (24.8%) and gravel (11.3%). Sparse grass was also important (16.6% of foraging time), e s p e c i a l l y i n the p a s t u r e - r e s i d e n t i a l habitat (43.5%). Nearly a l l the remaining foraging time was spent on lawns. Song Sparrows were never ob-served foraging above ground l e v e l . Although they often v i s i t b i r d -feeders, they were not seen to do so on the.study p l o t s . Song Sparrows usually forage near.shrubbery and often underneath i t , where they may be. 121 hard to see, so t h e i r use of loose earth may be even higher than the figures suggest. Judd (1901) states that the Song.Sparrow's di e t consists of 66% plant material and 34% animal material. Animal foods are mainly insects ( e s p e c i a l l y Coleoptera, Orthoptera, Hymenoptera, and Hemiptera) which make up h a l f the food between May and August. Plant foods are mainly weed seeds (50% of the t o t a l d i e t ) , with some grain and f r u i t s . The veg-etable portion of,the food, according to Martin, Zim and Nelson (1951), ranges from 54% i n spring to 92% i n autumn. Major plant foods i n the, northeastern United States (342 stomachs) were seeds of smartweed, b r i s t l e g r a s s , and ragweed ( e a c h l O to 25%) and of panicgrass (5% to 10%); and i n , C a l i f o r n i a (345 stomachs), pigweed (10% to 25%) and knotweed (5% to-10%). The resource u t i l i z a t i o n patterns of Song Sparrows were notably d i f f e r e n t from those of other p r i m a r i l y ground-foraging finches. Song Sparrows spent more time on loose earth, gravel, and lawn than White-crowned Sparrows, but less on sidewalks and sparse grass; more time on loose earth and gravel than House Finches i but none at a l l i n trees; much more time on lawn than Juncos, but none i n trees; and f a r more time on loose,earth than Savannah Sparrows, but less on lawns and t a l l grass (Table 23). These differences i n foraging patterns are accentuated by the differences i n seasonal occurrence and abundance of the f i v e species on the study p l o t s . Brewer's Blackbird - This species occurred r e g u l a r l y only on the Ferguson Road p l o t , and a l l observations were made on or near the p l o t . v-Hfet 122 ;^tS>s€rvations were made i n a l l seasons, with the most (16) i n summer and fewest (3) i n autumn (Appendix XXIII); most ;were made before 10:00. , Brewer's Blackbirds used sparse grass more (34.0% of o v e r a l l f o r -aging time) than any other species except the Zonotriohia sparrows. Their u t i l i z a t i o n of bare ground (18.2%, mainly loose earth and gravel) was also high, and was greatly exceeded only by Oregon Juncos and Song Sparrows. Nearly a l l the re s t of the foraging time was spent on lawn and pasture. Brewer's Blackbirds were the only passerine species I observed foraging by wading i n shallow water; however, the time spent there (0.5%, or 11 seconds) was t r i v i a l . Foraging i n shallow water by t h i s species has also been mentioned by Richardson (1947) and Williams ( i n Bent, 1958). Beal (1948) found that, of the food of 312 Brewer's Blackbirds taken throughout the year and;"representing e s p e c i a l l y the f r u i t and grain sections of southern C a l i f o r n i a , " animal matter made up 32% and plant matter,68%. The animal foods consisted of Lepidoptera (12%), other i n s e c t s , spiders, etc.; and the vegetable foods of grain (54%), weed seeds (9%), etc. In the food,of"908 specimens reported on by Martin, Zim and Nelson (1951), the plant component was 78% i n winter, but only 18% i n summer. In C a l i f o r n i a , the main plant food was oats (between 25% and 50%); che r r i e s , other grains, and weed seeds were of l e s s e r impor-tance. Corn was the main food (10 to 25%) of birds taken elsewhere i n the western United States, while oats made up 5% to 10%. Other d e t a i l e d studies of the food of Brewer's Blackbirds are those of Soriano (1931), Neff and Meanley (1957), and Orians and Horn (1969). The heavy use of sparse grass by Brewer's Blackbirds i n Vancouver 123 seems inconsistent with the r e l a t i v e unimportance of weed seeds i n the. d i e t indicated by the food-habits studies. However, i f one considers only observations on the Ferguson Road p l o t , Brewer's Blackbirds spent considerably l e s s time on sparse grass than did the two commonest ground-foraging finches (White-crowned and Song Sparrows). Much of the foraging on loose earth was among c a t t l e and barnyards; several authors (e.g., Rand, 1953; Heatwole, 1965) have shown that associating with c a t t l e may make foraging easier for an insectivorous b i r d . Northwestern Crow - Only 4 of 22 observations were made on the study p l o t s , but most were i n the well-wooded r e s i d e n t i a l habitat (12 observa-t i o n s , 1110 sec.) and the t y p i c a l r e s i d e n t i a l habitat (7 observations, 690 s e c ) . F i f t e e n of 22 observations were made i n summer and autumn, and 19 were made before 14:00. Crows spent more time foraging on roads (13.9% of t o t a l foraging time) and on a l l paved surfaces combined (24.0%) than any other species except for Rock Doves. However, lawns accounted for most (57.5%) of the foraging time; loose earth (14.8%) was the only other important micro-habitat. Glaucous-winged Gulls probably spent even more ,time foraging on roads within the study p l o t s than did Crows, but the sample obtained on Gulls was too small to be u s e f u l . The varied d i e t of Crows i s well known.. Martin, Zim and Nelson (1951), give no information on the d i e t of Northwestern Crows, but that of Common Crows i s probably s i m i l a r . In a sample of 1340 Common Crows, they give the.proportion of plant food as ranging from 54% i n spring to 85% i n winter. In the eastern United States (606 stomachs), the plant 124 food i s mainly corn (25% to 50%), while other grains, acorns, and berr i e s are also important; on the P r a i r i e s (529 stomachs), mainly corn and wheat (each 10% to 25%) and sorghum (5% to 10%); and i n the P a c i f i c States (168 stomachs), mainly corn, wheat, walnuts, oats, and barley (each 10% to 25%). The animal foods included insects (Orthoptera, Colepptera, Lepidoptera, e t c . ) , myriapods, crustaceans, r e p t i l e s , amphibians, b i r d s ' eggs, and carr i o n . The a c t i v i t i e s of Crows as nest predators have been w e l l docu-mented (e.g., Jewett et a l . , 1953, p. 469), and i t must be pointed out that b i r d s ' eggs are probably eaten much more,often than studies of stomach contents would suggest, since the s h e l l s are usually not swal-lowed and the contents are quickly digested. N e s t l i n g birds are also eaten; on May 16, 1969, a Crow was seen attempting to k i l l a well-grown Robin n e s t l i n g on the,19th and Yukon p l o t , despite the attacks of the frenzied parents; and another Crow was seen on May 20, 1969 ju s t outside the 14th and Spruce p l o t with a small Robin n e s t l i n g which i t had prob-ably k i l l e d . I t appears that Robins s u f f e r because they are the only abundant urban birds which are not hole-nesters. Garbage and carrion are probably also more,important i n the die t of urban Crows than i n that of the r u r a l birds described i n the food-habits studies. Savannah Sparrow - Nearly a l l Savannah Sparrow observations were made on the Ferguson Road p l o t ; i n summer (6 observations) or autumn (13 observa-t i o n s ) ; and before,10:00 (Table 23). Savannah Sparrows made greater use of grass (85.3% of t o t a l f o r -aging time) than any other species except the S t a r l i n g . They spent f ar 125 more time foraging i n t a l l grass (23.6%) than any other species; i n r e a l i t y , the use of t a l l grass i s probably much higher than t h i s , since the very height of the grass makes i t d i f f i c u l t to see birds foraging there. They also made considerable use of gravel road edges (8.4%), but l i t t l e use of roads themselves. The Savannah Sparrow, according to food-habits studies, i s more highly insectivorous than most finches. Judd (1901) found that the year-round food was 46% animal and 54% vegetable; insects alone made up 43%, mostly Coleoptera (15%), Lepidoptera (9%), and Orthoptera (8%). Martin, Zim and Nelson (1951) show the animal food as ranging from 8% i n winter to 74% i n summer. Weed seeds make up most of the plant food; i n the northeastern United States (113 stomachs, mainly spring, summer, and autumn), these included b r i s t l e g r a s s and crabgrass (each between 10% and 25% of the t o t a l food) and ragweed and panicgrass (each 5% to 10%). In 128 C a l i f o r n i a stomachs (112 taken i n autumn and winter), the main seeds were knotweed, turkey-mullein and pigweed (each 10% to 25%) and oats (5% to 10%). Quay (1957) found that the food of Savannah Sparrows wintering i n North Carolina was 97% vegetable; crabgrass seeds alone comprised 70% of the food., During the breeding season, Savannah Sparrows on the Ferguson Road p l o t occurred throughout the pasture areas (although perhaps more, where the grass w a s , t a l l e r ) , and probably fed mainly on i n s e c t s . However, migrant f l o c k s seen i n spring and autumn (e.g., 71 on 24 A p r i l 1969) con-centrated on roadside patches of sparse grass, and were apparently eating weed seeds. 126 Cody (1968), i n a study of.the ecology of.grassland b i r d s , found that Savannah Sparrows were more e x c l u s i v e l y ground feeders than other species i n the same habitat. Brown-headed Cowbird - Most observations (14 out of 22) were on the Ferguson Road p l o t ; nearly a l l were i n summer,(19) and before 10:00 (18). The o v e r a l l foraging pattern of Cowbirds was s i m i l a r to that of Brewer's Blackbirds, although the 8.2% use of paved surfaces by Cowbirds was a l l i n the Vancouver c i t y p l o t s , where Brewer's did not occur. The use of loose earth by Cowbirds (14.7%) was greater than that by Brewer's Blackbirds, and was s u b s t a n t i a l l y exceeded only by Oregon Juncos and Song Sparrows. The high use of loose earth, as with Brewer's Blackbirds, i s p a r t l y accounted for by a foraging association with c a t t l e i n barn-yards. The use of sparse grass (7.3%) was much less than that by Brewer's Blackbirds (34.0%). The foraging pattern of Red-winged Blackbirds appeared to be s i m i l a r to that of Cowbirds and Brewer's Blackbird (21% of t o t a l foraging time on bare ground, 73% on grass) although only 7 obser-vations (428 sec.) on Red-wings were made, a l l on or near the Ferguson Road p l o t . ' In l a t e summer, a l l three b l a c k b i r d species often foraged i n mixed' fl o c k s along Ferguson Road, occasionally joined by one or two Yellow-headed Blackbirds from a nesting colony i n a nearby marsh. According to Beal (1900), who examined 544 Cowbird stomachs, the food i s 22.3% animal and 77.7% vegetable. The animal food was mainly i n -sects (Orthoptera alone made up 11%), with some spiders and s n a i l s . Grain (oats, corn, wheat) comprised 16.5% of the food, but weed seeds accounted for more than 50%. 127 Martin, Zim and Nelson (1951) give the plant component of the Cowbird's d i e t as 48% i n summer, increasing to 94% i n winter. In the northeastern United States, the major plant foods included b r i s t l e g r a s s , ragweed, and oats (each 10% to 25%) and corn,(5% to 10%); i n the western United States, they included b r i s t l e g r a s s (25% to 50%) and oats (5% to 10%) . In view of the high degree of overlap found by Orians and Horn (1969) i n both the die t s and foraging habitats of Brewer's, Red-winged, and Yellow-headed Blackbirds i n eastern Washington, the apparent s i m i l a r -i t y i n the foraging pattern of Cowbirds, Brewer's Blackbirds, and Red-wings i n the present study i s of i n t e r e s t . The comparative foraging ecology of blackbirds would make a worthwhile object of study i n other parts of North America. Pine S i s k i n - Only 8 of 36 observations were on the study p l o t s , but most were i n the heavily-wooded r e s i d e n t i a l habitat (15, t o t a l l i n g 556 sec.) and the apartment habitat (14, t o t a l l i n g 391 s e c ) . Most observations were made i n the spring (29) and a f t e r 14:00 (23). Pine^Siskins spent more,of t h e i r foraging time i n trees (81.7%) than most other finches studied, mostly i n deciduous trees (75.1%). Ground foraging was almost e n t i r e l y on lawns (17.8%). Foraging i n trees covered a wide range of heights, and considerable time was spent even at heights of 40 feet or more (16.0% of t o t a l foraging time, i n 6 observa-t i o n s ) . No other common birds foraged so frequently at,these heights. Martin, Zim and Nelson (1951), give the Pine Siskin's food as ranging from 19% vegetable i n summer to 90% i n winter (304 stomachs). 128 The animal food i s mainly insects (Lepidoptera, Hemiptera, Diptera, e t c . ) , and spiders. The main plant foods of 105 Siskins from the western United States (mainly C a l i f o r n i a ) were seeds of f i l a r e e (25% to 50%), pine (5% to 10%), and alder, eucalyptus, s t a r t h i s t l e , miner's l e t t u c e , and sunflower (each 2% to 5%). In New York, McAtee (1926) l i s t e d the main foods as seeds of c o n i f e r s , alders, birches, and weeds ( e s p e c i a l l y ragweed). Bent (1968) also l i s t s t h i s t l e and dandelion seeds and elm buds among the foods. General observations i n the Vancouver area suggest that seeds of red alder, birches, and western red cedar are favoured i n winter by Si s k i n s , although weed seeds are also eaten. S p e c i f i c observations of foods were made i n 7 instances (39 b i r d s ) . The food items were b i r c h seeds (3 cases, 8 b i r d s ) ; alder seeds (2 cases, 7 b i r d s ) ; and maple buds (2 cases, 24 b i r d s ) . The birds attacking maple buds may a c t u a l l y have been eating i n -sects i n s i d e the buds. Only a few observations were obtained on two finches c l o s e l y re-lated to Pine S i s k i n s , the American Goldfinch (10 observations, 1017 sec.) and the Common Redpoll (4 observations, 115 s e c ) . A l l observations of Redpolls were i n b i r c h trees; however, Goldfinches appeared to be less arboreal i n t h e i r foraging than Siskins (30% of foraging time i n deciduous trees, 43% on the ground, almost e n t i r e l y lawns, and 18% i n herbaceious vegetation, i . e . , t a l l weeds). A l l three species frequently forage to-gether i n mixed fl o c k s during the winter. Common Bushtit - A l l observations were made i n the heavily-wooded residen-t i a l h a b i t a t , most of them on the 43rd and C h u r c h i l l p l o t . Most observa-tions were made i n winter or spring, and most were between 10:00 and 129 •14:00 (Appendix XXIII). Bushtits spent nearly h a l f t h e i r foraging time (43.9%) i n shrubs, f a r more than the Black-capped Chickadee, the only other insectivorous species which made s i g n i f i c a n t use of shrubs (6.4% of t o t a l foraging time). Purple Finches (see under House Finch) spent 67% of t h e i r foraging time i n shrubs, but ate b e r r i e s rather than i n s e c t s . When foraging i n shrubs, Bushtits spent most of t h e i r time (52.2%) at heights of less than 5 feet. Even when foraging i n trees, Bushtits tended to forage at lower heights than any other arboreal-foraging species; of the 43.4% of t o t a l time i n deciduous trees, 74.2% was at heights of les s than 20 feet, and of the 12.7% of t o t a l foraging time i n evergreens, 61.4% was at l e s s than 10 fBet. Beal (1907), reporting on the contents of 353 Bushtit stomachs from C a l i f o r n i a , found that the food was 81% animal and 19% plant. The animal food was e n t i r e l y insects and spiders. Bugs (Hemiptera and Homop-tera) made up 44% of the t o t a l food; Lepidoptera, 16%; and Coleoptera, 10%. The plant food was l a r g e l y u n i d e n t i f i a b l e , but i t included l e a f g a l l s , poison-oak b e r r i e s , and a few kinds of seeds. Bushtits appear to be mainly insectivorous even i n winter; Martin, Zim and Nelson (1951) give the percentage of plant food as 33% i n winter and 27% i n autumn. Balda (1969) studied the foraging ecology of Common Bushtits and other species i n the oak-juniper woodlands of southeastern Arizona. He found that, i n comparison with the crown volume a v a i l a b l e for foraging, lower heights were greatly overused, and greater heights underused. Foraging was concentrated at heights of 10 to 20 fe e t , but on occasion 130 ranged up to 40 feet. Another titmouse resident i n the area, the Bri d l e d Titmouse, had a very s i m i l a r foraging pattern; Balda suggested that appreciable competition might e x i s t between the two, p a r t i c u l a r l y since several instances of i n t e r s p e c i f i c aggression were noted. By way of con-t r a s t , the three species of titmice wintering on the 43rd and C h u r c h i l l p l o t showed a neat segregation of foraging patterns, with Black-capped Chickadees concentrating on the deciduous trees, Chestnut-backed Chickadees on"the c o n i f e r s , and Common Bushtits on the shrubs. The Long-tailed T i t of Europe, while not c l o s e l y r e l a t e d to the Common Bushtit, shows several s t r i k i n g s i m i l a r i t i e s not only i n foraging ecology but also i n behaviour and morphology (see Hartley, 1953; Gibb, 1954, 1960). Golden-crowned Kinglet - Most observations were made on the 43rd and C h u r c h i l l p l o t (20 out of 30); i n , s p r i n g (21); and between 10:00 and 14:00 (21). Golden-crowned Kinglets spent much more time (56.5% of t o t a l ) i n evergreen trees, e s p e c i a l l y c o n i f e r s , than any other species except Red-breasted Nuthatches (54.8% of 257 sec.; 13 observations) and Brown Creepers (55.0% of 207 s e c ; 14 observations). The two l a t t e r species, however, forage mainly on large limbs and trunks (St a l l c u p , 1968; Gibb, 1954; Willson, 1970) while Golden-crowned Kinglets forage mainly i n f o l i a g e t i p s (Morse, 1967b, 1970). The closest competitor of the Golden-crowned Kinglet, i n f a c t , i s probably the Chestnut-backed Chickadee (see below). Golden-crowned Kinglets foraged at greater heights than e i t h e r Black-capped or Chestnut-backed Chickadees; 45.8% of t h e i r t o t a l foraging 131 time was at heights of 20 feet or more,(cf. 28.0% f o r Black-capped Chicka-dees and 32.9% for Chestnut-backed Chickadees), and 16.1% at 30 feet or more. L i t t l e i s known about the food of Golden-crowned Kin g l e t s , but they apparently eat animal food (mainly insects) almost e x c l u s i v e l y . Bent'(1949) l i s t s Coleoptera, Hymenoptera, Hemiptera, Diptera, Lepidoptera, Orthoptera, and spiders among the foods u t i l i z e d . Beal (1907) examined 9 Golden-crowned Kinglet stomachs from C a l i f o r n i a , but said only that the food was of 100% animal o r i g i n , and that the composition of the insect d i e t was s i m i l a r to that of the Ruby-crowned Kinglet. The die t of 294 Ruby-crowns examined by Beal was 94% animal and 6% vegetable; of major importance were Hymenoptera (32%); Hemiptera and Homoptera (26%); Diptera (17%); and Coleoptera (13%). Ruby-crowned Kinglets apparently d i f f e r from Golden-crowns i n eating appreciable amounts of plant material, e s p e c i a l l y in-winter; Beal noted b e r r i e s , l e a f g a l l s and weed seeds. Golden-crowned Kinglet foraging ecology has been studied, both i n summer and winter, by Morse (1967a, 1967b, 1970). In a summer.study i n Maine spruce forest containing some birches (Morse, 1967b), the ki n g l e t s spent more time (99.2%) i n spruces than any of f i v e warbler species studied. The mean foraging height of k i n g l e t s was about 26 feet, compared with a l i t t l e l e s s than 20 feet i n the present study. The winter foraging patterns (Morse, 1970) are complicated by differences between habitats and geographic regions, but Golden-crowned Kinglets consistently concentrated on"conifers and on f o l i a g e t i p s . Gibb (1954, 1960) studied the Goldcrest, a c l o s e l y - r e l a t e d species 132 of s i m i l a r ecology, i n England. In deciduous forest (Gibb, 1954), Gold-crests foraged more cons i s t e n t l y i n twigs of trees and shrubs than f i v e of the s i x species of titmice present. S u r p r i s i n g l y , they used shrubs and herbs more than any of the s i x , and foraged at lower heights than most. In a coniferous p l a n t a t i o n , however, where Goldcrests were common perma-nent residents (Gibb, 1960), they foraged at greater heights, and foraged more.often i n l i v e f o l i a g e , than any of the t i t s . On the basis of both foods, and foraging patterns, Gibb concluded that considerable competition probably occurred between Goldcrests and Coal T i t s (the commonest t i t i n the p l a n t a t i o n ) . An analogous s i t u a t i o n may e x i s t i n P a c i f i c Northwest con i f e r forests with respect to the Golden-crowned Kinglet and Chestnut-backed Chickadee, which are both very common permanent residents; compe-t i t i o n between the two may be reduced by a greater concentration of kin g l e t s on the f o l i a g e t i p s . Only 13 observations, t o t a l l i n g 76 seconds, were made on Ruby- crowned Kinglets i n the present study. Eleven of these (62 sec.) were.on the 43rd and C h u r c h i l l p l o t , and 9 (47 sec.) i n spring. Ruby-crowns, unlike Golden-crowns; spent 97% of t h e i r foraging time i n deciduous trees and only 3% i n coni f e r s ; t h i s i s probably t y p i c a l of wintering and migrat-ing (but not of breeding) Ruby-crowns (see Morse, 1967b). S i x t y - s i x per cent of Ruby-crown foraging was at less than 20 feet, but 5% at more than 40 feet. Warblers - Most observations:on Audubon's Warblers were made on the 43rd and C h u r c h i l l p l o t ; i n spring; and before 10:00 (Appendix XXIII). Audubon's Warblers foraged both on the ground and i n trees. 133 Ground foraging, a l l on lawns,'accounted for 31.2% of the t o t a l foraging time, although occurring i n only 5 observations. Sixty-seven point s i x per cent of the time was spent i n deciduous trees, and only 1.2% i n evergreens; 31.5% of the time was spent at heights of 20 feet or more, and 17:1% at 30 feet or more. Only Pine Siskins has a foraging pattern at a l l s i m i l a r to Audubon's Warblers, but Siskins are l a r g e l y seed-eaters, while the warblers are insectivorous. Black-capped Chickadees avoided the ground and spent much more time i n evergreens than Audubon's Warblers. In any case, Audubon's Warblers were present i n numbers on the study plots only for short periods during migration; t h i s would greatly reduce the p o s s i -b i l i t i e s f o r i n t e r s p e c i f i c competition. Beal (1907) reported on the stomach contents of 383 Audubon's Warblers taken i n C a l i f o r n i a . The food was 85% animal and 15% vegetable. Hymenoptera (mostly ants) constituted 26%; bugs (Hemiptera and Homoptera) 20%; Diptera, 16%; and Lepidoptera, 14%. The plant food included poison-oak and sumac b e r r i e s , f i g s and weed seeds. According to Martin, Zim and Nelson (1951), plant food i s not taken i n spring and summer, but makes up 24% of the food i n autumn and 28% i n winter. In view of the widespread i n t e r e s t i n warbler foraging ecology (see MacArthur, 1958; Morse, 1967a, 1967b, 1968, 1970, 1971; Root, 1967; Balda, 1969), i t seems worthwhile to mention b r i e f l y the foraging pat-terns of several species f o r which the sample sizes are too small to warrant a d e t a i l e d a n a l y s i s . Orange-crowned Warblers were observed 14 times (294 s e c ) . Seven 134 observations (165 sec.) were on the 19th and Yukon p l o t , and 5 (37 sec.) on the 43rd and C h u r c h i l l p l o t . Five observations (112 sec.) were i n l a t e summer and 9 (182 sec.) i n autumn. A l l foraging was i n deciduous trees at heights of between 10 and 30 feet; 62% of the time was.at 20 feet or more. The absence of ground foraging was i n contrast with Audubon's Warblers. A l l of the 10 observations ' (136 sec.) on Myrtle Warblers were i n spring on the 43rd and C h u r c h i l l p l o t . Their foraging pattern was sim i -l a r to that of Audubon's Warblers; but foraging on lawns, although occur-r i n g i n only two observations,,accounted f o r 60% of the t o t a l foraging time. The remaining 40% was i n deciduous trees between heights of 10 and 40 feet. Only 10 observations (77 sec.) were made on Black-throated Gray  W a r b l e r s 6 of them (42 sec.) on the 14th and Spruce p l o t and 4 (35 sec.) on the 43rd and C h u r c h i l l p l o t . Three observations (29 sec.) were i n spring and 6 (42 sec.) i n l a t e summer. A l l foraging was i n deciduous trees at heights of 20 feet or more; 40% at 30 feet or more; and 14% at 40 feet or more. This suggests that migrant Black-throated Gray Warblers may forage at greater heights than other warblers. The frequency of ground foraging by Audubon's and Myrtle .Warblers . noted, i n t h i s study agrees with the findings of MacArthur (1958). In studying the comparative foraging ecology of f i v e congeneric species of warblers breeding i n New England conifer forests., MacArthur found that Myrtle Warblers spent 28% of t h e i r foraging time (but only 13% of observa-tions) within 10 feet of the ground, far more than any other species. He 135 reported that terrestrial foraging by Myrtle Warblers was mainly for crane f l i e s (Tipulidae). Of the five warblers, the Myrtle had the most varied foraging habits ( i . e . , was least restricted to certain microhabitats). My observations, both during the present study and at other times, suggest that MacArthur's characterization of the Myrtle .Warbler as a species which is " . . . less specialized and thus more flexible in i t s require-ments" applies also to the Audubon's Warbler, Morse (1970) studied the foraging ecology of Myrtle Warblers in Louisiana during the winter and in Maine during the summer. In both areas, the birds foraged, most frequently on the outer foliage at heights of 30 feet or less; in Maine, they also foraged on dead trees more than most other warblers. In Louisiana, Myrtle Warblers concentrated on.dedid-uous trees (Morse, 1967a), as did transient Myrtles and Audubon's i n . Vancouver; but on the Maine breeding grounds, they foraged exclusively in conifers (Morse, 1967b, 1970). A study of the foraging ecology of winter-ing and breeding Audubon's Warblers would probably reveal similar patterns. (b) The importance of individual microhabitats to terrestrial-foraging birds In the species accounts above, a general summary has been given of each species' foraging pattern, and some interspecific comparisons have been made. One way in.which these comparisons may be brought into sharper relief is to compare the per cent of a species' total foraging time spent in a given microhabitat with the availability of that micro-habitat in each of the study plots ( i . e . , the percentage of total area covered by the microhabitat). This is possible for terrestrial 136 Table 33. U t i l i z a t i o n of Individual Microhabitats by T e r r e s t r i a l - f o r a g i n g Birds NOTE: In each box, three figures are given. The upper figure i s the per-centage of t o t a l foraging time spent i n the microhabitat; the lower f i g -ures are the t o t a l number of seconds and the number of stopwatch observa-tions of the species foraging i n that microhabitat. Figures for percentage of foraging time are based on t o t a l foraging, not on t e r r e s t r i a l foraging only. Most species here considered foraged on the ground nearly 100% of the time (see Table 23). Species l i s t e d here are only those whose use of a microhabitat ex-ceeded the a v a i l a b i l i t y . Only species which were observed f i v e or more times i n a microhabitat are included. (a) Loose earth Plot 14th & Spruce 19th & Yukon 43rd & C h u r c h i l l Ferguson Road Extent of microhabitat T o t a l use -a l l species 2.9% 6.3% 4.3% 6.4% 10.0% 9.1% 5.2% 17.6% House Sparrow 6.2% (3016, 75) 4.4% (3762, 109) 87.4% (880, 18) Oregon Junco 3.3% (521, 9) 38.2% (1263, 30) 42.2% (733, 29) Song Sparrow 17.1% (1336, 15) 37.7% (1000, 16) Red-wngd Bl c k b i r d 26.9% (327, 6) Brn-headed Cowbird 26.2% (818, 14) Whte-crwnd Sparrow 19.5% (1596, 32) Gldn-crwnd Sparrow 19.1% (1144, 9) Robin 11.1% (3419, 28) 8.7% (8140, 83) 10.3% (3156, 31) 137 (Table 33 - continued) (a) Loose earth (continued) Plot 14th & Spruce 19th & Yukon 43rd & C h u r c h i l l Ferguson Road Brewer's Blackbird 11.0% (1661, 27) S t a r l i n g 6.6% (5119, 85) K i l l d e e r 5.9% (1354, 11) Crested Mynah 5.8% (189, 6) (b) Hard earth Plot 14th & Spruce 19 th & Yukon 43rd & C h u r c h i l l Ferguson Road Extent of microhabitat T o t a l use -a l l species < 1% 0.4% < 1% 0.1% < 1% N i l < 1% 0.7% Brewer's Blackbird 3.4% (1661, 27) Savannah Sparrow 2.0% (1326, 20) Rock Dove 1.4% (3430, 42) Whte-crwnd Sparrow 1.3% (1596, 32) 138 (Table 33 - continued) (c) Gravel Plot 14th & Spruce 19 th & Yukon 43rd & C h u r c h i l l Ferguson Road Extent of microhabitat T o t a l use -a l l species 12.8% 9.6% 7.7% 4.4% 5.7% 5.2% 3.6% 3.0% Rock Dove 17.5% (3430, 42) 18.7% (3743, 39) Song Sparrow 13.9% (1000, 16) House Sparrow 13.6% (3016, 75) Brewer's Blackbird 12.0% (1661, 27) Savannah Sparrow 10.0% (1326, 20) Robin 8.1% (6850, 85) (d) Road Plot 14th & Spruce 19 th & Yukon 43rd & C h u r c h i l l Ferguson Road Extent of microhabitat T o t a l use -a l l species 35.3% 8.4% 20.4% 9.3% 14.5% 5.1% 11.0% 1.3% House Sparrow 14.7% (394, 21) 139 (Table 33 - continued) (e) Sidewalk Plot 14 th & Spruce 19 th & Yukon 43rd & C h u r c h i l l Ferguson Road Extent of microhabitat T o t a l use -a l l species 12.7% 15.4% 6.7% " 7.3% 4.9% 11.8% N i l N i l Red-shftd F l i c k e r 77.2% (246, 5) Whte-crwnd Sparrow 38.1% (1072, 10) Crested Mynah 36.5% (1225, 17) Rock Dove 26.9% (3430, 42) 14.8% (3743, 39) House Sparrow 13.2% (2016, 75) 8.3% (3762, 109) 10.2% (394, 21) Robin 9.6% (6850, 85) Song Sparrow 9.0% (255, 6) (f) Lawn Plot 14th & Spruce 19 th & Yukon 43rd & C h u r c h i l l Ferguson Road Extent of microhabitat T o t a l use -a l l species 36.3% 55.4% 61.0% 64.5% 65.0% 66.7% 63.8% 49.3% Red-shftd F l i c k e r 83.7% (787, 7) 140 (Table 33 - continued) (f) Lawn (continued) Plot 14th & Spruce 19th & Yukon 43rd & C h u r c h i l l Ferguson Road Robin 81.9% (3419, 28) 76.4% (8140, 83) 66.0% (6850, 85) 76.5% (3156, 31) Hermit Thrush 80.7% (409, 9) S t a r l i n g 77.1% (1966, 39) 76.2% (5119, 85) 78.6% (1114, 14) 78.8% (1901, 22) Crested Mynah 53.6% (1225, 17) 77.5% (3630, 62) House Sparrow 42.4% (3016, 75) 70.6% (394, 21) Brn-headed Cowbird 70.4% (818, 14) Song Sparrow 70.2% (255, 6) 69.0% (1336, 15) (e) T a l l Grass Plot 14th & Spruce 19 th & Yukon 43rd & C h u r c h i l l Ferguson Road Extent of microhabitat T o t a l use -a l l species < 1% 0.3% < 1% 1.2% < 1% 1.2% ~ 8% 3.7% Crested Mynah 58.7% (189, 6) Song Sparrow 18.4% (255, 6) Oregon Junco 5.5% (1263, 30) 9.7% (733, 29) 141 (Table 33 - continued) (g) T a l l Grass (continued) Plot 14th & Spruce 19th & Yukon 43rd & C h u r c h i l l Ferguson Road Savannah Sparrow 9.4% (1326, 20) Whte-crwnd Sparrow 2.8% (1072, 10) S t a r l i n g 1.5% (5119, 85) (h) Sparse Grass Plot 14th & Spruce 19 th & Yukon 43rd & C h u r c h i l l Ferguson Road Extent of microhabitat T o t a l use -a l l species < 2% 4.1% < 2% 6.4% < 2% 0.5% ~ 8% 22.0% Whte-crwnd Sparrow 60.9% (412, 10) 76.8% (1596, 32) Gldn-crwnd Sparrow 72.6% (1144, 9) Song Sparrow 2.1% (1336, 15) 46.6% (1000, 16) Oregon Junco 13.1% (521, 9) 26.9% (1263, 30) K i l l d e e r 16.8% (1354, 11) S t a r l i n g 7.1% (1966, 39) 15.8% (1901, 22) 142 (Table 33 - continued) (h) Sparse Grass (continued) Plot 14 th & Spruce 19th & Yukon 43rd & C h u r c h i l l Ferguson Road House Sparrow 6.5% (3016, 75) 13.6% (3762, 109) Savannah Sparrow 12.7% (1326, 20) Rock Dove 4.3% (3430, 42) Shallow Water ) Miscellaneous t e r r e s t r i a l microhabitats ) 143 microhabitats, since the approximate percentage of area covered by each is known for each of the four study plots. The non-discrete nature of the stopwatch observations precludes the application of chi-square tests for differences between foraging patterns and habitat patterns, but this has been done on the spotchecks (for species with large samples). This treatment has not been possible for arboreal microhabitats; availability i s not known since the percentage of total crown volume in each level (see Balda, 1969) has not been calculated. Species were considered to be terrestrial foragers i f they spent more than 50% of their overall foraging time in ter r e s t r i a l microhabitats. The results have been arranged by microhabitat, and for each of the recognized microhabitats a table i s presented (Table 33, a-h) l i s t i n g a l l bird species for which the percentage foraging time exceeded the percen-tage of area covered by that microhabitat. (Species are not listed i f they were observed less than five times in the microhabitat in question.) In this way, l i s t s are presented of those species that concentrated on or "overused" each microhabitat. To supplement these tables, general remarks w i l l be made on the kinds of food li k e l y to be available to the birds in each microhabitat. Loose earth - This microhabitat could not be distinguished from hard earth in the aerial photographs, but since the latter i s a rare feature in any of the plots, l i t t l e error i s introduced by this limitation. As explained in the section on microhabitat composition, i t was possible to obtain at least crude approximations of the area covered by loose earth from the aerial photographs. 144 Loose earth was usually located beneath trees, shrubs or herbs, and would thus be favoured by b i r d s which prefer to forage under cover. On the Ferguson Road p l o t , however, much of the loose earth was i n the open i n barnyards, and was kept loose by the a c t i v i t i e s of l i v e s t o c k . Loose earth i s probably a good microhabitat for both insects and seeds. The enhanced v i s i b i l i t y of both due to the lack of obscuring vegetation should be advantageous to foraging b i r d s . Foraging f o r sub-surface organisms should be favoured because of the softness of the surface. When the t o t a l s for a l l species are considered, i t i s apparent that loose earth accounted for a disproportionately large share of foraging time on three of the four p l o t s , with a peak for the Ferguson Road p l o t . The e s p e c i a l attractiveness of loose earth here can be a t t r i b u t e d l a r g e l y to the presence of l i v e s t o c k , which probably disturbed insects which were then captured by b i r d s , and which also l e f t dung con-t a i n i n g edible grain. Hard earth - The percentage coverage of hard earth could not be determined exactly, but was estimated to be less than 1% on a l l the study p l o t s . Hard earth i s probably a poor substrate for foraging, since i t i s too hard-packed to permit digging, and since i t i s usually located i n the open where there would be few f a l l e n seeds or i n s e c t s . , The t o t a l u t i l i z a -t i o n of hard earth by a l l species was n e g l i g i b l e , and i n a l l cases well below the 1% estimated extent for the habitat. 145 Gravel - The value of gravel as a foraging substrate i s again much les s than that of loose earth; digging i n gravel would be d i f f i c u l t , and the usual l o c a t i o n of gravel i n the open means that f a l l e n seeds and insects are probably scarce. Birds which forage on gravel, l i k e those using roads, seem to obtain garbage more often than anything e l s e . However, Song Sparrows and Savannah Sparrows, which made heavy use of gravel road edges on the Ferguson Road p l o t , were probably obtaining weed seeds from sparse grass (weed patches, etc.) which bordered the gravel. The use of gravel by a l l species combined was generally about equal to or l e s s than the area occupied by gravel on the various p l o t s . Road - Aside from garbage and c a r r i o n , roads o f f e r very l i m i t e d oppor-t u n i t i e s f o r foraging. Any food item (insect, seed, berry, etc.) which fi n d s i t s way onto a road must ultimately come from elsewhere, often by f a l l i n g from a tree. It i s not s u r p r i s i n g , therefore, that scarcely any b i r d species forage on roads to a degree comparable to the area covered by the roads (the s i n g l e species l i s t e d i n the table i s the House Sparrow, matching road coverage with foraging time on one p l o t ) . Roads are very much u n d e r - u t i l i z e d by ground-foraging birds i n general. The per cent of t o t a l foraging time by a l l species on roads was well below the area offered on a l l p l o t s . , Sidewalk - Sidewalks have several differences from roads which may be important to b i r d s . They are located beneath trees much more often than are roads, and are more l i k e l y to o f f e r f a l l e n seeds, acorns, i n s e c t s , etc. Also, they are usually bordered by lawn, a very productive 146 microhabitat, and there are frequently t u f t s of grass growing between the slabs of concrete making up the sidewalk. Despite t h e i r smaller extent, sidewalks are more often used for foraging than are roads. The reactions of birds to sidewalks varied from species to species. Robins, for' example, frequently foraged on sidewalks; S t a r l i n g s , on the other hand, when foraging on a lawn and reaching a sidewalk, would often run across the sidewalk without foraging, and resume foraging on the lawn on the opposite side. The heavy use of sidewalks by migrating White-crowned and Golden-crowned Sparrows on the 43rd and C h u r c h i l l p l o t was related to the e x p l o i t a t i o n of f a l l e n b i r c h seeds, which were easier to see on the pave-ment than on the adjacent lawns. The combined use by a l l b i r d species exceeded the a v a i l a b i l i t y of sidewalks on a l l three p l o t s containing sidewalks. Lawn - Even though lawns covered between 60% and 65% of the t o t a l area on three of the p l o t s , the use of lawns was disproportionately high for numerous species. Lawns seem to be a favourable habitat for seeds ( e s p e c i a l l y of weeds such as dandelions and plantains) and for t e r r e s t r i a l i n s e c t s , as w e l l as such subsurface organisms as cranefly larvae (which feed on grass roots) and earthworms. The o v e r a l l use.of lawns by a l l species was higher than or equal to the percentage coverage on three p l o t s , and lower on the remaining p l o t (Ferguson Road) although s t i l l accounting for about h a l f of a l l f o r -aging time there. 147 T a l l grass - This microhabitat probably occupied le s s than 1% of the area i n the study p l o t s , except f o r Ferguson Road where t a l l grass occupied a s t r i p on each side of the ditches along both sides of the road. Exact figures for t h i s p l o t cannot be given, since on the a e r i a l photograph t a l l grass could not be distinguished from sparse grass; to-gether, the two occupied 16.5% of the area. As a rough estimate, each was judged to constitute about h a l f of t h i s t o t a l . T a l l grass i s prob-ably favourable from the point of view of seed and insect a v a i l a b i l i t y , but i s l i t t l e used by b i r d s , perhaps owing to the d i f f i c u l t y of movement and to problems of r e s t r i c t e d v i s i o n . Percentage t o t a l foraging time ( a l l species) was l e s s than or about equal to the extent of t a l l grass on a l l p l o t s , although one heavy user of t a l l grass was i d e n t i f i e d (Crested Mynah). Sparse grass - Despite i t s small extent, sparse grass, which consisted l a r g e l y of weed patches, was very important to b i r d s , e s p e c i a l l y to seed-eating finches. On the Vancouver c i t y p l o t s , the extent of t h i s microhabitat was estimated at less than 2%, and on the Ferguson Road p l o t i t was estimated at about 8%. In both areas there were several heavy users of sparse grass, notably White-crowned, GoIden-crowned, and Song Sparrows and Oregon Juncos. The o v e r a l l u t i l i z a t i o n of sparse grass by a l l species was high, and exceeded the a v a i l a b i l i t y on three of the four p l o t s . , Shallow water - Shallow water (wading depth), i n the form of r a i n pools, was a temporary feature only on the study p l o t s , and covered a t r i v i a l 148 area. The only passerine bird seen.to forage in pools was the Brewer's Blackbird, which spent 0.7% of i t s foraging time on the Ferguson Road plot (1661 seconds,.27 observations) in shallow water. The Killdeer, however, spent 20.4% of i t s foraging time on this plot (1354 seconds, 11 observations) in shallow water. Total bird use of shallow water on the Ferguson Road plot amounted to only 0.4%, and use of this microhabitat was not observed elsewhere. Miscellaneous terrestrial microhabitats - These microhabitats (listed in. the Microhabitat Composition section) covered only a tiny area, and u t i l i z a t i o n for foraging was negligible. Total bird use was only 0.4% of overall foraging time. (c) Spotchecks The method of obtaining spotchecks has been described above., In analysing the spotchecks, however, i t i s possible to tabulate the results in two different ways. Since spotchecks were often made simultaneously on several individual birds in a flock, results may be tabulated according to either the number of individuals or number of flocks (considering each group of one or more individuals as a flock). Although for any species the percentages of individuals and of flocks foraging i n a given micro-habitat tend to be similar, the presence of large flocks in certain micro-habitats may cause discrepancies, sometimes large, to arise between the foraging patterns measured by the two methods. One would think that a bird foraging in a flock would be influenced in i t s choice of microhabitat by the other members of the flock, and that 149 therefore an observation of a b i r d foraging i n a f l o c k i s less meaningful than one of a.bird foraging alone. I t might be possible to s t r i k e a com-promise between the two methods of tabulating the r e s u l t s , such as taking the square root of the number of b i r d s i n a f l o c k ; however, t h i s would be a r b i t r a r y since the magnitude of the e f f e c t of other f l o c k members on the foraging of an i n d i v i d u a l i s unknown. Furthermore, t h i s may not be important from the r e s o u r c e - u t i l i z a t i o n point of view, providing that d i f f e r e n t - s i z e d flocks have been observed i n about the same proportions i n which they occur i n the study area. Therefore, although analyses of spotchecks using both methods were c a r r i e d out, only those based on spot-checks of i n d i v i d u a l s are presented here. The r e s u l t s of the spotchecks <.on i n d i v i d u a l s , given for each species as the percentage of the t o t a l numbers of spotchecks i n each microhabitat, are summarized i n Table 34. A l l species with 40 or more spotchecks have been included. This leaves the same s i x species (Robin, S t a r l i n g , Rock Dove, House Sparrow, Crested Mynah, and Black-capped Chickadee) which rated highest i n the number of stopwatch observations. The r e s u l t s of the spotchecks have not been broken down further according to macrohabitat, season, time of day, l o c a t i o n i n s i d e or outside the study p l o t s , or weather. The foraging patterns of most of the top s i x species indicated by the spotchecks are remarkably s i m i l a r to those revealed by the,stopwatch observations. The closeness of the correspondence i s p a r t i c u l a r l y note-, worthy when one remembers that the two sets of figures are based on e n t i r e l y independent samples. As one might expect, the foraging patterns 150 Table 34. D i s t r i b u t i o n of foraging time f o r species with largest number of observations, as indicated by spotchecks ( a l l microhabitats, each i n d i v i d u a l treated as i f independent). Figures show percen-tage of t o t a l spotchecks i n each microhabitat. Microhabitat American S t a r l i n g Common House Crested Black-capped code Robin Pigeon Sparrow Mynah Chickadee 01 2.6 1.5 3.8 2.9 2.1 02 0.2 5.4 1.2 03 2.7 1.9 16.1 7.8 4.4 04 7.1 5.9 25.3 7.6 8.7 05 10.5 4.4 19.9 19.8 13.0 06 74.8 82.4 29.0 55.0 65.2 07 0.4 1.2 8.7 08 1.2 1.1 0.5 3.1 09 10 0.3 14.9 11 0.4 0.6 36.2 12 0.3 0.2 10.6 13 14 15 16 4.3 17 8.5 18 8.5 19 2.1 20 21 4.3 22 23 24 0.2 6.4 25 26 0.3 1.7 0.2 27 0.4 28 29 2.1 Number of "spotchecks-:-. 588 478 186 489 69 47 For explanation of code, see Table 23. 151 based on spotchecks of Individuals correspond much better to those based on stopwatch observation than do those based on spotchecks of f l o c k s . The major differences between Table 34 (spotchecks on i n d i v i d u a l s ) and Table 23 (stopwatch observations) are as follows: Robin - The percentage of spotchecks on loose earth was smaller (2.6% vs. 8.5%); on roads, larger (7.1% vs. 3.1%); on sidewalks, l a r g e r (10.5% vs. 5.4%); and i n trees, smaller (0.6% vs. 2.4%). Percentages f o r lawn were nearly i d e n t i c a l (spotchecks, 74.8%; stopwatch observa-t i o n s , 74.7%). S t a r l i n g - Percentage f o r lawn were very s i m i l a r (spotchecks, 82.4%; stopwatch observations, 81.0%). Roads and sidewalks were more important i n the spotchecks, while t a l l grass and sparse grass were much less important (combined t o t a l , 1.5% vs. 4.5%), as were decid-uous trees (0.6% vs. 1.9%). Miscellaneous ground accounted for 1.7% of spotchecks, but l e s s than 0.1% of stopwatch time. Rock Dove - Differences were perhaps larger than f o r Robins and S t a r l i n g s , but were s t i l l not great. Loose earth was more important i n spotchecks (3.8%) than i n stopwatch observations (0.9%); sparse grass was les s important (0.5% vs. 5.3%). Figures f o r other major microhabitats were i n closer agreement. House Sparrow - Major differences were i n use of loose earth (2.9% of spotchecks, 11.6% of stopwatch observations), sidewalks (19.8% vs. 10.1%) and sparse grass (3.1% vs. 9.2%). Use of lawn was also greater i n the spotchecks (55.0% vs. 48.3%). Crested Mynah - Figures f o r the two types of observations were i n 152 very close agreement; the only major d i f f e r e n c e was i n use of t a l l grass (8.7% of spotchecks, 3.4% of stopwatch time). Black-capped Chickadee - The foraging patterns suggested by the two methods were quite s i m i l a r ; the only major d i f f e r e n c e was i n use of feeders (6.4% of spotchecks, but 1.9% of stopwatch time). Although the spotcheck data appear to i n d i c a t e a more l i m i t e d range of forag-ing heights i n trees (no observations at le s s than 5 feet or more than 40 f e e t ) , the main reason i s probably the small sample s i z e (only 47 spotchecks). Comparisons of foraging patterns measured by spotchecks of flocks with those measured by spotchecks of i n d i v i d u a l s show differences which are very small i n some species but larger for others. The large s t d i f -ferences were i n species which usually foraged i n groups (e.g., S t a r l i n g s and House Sparrows). These differences w i l l not be reviewed i n d e t a i l here. (i ) Comparison of foraging patterns with microhabitat a v a i l a b i l i t y For those species on which more than 40 spotchecks had been made on a p l o t , chi-square tests were c a r r i e d out to test whether the d i s t r i -bution of spotchecks among the various microhabitats was s i g n i f i c a n t l y d i f f e r e n t from the extent (or a v a i l a b i l i t y ) of the microhabitats on the p l o t ( i . e . , whether or not foraging was :at random). The figures used for microhabitat a v a i l a b i l i t y are those given i n Table 22. For purposes of t e s t i n g , the microhabitats were grouped i n t o the f i v e categories shown * See page 73. 153 i n the table; further lumping of categories was necessary i n a few i n -stances when carrying out the computations because of the small expected frequencies., Tests were done on the foraging patterns of i n d i v i d u a l s only. A l i s t of the tests performed, together with the r e s u l t s , i s shown,in Table 35. Nine of the ten comparisons showed highly s i g n i f i c a n t departures from random foraging (p < .01). The lone exception was the Crested Mynah on the 19th and Yukon p l o t , which had a foraging pattern not s i g -n i f i c a n t l y d i f f e r e n t (p > .05) from the d i s t r i b u t i o n of microhabitats i n the p l o t . I t should be noted, however, that the number of spotchecks on mynahs on t h i s p l o t was small (51), n e c e s s i t a t i n g the lumping of the f i v e microhabitat categories i n t o only three when performing the t e s t . I t seems reasonable to suggest that the apparent random foraging of the Crested Mynah on t h i s p l o t i s merely the outcome of inadequate f i e l d observation. The r e s u l t s of these t e s t s on the spotcheck data confirm the impression gained from the stopwatch observations; namely, that no species of b i r d forages at random, but that each tends to concentrate i t s foraging i n c e r t a i n microhabitats. ( i i ) Comparisons between foraging patterns of d i f f e r e n t species ( a l l macrohabitats) Chi-square tests f o r i n t e r s p e c i f i c d ifferences i n foraging pat-terns were c a r r i e d out f o r i n d i v i d u a l s only. I examined the data f o r a l l ground-foraging species on which 40 or more spotchecks had been made (Robin, S t a r l i n g , Rock Dove, House Sparrow, and Crested Mynah). The 154 Table 35. Results of chi-square tests on randomness of foraging species plot p-value n (spotchecks) Robin 19th & Yukon ** 218 Robin 43rd & Churchill ** 315 Starling 19th & Yukon ** 267 Starling 43rd & Churchill ** 74 Starling Ferguson Road ** 108 Rock Dove 14th & Spruce ** 73 Rock Dove 19th & Yukon ** 113 House Sparrow 14th & Spruce ** 71 House Sparrow 19th & yukon ** 386 Crested Mynah 19th & Yukon greater than .05 51 Distribution of foraging time and distribution of micro-habitats differ at the .01 level of significance. Table 36. Results of chi-square tests for interspecific differences in foraging patterns - a l l plots combined Robin Starling Rock Dove House Sparrow Robin Starling ** Rock Dove ** ** House Sparrow ** ** ** Crested Mynah ns * ** ns **, dif f e r at .01 level of significance. *, di f f e r at .05 level of significance, ns, not significantly different. Sample sizes are given in Table 35. 155 comparison of a l l possible p a i r s thus involved ten t e s t s . The only other species with adequate data was the Black-capped Chickadee, whose foraging pattern was obviously d i f f e r e n t i n being l a r g e l y arboreal, so that de-t a i l e d s t a t i s t i c a l comparison was not considered necessary. Tests were ca r r i e d out only f o r differences i n o v e r a l l foraging patterns, not for differences i n the use of i n d i v i d u a l microhabitats (cf. S t a l l c u p , 1968), as I did not consider the l a t t e r procedure worthwhile. The r e s u l t s of the ten t e s t s are shown.in Table 36. Eight of the ten comparisons showed s i g n i f i c a n t differences (p < .05); seven of these were highly s i g n i f i c a n t (p < .01). The two differences which were not s i g n i f i c a n t again involved Crested Mynahs (Crested Mynah vs. Robin and Crested Mynah vs. House Sparrow). In a l l p r o b a b i l i t y , t h i s i s merely the r e s u l t of an i n s u f f i c i e n t sample s i z e . Greater s i g n i f i c a n c e should be attached to the very small d i f -ference between S t a r l i n g s and Robins. Owing to the large sample sizes f o r both species, even t h i s small d i f f e r e n c e proved to be s t a t i s t i c a l l y s i g n i f i c a n t (.05 < p < .01). However, t h i s d i f f e r e n c e may not be b i o -l o g i c a l l y meaningful. An error of up to 5% i n the estimation of percentage foraging time can be admitted. I f we change the values for the R o b i n — i n c r e a s i n g the percentage for lawn by 5% and decreasing the values for other microhabitats p r o p o r t i o n a t e l y — t h e Starling-Robin d i f -ference i s no longer s i g n i f i c a n t . At any rate, t h i s d i f f e r e n c e i s quite small; the stopwatch data confirm t h i s . Furthermore, i n the tests on spotchecks of flocks (not considered i n d e t a i l here), the d i f f e r e n c e i n foraging pattern between these two species, despite large sample s i z e s , 156 was extremely small (p ~ .90). The ways i n which Robins and St a r l i n g s may avoid competition are examined both i n the Discussion and the General Discussion. 4. Discussion Many studies of the foraging ecology of birds have been c a r r i e d out on c l o s e l y - r e l a t e d , often congeneric, sympatric species (e.g., Gibb 1954, MacArthur 1958). Most investigators have f e l t that c l o s e l y -r e l a t e d species tend to compete with one another more than d i s t a n t l y -r e l a t e d ones. Assuming the truth of Gause's P r i n c i p l e , that two species with very s i m i l a r e c o l o g i c a l c h a r a c t e r i s t i c s cannot both p e r s i s t indef-i n i t e l y i n the same environment i f there i s a shortage of resources e s s e n t i a l to both, the object of such studies has been to discover the differences i n foraging ecology which permit such species to coexist. This approach, while of great i n t e r e s t from the evolutionary standpoint, i s of l i t t l e value i n studies of community energetics or resource u t i l i z a t i o n (Orians and Kuhlman, 1956), since other abundant and impor-tant species are ignored. Moreover, as pointed out by Crombie (1947), d i s t a n t l y - r e l a t e d species may often be serious competitors. A d i f f e r e n t approach was followed by Root (1967). Root proposed the term " g u i l d " f o r a group of species (not nec e s s a r i l y related) that e x p l o i t the same class of environmental resources i n a s i m i l a r way, and applied i t to foliage-gleaning birds i n a C a l i f o r n i a oak woodland. In a s i m i l a r way, the Robin, S t a r l i n g , Rock Dove, House Sparrow, and Crested Mynah could be considered members of the ground-foraging g u i l d i n 157 Vancouver urban habitats. The g u i l d concept, l i k e the "feeding groups" of Sa l t (1953, 1957) i s fun c t i o n a l rather than taxonomic i n o r i e n t a t i o n , and i s more u s e f u l i n community studies. It has been claimed by some authors (e.g., Lack, 1954, 1966) that food a v a i l a b i l i t y i s the major factor c o n t r o l l i n g populations of many species of b i r d s . However, much of the evidence advanced to support t h i s view has been u n c r i t i c a l and often i n d i r e c t . Nevertheless, most ecologists w i l l agree that food a v a i l a b i l i t y i s an extremely important e c o l o g i c a l f a c t o r which i s at l e a s t p o t e n t i a l l y capable of regulating a species' numbers. This i n i t s e l f should be s u f f i c i e n t reason to look for i n t e r s p e c i f i c differences i n foraging ecology and d i e t . Only i f the differences i n foraging ecology between two species are small (as i n the,case of St a r l i n g s and Robins i n the present study) does one need to consider the p o s s i b i l i t y of s i g n i f i c a n t competition. The statement above needs some modification. Consider a hypo-t h e t i c a l s i t u a t i o n where two species of birds both feed c h i e f l y on a si n g l e species of i n s e c t , one b i r d species foraging mainly on the trunks and limbs of trees and the other i n the f o l i a g e . Suppose also that the insect lays i t s eggs on the trunks and limbs, but the larvae crawl i n t o the f o l i a g e and feed there. The two b i r d species could then become serious competitors by feeding on d i f f e r e n t stages i n the l i f e - c y c l e of a single.species of prey, even though they foraged l a r g e l y i n d i f f e r e n t places. This sort of s i t u a t i o n i s probably rather rare, however, and the contention of MacArthur (1958), that the use of d i f f e r e n t foraging zones generally means the use of d i f f e r e n t foods, i s probably correct. 158 There were large differences i n the o v e r a l l use of d i f f e r e n t microhabitats among the f i v e major ground-foraging species i n the present study. Use of pavement by Rock Doves was r e l a t i v e l y heavy, by House Sparrows and Crested Mynahs was moderate, and by Robins and S t a r l i n g s was l i g h t . Use of bare ground by Rock Doves and House Sparrows was heavy, by Robins was moderate, and by Mynahs and S t a r l i n g s was l i g h t . Use of lawn by Rock Doves was l i g h t , by House Sparrows was moderate, and by Mynahs, Robins, and S t a r l i n g s was heavy. Only S t a r l i n g and Robins foraged i n trees to any s i g n i f i c a n t extent. Information on the d i e t s of these species, both from the l i t e r a t u r e and from the present study, i n -dicates that these differences i n foraging patterns are accompanied by, and are at l e a s t p a r t l y responsible f o r , associated differences i n d i e t . Among the f i v e major species, only S t a r l i n g s and Robins f a i l e d to show large differences from one another i n o v e r a l l foraging patterns. However, the foraging methods of the two species are quite d i f f e r e n t . S t a r l i n g s forage l a r g e l y by probing the ground with t h e i r b i l l s . Although I know of no d e t a i l e d study of the sensory basis of S t a r l i n g foraging, i t appears that probing i s at random., The prey obtained from lawns seem to be mainly cranefly larvae and other s o i l arthropods, although earth-worms are also eaten (Dunnet, 1955). Robins, on the other hand, do not probe but rather extract earthworms from t h e i r burrows, apparently l o c a t i n g them by sight (Heppner, 1965). S o i l Arthropods are probably captured infrequently i f at a l l by Robins. The differences i n foraging techniques between Robins and S t a r l i n g s are unquestionably re l a t e d to the morphology of the b i l l . The general 159 c o r r e l a t i o n of avian b i l l structure with foraging habits i s w e l l known (e.g., Welty, 1962, pp. 101-107), although few d e t a i l e d f u n c t i o n a l analyses of b i l l structure have been made (but see Bowman, 1961 and Engels, 1940). The tapered, sharp-pointed b i l l of the S t a r l i n g appears to be an e f f i c i e n t t o o l f o r probing; the r e l a t i v e l y blunt-tipped b i l l of the Robin i s probably poorly-adapted f o r t h i s a c t i v i t y , but may be better for obtaining f r u i t . Similar comparisons could be made for other species, but a d e t a i l e d consideration of b i l l morphology i n r e l a t i o n to foraging habits i s beyond the scope of t h i s study. Of the various within-species differences i n foraging patterns, seasonal differences seem to be most cons i s t e n t l y present and largest i n magnitude. In most temperate areas of the world, the.seasonal v a r i a t i o n i n the food resources a v a i l a b l e to birds i s tremendous. Compilations such as that of Martin, Zim, and Nelson (1951) i n d i c a t e that great and consistent seasonal differences e x i s t i n the d i e t s of most species of b i r d s . Many species s h i f t from a d i e t i n c l u d i n g many insects i n summer to one of seeds and other plant material i n winter. Species incapable of switching from an insect to a plant d i e t (e.g., most Tyrannidae, Parulidae, and Vireonidae) usually migrate long distances to t r o p i c a l and s u b t r o p i c a l regions where insects are abundant even i n winter. Data both from the present study and from other studies (see below) suggest that changes i n foraging patterns, while often much l e s s s t r i k i n g than d i e t a r y changes, may s t i l l be large. Notable seasonal changes observed i n the present study include arboreal foraging by Robins and St a r l i n g s i n l a t e summer, autumn, and winter; the use of feeders i n winter and of 161 species of birds. Palmgren (1949) stated: "A tendency toward a diphasic sleep is inherent in most birds, indicated by their afternoon period of inactivity, well known to field ornithologists." Birds commonly spend more time foraging in morning and late afternoon, and less in midday, especially during the summer (see Baldwin and Kendeigh, 1938). Morton (1967) found that the intensity of foraging by White-crowned Sparrows decreased noticeably around midday even in the winter, but more so on sunny days than on cloudy days. Beer (1961) found that the number of House Sparrows visiting a Minnesota bird feeder in winter reached peaks near sunrise and sunset, and at midday was about half the peak number. On the other hand, Verner (1965) claimed that Long-billed Marsh Wrens spent most time foraging in early afternoon; however, his contention is open to dispute since the wrens were simply assumed to be foraging when they were silent and out of sight. In the present study, no attempt was made to estimate the percentage of time spent foraging at different times of day by various species. The third factor affecting foraging patterns, the macrohabitat, is one which appears to have received l i t t l e study (but see Morse, 1970). Evidence both from the present study and from others suggests that birds tend to forage in the same places regardless of the macrohabitat. For instance, MacArthur (1958), found that nine species of warblers wintering in Costa Rica used the same foraging methods and foraged at about the same heights as they did in summer in North America, despite the fact that the wintering habitats were wholly different. Morse (1967b) found that the foraging methods of Parula Warblers were similar in Maine 162 conifers and Louisiana deciduous f o r e s t . In the present study, the use of various microhabitats by ground-foraging b i r d s i n d i f f e r e n t macro-habitats did not seem to vary as much as the proportions of the micro-habitats themselves. When differences i n patterns of e x p l o i t a t i o n were found between d i f f e r e n t macrohabitats they were usually i n the same d i r e c t i o n as the differences i n a v a i l a b i l i t y of microhabitats. For example, the heavier use of lawns by Rock Doves and Crested Mynahs on the 19th and Yukon p l o t , as compared with the 14th and Spruce p l o t , was correlated with the much greater extent of lawn on the former. The only instance of the reverse s i t u a t i o n was i n the Robin, which used lawns, apparently the preferred microhabitat, most heavily in.the macrohabitat (apartments) where i t was scarcest. A possible explanation might be that the a v a i l a b i l i t y of s u i t a b l e n e s t - s i t e s i s a more important factor i n determining Robin de n s i t i e s than the extent of the preferred foraging microhabitat (lawn), and that the high density of Robins i n the w e l l -wooded r e s i d e n t i a l habitat may r e s u l t i n the.compression of t e r r i t o r i e s to the point where the b i r d s are forced to use suboptimal microhabitats for foraging. The e f f e c t of weather on foraging patterns was not examined i n the present study, because few observations were made i n poor weather. However, no obvious e f f e c t s of weather on foraging patterns were noted, a l -though weather had a considerable e f f e c t on the per cent of time spent i n foraging. Observations made both i n s i d e and outside the study areas sug-gested that long-continued l i g h t r a i n caused an increase i n foraging by some species (e.g., Robins and Varied Thrushes, which fed on worms flushed out of t h e i r burrows), while heavy r a i n caused a sharp decrease i n f o r -aging a c t i v i t y by a l l species. 163 D. NEST-SITES 1. Methods The great majority of nests were found while conducting e i t h e r censuses or foraging observations: only a few s p e c i a l nest searches were c a r r i e d out,. Most nests discovered were of hole-nesting species, so that the nest contents could not be seen. Evidence considered acceptable f o r the presence of a nest included: nes t l i n g s seen or heard c a l l i n g ; adult b i r d seen carrying food to a suspected n e s t - s i t e ; or adult b i r d seen carrying nesting material. In most.instances, nests were located by, tracking down,the c a l l s of n e s t l i n g s . The p o s i t i o n and height of each nest were recorded. 2. Results During the breeding seasons,of 1968 and 1969, 207 nests were found on the study plots and i n s i m i l a r habitats nearby (57 i n 1968, 150 i n 1969). In 1968, e f f o r t s to f i n d nests did not begin u n t i l mid-June, so that most f i r s t - b r o o d , S t a r l i n g s and House Sparrows had already fledged, and the t o t a l number of nests found was small. A l i s t of a l l nests found i s given i n Appendices XXIV and XXV. The height d i s t r i b u t i o n of these nests i s summarized i n Table 37, and t h e i r locations i n Table 38. Nest-finding was p a r t i c u l a r l y successful f o r St a r l i n g s and House Sparrows. These two species nested l a r g e l y i n i n a c c e s s i b l e crevices i n bu i l d i n g s , and made l i t t l e attempt to conceal t h e i r n e s t - s i t e s . In sharp 164 Table 37. Height d i s t r i b u t i o n of nests, 1968-1969 Species 0-5 Height above ground i n feet 5-10 10-15 15-20 20-25 25-30 30+ T o t a l nests S t a r l i n g — 4 16 13 25 14 1 73 House Sparrow — 1 26 13 17 3 1 61 Barn Swallow — 2 10 4 — 2 — 18 American Robin — 3 8 6 — — — 17 Crested Mynah — — 1 1 — 7 3 12 Violet-green Swallow — 5 2 1 3 — 11 Common Pigeon — — 2 5 — 2 9 C l i f f Swallow — — 2 2 American Goldfinch — — — 1 — — 1 Brewer's Blackbird — 1 1 Red-breasted Nuthatch — — — 1 — — 1 House Finch — — 1 — — — 1 Totals 0 11 69 41 49 29 7 207 165 Table 38. Location of nests, 1968-1969 Species Deciduous tree Nest l o c a t i o n Evergreen Vine tree B u i l d i n g T o t a l nests S t a r l i n g 2 — — 71 73 House Sparrow 4 — 1 56 61 Barn Swallow — — — 18 18 American Robin 9 4 — 4 17 Crested Mynah — — — 12 12 Violet-green Swallow — — — 11 11 Common Pigeon — — — 9 9 C l i f f Swallow -- — 2 2 American Goldfinch 1 — — — 1 Brewer's Blackbird — 1 — 1 Red-breasted Nuthatch 1 — — 1 House Finch — — — 1 1 Totals 17 5 1 183 207 166 contrast, the nests of Robins and other open-nesting species were quite d i f f i c u l t to locate. The scarcity of bird nests near ground level in Vancouver residen-t i a l areas is clearly demonstrated by Table 37. Not a single nest was found at less than 5 feet above ground level, and none of the commoner species had a mean nesting height of less than 10 feet. The Crested Mynah appeared to have the greatest mean nesting height, and the Robin and Barn Swallow the least. The importance of buildings as nesting-sites is also made obvious by Table 38. One hundred and eighty-three out of the 206 nests were in buildings. While i t must be conceded that nests in trees are harder to find than those in buildings, only the Robin, among the more numerous species, seemed to nest more often in trees. 3. Discussion The most striking feature of the distrubution of nest-heights in Vancouver was the absence of nests at or near ground level. This stands in sharp contrast to the situation in a Pennsylvania bird sanctuary, con-sisting chiefly of upland deciduous forest and brushy old fields (Preston and Norris, 1947), where half of a l l bird nests were at heights of three, feet or less. However, other urban areas in London, England (Simms, 1962) and in Butler, Pennsylvania (Preston and Norris, 1947) also showed a dearth of nests below a height of five feet. In an area of mixed habitats (not described in detail) in Louisiana, nest heights were intermediate between these extremes—about 18% were three feet or less above the ground (Taylor, 1965). 167 Preston and Norris (1947), in the most detailed analysis of nest heights yet made, found that the distribution of nest heights in the sanc-tuary was approximated by a simple equation which states, in effect, that the number of nests per foot of height decreases in logarithmic fashion with increasing height. The distribution of nests in the residential area, furthermore, could be approximated by adding a term representing an "attrition factor" which operated strongly at ground level , but ceased to have effect at heights of more than 5 or 10 feet.' This attrition factor could include, among other things, accidental or intentional dis-turbance of birds by humans and predation by cats and other domestic animals. (The reports of McMurry and Sperry (1941), Matheson (1944), and Evenden (1957) suggest that cats may have a great effect on urban birds.) The attrition factor could operate, assuming that a bird's preference for a certain range of nest-sites is inherited, by selective elimination of ground-nesting bird species or by elimination of low-nesting populations of arboreal species. It could also result from birds learning to increase their nesting height as a result of constant disturbance. The predominance of hole-nesting birds in urban habitats has a l -ready been noted. This, together with the abundance, of nest-sites, may help to explain the high breeding bird densities characteristic of urban areas. As pointed out by von Haartman (1957), hole-nesting birds tend to. be weakly t e r r i t o r i a l , and their t e r r i t o r i a l defence is strongly concen-trated around the nest-hole. The densities of such birds are often limited, in natural habitats, by the number of nest-holes, and an a r t i f i c i a l 168 increase i n nesting-sites may allow the species' population to increase enormously (see von Haartman, 1956). This may be what has happened i n the case of such urban birds as S t a r l i n g s and House Sparrows: t e r r i t o r i a l behaviour does not seem to l i m i t t h e i r numbers, and i t i s common to see two or three S t a r l i n g or House Sparrow nests i n the same b u i l d i n g . I n t e r s p e c i f i c competition for n e s t - s i t e s i s often severe among hole-nesting b i r d s (von Haartman, 1957). Competition may be avoided by differences i n nesting seasons l i k e those described by Berger (1954); but there was l i t t l e evidence of such differences i n the present study, although Rock Doves may begin nesting e a r l i e r than other species. Obviously, the s i z e of the species also a f f e c t s competitive r e l a t i o n s h i p s ; S t a r l i n g s can enter holes too small f o r Rock Doves, and House Sparrows can enter holes too small for S t a r l i n g s . Nevertheless, and despite the o v e r a l l abundance of n e s t - s i t e s , there s t i l l seemed to be considerable . competition for n e s t - s i t e s i n Vancouver; perhaps some s i t e s are favoured by birds much more than others. Competition between S t a r l i n g s and Crested Mynahs was p a r t i c u l a r l y noticeable, and several apparent cases of each. species taking over a nest of the other were noted by both Steve R. . ; . Johnson (pers. comm.) and the author. 169 E. GENERAL DISCUSSION The Interrelationships of Foraging Ecology, Nest-Sites, and Urban Bird Populations Many studies of avian population ecology have been carried out in an effort to find out whether the numbers of a species in a particular habitat are controlled by food availability , t e r r i t o r i a l behaviour, pre-dation, nest-site availability (especially in hole-nesting species) or another factor, or by some combination of these. Few such studies, how-ever, have attempted to relate bird populations to the availability of suitable foraging habitats rather than to food availability per se. The findings of the present study invite some speculation in this direction. . As outlined previously, most of the bird species studied seem to have rather stereotyped foraging patterns, in that they tend to forage in the same microhabitats regardless of which macrohabitat they are i n . The limitations imposed on each species by i t s genetically-determined morphological and behavioural characteristics restrict i t to effective foraging in only a few microhabitats. Thus the extent of these micro-habitats, in conjunction with nest-site availability and other factors, may greatly affect the population of the species in question. The Rock Dove appears to be,the only urban bird species in Vancouver capable of effective foraging on paved surfaces without also having access to lawn and/or bare ground. It is capable of l iving almost entirely on bread, grain and other food provided deliberately or 170 unintentionally by man. This helps to explain why the Rock Dove is the dominant bird species in urban-core areas. Nest-sites suitable for Rock Doves are numerous in such areas, and do not severely limit Rock Dove populations. The other bird species which make considerable use of pave-ment, House Sparrows and Crested Mynahs, seem also to require lawns or bare ground, and are scarce or absent in downtown areas where buildings and pavement coyer nearly 100% of the area. At the,other extreme from Rock Doves are Robins and Starlings. These two species, particularly Starlings, appear to require grassy areas, preferably lawns, for foraging. It has been pointed out that these two species are more similar in their foraging patterns than any other pair of species; and although their foraging methods differ , i t seems certain that some competition for food must occur between them, at least for earthworms. However, these two species avoid competition to some extent by reaching their maximum abundance in different macrohabitats. The small extent of lawns and the scarcity of preferred nesting-sites (densely-foliaged trees) are probably both reasons for the low number of Robins breeding on the,14th and Spruce plot. On the other hand, the lower number of Starlings on the 43rd and Churchill plot appears to be related not to a shortage of nesting-sites or of lawn per se, but perhaps to a shortage of open, unshaded lawn ( i . e . , lawn not overshadowed by trees), which seems to be preferred for foraging by Starlings. An additional point concerning the Starling is that i t does not defend an exclusive feeding territory and often forages at some distance from i t s nest; Dunnet (1955) frequently saw marked Starlings foraging 171 h a l f a mile from t h e i r n e s t - s i t e s . Thus S t a r l i n g s can and do nest i n com-mercial d i s t r i c t s at some distance from the nearest possible foraging area, even though they appear,to be more.dependent on lawns than Robins, which do not nest i n such areas. The s i t u a t i o n with S t a r l i n g s and Robins i s probably t y p i c a l of that where two species with s i m i l a r foraging ecology occur i n the same area. In most,cases, such species w i l l be most abundant i n d i f f e r e n t macrohabitats. The truth of th i s p r i n c i p l e has long been recognized for c l o s e l y - r e l a t e d species, but i t i s also true, i f to a les s e r degree, f o r unrelated species. Differences i n n e s t - s i t e preference w i l l reduce com-p e t i t i o n s t i l l f urther, but they are l i k e l y to be much greater between unrelated species than between rel a t e d species. B i l l s t ructure, which i s c r u c i a l to feeding and foraging ecology, appears to be a rather p l a s t i c , feature i n evolution, while n e s t - s i t e preferences are probably changed l e s s e a s i l y . Thus the extent of overlap i n macrohabitat occupancy pos-s i b l e between two unrelated species with s i m i l a r foraging ecology may be somewhat greater than between two related species. The prevalence of ground-foraging, omnivorous, hole-nesting birds i n urban b i r d communities has already been pointed out, and i s e a s i l y explained i n terms of the resources offered to birds by urban hab i t a t s . Since many of the food sources a v a i l a b l e to urban birds may be termed allochthonous ( i . e . , not o r i g i n a t i n g i n the microhabitat i n which they are u t i l i z e d by b i r d s ) — t h i s would include garbage, bread crumbs, seeds at feeders, e t c . — o n e might expect a greater degree of overlap i n the foraging patterns of urban birds than i n those of non-urban b i r d s . On 172 the other hand, the a v a i l a b i l i t y of n e s t - s i t e s i s l i k e l y to be more c r u c i a l to urban than to non-urban b i r d s , l a r g e l y as a r e s u l t of the s c a r c i t y of trees i n most,urban areas and the d i f f i c u l t i e s evidently posed by.predation and disturbance for ground-nesting species. While c a v i t i e s s u i t a b l e f or hole-nesting birds seem i n general to be abundant i n urban areas, i t may be that c a v i t i e s of the most-favoured types are not numerous, and that competition for n e s t - s i t e s (e.g., between St a r l i n g s and Crested Mynahs) may be considerable despite the existence of many unused, apparently s u i t a b l e s i t e s . No method has yet been devised for q u a n t i t a t i v e l y determining the a v a i l a b i l i t y of p o t e n t i a l n e s t - s i t e s for any species of b i r d , and the true importance,of n e s t - s i t e s .to urban birds i s therefore d i f f i c u l t . t o assess. F. SUMMARY The object of the present study was to investigate c e r t a i n aspects of the ecology of birds i n urban habi t a t s . The bulk of e f f o r t was devoted to studies of populations and of foraging ecology, but nest-s i t e s were also studied. Most of the work on populations was ca r r i e d out i n Vancouver, B r i t i s h Columbia, between 1968 and 1970. Four study plots i n Vancouver were censused year-round; the 19th and Yukon p l o t , i n a t y p i c a l ( s i n g l e -dwelling) r e s i d e n t i a l d i s t r i c t ; the 14th and Spruce p l o t , i n an apartment d i s t r i c t ; the 43rd and C h u r c h i l l p l o t , i n a well-wooded r e s i d e n t i a l d i s t r i c t ; and the Ferguson Road p l o t , i n a semi-rural d i s t r i c t . B r i e f winter population studies were made on two plots i n Sacramento, C a l i f o r n i a (the F and 21st and S and 24th plots) and i n Ottawa, Ontario (the R o c k c l i f f e Park and A l t a V i s t a p l o t s ) . In addition, winter studies were made by Michael G. Shepard on two more plot s i n Vancouver, the 33rd and Dunbar and 22nd and Dunbar p l o t s . The vegetation and the ph y s i c a l structure of the habitat were studied i n d e t a i l on each of these p l o t s . For the four main Vancouver p l o t s , mean de n s i t i e s of breeding b i r d s , breeding-season b i r d s , wintering b i r d s , and transient (migrant) birds are presented i n tabular form. A d i s t i n c t i o n i s made between breeding-season populations, i n which non-breeding v i s i t o r s are included, and 173 174 breeding-populations, i n which v i s i t o r s are excluded. It i s emphas-ized that winter populations can be f a i r l y compared only with breeding-season populations, and not with breeding populations. 6. The four main Vancouver plots had breeding b i r d d e n s i t i e s ranging from 167 to 196 males per 100 acres. These den s i t i e s are lower than those i n some other urban areas, but are comparable to de n s i t i e s i n many non-urban habitats. I t i s suggested that the r e l a t i v e abundance of food and n e s t - s i t e s may be p a r t l y responsible for the high den-s i t i e s of birds i n c i t i e s . Densities were lowest i n the most heavily urbanized habitats; t h i s pattern i s confirmed by other studies. 7. Breeding-season de n s i t i e s on the Vancouver plo t s showed the same pattern as breeding d e n s i t i e s . 8. Winter b i r d densities i n Vancouver ranged from 186 to 1021 b i r d s per 100 acres, with a mean of 450. Winter d e n s i t i e s i n Ottawa were lower than i n Vancouver, probably because of a heavy snow cover which r e s t r i c t s foraging opportunities for b i r d s ; they were also lower i n Sacramento, for unknown reasons. Densities of wintering birds i n urban habitats are generally much higher than elsewhere; the a v a i l -a b i l i t y of food i n c i t i e s i s probably the major reason. In contrast to breeding d e n s i t i e s , winter d e n s i t i e s were lowest i n well-wooded areas. 9. Winter d e n s i t i e s generally exceeded breeding-season d e n s i t i e s on the Vancouver p l o t s , a pattern which appears c h a r a c t e r i s t i c only of areas with mild winter climates. 10. Transient birds were abundant on the Vancouver plo t s i n spring and 175 f a l l . On individual plots they comprised from 1.7% of the total bird population (14th and Spruce plot, autumn) to 23.9% (Ferguson Road plot., spring) . Autumn migrants appeared to be scarcer than spring migrants, but this is probably because of sampling error. 11. The diversity of the avian communities studied was measured in three ways: by the species richness (number of species); by the equita-b i l i t y (relative abundance of species); and by the index of diversity, combining the other two measures. 12. The number of breeding bird species on the Vancouver plots ranged from 8 to. 15, with fewest on the most urbanized plot. Other urban areas have a comparable paucity of species, but most non-urban habitats have between 16 and 25 breeding species on similar-sized study plots. The Vancouver plots also had a low equitability; the mean J ' value for the four plots was .812, much lower than for most other habitats. Finally, the species diversity on the Vancouver plots was very low (mean H' value, 1.887), much lower than for most other habitats. This low species diversity results both from a small number of species and a low equitability ( i . e . , dominance of the population by a relatively few species). 13. . Species richness, equitability, and species diversity for breeding-season populations paralleled those for breeding populations. Breed-ing-season diversity was much higher than breeding diversity on two plots because of the presence of several non-breeding v i s i t o r s . 14. The Vancouver census plots had between 11 and 29 wintering bird species, while those in Ottawa and Sacramento a l l had between 11 and 14 species. The mean for a l l plots was 16.6 species, which differs l i t t l e from the number of wintering species in most other North American habitats. 15. Winter equitability values in Vancouver were lower than breeding-season equitabilities. This is probably due, at least in part, to the effect of t e r r i t o r i a l behaviour in the breeding season, making i t less likely that one or two species w i l l dominate the community. Species diversity in winter was also lower than in the breeding season, owing mainly to the lower equitability. Equitability values in Sacramento were higher than in Vancouver, while those in Ottawa were similar; diversities in Sacramento were about equal to those in Vancouver, while those in Ottawa were lower. 16. The House Sparrow was the most abundant breeding species on the 19th and Yukon and 14th and Spruce plots; the Robin on the 43rd and Churchill plot; and the Barn Swallow on the Ferguson Road plot. 17. In the winter censuses, the Starling was the commonest species on the 19th and Yukon, Ferguson Road, and Alta Vista plots; the House Sparrow on the 14th and Spruce, F and 21st, and S and 24th plots; the Oregon Junco on the 43rd and Churchill, 33rd and Dunbar, and 22nd and Dunbar plots; and the Evening Grosbeak on the Rockcliffe Park plot. 18. Both in winter and summer, the typical urban species (House Sparrow, Starling, Rock Dove) were most numerous in the most urbanized areas. In the well-wooded areas, forest and forest-edge species became more abundant. 177 19. An attempt i s made to explain the success of House Sparrows, S t a r l i n g s , and Rock Doves i n urban hab i t a t s . A l l three species are hole-nesting, non-migratory, ground-foraging, and omnivorous; each of these features has c e r t a i n advantages i n urban areas. In addition, the aggressiveness of Starl i n g s and House Sparrows i n f o r c i n g other birds from t h e i r n e s t ing-sites must also be important to t h e i r suc-cess i n urban h a b i t a t s . : 20. In the studies of foraging ecology, two types of observations were made. In the f i r s t — s t o p w a t c h o b s e r v a t i o n s — a bird's foraging a c t i v i t y was followed with a stopwatch. Twenty-nine microhabitats, or foraging zones, were recognized and the number of seconds spent i n each was recorded. In the second type of o b s e r v a t i o n — s p o t c h e c k s — only the microhabitat where the b i r d was f i r s t seen was recorded. Foraging ecology was studied only on and near the four main Vancouver p l o t s . 21. The extent of each of eight t e r r e s t r i a l microhabitats was determined on each study p l o t with the aid of a e r i a l photographs. 22. A t o t a l of 1866 stopwatch observations were made on 54 species of i b i r ds i n h a b i t i n g the study p l o t s . More than 100 observations were made on each of s i x species. One of these, the Black-capped Chickadee, i s an arboreal forager; the other f i v e are mainly t e r r e s -t r i a l foragers. 23. For each of the 18 species observed most often, a summary of the foraging pattern i s presented, and comparisons are made with other species. Published food-habits studies are summarized, and an 178 attempt is made to relate the observed foraging pattern to the known diet. 24. The five ground-foraging species with'large sample sizes a l l had for-aging patterns which differed greatly from one another, with the single exception of the Robin and the Starling. These two had rather similar patterns. However, the foraging methods of Starlings and Robins are quite different, and there is also a large difference in the actual foods util ized. 25. The use of each terrestrial microhabitat by a l l bird species and by individual species is discussed. Loose earth, sidewalks, lawns, and sparse grass were proportionately overutilized by birds (use greater than availability) ; while hard earth, gravel, roads, and t a l l grass were underutilized. 26. The results of the spotchecks were very similar to those obtained from the stopwatch observations, although based on a completely independent sample. For some species, percentage use of different microhabitats indicated by the two methods was nearly identical. 27. Owing to the discrete nature of the spotchecks, chi-square tests are permissible. Two types of tests were performed; tests to find out whether the use of microhabitats corresponded to their availability , and tests for differences between species. 28. In the tests on use of microhabitats, only one species showed a foraging pattern not significantly different from the availability of microhabitats: the Crested Mynah on the 19th and Yukon plot. The lack of significance probably resulted merely from a small sample 179 s i z e . In tests for i n t e r s p e c i f i c d i f f e r e n c e s , two differences were not s i g n i f i c a n t ; both involved Crested Mynahs again, probably because of the sample s i z e once more. The di f f e r e n c e between Robins and S t a r l i n g s , though s i g n i f i c a n t , was very small. 29. In studies of foraging ecology, the importance of the " g u i l d " con-cept, and of studying unrelated species as w e l l as r e l a t e d ones, i s stressed. I t i s emphasized that even when two species have s i m i l a r foraging patterns, t h e i r foraging methods may d i f f e r . Foraging methods are c e r t a i n l y r e l a t e d to the morphology of the b i l l , although t h i s has received l i t t l e study. The e f f e c t s of various factors (season, time of day, and macrohabitat) on the foraging pattern of a species are discussed. 30. Two hundred and seven nests of various species were found during the study. I n t e r s p e c i f i c differences i n the height and l o c a t i o n of nests were evident. Crested Mynahs nested highest, and Robins and Barn Swallows lowest. Robins, were the only common species which nested more often i n trees than i n b u i l d i n g s . 31. The o v e r a l l height d i s t r i b u t i o n of b i r d nests i s discussed. Ground nesters were v i r t u a l l y absent; not one of the nests found was at a height of le s s than 5 f e e t . 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An e c o l o g i c a l analysis of three C a l i f o r n i a a v i -faunas. Condor 55:258-273. Sa l t , George W. 1957. An analysis of avifaunas i n the Teton Mountains and Jackson Hole, Wyoming. Condor 59:373-393. Scheffer, Theo H. and Clarence Cottam. 1935. The Crested Mynah, or Chinese S t a r l i n g , i n the P a c i f i c Northwest. U.S. Dept. of A g r i c u l -ture, Tech. B u l l . 467. Shadowen, Herbert E. 1969. The d i e t of the S t a r l i n g . , Kentucky,Warbler 45:27-28. 188 Shannon, C. E. and W. Weaver. 1949. The mathematical theory of communi-cation. Urbana: Uni v e r s i t y of I l l i n o i s Press. , Sheldon, Andrew L. 1969. E q u i t a b i l i t y i n d i c e s : dependence on the species count. Ecology.50:466-467. Shepard, Michael G. (Unpublished MS, Zool, , Dept., Univ.. o f , B r i t . Col.,. 1970). The winter .bird population of the Dunbar area. S i e g f r i e d , W. R. 1968. E c o l o g i c a l composition of the avifaunal community i n a Stellenbosch suburb. 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APPENDIX I SYMBOLS USED FOR BIRD SPECIES RECORDED DURING CENSUSES OF VANCOUVER STUDY PLOTS, 1968-1970 (see page 26) APPENDIX II PLANTS PRESENT ON VANCOUVER STUDY PLOTS 191 192 Appendix I I Plants present on Vancouver study p l o t s * 19th & 14th & 43rd & Ferguson Species Yukon Spruce C h u r c h i l l Road TREES Acer spp. (mostly Acer saocharum, sugar maple) C c c • Ulmus amerioana, elm 0 X c • Chamaeoyparis lawsoniana, Port Orford cedar C c c c Thuja plioata, Western red cedar c X c X Betula pendula, European white b i r c h X c c c Sovbus auouparia, European mountain ash c c c X Ilex aquifolium, English h o l l y X c c X Malus s y l v e s t r i s , apple Crataegus oxyaoantha, E n g l i s h c c c X hawthorn X c c c Thuja oooidentalis, northern white cedar c c c X Prunus oerasifera, purple-leaf plum X X c X Prunus serrulata, Japanese flowering cherry c c c c Prunus virginiana, chokecherry • • c Chamaeoyparis p i s i f e r a , Sawara cypress • • X Comus n u t t a l l i i , P a c i f i c dogwood X X c Araucaria arauoana, monkeypuzzle X X X Cedrus deodara, deodar cedar X X c X Pinus mugo, Swiss mountain pine • X Ilex crenata, Japanese h o l l y • • X Acer palmatum, Japanese maple X X X Cedrus atlantioa, A t l a s cedar * X X Magnolia sp., magnolia Prunus s u b h i r t e l l a , rosebud cherry • • X X Catalpa bignonioides, southern catalpa • X Pseudotsuga menziesii, Douglas f i r c X c X Pinus s y l v e s t r i s , Scots pine X X Pioea abies, Norway spruce - X X c Acer maorophyllum, broadleaf maple X X X *C means common; X, present but not common., For d e f i n i t i o n of "common", see page 17. 193 (Appendix II - continued) 19th & 14th & 43rd & Ferguson Species Yukon Spruce C h u r c h i l l Road TREES (conto) Sali-x babylonica, weeping: willow X o X X Abies grandis, grand f i r 0 X Alnus rubra, red alder X X X Platanus a c e r i f o l i a , London plane . 0 X Populus nigra, Lombardy poplar o 0 c X Laburnum watereri, laburnum X X c X Picea pungens, blue spruce X X c Quercus spp., oak Aesoulus hippo eastanum, horse- c X X - . ches tnut X X X 0 Tsuga heterophylla, western hemlock X X c X Prunus persioa, peach X X X X Robinia pseudoacacia, black locust X X . Acer negundo, box elder . X c Pinus contorta, shore pine X X X 0 Pinus ponderosa, ponderosa pine o » X Sequoia gigantea, sequoia . 0 X • Ailanthus altissima, tree-of-heaven X X X • Arbutus menziesii, arbutus X o Pyrus communis, pear X X c Castanea sativa, chestnut X 0 o „ Acer saccharinum, s i l v e r maple „ o 0 X Pinus sp., pine X X 0 O Malus sp», crabapple X e 0 Cupressus sp., cypress X X a SHRUBS Prunus laurocerasus, cherry l a u r e l C c c Hydrangea opuloides, hydrangea C c c Rhododendron s p 0 > rhododendron c c c Rosa sp„, rose c c c X Rubus taciniatus, evergreen black-berry X X c X Juniperus sp., juniper X X X * Aucuba Qaponica, gold-dust plant X X X • Myrtus communis, myrtle X c X • Springa vulgaris, l i l a c c X X Rubus sp., garden raspberries c X X 9 Forsythia sp., f o r s y t h i a c X X 0 Rubus spectabilis, salmonberry . . . C 194 (Appendix II - continued) 19 th & 14th & 43rd & Ferguson Species Yukon Spruce C h u r c h i l l Road SHRUBS (conto) Symphoricarpos albus, waxb.erry - • 0 X C Rubus sp., English blackberry 0 e C Cotoneaster sp,, cotoneaster e X X • Azalea spp», azalea X X X c Juniperus' chinensis, Chinese juniper « 0 X • Phyllostachys ai.xrea, bamboo X X X Taxus baccata, English yew X X X 0 Erica sp „, heather. . X X X ft Ligustrum vulgare, p r i v e t X X X X Berberis thunbergii, Japanese barberry • 0 X « Fuchsia hybrida, fuchsia X X X • Hydrangea paniculata, hydrangea X X X 0 Pyracantha sp., f i r e t h o r n X 0 X X Hedera helix, English ivy X X X e Polygonum sp., knotweed X X X * Ribes sanguineum, red-flowering currant X 0 X s Rubus parviflorus, thimbleberry X 0 Wisteria sinensis, Chinese w i s t e r i a 0 X 0 Spiraea douglasii, hardhack X X X Camellia japonica, camellia o X X . Cytisus scoparius, broom X X X X Rhus sp„, sumac X X X X Sambucus sp., elder 0 X X « V i t i s sp., grape Philadelphus sp., mock orange X • X e X X . Fatsiajaponica, f a t s i a e X . • o Mahonia nervosa, Oregon grape . X « ft Hedera canariensis, ivy X 0 Comus stolonifera, red-osier dogwood X Ribes sp., currant X • • Sambucus pubens9 red-berry elder 0 0 X HERBS Lobularia maritima, sweet alyssum C c X Pelargonium sp., geranium c c c X Petunia hybrida, garden petunia X X X X 195 Appendix II - continued) Species HERBS (cont„) 19th & Yukon 14 th & Spruce 43rd & C h u r c h i l l Ferguson Road Peonia a l b i f l o r a , peony 0 c X • Tagetes sp., marigold C c c Dahlia sp., d a h l i a C c c 0 Taraxacum o f f i c i n a l e , dandelion C c c X Trifolium pratense, red clover C 0 c X Ipomea sp„, morning glory C c c • Crocus sp., crocus 0 0 X • Antirrhinum majalis, snapdragon C c X a I r i s sp., i r i s Plantago lanceolata, p l a n t a i n X c X X c c X X Trifolium repens, white clover c X X • Cirsium sp„, t h i s t l e . fi a c Lernna sp„, duckweed • * 0 c Astragalus sp., milkvetch 0 . c Hypericum sp., St„ Johnswort t 0 0 c D i g i t a l i s purpurea, foxglove X X X Rudbeckia t r i l o b a , brown-^eyed Susan a • X Pteridium aquilinum, bracken X X X Vinca minor, periwinkle e 0 X Phlox sp., phlox X . X Althea rosea, hollyhocks X X Solidago sp., goldenrod O ' X Rheum rhapontium, rhubarb X • X Tropeolum major, nasturtium X X X Blechnum spicant, deer fern « a X Gladiolus sp., gladiolus X X X Zinnia sp., z i n n i a X X X Chrysanthemum leucanthemum, oxeye daisy X a X . Polystichum munitum, sword fern X X X X Lycopersicon esculentum, tomato X X X X Helianthus anuus, sunflower • X X 0 Zea mays, Indian corn Cucurbita sp„, squash X fi X X X X X Viola t r i c o l o r , pansy' 0 X X Cortaderia argentea, Pampas grass X X X Phaseolus vulgaris, kidney bean X X X Dodecathon meadia, shootingstar . X X Bergenia c r a s s i f o l i a , winter primrose. X « X Papaver s p ? , poppy Beta vulgaris, beet X s X . X X c X Daucus carota, carrot X X 0 X 196 (Appendix II - continued) Species  HERBS (cont„) Achillea millefolium, yarrow Ranunculus sp., buttercup Equisetum sp., h o r s e t a i l Woodsia sp., rock fern Lathyrus odoraius, sweet pea Eschscholzia californica, C a l i f o r n i a poppy Pisum sativum, garden.pea Dianthus plumarius, pinks Urtica l y a l l i i , s t i n g i n g n e t t l e Typha l a t i f o l i a , c a t - t a i l Juncus sp., sedge Verbascum sp., mullein Narcissus pseudo-narcissus, d a f f o d i l 19th & 14th & 43rd 6c Ferguson Yukon Spruce C h u r c h i l l Road X X A X X X X X s X X X • X X X X X X APPENDIX I I I CENSUS OF TREES PRESENT ON VANCOUVER STUDY PLOTS 197 198 Appendix I I I Census of trees present on Vancouver study pl o t s 19 th & 14th & 43rd & Fergu Species Yukon Spruce C h u r c h i l l * Roa Acer spp. (mostly Acer saccharum, (sugar maple) 132 32 67 ft ft 0 Malus s y l v e s t r i s , apple 107 14 53 1 Prunus serrulate/., Japanese flowering cherry 69 15 42 5 Queraus spp., oaks 41 7 1 • • • Chamaecyparis lawsoniana, Port Orford cedar 43 31 47 13 Thuja oceialentalis , northern white . cedar 35 10 15 • • • Thuja p l i c a t a , western red cedar 14 3 49 2 Sorbus aucuparia, European mountain ash 12 10 20 • a • Pseudutsuga menziesii, Douglas f i r 9 2 18 3 Comus n u t t a l l i i , P a c i f i c dogwood 8 3 26 • • • Prunus oerasifera, purple-leaf plum 6 6 24 3 Betula pendula, European white b i r c h Ilex aquifolium, English h o l l y 5 40 38 5 5 21 19 2 Cupressus sp., cypress 5 ft a 0 2 • • • Pieea pungens, blue spruce 4 • O f t 6 • • • Pyrus communis, pear Tsuga heterophylla, western hemlock 4 • O f t 1 49 4 1 8 a • • Taxus baccata, English yew 4 1 • • • • • • Alnus rubra, red alder, 3 3 1 • • a Crataegus oxyacantha, English hawthorn 3 17 14 8 Picea abies, Norway spruce 2 2 9 • • • Salix babyloniaa, weeping willow 2 • • « 1 2 Prunus persica, peach 2 • a • • a a Pinus contorta, shore,pine 2 • * • 2 Syringa vulgaris, l i l a c 2 4 5 Rhus typhina, staghorn sumac.. 2 3 1 Aesculus hippocastanum, horse chestnut 1 2 3 . . . Cedrus deodara, deodar cedar 1 3 5 . . . Arbutus menziesii,- arbutus 1 • • 0 • a' • . . . Ma%iiS>-s^. , crabapple 1 • • « ft ft A 'Arducaria araucana, monkey-puzzle 1 2 ft ft O *Census of,three blocks (43% of p l o t ) , not e n t i r e p l o t . 199 (Appendix I I I - continued) Species U n i d e n t i f i e d deciduous trees Laburnum watereri, laburnum Ulmus amerioana, American elm Rhododendron sp„, rhododendron Pinus s y l v e s t r i s , Scots pine Aoer macrophyllum, broadleaf maple Ailanthus altissima, tree-of-heaven Juniperus sp., juniper Cedrus atlantioa, A t l a s cedar Robinia pseudoaoaoia, black locust Pinus sp., pine Populus nigra, Lombardy poplar Chamaecyparis p i s i f e r a , Sawara cypress Magnolia sp., magnolia Catalpa bignonioides, catalpa Polygonum sp., knotweed Prunus virginiana, chokecherry Acer sacoharinum, s i l v e r maple U n i d e n t i f i e d evergreens TOTAL 19th & 14th & 43rd & Ferguson Yukon Spruce Churchill Road 37 32 47 3 O 0 0 8 9 1 0 * 0 6 58 e o a o a o 2 o o a 9 a o • 0 0 1 a o a 9 9 9 • a • 1 . 1 9 9 9 a a o 1 a a o 9 9 0 o o o 1 o o o 9 9 9 0 0 0 1 1 o o o 0 9 9 1 a o o 9 0 0 • 0 0 1 a a a 9 9 9 • 0 0 • 0 0 6 9 9 9 • 0 0 • • 0 3 9 9 9 0 0 0 0 0 0 1 a a a o o o • o o 1 9 9 9 • 0 0 • 0 0 1 9 9 0 o o o o o o a a o 96 * 9 0 * a o o a o 1 • « 0 a a o 1 a a a 567 287 607 194 APPENDIX IV HEIGHTS OF TREES ON VANCOUVER STUDY PLOTS 200 201 Appendix IV Heights of trees on Vancouver study pl o t s 19th & 14th & 43rd & Ferguson Height class Yukon Spruce C h u r c h i l l Road 15 - 20' 229 99 145 87 20 - 30* 209 113 146 102 30 - 40' 96 42 108 5 40 - 50' 29 20 131 50 - 60' 1 10 58 6 0 - 7 0 ' ... 3 10 7 0 - 8 0 ' . . . . . . 5 80' plus ... ... 3 TOTAL 564 287 606 194 APPENDIX V RESULTS OF BIRD CENSUSES ON VANCOUVER STUDY PLOTS, 1968-1970 202 203 Appendix V Results of b i r d census on Vancouver study p l o t s , 1968-1970 t o r o 00 r H r H cn C O C M o o r H C M r H r H r H C M m r H 00 C M C M C M C M 0 v O • o C O CD >>, >> * O O 0 o\ C r O . U &" C r H r - ! 6 0 6 0 a •u • U > r H CCj 0) <D cd cfl 3 3 3 3 0 O O 0 Pn Pn s £ •-) >-} i-i < < O O S5 a s 140 228 65 40 30 36 16 39 18 30 21 30 28 84 131 82 HS 57 37 37 54 73 56 77 68 112 63 65 62 64 113 64 99 CM 22 17 18 15 5 8 6 10 6 10 13 15 17. 23 13 6 CP 21 16 15 16 11 11 6 4 10 5 40 8 3 14 12 3 OJ 8 8 7 15 0 0 • » 0 0 0 0 0 0 » » e 0 2 24 29 20 10 AR 7 3 35 41 29 30 47 61 34 36 13 50 99 8 8 7 SS 5 3 6 11 0 « • 0 0 0 0 0 a * 0 0 1 9 2 1 2 HF 3 3 7 3 5 9 22 6 2 4 1 3 7 1 1 2 GWG 2 3 3 3 4 9 O 11 1 1 1 33 18 3 3 2 NWC 1 0 0 t> • o t>' O 0 0 0 0 0 9 A 0 0 0 0 O 0 1 1 3 4 1 RSF 1 1 o • 2 o a 0 0 0 0 « 0 1 0 0 0 a 1 1 0 0 1 2 BCC 0 0 1 2 o o 3 4 2 0 0 1 0 0 7 9 9 5 5 2 5 PSK • « 14 . . 0 • 2 1 2 1 1 1 0 0 2 0 0 0 0 0 0 8 VT 0 0 » • o • 3 O 0 0 0 0 o 0 0 0 0 • 0 0 9 1 3 0 0 0 0 9 9 RCK 0 0 0 0 O 0 1 0 0 0 0 O 0 0 9 0 0 0 0 0 0 0 0 1 a 0 0 0 0 9 BS 0 9 • 0 a « o a 9 11 . 10 16 9 9 12 2 0 0 0 0 0 9 9 0 VGS O 0 a » o e e a 4 6 14 5 0 0 0 0 0 0 0 0 s 0 0 e 0 9 0 9 AG IITTAT « 0 .. 0 0 2 o 8 1 4 1 1 5 1 1 1 0 0 » e W W MGW © 0 e o « o * c 0 o o e 0 0 O 0 Z 2 0 0 0 0 O 0 0 0 9 O c 0 » 0 0 0 0 0 0 e r> • 0 0 0 0 0 9 a a a 0 0 0 0 0 0 0 0 0 CC • . a 0 • 0 O 0 1 2 2 1 0 0 a 0 0 0 0 0 0 0 0 « 0 0 0 0' YW 0 0 • 0 0 0 0 o 1 S 0 0 0 9 O 0 9 2 4 9 0 9 0 9 0 0 0 0 0 EG o a 0 o • 0 9 o 22 1 0 0 0 0 0 0 0 9 9 0 CW a o o a 0 0 0 0 2 2 o 0 0 9 0 0 0 0' 0 0 2 9 0 ' 10 0 0 0 0 ' RBN 0 0 1 0 0' 9 0 0 0' 9 0 0 0 9 9 0 0' 0 0 0 9 0 0 CSR 0 o a # a o a e 0 0 0 0 3 9 9 ' 0 0 e 0 0 0 0 0 0 0 0 e 9 0 A o' BSW 0 9 • 0 O 0 0 0 o • 0 0 0 0 62 0 0 0 0 0 0 0 0 0 0 0 0 0 9 9 0 K O 9 C 0 9 O a o o e O 0 0 0 1 0 0 0 0 0 0 0 0 0 s 0 0 9 O 0 0 GBH 9 O a o a o o 0 O 0 0 0 9 0 0 0 1 9 0' ft 0 9 ft 0 0 0 0 0 9 9 O OCW © 0 o a 9 O 0 0 0 0 0 0 9 ft 2 10 2 2 9 0 0 ft 9 0 WF a o O O 0 O 0 0 0 O O 9 0 0 O O 1 0 0 9 0 9 0 0 9 e 0 WV o « a • « o a a 0 a O O 9 0 1 9 0 0 0 0 0' 0 0 0 0 DW « c • 0 O 0 o a 0 0 o a 0 0' 0 0 O 0 0 0 1 0 0 0 a 0 0 9 0 0 9 AP « e a e> • a 0 0 O 0 O 0 9 O 0 0 0 O 0 0 3 1 0 0 0 0 0 O 0 9 SVS o • e a 0 0 0 9 0 0 O 0 O • e 0 0 0 0 0 2 • 0 0 0 0 0 O 0 0 0 TOTAL SPP. 11 11 10 11 14 13 11 9 11 . 11 12 17 19 15 12 12 TOTAL INDo 267 320 196 201 17.7 184 204 213 195 163 188 202 31.4 307 260 221 I t a l i c i s e d numbers i n d i c a t e birds seen j u s t outside the p l o t or i n f l i g h t over, the plot; : these numbers are not included i n the t o t a l s . For explanation of symbols f o r species, see Appendix.!, page 26. 204 (Appendix V - continued) 19th and Yukon p l o t 0 0 r H r H a\ L O o < t r H u n CM oo o C M r H C O r H O N vO CM r H C M r H C M r H C M vO •U o O o o a VO o o o s 0 • « o © O N O. •u > > o CJ O N a a Xi u U U u S-l r H a) o C J o o a) CD r H ns CO cu cu crj cfl C O o O 5 3 5 3 Q Q >-> >-> fe fe a a < < < BTP 14 38 3 9 9 0 0 « e a o 9 0 o a 9 0 0 0 O 0 0 . 0 0 0 0 O 0 GCK 5 3 1 • 0 9 • • 8 0 0 0 0 0 0 • Q 0 o 6 0 1 9 0 • 0 AW 4 3 8 • 0 ft o 0 0 o o 9 s 9 0 0 0 fi 0 • 0 . 0 9 0 1 WCS 1 5 9 9 • • 0 9 9 • 0 9 9 0 0 0 0 0 O 0 0 . e . . 3 BTGW 1 • a • o o • a • o e 0 e 0 • O 0 9 9 9 0 0 0 9 0 0 0 HT « . 1 o • 0 « « 0 9 0 0 9 0 0 0 9 0 9 • 0 0 0 0 . 0 0 1 MW . a 1 o • CG . . 90 MG a « 7 • • a 0 13 2 1 PF . . 2 1 1 GCS . a .. 2 BB e a 1 * a 9 9 • 0 9 0 • 0 0 0 0 0 » e DCC . . • • • • 1 « • • 9 0 0 0 0 « 0 0 0 9 A , . • . • . HS 109 88 56 70 72 49 46 40 32 28 31 S 103 84 120 140 137 231 88 37 5 33 23 OJ 19 4 24 12 17 9 5 7 9 9 0 0 1 CP 8 6 9 15 7 13 8 4 5 10 5 CM 3 4 7 3 11 4 5 13 3 9 4 GWG 3 3 4 5 4 5 4 0 0 1 a a 1 AR 2 2 2 2 2 14 15 18 9 30 21 SS 2 2 3 2 1 1 2 c 0 0 0 0 0 .. BCC 1 3 1 0 0 9 0 0 0 3 1 2 4 2 RSF 1 0 0 0 a 0 0 0 0 1 0 0 1 0 0 0 a 0 0 HF • 0 o o 17 8 10 0 0 8 3 10 3 CW 2 0 0 9 9 9 0 0 0 0 0 9 0 0 O 0 0 0 0 0 0 NWC 9 • 1 0 9 2 1 3 9 0 1 0 0 0 0 0 0 PSK 0 O • 0 9 » 0 0 0 0 5 o a 0 0 0 0 0 0 3 VGS o • o 0 0 0 2 13 1 RCK 0 0 0 0 a a 0 0 0 0 0 0 a 9 0 0 0 o 2 16 RHB a • 2 5 VT • o 0 0 • 9 0 0 0 0 0 o 0 0 0 o 0 9 1 1 AP • 0 • 0 0 9 0 9 0 9 9 0 0 9 0 0 9 0 4 9 0 AG 9 O • • • O 9 9 0 0 O 9 a • 9 0 2 0 0 TOTAL SPP. 10 10 9 9 10 11 9 10 9 11 14 TOTAL INDIV. 251 197 226 266 260 340 173 130 62 142 117 205 (Appendix V - continued) 19th and Yukon p l o t 1969 Apr.28 May 5 May 12 May 20 May 26 June 2 June 9 June 24 June 30 July 7 July 16 July 21 July 28 Aug. 3 Aug. 13 Aug. 26 WCS 49 3 O 0 0 0 0 0 0 0 . . O 0 0 0 0 0 0 0 o o 0 0 a .o a o 0 0 HS 28 36 34 45 54 64 53 99 94 94 77 87 113 103 95 73 AR 22 31 32 34 27 32 20 28 37 47 37 36 21 30 15 9 S 21 28 28 25 18 40 28 20 31 44 60 33 31 32 31 43 CP 12 14 12 13 3 11 11 14 21 5 12 12 9 12 12 19 CM 7 6 5 4 2 5 3 6 4 4 3 8 5 10 8 8 VGS 7 13 9 7 8 6 6 11 8 10 8 2 a a 0 0 0 0 2 RCK 7 AW 5 2 0 ft HF 4 6 5 3 3 4 4 4 15 4 4 1 1 2 4 4 BS 3 4 10 9 10 10 9 12 10 12 10 8 9 11 6 8 HT 3 1 BCC 1 1 0 0 2 0 0 7 5 3 3 8 3 3 •. 2 3 2 OCW 1 1 2 0 0 0 0 9 9 9 a 9 o O 0 0 0 1 1 RHB 1 2 VT 1 . . PSK 1 1 1 0 0 0 0 1 1 0 0 o a 0 a 0 a • • 6 • • • • 0 SVS 1 0 0 1 NWC 1 1 1 0 0 1 1 a o 0 o 0 0 a « 6 . o 0 • 1 AP 4 0 0 0 a o • 9 O o o 9 0 0 0 O ft • e 0 0 GWG 2 0 0 . 3 2 27 0 a 3 2 1 5 0 a 3 AG 1 ,4 2 2 3 2 5 1 0 0 2 2 1 1 0 a 4 GBH 1 0 0 0 0 1 1 a o 0 0 a a 9 9 0 0 0 9 a a a a a o CC • ft 1 1 2 1 0 9 o 0 4 1 X <-> 0 0 O 0 0 0 a o a a WW CS EG BG YW c 0 0 0 2 1 0 a «2 o a 9 O 9 ft O 0 0 O o o 1 9 0 e o 0 0 0 0 0 0 X 3 7 0 0 0 0 9 9 a a a a a o 0 0 O 0 0 o 0 9 0 0 0 0 O 0 O 9 0 ft ft 0 0 0 0 O O 0 2 0 O 0 0 1 0 0 0 9 0 0 o a 3 a 0 0 0 9 9 0 O 0 0 a 0 9 O o a 0 0 O 9 0 0 0 0 0 0 a o 0 ft 1 MGW • 0 0 0 0 0 0 0 2 a o 9 9 O 0 o o O O 0 0 O 0 a a . , 0 a a a OSF • 0 0 0 O 0 0 0 a 0 1 0 0 o o 0 0 a o a o O 0 a a ft . 9 0 9 0 CSR 9 0 0 0 0 0 0 0 9 0 1 0 9 o o o o O 0 O 0 0 9 a a O . a o 0 0 CW PF 0 0 0 0 o o 0 0 0 0 ft 0 a o a ft 2 0 » 0 0 0 0 O 0 0 a 0 0 0 0 O O 0 0 0 • o a a a C ft 3 BSW BTGW WT 0 0 0 0 0 0 0 9 0 0 » • 0 O 0 0 0 0 0 0 O 0 0 0 0 0 0 a a o a a 0 0 1 0 0 0 0 1 TOTAL SPP. 20 16 13 11 14 11 10 9 10 10 10 10 7 8 11 13 TOTAL IND. 179 153 142 .146 138 182 141 197 224 230 215 191 189 202 177 175 (Appendix V - continued) 19th and Yukon plo t CO <i-CN VO r H L O r H L O o o CO <j\ o\ • * CM r H r H CO o r H VO U 4 J 9 • e 0 a o a a a > > CJ o a ON a r H CU cu O O o o a) cu cu H cfl cd Q) cu CO w o o 53 Q p Q >-) fe fe HS 83 97 74 55 75 81 60 38 58 58 50 72 62 AR 46 29 .24 - 9 9 9 O 0 9 9 0 o 1 0 0 1 3 1 S 35 23 57 84 36 46 123 119 91 69 73 105 70 CP 23 12 14 21 20 11 20 7 10 13 8 16 6 BS 14 • 0 a a HF 6 9 6 2 2 2 9 9 1 2 3 0 9 7 a a BCC 6 2 3 3 2 5 2 1 3 1 3 2 2 CM •5 21 7 2 2 10 15 4 8 »• 2 3 a a OCW 5 10 0 0 1 9 9 9 9 0 0 0 0 a a a . . a WCS 2 22 5 4 0 9 9 0 9 9 9 0 . . . . a a OJ 1 14 11 14 8 12 16 21 14 BTP 1 35 9 2 3 0 0 9 0 9 9 • 0 • • a a a a a a SVS 1 2 1 9 9 0 0 0 0 0 0 0 9 0 o a . a a . a AG 6 4 1 9 9 0 9 0 0 0 0 0 0 . . 0 . a a a a a a CW 2 1 1 0 0 0 0 9 0 0 9 0 0 . a . . a a a a a a K 1 0 0 0 0 . . 0 0 O 0 9 9 9 0 • 0 a a a a a a GCS 0 0 6 5 0 0 a a 9 0 0 9 • * a a . . a a SS • a 5 4 7 6 6 AW • • 5 1 0 0 . « 0 0 9 9 a « a a a a . a NWC • o 2 2 3 1 3 . . a a . a a a RBN • o 2 0 • 0 • 0 0 .. 0 0 0 0 a a a a a a RSF o • 1 0 0 2 9 0 1 0 9 0 0 , . a a a a WW o • 1 9 9 0 0 0 9 0 9 0 0 0 0 • a a a . , a a HT * 6 1 0 9 0 0 9 0 O 0 0 0 O 0 0 a . 0 a a a a a a MGW • 0 1 0 9 0 0 0 0 0 0 0 9 0 0 • 0 . 0 a a a a a a FS • 0 1 0 0 a 0 0 0 0 0 9 9 0 0 . , a a a a a a AP . # 1 0 0 0 0 1 O 0 0 9 0 0 0 • a a a a . . GWG 13 7 1 9 1 4 5 3 3 EG • e 13 2 1 0 9 1 0 9 0 0 a o 0 • 5 a a a a PSK • * 6 1 1 0 0 0 0 O 0 2 15 0 0 9 0 a a a a BB • • 5 9 0 0 3 0 0 0 0 0 0 0 0 a o' 0 0 . . . , MG o e 2 3 5 3 1 9 9 O 0 25 a a 9 0 a a VT 0 0 1 0 0 0 0 0 0 9 O 0 • 0 9 a a 0 0 a a a a RWB • « 0 0 5 0 0 0 0 0 0 0 0 o o 0 0 a a 9 0 a a . . PH e 0 0 0 0 0 1 0 0 9 O 0 0 0 0 0 0 a a ft 0 . . a a MDK « • 0 9 0 0 2 0 0 0 9 0 0 9 O O 0 a a 0 0 a a . . CRP a o a a 0 0 1 TOTAL SPP. 13 23 18 16 10 9 9 9 11 8 9 10 8 TOTAL IND. 228 304 227 211 152 174 249 203 195 150 150 223 159 207 (Appendix V - continued) V D o o o o C U £ > t £ > > . « - M 4 - ) « o . « CJ\ <3 .O U U > » C S H r - l M 6 0 O. f l 4-1 4 J > > r H c f l c U c d 0 . c d 3 3 3 3 3 c U c U O O O O ' T ) f e a < ! a , - ) , - ) , - ) < ) < ! 0 0 0 0 O O a j 3 HS 29 43 34 25 29 43 47 57 49 62 116 69 72 52 73 33 CP 21 35 34 31 27 35 42 38 36 46 35 51 29 17 17 27 S 18 19 14 8 19 16 19 28 13 16 25 25 42 39 35 39 GWG 9 8 1 3 3 . . 6 4 1 4 1 2 2 7 6 U AR 1 2 11 16 13 14 10 9 12 5 4 12 26 7 .. .. HF 1 4 9 12 7 1 1 .. 3 2 1 2 . . 3 3 2 SS 1 4 2 2 .. 2 4 . . 2 RSF 1 .. . . .. .. OJ .. 4 2 2 . . . . . . . . . . 5 8 3 11 CM 2 5 2 4 7 3 6 4 8 2 4 3 9 12 9 NWC . . . . 1 1 1 1 3 2 4 2 . . 7 5 12 6 . . PSK 2 6 2 .. .. 1 .. . . 1 .. . . .. . . RCK • • •« 0 • 2 • • •• •» «• •• •• •• •• 1 •• •• VGS 1 3 2 5 4 .. . . . . .. SH 1 CW 6 10 2 .. .. .. AG 1 4 1 1 2 3 5 2 1 . . 3 . . . . BS 4 2 2 1 2 11 6 2 . . .. .. .. MGW . . 1 EG 2 .. .. . , .. .. . . BCC 1 2 4 .. .. GBH .. .. 2 1 CS .. .. .. 2 ...... .. CNH * « • « e o Q » • • • » B • J- o e e 0 A f t « • « • ft* YW . . 2 2 .. CSR .. . . . . . . . . . . . . 1 .. .. GCK A O A f t ftO A 0 A f t O A A O A f t A O ftft ftft 1 A A A A O A • « AW .. .. . . .. 5 .. . . WCS .. .. .. .. 1 4 . . VT .. • 1 .. .. DW 1 TOTAL SPP. 8 9 10 13 11 9 10 8 7 9 9 10 12 12 8 8 TOTAL IND. 81 121 113 107 112 121 132 145 120 154 193 169 193 163 155 126 (Appendix V - continued) 208 14th and Spruce p l o t S HS CP GWG OJ CM AR NWC SS HF RSF VGS BCC WCS RCK RHB PSK BS VT AW OCW GCK GBH CSR AP AG WW CG YW oo v o • ON. CJ r H CD — a . 53 38 14 13 13 7 2 2 1 3 r H 0 0 • v O • O O N C! t l H i 6 14 6 1 2 1 6 C N e. a CO 40 37 102 39 60 41 25 17 7 4 8 1 1 a • 20 1 8 3 10 6 4 1 1 1 r Q C N r Q 20 40 53 33 33 34 4 7 4 .. 12 11 3 5 2 1 2 1 1 rt 31 35 25 3 4 12 3 Mar.25 Apr. 9 Apr.16 Apr.23 o C O u < (May 6 May 13 May 22 May 27 28 24 29 17 25 14 24 26 30 28 27 27 17 36 33 29 30 44 39 33 33 23 54 41 42 28 19 3 3 1 . 1 3 4 1 I a • • 6 1 • • a a • a a a a a e • 4 7 6 4 5 2 5 2 5 8 16 24 12 13 5 9 16 14 7 • • 1 • ft 2 4 1 1 1 » a 1 3 10 7 1 4 1 1 1 2 • • • • • • a a a a a a a a a a • • 9 5 • • 6 7 10 8 2 • • 2 2 1 a a * a • • 1 16 • • . . 1 2 2 • a . . . 1 1 ft ft 1 a a a a 3 a a a a 3 1 1 3 7 1 2 1 1 1 1 1 1 1 . 2 . o a a 1 1 2 a a a a 1 o a 1 TOTAL SPP. 9 9 8 10 9 9 8 7 10 12 10 13 11 12 9 10 TOTAL IND. 143 159 135 175 131 135 117 117 132 137 79 166 115 131 113 119 209 (Appendix V - continued) 14th and Spruce p l o t o v O C M ON v O oo ON in C O r o CN! C M r H C O r H C M C M r H C M C M C M - o e v O CD <D CD r S > N > N > s e 0 a u •u • o 0 ON. a a rt r H r H r H r H r H 60 00 60 Cu a. 4-1 4 J > r H 3 3 3 3 3 3 3 3 3 3 CD CD o o o *-i •n r> >-> >-> >-> <! < < CO co o o CP 39 30 35 39 39 48 28 48 37 40 27 42 36 31 25 23 HS 35 33 51 50 36 41 72 42 47 80 37 56 73 70 52 80 S 23 22 .9 9 27 14 25 18 12 26 19 26 27 33 36 28 AR 9 10 9 11 7 7 7 9 7 3 0 9 1 12 32 9 1 CM 6 3 2 5 3 7 7 5 2 3 6 4 10 6 2 4 VGS 4 4 5 6 11 3 3 9 O 9 9 2 2 9 0 9 9 9 9 ft 0 9 9 HF 4 8 3 1 3 4 4 3 1 5 2 . 5 1 1 2 1 BS 2 3 2 5 1 3 5 2 6 5 10 4 2 0 0 9 9 9 9 NWC 3 1 1 5 • • ft 9 1 2 9 9 9 9 0 0 1 1 4 0 9 1 PSK 2 .. 1 • • 1 .. 2 9 9 9 0 0 0 9 9 0 0 2 9 0 GWG 1 a o a • 1 1 2 4 1 2 1 1 2 5 CC 1 • • • a 0 ft ft 9 . . 0 9 9 9 0 0 9 9 0 9 a a AG .. 1 1 1 1 1 2 1 2 2 1 0 0 BCC 4 2 1 2 1 1 1 9 0 1 3 1 CS 1 . . , . 0 ft 0 0 0 • 9 9 9 9 0 . 0 ft CW 2 0 0 9 9 9 9 9 9 0 0 • . 2 1 a a RHB ft 9 9 9 1 0 , ft • 9 0 0 9 ft 9 GBH 9 9 , , 9 9 0 . 9 0 9 9 9 9 .. a 9 K 0 0 • • 4 9 0 9 0 0 0 0 9 9 9 9 9 0 0 9 ft YW • 0 • • 0 0 9 0 0 0 0 0 9 9 9 9 9 9 0 0 ft 9 OCW 0 0 9 9 . , 2 2 3 9 0 0 0 a 9 BTGW 0 0 9 9 9 9 1 9 9 9 O 9 9 .. a a PF • « 0 0 . , 0 0 9 « 9 9 1 0 0 9 O 0 9 0 9 . 0 a a OJ • 0 .. 0 0 • a 0 0 • 0 • 9 9 O 0 0 4 12 2 5 13 10 WW 6 0 0 0 0 « 0 0 O 0 9 9 O 9 0 0 1 0 a 0 0 9 9 a a CNH , „ • 0 ft 0 0 0 0 0 9 9 9 O 0 a 1 9 9 0 0 9 9 • a SVS • 0 0 0 .. 0 0 , , 0 0 0 O ft O 9 9 0 0 1 1 O 0 0 9 0 0 9 0 WCS 0 » 0 0 0 0 ft 0 0 0 0 0 0 0 9 O 0 0 9 O 2 4 1 0 0 a 0 BB 0 0 0 0 0 o . 0 ft 0 0 » 0 0 ft fi 0 O 0 o ft O 3 0 0 9 A 0 a AW • • 0 o 0 0 0 0 9 9 0 0 0 0 0 0 0 0 0 0 0 0 9 « 3 1 .. a a SS a o 0 0 0 0 , , 9 O 0 e 0 0 9 fi 0 0 O 0 0 0 O 0 1 1 0 0 2 GCS • 0 0 0 0 0 0 0 9 9 . . 0 0 ft o 0 0 0 0 9 0 0 9 0 0 3 0 0 a o BTP • « 0 0 0 0 . 0 ft ft 0 . 0 0 9 ft 9 0 0 o 0 0 0 O 0 0 12 0 0 a a EG 0 0 0 0 0 0 , , ft ft 0 0 0 0 0 0 9 9 0 0 9 0 9 0 0 ft 9 1 6 MG 0 0 0 0 0 0 0 0 9 ft 0 0 0 0 0 9 0 0 0 0 0 0 0 9 9 0 9 9 24 7 MDK 0 0 0 0 1 TOTAL SPP. 8 8 7 11 10 9 9 9 8 12 12 11 16 13 8 10 TOTAL IND. 122 106 113 136 130 128 153 130 113 170 110 145 179 188 141 155 (Appendix V - continued) 14th and Spruce p l o t 1969 Nov.18 cn v O rH o\ C M v O o iH iH o rH 1969 Nov.18 Dec, Dec, Dec. CT\ fl rH Cd >-> Jan. Feb. Feb. s 56 35 43 45 25 37 28 28 HS 55 52 53 64 79 61 92 35 CP 29 37 41 38 38 23 23 39 CM 7 10 9 5 5 5 9 4 GWG 5 4 7 6 5 7 6 5 OJ 4 2 8 3 3 14 10 7 NWC 4 3 • » 2 • • 4 • • 2 SS 2 1 5 2 1 3 1 2 BCC 3 1 1 • • • • 1 1 1 AG • HF 1 5 6 8 2 3 6 1 PSK 1 • • 6 EG • * 1 MG. • • » • 13 CRP 2 1 • • AR 1 2 TOTAL SPP. 10 10 10 9 8 11 10 9 TOTAL IND. 167 150 179 173 158 160 177 123 (Appendix V - continued) 43rd and C h u r c h i l l p l o t 211 1968 Feb. 16 o eg C M C M O N C M • H r H C O C M C M V O C M O N C O C M r H C M 1968 Feb. 16 Mar, Apr, May Jun, Jul, Jul, Aug, Aug. Sep. Sep. Oct. Oct. > > o o C J cu ,f3 OJ 53 46 8 2 18 29 35 Ih 45 41 s 53 17 8 18 11 55 48 9 10 41 27 14 4 6 a a HF 18 13 11 22 21 14 10 9 16 15 10 « • 1 2 2 2 AR 17 68 75 75 57 72 107 73 40 83 94 102 1 6 7 1 VT 13 6 8 1 • « 1 • « 2 BT 12 3 2 1 1 • • • ft 17 11 HS 8 7 7 12 18 19 24 11 25 15 19 13 4 3 2 5 BCC 8 7 6 8 14 19 30 15 7 15 13 19 10 10 11 9 SS 7 16 5 5 6 4 5 1 • • * a 2 3 2 4 2 5 GCK 6 • • 3 1 5 5 1 15 6 2 PF 4 2 3 1 » • 6 RSF 3 3 1 1 1 1 1 • • FS 2 • • 1 SJ 1 1 • • 1 GWG 3 3 2 2 2 2 • • 2 3 1 PSK ., 94 14 5 6 5 2 2 2 3 7 2 3 2 • • 1 NWC 6 1 3 • • 1 1 4 • • 1 AG 3 • » 8 3 6 2 5 8 1 8 9 17 22 • a 2 CM 2 • » 2 5 1 1 4 2 CP 2 • « 1 ft • 2 • • • • 3 6 2 RCK 1 4 2 • • 1 3 1 ft 0 BC 1 VGS 3 5 2 4 6 7 11 BTP 8 1 2 1 • • 1 • « 10 1 1 MW 4 1 RHB 1 2 OCW 1 3 1 1 WWR 1 1 1 1 « A * * AW 1 2 1 TSL 1 CW 11 1 • » • • 1 • • 1 1 1 EG 9 2 BS a a 5 2 6 4 13 10 2 CC 3 2 2 6 CSR # # 2 • • 1 WV 2 1 1 • • 1 • • 4 1 WT 2 a a • • 1 2 5 WWP a « 1 . , • • • « 4 CS , a 2 BWR 1 1 2 2 1 WW • • • » 5 YW a , • « » ft 3 5 BTGW . , • • 2 A a' O ft a « • • « • ft « BSW • • ft A 2 TOTAL SPP 14 19 20 23 15 15 15 17 16 18 18 14. 12 13 9 12 TOTAL INDv 205 298 175 199 153 212 250 175 141 205 219 210 59 106 77 74 212 (Appendix.V - continued) 43rd and C h u r c h i l l p l o t oo vo • r H cu C/3 C M a. cu CO CO CM CJ o o a cu vo o CM ON CM • vO • CJ ON a CU r H CD Q <-> Xi cu fe v O CM a X cu fe C M U cd a CM U cd oo rl u 3? L O C M r H r>-U >. > N Pi H I f <s a a MGW BHG CNH AP WCS MG ST OJ HF BCC S HS AG GCK NWC SS RCK CP AR RSF GWG PSK PF BE BT CRP VT CH CM BTP VGS FS RHB SJ AW OCW RBN GCS CW CC HT MW BS CSR TS GBH TOTAL SPP. TOTAL IND. 1 2 1 2 5 19 6 62 41 33 48 60 28 17 3 5 2 • a 19 34 14 11 14 22 17 9 8 9 12 10 8 18 16 12 9 8 10 9 5 6 9 59 23 14 8 2 22 14 6 9 9 7 14 4 7 11 8 10 9 10 11 13 6 2 * • • 0 14 4 8 4 10 7 5 6 • a 2 9 i 7 8 7 3 5 1 5 4 • • • a 1 3 2 2 3 6 7 3 8 6 6 12 7 9 2 4 4 2 2 1 1 1 1 1 5 11 12 16 1 2 1 • • a 1 • « 2 1 2 * a 2 1 18 7 35 41 45 62 52 37 47 39 1 3 2 2 2 1 a a • • 61 3 2 2 2 3 2 • • 2 5 2 32 9 2 3 11 5 17 2 10 • • 1 2 3 8 4 9 6 5 • • 2 1 • * 1 • • 25 • • 1 3 6 3 1 1 2 2 • • 8 27 • 0 3 -1 j . 1 2 • • 3 • e • o • • • • 1 2 • • • • 2 2 • 0 3 4 4 2 2 28 4 1 70 5 a o 2 1 2 8 2 4 4 4 3 1 4 5 7 9 11 5 3 3 1 . . 2 92 5 11 a a a a 14 12 8 . . 1 5 9 3 1 1 .. 2 2 3 6 1 2 1 3 i a' 1 1 i a 7 1 13 16 15 16 14 16 20 19 31 33 26 133 232 150 161 198 182 276 146 197 311 134 (Appendix V - continued) 43rd and C h u r c h i l l p l o t 1 1969 May 1 May 7 May 14 May 21 May 28 June. 4 June 22 June 27 C O > > 3 July 9 July 18 July 23 July 30 Aug. 5 Aug. 17 o\ C N 00 svs 2 1 wv 1 3 • a 3 2 2 ft ft * 0 • • 1 2 WW 1 . . 13 2 13 1 1 YW 1 5 . . 1 2 BTGW 1 SEO 1 EG 3 2 e o « • a e CS a a 1 . . 1 2 • a RWS • • RC • • 2 e • 2 6 AR 57 60 59 60 71 81 56 62 86 93 73 66 71 73 HF 21 15 23 23 19 14 12 28 10 10 2 8 3 3 BS 14 6 13 6 8 11 10 10 5 10 9 9 14 7 AG 11 4 6 6 5 6 3 4 4 2 5 4 4 5 BCC 10 10 10 17 14 24 13 18 21 16 13 18 10 13 HS 10 9 11 11 15 9 17 21 27 24 14 2 17 3 S 7 9 12 7 16 11 18 14 24 26 10 12 26 18 VGS 7 3 4 3 5 11 5 4 6 2 3 CC 5 6 1 4 2 3 3 2 2 1 CM 4 2 2 3 5 6 2 7 2 2 1 • • * e' 5 SS 4 3 2 2 2 2 1 3 2 4 2 1 2 • • BTP 4 2 1 ft 9 2 • • 1 1 1 BT 3 4 • • 2 • « • « 8 ft 0 • ft 18 10 10 ft A GCK 3 1 2 3 NWC 2 2 3 3 6 1 5 • 6 2 PSK 2 3 6 1 3 • • 2 2 1 2 • • ft ft' CP 2 3 A 1 i b U 3 7 CW 2 • • 2 1 2 2 • • 2 ft 0 2 TW 2 RBN 1 • • • • 1 * » 1 • « ft • t ft 2 5 3 2 RSF 1 • • • 0 • « • e ft ft 0 ft • c ft A . . ft a 3 1 OSF 1. 1 1 GWG 2 • * 2 • • • • 2 « • 1 0 ft « 0 • » 2 5 WT • • 2 1 a • ft ft 1 a • 0 ft 2 2 * • 2 1 PF • • 1 • a • • 1 5 2 e « OCW • • 1 1 1 1 « « • •' 1 1 5 CSR • • 1 1 e a « e • • ft 0 • a MGW • • 1 1 1 1 • 0 WWP • • 1 1 • ft • o • e ft 0 • • • a a • 1 • « WF • • • ft 1 2 RHB 2 1 1 BB 1 DW 1 ft ft 1 • • BSW 8 BC 1 1 K 2 BHG ft 0 2 SJ 1 • a TOTAL SPP. 25 22 22 21 15 16 14 14 14 16 15 11 21 20 TOTAL IND. 194 146 176 159 174 187 147 182 193 214 148 136 166 153 (Appendix V - continued) 43rd and C h u r c h i l l p l o t 214 1969 Aug.29 Sep.10 Sep.26 Oct. 9 Oct.28 Nov.10 Nov.21 Dec. 4 Dec.19 Dec.31 1970 Jan. 7 Jan.12 Feb. 6 Feb.11 OJ 3 8 34 21 36 41 25 30 24 29 30 46 32 52 vsw 2 AW 2 1 3 2 • * 0 0 0 0 0 0 . . 0 0 a o 0 0 0 a 9 O WWC 1 AR 66 105 85 30 2 1 4 5 12 11 5 4 5 S 22 53 11 6 6 15 0 0 3 1 3 a a 7 11 BCC 17 17 16 14 17 17 17 16 13 21 12 12 13 EG 10 11 2 17 2 1 2 0 0 5 2 HS 9 6 11 5 5 1 4 5 20 22 36 21 15 HF 5 10 3 4 7 7 12 14 11 23 15 13 14 AG 4 4 3 0 « 0 0 0 o 0 0 o a 2 9 9 a a a a 0 0 SS 3 5 8 16 5 9 7 8 11 6 9 9 7 OCW 3 2 BS 3 RSF 2 2 1 2 1 2 1 0 a 0 a 1 1 1 1 VGS 2 YW 2 WT 2 SVS 2 BT 2 24 18 a a 15 a a 0 0 4 BTP 3 5 2 GCK 1 4 13 2 CP 1 3 0 a 3 CW 1 1 2 DW 1 1 BTGW 1 YBS 1 YT 1 PF 3 1 1 1 0 0 1 3 0 0 5 2 4 1 7 GWG 1 3 5 0 0 5 1 1 1 4 1 a a 2 2 AP 1 7 • a 1 0 0 0 0 0 0 0 0 9 0 a 0 9 9 a a 9 9 WCS • • 7 1 VT fr • 0 1 1 0 0 0 0 o a a a 0 0 0 C 2 9 9 GCS 3 O 0 0 9 0 0 a 9 a a 0 9 RBN . 0 2 1 0 0 0 0 2 1 2 2 2 9 9 9 0 1 PSK 1 1 2 4 80 12 2 12 0 0 0 9 1 3 NWC 1 1 0 0 1 2 0 0 0 0 2 1 9 a 3 0 9 SJ 1 • • 1 1 2 0 0 0 a 2 a a . . 2 2 FS 1 2 9 0 0 0 0 0 0 0 a a 0 0 0 a 0 0 0 0 a a BB 6 0 0 0 0 0 0 0 0 a a a a o a o a 0 O a o RCK . e # # 5 1 0 0 1 1 2 1 0 0 1 a 0 1 CBC 3 1 0 0 2 1 1 1 3 2 a a 2 ST 1 0 0 1 2 0 0 a a 2 2 0 0 a a 0 0 MG • s 1 0 0 0 0 0 9 9 0 0 0 0 0 0 0 0 0 a a 0 a BC 2 1 2 1 0 0 2 1 0 0 a a a a CM 2 2 a a 2 o a HT 1 CRP 1 1 61 a a 1 a a SSH o a 0 » 9 9 0 0 0 0 a a 0 0 1 0 0 o a RC 0 0 0 • 0 0 0 0 a a 0 0 o a 0 a 1 20 NS 1 TOTAL SPP. 26 23 19 17 12 16 15 13 14 15 11 12 15 TOTAL IND. 173 284 190 125 88 91 119 103 112 144 132 106 138 (Appendix V - continued) Ferguson Road pl o t 215 L O 0 0 C M L O oo S 87 HS 31 CM 25 BB 18 HF 4 RWB 3 SS 2 AR 1 WCS 1 GWG 5 MG 3 AP 3 CP 2 GYL 1 PGF 2 . .. HG ., 2 .. . . PT 5 .. .. PF . . . . 14 24 BWR . . . . 1 1 AW . . . . 1 ... ACT . . .. 1 .. RNP 4 NS 1 RLH . . . . . . 2 GBH SB .. BCC MH ST SVS NWC VGS CSN CC CS TSL BS MDK GCS RCK RHB . . . . . . GCK .. . . . . 43 70 67 65 201 94 49 48 21 16 10 5 8 12 10 60 24 23 17 69 32 21 21 13 13 16 24 19 13 15 11 20 8 14 2 5 5 2 3 2 1 2 . 99 10 3 20 26 37 3 13 28 13 15 10 11 10 16 5 9 11 • i 2 3 3 2 5 3 6 1 « • 2 2 • • . 1 • • « • 3 3 1 2 1 2 7 2 3 2 6 4 3 2 5 4 7 6 2 2 1 1 1 2 20 3 15 2 43 31 22 44 31 17 9 16 11 14 28 • * 2 5 3 8 2 8 10 2 10 31 12 a * 2 • c 1 1 1 1 u a 1 6 a o o 1 2 37 40 « • 30 I 10 • a 1 • • 17 8 * • 2 11 5 3 • • 1 2 • • • • 1 11 1 1 2 1 1 1 2 4 71 17 4 9 6 1 ^' 4 1 .. .. 2 .. 2 47 3 .. 4 4 1 2 5 .. 1 3 4 1 20 15 10 7 2 1 • .. 3 .. 5 2 1 .. 4 5 10 11 19 20 20 2 ..• 2 2 .. 2 1 5 11 1 1 1 1 ' TOTAL SPP. 9 • • • .. 1 .. 7 15 12 9 10 11 9 12 15 17 20 19 15 13 14 TOTAL IND. 172 229 165 165 133 360 213 119 152 166 95 209 146 103 92 113 (Appendix V - continued.) Ferguson Road p l o t 216 <r C M o\ • ON a, H # May 2 May 9 May 15 May 25 May 30 Jun. 5 Jun.23 Jun.28 July 4 Jul.15 Jul.19 Jul.24 Jul.31 Aug. 6 Aug.18 WM 1 BTP 9 • • 3 6 AG 1 2 3 1 2 1 1 2 1 4 1 1 4 1 1 2 GWT 1 LSP . , 6 OCW 1 1 TW 1 K 2 1 a a 1 a a 5 a a 1 1 I 5 YHB • • 1 1 1 a a WW a • 1 1 1 HT • a 1 WT 1 1 a a a a YW 2 1 BS 22 17 19 21 28 23 56 49 31 110 26 AR 18 16 23 17 14 12 7 9 10 9 3 BB 15 19 55 10 17 11 12 37 57 25 21 HS 11 20 13 9 29 30 24 20 57 105 16 S 8 12 123 19 23 27 30 35 20 23 26 SVS 7 7 8 7 8 8 5 3 6 12 3 CP 3 3 a a 2 3 5 4 4 6 6 a a RNP 3 RWB 2 1 7 3 18 2 1 1 1 90 a a HF 1 2 a a 1 3 6 12 33 70 75 6 CC 1 1 3 3 4 1 1 7 49 35 4 SS 1 1 .2 3 1 3 1 1 3 2 1 VGS 1 1 a a 4 a a 5 4 15 3 4 1 CW 4 6 a a a a . j a a a a 2 a a a a NWC 2 1 2 a a 1 1 a a Z a a GWG 1 1 0 0 o a 1 a a CM a a 1 2 a o 4 a a a a 1 5 3 2 CS • a a a 2 2 14 17 46 5 4 8 7 BSW a a a a 2 17 a « a a a o 0 0 a a a a a a GBH a a a a 1 a .a 1 GYL BCC 2 a a a a 5 1 . » 2 BHG 1 PSK a o I WCS 2 BK 2 a a a a YT 1 TOTAL SPP. TOTAL IND. 15 14 12 14 17 13 14 17 19 16 15 95 102 259 101 174 149 205 230 328 510 124 217 (Appendix V -- continued) r H r H C M 0 \ C O r H Ferguson Road j p l o t 0 0 C M < H C N L O <• C M C M O oo C O r H L O C M r H C T \ 6 0 Sep, Oct, Oct, Nov. > o Nov. Dec. Dec. 19/ Jan, Jan, Jan. Feb. Feb. RWB 151 36 •1 20i 40 a a • 4 a V A •-s 6 BS 119 48 4 S 94 138 95 108 219 152 299 24 18 80 49 15 17 371 HS 84 79 74 57 48 42 11 32 36 22 23 16 21 17 CS 22 CM 17 6 3 11 24 19 15 4 2 27 48 a a 5 12 BB 10 41 7 7 16 4 51 206 1 23 48 8 1 18 SVS 9 18 14 • a • a 6 0 a a a o a a a a a a a a a a CP 6 4 1 1 5 3 6 5 7 1 a a a a 4 4 AG 5 a a 4 3 AR 2 4 5 13 8 8 4 2 10 8 10 a a 5 14 SS 1 2 3 7 9 5 3 1 5 7 5 3 6 7 HF 1 3 2 7 1 2 3 1 3 1 , . 1 6 8 BCC 1 • * * a •. 1 a a 2 1 a a a a •. 2 CC 1 • • • • • • a a • a . , .. YW 1 2 • • • • a a . a a a RBN 1 • • • a a a , , PSK 3 1 1 • • a a 37 a a NWC 2 • 0 • • a a a a , . a a AP 1 8 2 • 0 a a a a a a a a WCS ,. 4 8 5 8 10 a a 8 16 14 OCW 1 1 • e a a a a CTR 7 • a ,. • • a a a a GWG 2 • • 1 a • 1 1 1 1 MG • • 1 1 17 5 500 15 145 a a a a 81 AW 1 1 a • a s a a a . a a a a • a PF ,. 4 • a 1 3 . . 2 2 • . a a ST 2 1 3 a o a a 3 a o 0 0 a o . a EG 2 • * 3 a a a a • a a a a o a a a a CSN 1 4 • a a a a o a a o a a a a . RSF 1 „ „ • « • e a a a a 0 0 a a a a . . OJ .. 2 4 a a a a a a a a a a a a MH 1 • • • • a a a a a a . a a a a a FS 1 a a a a a a , , « 0 a a SSH • a 1 a a a a a a a a a a a a RNP 2 a a a o a a a a a a MDK 3 15 2 a a a a a a a o GCS a a , , 1 • 0 a a 0 0 1 CH a a 1 a a , , a a a « K a a 27 a a a a a a a a GBH a a a a 1 2 a a a o a o PH a e a a 1 a a a a a a CW a a a a 12 a a a e a a NS a a a a a a 1 1 a a RLH a a a a a a a a a a e a 2 , , HG . . a a a e a a a a a a o a .. 2 BE 0 I a a a a a e a a a » o a a a a . 1 TOTAL SPP. 17 15 20 14 15 17 10 11 13 12 10 9 11 16 TOTAL IND. 525 387 233 229 362 260 440 290 235 179 200 143 81 471 APPENDIX VI NUMBER OF TREES ON SHEPARD'S STUDY PLOTS 218 219 Appendix VI Numbers of trees on Shepard's study pl o t s 22nd & 33rd & Species Dunbar Dunbar Pseudotsuga menziesii, Douglas f i r 21 130 Tsuga heterophylla, western hemlock,) 4fi ) 25 42 Thuja plioata, western red cedar ) Ornamental conifers 89 56 Comus n u t t a l l i i . P a c i f i c dogwood 71 95 Acer spp„, maples 57 42 Ulmus amerioana, elm 50 32 Betula pendula, European white b i r c h 12 84 Prunus serrulata, Japanese flowering cherry 76 66 Other deciduous trees 337 185 TOTAL 738 732 APPENDIX VII RESULTS OF CENSUSES ON SHEPARD'S STUDY PLOTS, 1969-1970 220 221 Appendix VII Results of.censuses on Shepard's study p l o t s , 1969-1970 22nd and Dunbar 33rd and Dunbar m oo 1 1969 Dec. 5 | Dec. 7 Dec.12 1970 Jan. 6 Jan.l6 Feb. 1 Feb.21 Mar. 4 ! 1969 Dec. 7 Dec. 9 Dec.15 1970 Jan. 8 Jan.26 Feb. I] Feb. 2! Mar. 9 OJ 20 17 20 23 23 22 22 18 30 50 40 17 40 70 70 28 HS 18 20 14 10 17 31 32 10 32 34 28 24 20 36 34 22 HF 2 • • 6 9 3 8 9 3 17 20 28 60 23 36 16 16 BCC 4 7 3 2 7 4 5 8 20 20 20 14 14 20 17 17 S 3 16 50 • • 13 14 25 ft • • • • • 3 • • 1 9 8 3 AR 1 5 • • 17 5 2 • • 10 1 1 25 21 16 SS 8 6 7 8 6 5 6 4 10 9 5 4 3 6 6 6 ST 2 1 5 4 9 9 4 6 2 2 2 PSK • • • • . • • • • • 6 . , • • 15 25 GP 10 8 7 1 3 10 2 PF 9 3 .. ,. • • 1 1 8 2 BT • • 1 • • • • 20 RC » ft 15 SJ • • 4 5 1 2 1 CBC • • 4 2 2 • • 3 2 • • • • RSF 2 1 • • 1 1 2 1 GWG 1 1 3 2 CRP • • • • 5 WCS 1 3 DW 1 1 • • • • 1 CM • • EG 1 2 RBN • • • » • • 1 1 GCK • • 2 * • • « RCK •• 1 ft • •• TOTAL SPP. 8 9 10 9 15 12 12 10 10 12 13 9 9 11 9 12 TOTAL INDIV. 58 87 115 62 99 102 133 66 123 161 161 128 106 208 182 150 APPENDIX VIII TIMES AND WEATHER CONDITIONS DURING CENSUSES OF VANCOUVER STUDY PLOTS, 1968-1970 222 223 Appendix VIII Times and weather conditions.during censuses of Vancouver Study P l o t s , 1968-1970 Date Pl o t censused Start of census Duration of census Weather conditions 1968 23 January 19 th & Yukon 0835 hr. 80 min. Overcast, warm 24 January 14 th & Spruce, 0825 65 P a r t l y cloudy, warm; strong W breeze 7 February 19 th & Yukon 0835 85 Clear, cold 13 February 14th & Spruce 0840 60 Clear, cold 16 February 43rd & C h u r c h i l l 0915 85 Clear, cold 28 February 19 th & Yukon 0825 70 Clear, cool 16 March 14 th & Spruce 1030 65 Cloudy, warm 20 March 43rd & C h u r c h i l l 0810 105 Clear, cool 22 March 19th & Yukon 0855 80 High overcast, warm 16 A p r i l 14th & Spruce, 0845 85 Mostly c l e a r , cool; l i g h t W breeze 22 A p r i l 43rd & C h u r c h i l l 0830 110 Clear, warm 28 May 19 th & Yukon 0510 95 Overcastj warm 29 May 43rd & C h u r c h i l l 0530 115 Mostly c l e a r 31 May 14th & Spruce 0630 ? Sunny 14 June 19 th & Yukon 0525 90 Clear, cool 15 June 14 th & Spruce 0545 75 Clear, cool 17 June 43rd & C h u r c h i l l 0535 95 Clear, cool. 2 J u l y 19th & Yukon 0540 95 Clear, warm 3 July 14th & Spruce 0535 90 Clear, warm 4 July 43rd & C h u r c h i l l 0540 115 P a r t l y cloudy, warm 15 July 19 th & Yukon 0540 90 Overcast, cool 16 J u l y 14th & Spruce 0530 85 Clear, cool 17 J u l y 43rd & C h u r c h i l l 0545 105 Clear, cool 1 August 19 th & Yukon 0545 110 Clear, warm 2 August 14th & Spruce 0550 85 Clear, warm 3 August 43rd & C h u r c h i l l 0610 100 Mostly cloudy, warm; strong breeze 16 August 19th & Yukon 0555 105 Mostly c l e a r , cool 19 August 14 th & Spruce 0545 75 Cloudy, cool 22 August 43rd & C h u r c h i l l 0545 110 Cloudy, cool 3 September 19 th & Yukon 0550 95 P a r t l y cloudy 4 September 14th & Spruce 0600 70 Clear 6 September 43rd & C h u r c h i l l 0605 125 Cloudy, warm 18 September 19 th & Yukon 0610 95 P a r t l y cloudy, cool (52 ); breezy 20 September 14th & Spruce 0620 75 Clear, cool 24 September 43rd & C h u r c h i l l 0625 105 Clear, warm 7 October 19 th & Yukon 0653 112 Cloudy, cool 8 October 14th & Spruce 0710 75 Overcast, cool. 9 October 43rd & C h u r c h i l l 0730 95 Overcast, cool; r a i n NOTE: A l l times are P a c i f i c Standard Time. Unless otherwise stated, there was no p r e c i p i t a t i o n and winds were n e g l i g i b l e . 224 (Appendix VIII - continued) Start of Duration Date Plot censused census of census Weather conditions 21 October 19 th & Yukon 0755 hr. 110 min. Overcast, cool (52°) 22 October 14 th & Spruce 0745 80 Mostly c l e a r , cool. 23 October 43rd & C h u r c h i l l 0820 120 Overcast, warm (57°) showers 25 October Ferguson Road 0835 35 Overcast 5 November 19 th & Yukon 0820 85 Cloudy, l i g h t r a i n 6 November 14th & Spruce 0830 65 Clear, cold 7 November 43rd & C h u r c h i l l 0830 ? Cloudy, warm 8 November Ferguson Road 0940. 30 Cloudy, warm 19 November 19 th & Yukon 0820 95 Cloudy, warm 20 November 14th & Spruce 0835 1 Warm 21 November 43rd & C h u r c h i l l , 0915 75 Cloudy, warm; r a i n 22 November Ferguson Road 0825 35 Cloudy, warm 3 December 19 th & Yukon 0930 85 Cloudy, warm; r a i n 4 December 43rd & C h u r c h i l l 1000 90 Clear, cold 5 December Ferguson Road 0940 40 ? 6 December 14th & Spruce 0930 65 Overcast, cold; snow cover 17 December 19 th & Yukon 0900 100 Cloudy, cool; r a i n 18 December Ferguson Road 1040 30 Clear, windy 19 December 14 th & Spruce 0900 60 Clear 26 December 43rd & C h u r c h i l l 0955 80 Overcast, snow 1969 6 January 19th & Yukon 0955 85 Cloudy, cool; r a i n 8 January 14 th & Spruce 0955 55 Overcast, cool; l i g h t E breeze 20 January 43rd & C h u r c h i l l 1010 120 P a r t l y cloudy, snow; very cold, 1! snow cover 25 January 19 th & Yukon 1055 90 Clear, very cold 27 January 14th & Spruce 0950 70 Cloudy, very cold; snow 10 February 19 th & Yukon 0925 85 Cloudy, warm 11 February 14th & Spruce 0935 75 Pa r t l y cloudy, showe: 11 February Ferguson Road 1200 35 Cloudy, warm 13 February 43rd & C h u r c h i l l 0920 105 P a r t l y cloudy, cool 24 February 19 th & Yukon 0840 65 Clear, warm 25 February 14th & Spruce 0900 65 Mostly c l e a r 26 February 43rd & C h u r c h i l l 0910 95 P a r t l y cloudy 27 February Ferguson Road 1030 45 Sunny 10 March 14 th & Spruce 0950 60 Clear, cool 11 March 19 th & Yukon 0925 80 Clear, cool 12 March 43rd & C h u r c h i l l 0810 100 Clear, cool 13 March Ferguson Road 1000 35 Clear, cool. 225 (Appendix VIII - continued) Start of Duration Date. P l o t censused census of census Weather conditions 24 March 19th & Yukon ? ? ? 25 March 14th & Spruce 0900 hr. 60 min. Sunny 26 March Ferguson Road 0920 60 Pa r t l y cloudy, warm 27 March 43rd & C h u r c h i l l 0905 85 Sunny, warm 7 A p r i l 19th & Yukon 0935 70 P a r t l y cloudy, cool 8 A p r i l 43rd & C h u r c h i l l 0700 105 Clear, cool 9 A p r i l 14th & Spruce 0630 65 Cloudy 10 A p r i l Ferguson Road 0740 40 Warm 15 A p r i l 19th & Yukon 0720 70 Clear 16 A p r i l 14th & Spruce 0655 55 Overcast, warm 17 A p r i l Ferguson Road 0815 45 Overcast 18 A p r i l 43rd & C h u r c h i l l 0710 90 Overcast 22 A p r i l 19th & Yukon 0710 80 Overcast, d r i z z l e , 23 A p r i l 14th & Spruce 0725 ? Overcast, r a i n 24 A p r i l Ferguson Road 0740 40 P a r t l y cloudy 25 A p r i l 43rd & C h u r c h i l l 0700 110 Sunny 28 A p r i l 19th & Yukon 0545 80 Overcast 30 A p r i l 14th & Spruce 0600 70 Overcast 1 May 43rd & C h u r c h i l l 0620 150 Overcast, cool; r a i n 2 May Ferguson Road 0655 45 Cool 5 May 19th & Yukon 0630 85 Pa r t l y cloudy 6 May 14th & Spruce 0620 65 Clear, cool 7 May 43rd & C h u r c h i l l 0555 85 Clear, warm 9 May Ferguson Road 0710 40 Cloudy 12 May 19th & Yukon 0600 100 Clear 13 May 14th & Spruce 0530 95 Clear 14 May 43rd & C h u r c h i l l 0545 115 P a r t l y cloudy 15 May Ferguson Road 0555 35 Mostly c l e a r , cool 20 May 19 th .& Yukon 0620 85 Clear, warm (51°) 21 May 43rd & C h u r c h i l l 0615 90 Clear, warm 22 May 14th & Spruce 0635 80 1 25 May Ferguson Road 0850 1 Overcast, warm 26 May 19th & Yukon 0645 75 Cloudy 27 May 14th & Spruce 0635 65 Cloudy, cool 28 May 43rd & C h u r c h i l l 0620 110 Cloudy, cool 30 May Ferguson Road 0710 35 Cloudy; W breeze 2 June 19th & Yukon 0620 85 Mostly c l e a r , warm 3 June 14th & Spruce 0620 70 Clear, warm 4 June 43rd & C h u r c h i l l 0620 95 Clear, warm 5 June Ferguson Road 0740 50 Clear, warm 9 June 19th & Yukon 0605 90 Clear, warm 20 June , 14th & Spruce 0635 65 Cloudy 22 June 43rd & C h u r c h i l l 0625 95 Cloudy 23 June Ferguson Road 0610 40 1 24 June 19th & Yukon 0610 85 Mostly cloudy, cool 226 (Appendix VIII - continued) Start of Duration Date Plot censused census of census Weather conditions 26 June 14th & Spruce 0610 hr. 65 min. Par t l y cloudy 2 7 June 43rd & C h u r c h i l l 0535 85 Cloudy, cool; r a i n 28 June Ferguson Road 0640 ? Cloudy, cool 30 June 19th & Yukon 0620 95 Mostly c l e a r 1 J u l y 14th & Spruce 0630 80 Clear 3 July 43rd & C h u r c h i l l 0615 85 Cloudy, 550 4 July Ferguson Road 0640 45 P a r t l y cloudy, cool 7 July 19th & Yukon 0630 80 P a r t l y cloudy 8 July 14th & Spruce 0555 75 Cloudy 9 July 43rd & C h u r c h i l l 0520 105 Clear, warm 15 July Ferguson Road 0640 45 P a r t l y cloudy 16 July 19th & Yukon 0620 95 ? 17 July 14th & Spruce 0615 65 Clear 18 Ju l y 43rd & C h u r c h i l l 0620 90 Clear 19 July Ferguson Road 0720 40 Clear, warm 21 Ju l y 19th & Yukon 0630 80 Mostly clear 22 July 14th & Spruce 0605 65 Clear, 56° 23 July 43rd & C h u r c h i l l 0600 100 Clear, warm (59°) 24 July Ferguson Road 0625 40 Clear, warm (61°) 28 July 19th & Yukon 0555 75 Cloudy, 57°; l i g h t SE breeze 29 Ju l y 14th & Spruce 0550 75 Clear, cool (51°) 30 Ju l y 43rd & C h u r c h i l l 0600 90 Clear, 56° 31 Ju l y Ferguson Road 0625 40 Mostly c l e a r , 55° 3 August 19th & Yukon 0620 90 Clear, cool. 4 August 14th & Spruce 0600 65 Cloudy, l i g h t r a i n 5 August 43rd & C h u r c h i l l 0615 75 Mostly c l e a r , 53° 6 August Ferguson Road 0630 55 P a r t l y cloudy 13 August 19th & Yukon 0605 80 Cloudy, 57° 16 August 14th & Spruce 0610 70 P a r t l y cloudy, 57° 17 August 43rd & C h u r c h i l l 0615 110 Overcast, cool 18 August Ferguson Road 0645 40 Rain 26 August 19th & Yukon 0630 80 Clear, cool 28 August 14th & Spruce 0610 65 Mostly c l e a r , cool 29 August 43rd & C h u r c h i l l 0610 85 Clear,,cool 31 August Ferguson Road 0700 50 Clear, cool 8 September 19th & Yukon 0625 85 Clear, 53° 9 September 14th & Spruce 0650 60 P a r t l y cloudy, warm (64°) 10 September 43rd & C h u r c h i l l 0625 90 Clear, 55° 11 September Ferguson Road 0605 45 Fog patches, 57° 24 September 19th & Yukon 0610 115 P a r t l y cloudy 25 September 14th & Spruce 0620 75 Mostly c l e a r 26 September 43rd & C h u r c h i l l 0615 115 Overcast 2 October Ferguson Road 0720 40 Clear 6 October 19th & Yukon 0630 95 Clear, cool (42°) 227 (Appendix VIII - continued) Start,of Duration Date Plot censused census of census Weather conditions 7 October 14th & Spruce, 0620 hr. 70 min. Overcast, warm (52°) 8 October Ferguson Road 0655 45 Overcast, warm; l i g h t showers 9 October 43rd & C h u r c h i l l 0630 85 Mostly cloudy 21 October 19th & Yukon 0650 95 Overcast, warm (53°) 23 October 14th & Spruce 0650 ? Overcast 28 October 43rd & C h u r c h i l l 0750 80 Clear, cool 2 November Ferguson Road 0730 40 Cloudy 5 November 19th & Yukon 0715 75 Overcast, warm (47°) 7 November 14th & Spruce 0730 65 Overcast, warm 10 November 43rd & C h u r c h i l l 0725 80 Overcast, warm 11 November Ferguson Road 0820 45 Overcast, warm; d r i z z l e 17 November 19th & Yukon 0740 75 Overcast, cool (37°) 18 November 14th & Spruce 0750 60 Overcast, 43° 21 November 43rd & C h u r c h i l l 0735 80 Mostly clear 24 November Ferguson Road 0750 35 Overcast 1 December 19th & Yukon 0755 75 Clear, cold 3 December 14th & Spruce 0755 60 Overcast, warm 4 December 43rd & C h u r c h i l l 0925 110 P a r t l y cloudy, warm (44°) 5 December Ferguson Road 0810. 55 Overcast, 35° 15 December 19th & Yukon 0835 60 Overcast, warm 16 December 14th & Spruce 0925 65 Overcast 19 December 43rd & C h u r c h i l l 0850 70 Clear, 34° 24 December Ferguson Road 0920 50 Overcast 29 December 14th & Spruce 0835 65 Overcast 30 December 19th & Yukon 0900 80 Overcast, d r i z z l e 31 December 43rd & C h u r c h i l l 0955 95 Overcast 1970 2 January Ferguson Road 1050 50 Overcast, 36° 5 January 19th & Yukon 0950 80 Overcast, 36° 6 January 14th & Spruce 0940 50 Mostly c l e a r , 36° 7 January 43rd & C h u r c h i l l 0950 100 Cloudy, 34° 8 January Ferguson Road 1005 30 Overcast, 37° 10 January 19th & Yukon 0840 60 Overcast, 34° 11 January 14th & Spruce 1005 80 Overcast, 42° 12 January 43rd & C h u r c h i l l 1135 75 Overcast, 41° 13 January Ferguson Road 1445 35 Rain, 38° 3 February 19th & Yukon 0900 70 Clear, 42° 4 February 14th & Spruce 0930 60 Overcast, 38° 5 February Ferguson Road 0925 35 Overcast, 34° 6 February 43rd & C h u r c h i l l 0920 85 Mostly c l e a r , 40° 9 February 19th & Yukon . 0920 90 Dense fog, 40° 10 February 14th & Spruce 0940 65 Clear, 40° 11. February 43rd & C h u r c h i l l 0915 85 Clear, 42° 12 February Ferguson Road 1000 40 Overcast, 44° APPENDIX IV TEMPERATURES DURING STUDY PERIOD, COMPARED TO NORMALS (1931-1960) 228 229 Appendix IX Temperatures during study period, compared to normals (1931-1960) 1968 1969 1970 Normal Month Mean Max. Min. Mean Max. Min. Mean Max. Min. Mean Max. Min January 38.8 58 17 26.8 44 3 37.5 55 23 37.2 58 0 February 41.9 58 23 37.3 49 18 41.6 54 29 39.4 59 3 March 45.7 59 32 42.7 63 28 43.2 67 15 April 47.1 66 30 47.1 60 34 48.3 76 26 May 54.6 72 39 55.7 77 40 55.0 84 33 June 58.9 74 46 63.1 84 48 60.4 87 40 July 64.2 81 48 62.9 79 50 63.8 89 44 August 61.4 80 48 60.3 77 46 63.6 92 43 September 56.7 71 39 57.3 74 43 57.8 84 33 October 49.5 64 36 49.4 66 35 50.3 73 27 November 44.1 60 28 43.7 60 28 43.1 62 10 December 34.1 50 0 41.5 54 27 39.6 58 0 YEAR 49.8 81 0 49.0 84 3 50.4 92 0 Figures above are from the Vancouver International Airport weather office on Sea Island. (All temperatures are in degrees Fahrenheit). Maximum and Minimum temperatures list e d are extremes for each year and for the com-plete station record (1937-1970). APPENDIX X PRECIPITATION DURING STUDY PERIOD, COMPARED TO NORMALS (1931-1960) 230 231 Appendix X Precipitation during study period, compared to normals (1931-1960) 1968 1969 1970 Normal Month Rain Snow Total Rain Snow Total Rain Snow Total Rain Snow Total January 13.2 13.3 14.5 3.9 31.9 7.1 5.4 3.3 5.7 7.5 9.4 8.4 February 6.0 6.0 2.7 6.8 3.4 3.5 0.2 3,5 5.8 5.7 6.4 March 7.5 7.5 5.2 « • e 5.2 5.7 2.0 5.9 April 2.8 2.8 6.0 ... 6.0 3.5 0.8 3.6 May 2.6 2.6 1.7 1.7 2.7 • • • 2.7 June 3.0 3,0 1.0 1.0 2.6 • * • 2.6 July 1.4 1.4 1.0 1.0 1.6 ••• 1.6 August 2.9 2.9 2.2 2.2 1.7 • • • 1.7 September 5.1 5.1 7.9 7.9 3,3 • • • 3.3 October 9.3 9.3 5.1 5.1 6.8 • • • 6.8 November 8.3 2.0 8.5 5.1 5.1 7.7 0.7 7,8 December 7.7 25.1 10.2 7.5 7.5 9.1 4.5 9.6 YEAR 70.0 40.4 74.0 49.3 38.7 53.1 57.9 23.1 60.2 Figures above are from the Vancouver City weather office. (All measurements are in inches; 10 inches of snow is equivalent to one inch of rain). Precipitation at the Vancouver International Airport i s much less (mean annual total 41.1 inches, including 17.8 inches of snow), but month-to-month trends during the study period were similar. APPENDIX XI PLANTS PRESENT ON SACRAMENTO STUDY PLOTS 232 233 Appendix XI Plants present on Sacramento study p l o t s * Species F & 21st S & 24th TREES Ulmus sp., elm C C Platanus occidentalis3 American sycamore C C Cupressus sempervirens3 I t a l i a n cypress C C Ilex aquifolium3 English h o l l y C X Juglans regia3 Persian walnut C C Citrus sinensis3 orange ) Citrus paradisi3 grapefruit) Citrus spp. C C Citrus limonia3 lemon ) Liboaedrus deaurrens3 incense cedar C X Trachycarpus fortunei3 windmill palm C X Phoenix canariensis3 Canary Island date palm C C Washingtonia robusta3 Mexican Washington palm C C Liriodendron t u l i p i f e r a 3 t u l i p t r e e X X Pious c a r i c a 3 f i g X C A l b i z z i a j u l i b r i s s i n 3 s i l k t r e e X Eriobotrya japonica3 loquat C C Zelkova serrata3 Japanese zelkova C C Ginkgo biloba3 ginkgo X Betula pendula3 European white b i r c h C X Cinnamomum camphora3 camphor-tree C C Cedrus deodara, deodar cedar X Picea abies3 Norway spruce X X Magnolia soulangeana3 saucer magnolia X Magnolia s t e l l a t a 3 star magnolia X Pinus sabiniana3 digger pine X Pinus pinea3 I t a l i a n stone pine X Umbellularia c a l i f o r n i c a 3 C a l i f o r n i a l a u r e l X X Acacia melanoxylon3 blackwood acacia X Pseudotsuga menziesii3 Douglas f i r X Laurus n o b i l i s 3 Grecian l a u r e l C X Sequoia sempervirens3 redwood X X Fraxinus velutina3 Arizona ash C C Arbutus unedo3 strawberry tree X X Picea pungens3 blue spruce X Chamaecyparis lawsoniana3 Port,Orford cedar X Prunus persica3 peach ) Prunus amygdalus3 almond ) Prunus spp. . C Prunus domestica3 plum ) Pinus sp., pine . X Juniperus sp., juniper . X Eucalyptus polyanthemos3 red-box . X *C means common; X, present but not common. For d e f i n i t i o n of "common," see page 17. 234 (Appendix XI - continued) Species F & 21st S & 24th TREES (cont.) Photinia s e r r u l a t a X X Magnolia sp., magnolia . X Fortunella margarita3 kumquat . X Robinia pseudoacacia3 black locust . X SHRUBS Camellia japonica3 camellia C C Auouba japonica3 gold-dust plant C C Pyracantha graberi3 f i r e t h o r n C C Pittosporum tobira3 Japanese pittosporum C C Fatsia japonica C X Juniperus chinensis3 Chinese juniper C C Thuja occidentalis 3 northern white cedar C C Buxus microphylla3 boxwood C Cotoneaster parnyii C X Azalea spp., l a r g e l y A. obtusa (Kurume,azalea type) C C Ligustrum japonicum3 p r i v e t C C Chaenomeles sinensis3 Chinese flowering quince C C Pelargonium hortum3 geranium X C Callistemmon oitrinus3 bottlebrush X C Nerium oleander3 oleander X C Rosa spp. , roses X C Nandina domestica X C Ligustrum texonum3 p r i v e t X X Ligustrum luoidum3 p r i v e t X X Spiraea sp., s p i r e a X Euonymus japonioa3 spindle tree X Opuntia sp., p r i c k l y p e a r cactus X Eohinopsis sp., b a r r e l cactus X G r e v i l l i a r o s m a r i n i f o l i a X Rhododendron sp., rhododendron X X Lonioera japonica3 honeysuckle X Yucca sp., yucca X X Myrtus sp., myrtle X X Kerria japonica3 Japanese k e r r i a X X Erica mediterranea3 Mediterranean heather X X Hydrangea sp., hydrangea X X Olea europaea3 o l i v e X Taxus baccata3 English yew X X V i t i s sp., grapes X Choisya ternata3 Mexican mockorange X D i e r v i l l a f l o r i d a 3 weigela X 235 (Appendix XI - continued) Species F & 21st S & 24th SHRUBS (Cont.) Cotoneaster microphylla X Trachelospermum j'asminoides, star jasmine X Viburnum tinus X Prunus laurocerasus, cherry l a u r e l , X X Raphiolepis indica, pink Indian hawthorn X C Rosmarinus officinalis, rosemary X Podocarpus microphylla X Rubus laciniatus, evergreen blackberry . X Mahonia sp„, Oregon grape . X Washingtonia f i l i f e r a , C a l i f o r n i a fan palm X Hedera helix, English i vy C C Hedera canariensis, ivy C C Daphne odor a X X HERBS Nephrolepis exaltata, sword fern C Woodwardia,fimbriata (a fern) C Cynodon dactylon, Bermuda grass C C Bergenia c r a s s i f o l i a , winter primrose X C Asparagus plumosus, asparagus X C Asparagus sprengeri, asparagus X Convallaria majalis, l i l y - o f - t h e - v a l l e y X Viola odorata, v i o l e t X X Alyssum sp., alyssum X Echeveria elegans X X Papaver nudicaule, Iceland poppy . X I r i s sp., i r i s . X Pteridium aquilinum, bracken . X Lathyrus odoratus, sweet pea . X Daucus carota, carrot . X Beta vulgaris, beet . X Lactuca sativa, l e t t u c e . X Allium cepa, onion . X Pisum sativum, garden pea . X APPENDIX XII CENSUS OF TREES PRESENT ON SACRAMENTO STUDY PLOTS (33% SAMPLE) 236 237 Appendix XII Census of trees present on Sacramento study plots (33% sample) Species Ulmus sp., elm Platanus occidentalis3 American sycamore Cupressus sempervirens3 I t a l i a n cypress Citrus spp. Trachycarpus fortunei3 windmill palm Zelkova serrata3 Japanese zelkova Washingtonia robusta3 Mexican fan palm Betula pendula3 European white b i r c h Pyracantha graberi3 f i r e t h o r n , Juglahs regia, Persian walnut Cinnamomum camphora3 camphor-tree Camellia japonioa, camellia Fraxinus velutina3 Arizona ash Phoenix canariensis3 Canary Island date palm Libooedrus decurrens3 incense cedar Eriobotrya Qaponica3 loquat Pittosporum tobira3 Japanese pittosporum Laurus n o b i l i s 3 Grecian l a u r e l A l b i z z i a j u l i b r i s s i n , s i l k - t r e e Sequoia sempervirens 3 redwood Prunus laurocerasus 3 cherry l a u r e l Ginkgo biloba3 ginkgo Ficus c a r i c a 3 f i g Liriodendron t u l i p i f e r a 3 t u l i p t r e e Ligustrum lucidum3 p r i v e t Picea abies3 Norway spruce Cedrus deodara3 deodar cedar Picea pungens3 blue spruce, Pseudotsuga menziesii3 Douglas f i r Olea europaea3 o l i v e Photinia s e r r u l a t a Magnolia s t e l l a t a 3 s t a r magnolia Prunus spp. Callistemmon c i t r i n u s 3 bottlebrush Rosa spp., roses Arbutus unedo, strawberry-tree Nerium oleander3 oleander Thuja, oacidentalis3 northern white cedar Chaenomeles sinensis3 Chinese flowering quince Robinia .pseudacacia3 black locust Pinus sp. Eucalyptus polyanthemos3 red-box Juniperus sp., juniper U n i d e n t i f i e d broad-leaved trees U n i d e n t i f i e d conifers F & 21st 44 22 21 12 12 9 8 8 7 6 5 5 4 4 4 3 3 3 2 2 2 2 1 1 1 1 1 . 1 1 1 1 1 S & 24th 9 49 9 6 2 4 2 2 3 1 1 * • 4 2 2 20 7 9 3 3 2 1 1 1 1 1 1 1 30 5 TOTAL 225 179 APPENDIX XIII HEIGHTS OF 33% SAMPLE OF TREES ON SACRAMENTO STUDY PLOTS 238 Appendix XIII Heights of 33% sample of trees on Sacramento study pl o t s Height class F & 21st p l o t S & 24th p i 15-20' 35 30 20-30* 55 47 30-40* 35 45 40-50' 20 39 50-60' 24 13 60-70' 20 2 70-80' 9 0 80' plus 27 3 TOTAL 225 179 APPENDIX XIV RESULTS OF BIRD CENSUSES ON SACRAMENTO STUDY PLOTS 240 241 Species House Sparrow American Goldfinch S t a r l i n g Oregon Junco Scrub Jay White-crowned Sparrow Common Crow Robin Pine S i s k i n Red-shafted F l i c k e r Audubon's Warbler Red-breasted Nuthatch Mockingbird Rock Dove Sparrow Hawk Rufous-sided Towhee White-fronted Goose Red-winged Blackbird C a l i f o r n i a G u l l Snow Goose Brown-headed Cowbird House Finch Whistling Swan Water P i p i t Cedar Waxwing Brewer's Blackbird Appendix XIV Results of b i r d censuses on Sacramento study plots S & 24th r-» o ro un r-^  r H C M C M C M C M d 0 (3 C C Cd CO CTJ Cd CtJ I - J r - j r - j r - j r - , 13 12 12 16 9 5 6 10 1 6 1 12 3 20 9 7 9 4 8 1 5 3 2 8 4 6 6 4 6 3 3 3 .. 1 1 2 • • 5 5 • • «« 8 3 1 • • 2 1 1 1 . . 2 2 1 17 9 25 1 1 1 . . 1 1 1 .. 80 .. 164 .. 16 2 31 3 12 70 1 1 .. 1 1 2 1 .. 1 .. 1 1 1 .. F & 21st O V C M 00 O r H C M . C M C M C M • o\ C cj a c a i — i ca cd *-i >-} 33 21 32 28 6 32 16 9 2 14 10 3 17 18 7 • • 6 10 8 8 5 3 5 3 2 • • 2 6 5 4 2 1 16 I 3 2 • • 1 • • 2 3 1 • • 3 1 1 1 * « 1 • • 1 1 2 2 1 , , l 1 1 2 3 3 332 18 14 20 1 2 6 TOTAL SPECIES TOTAL INDIVIDUALS 8 9 9 8 11 87 54 97 67 48 9 10 41 70 5 13 9 32 94 36 I t a l i c i z e d numbers indic a t e birds seen j u s t outside the p l o t or i n f l i g h t over the p l o t ; these numbers are not included i n the t o t a l s . APPENDIX XV TIMES AND WEATHER CONDITIONS DURING CENSUSES OF SACRAMENTO PLOTS, 1970 242 243 Appendix XV Times and weather conditions during censuses of Sacramento p l o t s , 1970 Date Plot censused Start of census Duration of census Temp. Weather conditions 17 January S & 24th 0930 hr. 60 min. 56°F. P a r t l y cloudy, wind MPH, SSW 19 January F & 21st 0835 70 53 Overcast, showers 20 January S & 24th 0840 65 56 P a r t l y cloudy, c l e a r i n g 22 January F & 21st 1000 60 59 Cloudy 23 January S & 24th 0900 55 57 Overcast; gusty W breeze 24 January F & 21st 0755 70 53 Mostly clear 25 January S & 24th 0810 60 45 Mostly clear 26 January F & 21st 0850 70 50 Mostly c l e a r 27 January S & 24th 0835 55 53 Clear 28 January F & 21st 0835 39 Clear APPENDIX XVI PLANTS PRESENT ON OTTAWA STUDY PLOTS 244 245 Appendix XVI Plants present on Ottawa study p l o t s * R o c k c l i f f e A l t a Species Park V i s t a TREES Ulmus americana, American elm VC VC Acer spp. (mainly A. saccharum, sugar maple) VC VC Thuja occidentalia, northern white cedar VC VC Picea abies, Norway spruce C VC Picea pungens, blue spruce C VC fraxinus sp., ash C X Betula pendula, European white b i r c h C VC Salix babylonica, weeping willow X C Pinus s y l v e s t r i s , Scots pine X C Pinus resinosa, red pine X X Larix decidua, European l a r c h X X Malus sp., probably M. baccata, Siberian crabapple X C Sorbus aucuparia, European mountain ash X C Quercus sp. (red oak type) . X Quercus sp. (white oak type) X Malus s y l v e s t r i s , apple X X Betula papyrifera, white b i r c h X Populus nigra, Lombardy poplar X Robinia pseudoacacia, black locust X Acer negundo, Box elder . X Catalpa sp., catalpa . X Prunus sp. X Cupressus sp, X Populus sp. X Pinus strobus, eastern white pine X X SHRUBS Hydrangea sp. X X Taxus baccata, English yew X C Syringa vulgaris, l i l a c C X Rhus typhina, staghorn sumac X X Ulmus p a r v i f o l i a , Chinese elm (hedges) X X Ligustrum vulgare, common p r i v e t X X *VC means very common; C, common; X, present b,ut not common. For d e f i n i t i o n of "common" and "very common," see pages 17 and 25. APPENDIX XVII CENSUS OF TREES PRESENT ON OTTAWA STUDY PLOTS (SMALL SAMPLE) 246 247 Appendix XVII Census of trees present on Ottawa study plots (small sample) R o c k c l i f f e A l t a Species Park V i s t a Acer spp. (mainly A. saccharum, sugar maple) 57 33 Ulmus americana, American elm 42 15 Thuja oocidentalis, northern white cedar 28 3 Fraxinus sp., ash 15 2 Picea abies, Norway spruce 12 13 Picea pungens, blue spruce 8 7 Betula pendula, European white b i r c h 7 33 Syringa vulgaris, l i l a c 5 1 Pinus strobus, eastern white pine 2 2 Sorbus aucuparia, European mountain ash 2 8 Salix babylonica, weeping willow 1 1 Pinus s y l v e s t r i s , Scots pine . 7 Pinus resinosa, red pine 3 Quercus sp., oak (red oak type) 3 Malus sp. (probably M. baccata, Siberian crabapple) 3 Acer negundo, box elder 2 Prunus sp. 2 Populus nigra, Lombardy poplar 2 Catalpa sp., catalpa 1 Cupressus sp., cypress 1 Populus sp., poplar 1 Un i d e n t i f i e d broad-leaved trees 2 14 TOTAL 181 157 APPENDIX XVIII HEIGHTS OF SAMPLE OF TREES ON OTTAWA STUDY PLOTS 248 249 Appendix XVIII Heights of sample of trees on Ottawa study pl o t s Height cl a s s R o c k c l i f f e Park A l t a V i s t a 15-20' 21 50 20-30' 35 56 30-40' 38 27 40-50' 30 10 50-60' 21 5 60-70* 19 7 70' plus 17 2 TOTAL 181 157 APPENDIX XIX RESULTS OF BIRD CENSUSES ON OTTAWA STUDY PLOTS 250 Appendix XIX Results of b i r d censuses on Ottawa study plo t s Species R o c k c l i f f e Park A l t a V i s t a 1970 Feb.17 r-i 4 fe Feb.21 Feb.23 Feb.18 Feb.20 Feb.22 Feb.25 Evening Grosbeak 48 43 41 50 109 57 83 42 House Sparrow 12 16 14 18 72 57 64 40 Common Redpoll 4 23 23 16 38 13 56 32 Black-capped Chickadee 7 9 10 7 2 • • 2 3 Rock Dove 10 8 1 4 83 46 36 24 White-breasted Nuthatch 2 1 2 1 1 • • 1 • « Boreal Chickadee 1 1 1 1 Downy Woodpecker 2 1 * • • • .jpRecbb Eeafete d? Nuthatch: • • • • 3 1 • • • • • • • • Common Crow • • 2 • • • • 2 • • 2 2 Pine Grosbeak 2 S t a r l i n g 1 • • 1 119 90 108 148 Black-backed Three-toed Woodpecker 1 Bohemian Waxwing 43 Blue Jay 1 1 1 • • Ring-necked Pheasant 1 • • • 1 TOTAL SPECIES 9 9 8 9 8 6 9 8 TOTAL INDIVIDUALS 87 104 95 100 466 264 353 292 I t a l i c i s e d numbers in d i c a t e birds seen j u s t outside the p l o t or i n f l i g h t over the p l o t ; these numbers are not.included i n the t o t a l s . APPENDIX XX TIMES AND WEATHER CONDITIONS DURING CENSUSES OF OTTAWA PLOTS, 1970 252 253 Appendix XX Times and weather conditions during censuses of Ottawa p l o t s , 1970 Start of . Duration Date Plpt censused census of census Weather conditions 17 February R o c k c l i f f e Park 0925 hr. 145 min. Overcast, c l e a r i n g ; 14° to 18° 18 February A l t a V i s t a 0900 120 Overcast; 15° to 20° 19 February R o c k c l i f f e Park 0 9 9 0 125 Clear, l i g h t NW breeze; 5° to 7° 20 February A l t a V i s t a 0850 125 Clear, l i g h t NW breeze; -1° 21 February R o c k c l i f f e Park 0855 135 Clear; 5° to 16° 22 February A l t a V i s t a 0915 120 Cloudy; 32° 23 February R o c k c l i f f e Park 0925 130 Clear; 4° to 6° 25 February A l t a V i s t a 0900 120 Clear, clouding over; wind W, 2 to 20 MPH; 70 APPENDIX XXI MICROHABITAT COMPOSITION OF STUDY PLOTS: TOTAL AREA OF PLOTS, INCLUDING TREES 254 255 Appendix XXI Microhabitat composition of study p l o t s : t o t a l area of p l o t s , including trees Microhabitat Plot 14 th & 19 th & 43rd & Fergusi Code Description Spruce Yukon C h u r c h i l l Road Houses , 7.5% 22.6% 12.8% 3.1% Garages 1.4 6.9 2.1 • • * Apartment Blocks 27.2 • • • • • • • • • Barns • • t • • • • • • 0.9 01 Gardens 1.4 2.7 5.7 0.9 01, 02 Bare Earth • • • • • • • • • 3.7 03 Lanes 6.1 4.8 3.9 • * O 03 Road Edges 2.0 0.5 • • • 3.4 04 Roads 12.8 12.9 3.0 7.5 04 Parking Areas, Driveways 8.4 0.8 2.1 3.1 05 Sidewalks 7.8 3.6 1.5 • • • 06 Lawn and Pasture 20.6 35.4 32.8 55.6 07, 08 Rough Grass • • • * • • • • • 14.0 Trees and Large Shrubs 4.8 9.9 36.2 7.8 To t a l number of dots 3496 2911 2808 322 NOTE: The above figures were obtained by counting dots on an area dot g r i d , as explained on pp. 80-81, APPENDIX XXII MICROHABITAT COMPOSITION OF STUDY PLOTS: AREA NOT COVERED BY BUILDINGS, IGNORING TREES 256 257 Appendix XXII Microhabitat composition of study p l o t s : area not covered by b u i l d i n g s , ignoring trees Microhabitat Plot 14th & 19th & 43rd & Ferguson Code Description Spruce Yukon C h u r c h i l l Road 01 Gardens 2.9% 4.3% 10.0% 1.0% 01, 02 Bare Earth ... ... ... 4.2 03 Lanes 9.7 6.9 5.7 03 Road Edges 3.1 0.7 ... 3.6 04 Roads 21.9 19.2 11.5 7.8 04 Parking Areas, Driveways 13.4 1.2 2.9 3.2 05 Sidewalks 12.7 6.6 4.9 06 Lawn and Pasture 36.3 61.0 65.0 63.8 07, 08 Rough.Grass ... ... ... 16.5 APPENDIX XXIII BREAKDOWN OF STOPWATCH OBSERVATIONS ON TOP 18 SPECIES ACCORDING TO LOCATION, SEASON, AND TIME OF DAY 258 259 Appendix XXIII Breakdown of stopwatch observations on top 18 species according to l o c a t i o n , season, and time of day Rock House Crested Black-c Robin S t a r l i n g Dove Sparrow Mynah Chickadf TOTAL OBSERVATIONS Number 245 210 128 272 123 160 Time i n seconds 23400 14222 13039 10073 7457 1840 OBSERVATIONS ON PLOTS Number 227 160 83 223 86 134 Time i n seconds 21565 10100 7362 8052 5087 1514 19th & YUKON PLOT Number 83 85* 39 109 62* 21 Time i n seconds 8140 5119* 3743* 3762 3630* 206 14th & SPRUCE PLOT Number 28 39 42* 75 17 26 Time i n seconds 3419 1966 3430 3016 1225 324 43rd & CHURCHILL PLOT Number 85 14 2 21 1 80* Time i n seconds 6850 1114 189 394 43 762* FERGUSON ROAD PLOT Number 31 22 • • • 18 6 7 Time i n seconds 3156 1901 • • • 880 189 222 WINTER OBSERVATIONS Number 7 47 21 19 23 Time i n seconds 443 1998 968 421 640 273 SPRING OBSERVATIONS Number 72 28 21 35 10 26 Time i n seconds 8200 1542 1990 765 477 275 SUMMER OBSERVATIONS Number 116 87 36 139* 40 59 Time i n seconds 11610 8447* 5817 5203* 2694 719 AUTUMN OBSERVATIONS Number 50 48 50 79 59 52 Time In seconds 3147 2235 4264 3684 3646 573 MORNING OBSERVATIONS Number 120 104 61: 143* 72* 107* Time i n seconds 10705 8185* 6353 5310* 4616* 1262* MIDDAY OBSERVATIONS Number 52 46 27 73 24 29 Time i n seconds 6304 2655 2549 2813 1074 311 AFTERNOON OBSERVATIONS Number 73 60 40 56 27 24 Time i n seconds 6391 3382 4137 1950 1767 267 s i g n i f i e s that f i g u r e (either number of observations or number of seconds) represents more than h a l f the t o t a l . D e f i n i t i o n s of seasons; Winter - December 1 to February 28 (29) Spring - March 1 to May 31 Summer - June 1 to August 31 Autumn - September 1 to November 30 D e f i n i t i o n s of times of day: Morning' - 0001 to 1000 hours Midday - 1001 to 1400 Afternoon - 1401 to 2400 260 (Appendix XXIII - continued) White-c. House Oregon Song Brewer 1s N.W. Sparrow Finch Junco Sparrow Blackbird Crow TOTAL OBSERVATIONS Number 58 35 79 46 34 22 Time i n seconds 3438 3275 2993 2984 2395 1935 OBSERVATIONS ON PLOTS Number 56 16 70 40 27 4 Time i n seconds 3357 1593 2636 2616 1661 193 19th & YUKON PLOT Number 10 3 30 6 • • • 2 Time i n seconds 412 685 1263 255 • • . 129 14th & SPRUCE Number 4 6 9 3 • • • 2 Time i n seconds 277 401 521 25 •.. 64 43rd & CHURCHILL Number 10 4 29 15 > .. • * • Time i n seconds 1072 172 733 1336* ... « * a FERGUSON ROAD PLOT Number 32* 3 2 16 27* • • • Time i n seconds 1596 335 119 1000 1661* • a * WINTER OBSERVATIONS Number 17 7 25 15 9 3 Time i n seconds 1144 535 693 766 254 351 SPRING OBSERVATIONS Number 16 9 10 4 6 4 Time i n seconds 1307 960 361 1112* 546 436 SUMMER OBSERVATIONS Numb er • • • 13 • a a 8 16 7 Time i n seconds • • • 1087 a a a 289 1285* 415 AUTUMN OBSERVATIONS Number 25 6 44* 19 3 8 Time i n secondg 987 693 1939* 816 310 733 MORNING OBSERVATIONS Number 23 25* 30 20 19* 9 Time i n seconds 821 1882* 1505* 1293 1595* 544 MIDDAY OBSERVATIONS Number 16 9 39 9 13 10 Time i n seconds 750 877 1088 298 574 1040 AFTERNOON OBSERVATIONS Number 19 1 10 17 2 3 Time i n seconds 1867* 516 400 1393 226 351 261 (Appendix XXIII - continued) Savannah Brown-h. Pine Common Golden-c. Audubon's Spar-row Cowbird S i s k i n Bushtit Kinglet Warbler TOTAL OBSERVATIONS Number Time i n seconds OBSERVATIONS ON PLOTS Number Time i n seconds 19th & YUKON PLOT Number Time i n seconds 14th & SPRUCE PLOT Number Time i n seconds 43rd & CHURCHILL PLOT Number Time i n seconds FERGUSON ROAD PLOT Number Time i n seconds WINTER OBSERVATIONS Number Time i n seconds SPRING OBSERVATIONS Number Time i n seconds SUMMER OBSERVATIONS Number Time i n seconds AUTUMN OBSERVATIONS Number Time i n seconds MORNING OBSERVATIONS Number Time i n seconds MIDDAY OBSERVATIONS Number Time i n seconds AFTERNOON OBSERVATIONS Number Time i n seconds 22 1573 21 1456 1 130 20* 1326* 3 155 6 702 13* 716 19* 1418* 3 155 • » t • • 9 21 1542 19 1305 1 170 4 317 14* 818* 1 152 19* 1231* 1 69 18* 1061* 36 1318 8 407 4 320* 4 87 7 220 29* 1098* 3 391 5 242 8 489 23* 587 47 680 34 419 34* 419* 18 165 21 385* 8 130 3 85 33* 440* 11 155 30 400 25 354 3 17 20* 312* 2 25 21* 324* 2 7 7 69 3 22 21* 315* 6 63 25 340 23 296 5 63 16* 211* 2 22 18* 228* 1 8 6 104 20* 300* 4 32 1 8 APPENDIX XXIV NESTS DISCOVERED IN 1968 262 Appendix XXIV Nests discovered in 1968 263 Date Location HOUSE SPARROW 3 3 4 4 9 15 June 15 June 15 June 15 June 17 June July July July July July 10 July 11 July 11 July 11 July 15 July 15 July 16 July 17 July 25 July 1 Aug. 3 Aug. 590 W 16th 1304 W 14th 2835 Spruce .6111 Marguerite 1106 W 13th 1386 W 13th 1638 W 43rd 5987 Adera 806 W 19th 16 W 21st 1045 W 15th 1205 W 14th 1106 W 13th 85 W 21st 5989 Adera 173 W 20th 433 W 20th 6187 Churchill BARN SWALLOW 12 June 1256 W 13th 24 June 6111 Adera 27 June 127 W 20th 4 July 6212 Wiltshire 8 July Hut M-9, U.B.C. 15 July 186 W 20th 21 July Grauer's Store, Sea I. 29 July 591 W 18th: 2 Aug. 766 W 16th Nest p o s i t i o n and height Young Under eaves, 101 Under eaves, 22' Under roof apex, 30' Under eaves, 12 Crevice in house, 12' Beam under gable, 20' Under roof corner. 21' Beam under eaves, 18' Under eaves, 10' Beam under roof apex, 15' Under eaves, 15' Under shingles, 10' Crevice in house, 13' Under eaves by chimney, 16' Under shingles, 12' Bird house, 14' Ventilator, 20' Birdbox, 11' House corner, 12' Under eaves, 13' Under eaves, 20' Under eavps, 17' Under roof apex, 26' Under verandah, 10' Under eaves, 10' Under verandah, 10' > Under porch, 12" Crevice under eayes, 25' Under verandah, 11' Under eaves, 11' X X X X X X X X X X X X X X X X X • X X X X X X X NOTE: Date - date of f i r s t discovery of nest Young - "X" indicates that young were present in the nest when i t was f i r s t discovered; a date indicates the date when young were f i r s t heard or seen. * - Nest discovered after the breeding season, so the date i s irrelevant. 264 (Appendix XXIV - continued) Date Location Nest p o s i t i o n and height Young CRESTED MYNAH May 328 W 17th Ledge under roof apex, 32' • 28 May 95 W 21st Crevice under eaves, 14' • 15 June 2847 Spruce Hole i n house, 28' • 18 June 116 W 19th Under shingles, 28' • 24 June 58 W 23rd Under roof apex, 28' X 15 July 3480 Yukon Under eaves, 26* x 19 Aug. 2847 Spruce Beam under apex, 36' • STARLING May 3300 Yukon A t t i c v e n t i l a t o r , 14* • 15 June 1305 W 13th Under eaves, 27' X 21 June 1305 W 13th Under eaves, 23' X 24 June 6081 Marguerite Under shingles, 20' X 3 Ju l y Roof edge, 18' X ROBIN 16 A p r i l 14 th & Spruce Hawthorn, 12' • 15 June 13th & Spruce Ledge under roof, 18' • 15 June 15 th & Hemlock Cherry bush, 10' X 2 July 1340 W 14th Holly t r e e , 7' X 25 Ju l y 45th & Marguerite Maple, 11* X VIOLET-GREEN SWALLOW 18 June 295 W 18th Creek i n shingles, 10' X 24 June 6211 C h u r c h i l l Under roof apex, 25' X 10 July 218 W 22nd Pipe, 11' X 17 J u l y 6061 C h u r c h i l l Roof edge, 17' X ROCK DOVE 3 Ju l y 1106 W 13th Under gable, 20' X 11 Ju l y 2648 Alder Under eaves, 15' • 11 Ju l y 14th & Hemlock On drainpipe under eaves, 20' • CLIFF SWALLOW * Ferguson Road Under.eaves, 13' • * Ferguson Road Under eaves, 13' • AMERICAN GOLDFINCH 7 Aug. 5988 Wi l t s h i r e Maple, 20' • APPENDIX XXV NESTS DISCOVERED IN 1969 265 266 Appendix XXV Nests discovered i n 1969 Date Location Nest p o s i t i o n and height Young STARLING 5 May 208 W 20th Pipe, 14' X 6 May 14th & Alder Under roof apex, 28' 13 May 7 May 5987 Adera Box under eaves, 19' • 12 May 33 W 19 th Crevice under roof apex, 25' • 12 May 122 W 19th Crevice under eaves, 18' X 12 May 252 W 19th Under roof edge, 11' • 12 May 39 W 21st Bird box, 20' X 12 May 3460 Yukon Ledge under eaves, 18' X 13 May 14 th & Alder Hole i n ledge, 19' X 13 May 1305 W 13th Under eaves, 20' X 13 May 1305 W 13th Under eaves, 20' X 13 May 1305 W 13th Under eaves, 20' X 13 May 1346 W 13th Under eaves, 20' X 13 May 1265 •W 13th Pipe opening, 20' X 13 May 1316 W 11th Under eaves, 27' X 13 May 1135 W 11th Under eaves, 20' X 13 May 1106 W 13th Ledge under apex, 26' . 14 May 5961 C h u r c h i l l Under eaves, 20' X 14 May 6038 C h u r c h i l l Eavestrough, 18' X 14 May 6187 Adera Under roof apex, 23' X 14 May 6312 Adera Eavestrough, 19' X 14 May 6337 Adera Box on side of house, 8' * 15 May 459 Ferguson A t t i c v e n t i l a t o r , 13' Bird box, 7' • 15 May Macdonald & Ferguson 16 May 3300 Yukon Under roof edge, 11' X 16 May 80 W 19th Ledge under roof apex, 24' • 16 May 186 W 20th Under roof corner, 20' X 16 May 275 W 22nd Under roof corner, 22' X 16 May 246 W 13th . Under roof corner, 19' X 16 May 196 W 13th In window box, 15' X 16 May 123 W 13th Hole i n roof, 25' X 16 May 58 W 13th Under roof edge, 20' X 16 May 33 W 14th Eavestrough, 19' X 16 May 150 W 14th Under roof corner, 13' X 16 May 204 W 14th Under roof corner, 22' X 16 May 354 W 14th In roof corner, 14' X 16 May 241 W 16th Ledge under eaves, 16' X 20 May 39 W 20th Roof corner, 23' X 20 May 1135 W 13th Eavestrough, 15' X 21 May 6011 Marguerite Under eaves, 23' 28 May 21 May 6187 Marguerite Under eaves, 24' 28 May NOTE: See page 263 for d e f i n i t i o n of "Date," "Young," and "*." (Appendix XXV - continued) Date Location Nest p o s i t i o n and height Young STARLING (cont.) 22 May 1190 W 12th Crack i n edging, 23' X 22 May 1374 W 10th Under eaves, 23' X 22 May 1338 W 10th Under eaves, 26' X 22 May 1275 W 10th Under eaves, 25' X 22 May 1298 W 10th Hole under ledge, 45' X 22 May 1245 W 10th Crevice under eaves, 27' X 22 May 664 W 17th Hole i n w a l l , 18' X 27 May 13th & Hemlock Hole under eaves, 28' X 28 May 6111 Adera Hole i n b i r c h , 12' X 28 May 6287 W i l t s h i r e Hole.in tree, 8' (J 28 May 5911 Marguerite Under gable corner, 12' X 30 May Ferguson Road Roof corner, 12' • 3 June 1316 W 11th Under eaves, 28' X 5 June 112 Macdonald, ; ..Seafl. A t t i c vent, 14' « 9 June 3560 Ontario Under roof edge, 12' X 23 June Ferguson Road Under roof, 12' X 24 June 262 West 19th Under roof edge, 13' X 24 June 351 W 20th In roof edge, 25' X 27 June 6231 C h u r c h i l l Roof corner, 20' X 28 June Ferguson Road Under eaves, 13' X 30 June 39 W 21st Under roof corner, 20' » 30 June 1225 W 12th Under eaves, 24' • 1 July 13th & Hemlock V e n t i l a t o r chute, 26' X 4 July. 475 Ferguson Hole i n shingles, 7' X 7 July 116 W 14th Eavestrough, ?5' X 8 J u l y 1136 W 11th Eaves, 24' X 15 July 330 Ferguson Under eaves, 14' X HOUSE SPARROW 12 May 361 W 19th Ledge under roof apex, 21* X 12 May 66 W 19th Ledge under eaves, 19' X 12 May 375 W 20th Under roof apex, 24' m 12 May 361 W 20th Under eaves, 18' 16 May 12 May 60 W 20th Under roof, 14' « 12 May 285 W 19th Ledge under apex, 20' X 12 May 419 W 19th Under roof apex, 25' X 13 May 1255 W 12th Crevice under roof, 17' X 13 May 1106 W 13th . Ledge under eaves, 19' X 16 May 173 W 20th Under roof edge, 16' X 16 May 160 W 20th Ledge under roof, 14' X 16 May 16 W 20th Ledge under roof, 21' X 16 May 234 W 13th Ledge under eaves, 21' X 20 May 228 W 19th Ledge under eaves, 24' X 20 May 74 W 20th Base of wires, 12' X 22 May 14th & Alder Vines, 25' X 268 (Appendix XXV - continued) Date Location Nest p o s i t i o n and height Young HOUSE SPARROW (Cont.) 22 May 1126 W 12th Crevice under eaves, 25' X 25 May Ferguson Road Crabapple, 18' X 28 May 6111 Marguerite Hole under abutment, 13' X 30 May Ferguson Road Chokecherry, 20' • 30 May Ferguson Road Chokecherry, 20' • 3 June 2848 Birch Under eaves, 23' X 7 June 2706 W 15th Ledge under eaves, 19' X 7 June Hut B - l , U.B.C. Roof corner, 13' X 7 June U.B.C. Extension annex Under eaves, 13' X 7 June U.B.C. Extension b u i l d i n g Hole under eaves, 12' X 23 June Ferguson Road Under roof edge, 11' X 23 June Ferguson Road Under roof edge, 11' X 7 July 434 W 17th Inside of ladder, 11' X 7 July 43 W 17th Under roof corner, 20' X 7 July 374 W 14th Under eaves, 24' X 7 July 4 East 13th Roof edge, 22' X 7 Jul y U.B.C. Vivarium Deciduous tree, 11' X 16 July 217 W 21st Eavestrough, 12' X 21 Ju l y 53 W 19th Eavestrough, 17' X 21 July 139 W 21st V e n t i l a t o r , 14' X 28 July 66 W 19th Under roof edge, 19' X 28 July 80 W 20th Eavestrough, 11' X 13 Aug. 389 W 22nd Under porch edge, 14' X 16 Aug. 6161 Adera Bird box, 9' X ROBIN 18 Apr. 5937 Marguerite Ledge i n carport, 8' • 5 May 69 W 22nd Spruce, 10' X 14 May 5988 C h u r c h i l l Cedar shrub, 11' X 14 May 6287 C h u r c h i l l Ledge under eaves, 18' X 16 May 207 W 20th Mountain ash, 13' X 28 May 6161 W i l t s h i r e Mountain ash, 16' • 23 June Ferguson Road Chokecherry, 15' X 16 July 261 W 21st Ledge on house, 10' X 17 Aug. 6187 Adera Deciduous tree, 12' X * 165 W 22nd Oak, 16' • * 133 W 22nd Oak, 16' • * Westham I. Douglas f i r , 8' • BARN SWALLOW 7 June, 2195 W 15th Inside verandah, 14' • 24 June 127 W 20th Inside verandah, 14' X 24 June 3732 Ontario Under porch, 15' X 2 7 June Point Roberts Light under garage roof, 11' • 3 Ju l y 317 W 18th Inside verandah, 14' X 269 (Appendix XXV - continued) Date Location BARN SWALLOW (Cont.) 10 July 39 W 22nd 15 July 469 Ferguson 19 July 457 Ferguson 26 Aug. 403 W 21st VIOLET-GREEN SWALLOW 12 May 24 June 26 June 26 June 27 June 30 June 3 July ROCK DOVE 13 May 13 May 16 May 24 June * 166 W 19th 102 W 20th'.. 1255 W 14th 1365 W 12th 6211 C h u r c h i l l 218 W 22nd 295 W 18th 1256 W 12th 1272 W 12th 162 W 13th 327 W 20th 2847 Spruce 2847 Spruce CRESTED MYNAH 16 May 116 W 19th 7 June 12th & Stephens 7 July. 116 W 14th 8 July 12th and Cambie 8 Ju l y Grandview & Kaslo HOUSE FINCH 16 Aug. 13th and Birch BREWER'S BLACKBIRD 25 May . 459 Ferguson RED-BREASTED NUTHATCH Nest p o s i t i o n and height Verandah corner, 16' Inside carport, 7' Under roof apex, 9' Under roof apex, 18' Crack under abutment, 16' Roof corner, 14' Eavestrough, 25' Ve n t i l a t o r chute, 22' Roof apex, 25' Eavestrough, 14' Under roof edge, 13' Under roof corner, 16' Ledge under eaves, 22' Ledge under eaves, 22' Roof, under edge, 24' Under roof edge, 30' Under roof edge, 30' Under roof edge, 25' Atop telephone pole, 32' Eavestrough, 25' Under roof apex, 27' Under roof, 17' In flowerpot, 13' Cedar shrub, 8' Young X X X X X X X July X X X X X X 27 June 43rd & W i l t s h i r e Hole i n maple, 18' 

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