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A study of the life history and population dynamics of the sooty grouse, "dendragapus obscurus fuliginosus"… Bendell, James Francis S. 1954

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A STUDY OF THE LIFE HISTORY AND POPULATION DYNAMICS OF THE SOOTY GROUSE, DENDRAGAPUS OBSCURUS FULIGIN0SU3 (RIDGWAY) by James F. S. Bendell A Thesis Submitted i n P a r t i a l Fulfilment of the Requirements f o r the Degree of DOCTOR OF PHILOSOPHY in the Department of ZOOLOGY We accept t h i s thesis as conforming to the standard required from candidates f o r the degree of DOCTOR OF PHILOSOPHY. THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , 1954 ABSTRACT A population of sooty grouse (Dendragapus obscurus  fuliginosus) has been studied on i t s summer range over the years 1950 to 1953. Data on moult, aging c r i t e r i a , weight and behaviour are presented as l i f e h i s t o r y . Some of these data are u t i l i z e d i n a consideration of the present popula-t i o n status of grouse on the study area. Mor t a l i t y , productivity, emigration and immigration, have been studied as factors influencing population size and status. The population i s apparently stable, a res u l t of an equilibrium between death i n the older age classes and replace-ment by surviving young. Disease i s an important mortality factor i n the chicks and a major fa c t o r affecting population size and s t a b i l i t y . TABLE OF CONTENTS Page INTRODUCTION AND LITERATURE REVIEW 1 ACKNOWLEDGMENTS 8 BASIC MATERIALS AND METHODS 9 Time and Place of Study 9 Financial Support 9 Fi e l d Equipment and Marking Techniques 9 Recording Techniques 12 Autopsy Procedure 12 Weather Records and Week Numbers 14 Vegetational Analyses 15 THE STUDY AREA 18 THE SPRING AND SUMMER CLIMATE 19 THE VEGETATION AS HABITAT 21 TOPIC I NATURAL HISTORY . 29 Moult 29 Age C r i t e r i a 32 Weight of Yearlings and Adults 35 The Spring Migration 36 T e r r i t o r i a l Behaviour of the Adult Male 37 Sexual A c t i v i t i e s of the Adult Male 43 General A c t i v i t i e s of the Adult Male 58 * Seasonal Behaviour of the Adult Male 59 The Behaviour of the Yearling Male 61 Spring Migration i n the Yearling Male 63 Spring Behaviour of the Female 6 4 Nesting Behaviour of the Female 68 The Diurnal A c t i v i t y Rhythm 76 Time of Incubation and Hatch 80 Behaviour of the Female and Brood 81 Movements of the Female and Brood 86 Sex Ratio and Weight Development i n the Young 90 The L i f e History Study as a Basis f o r the Analysis of Population Dynamics 92 TOPIC I I POPULATION DYNAMICS 96 Population Size and Status 96 Mortality i n the Adults 101 Mortality Factors i n the Adults , 103 Mort a l i t y i n the Chicks 107 Mor t a l i t y Factors i n the Chicks 117 Di s t r i b u t i o n of Dispharynx and Plagiorhyncfcs. 128 DISCUSSION 132 SUMMARY AND CONCLUSIONS 135 TABLE OF CONTENTS (Continued) Page LITERATURE CITED 142 APPENDIX 146 1 INTRODUCTION AND LITERATURE REVIEW The study has two purposes, the f i r s t the recording and int e r p r e t a t i o n of data pertinent to the l i f e h i s t o r y of the sooty grouse (Dendragapus obscurus f u l i g i n o s u s ) . the second the u t i l i z -a t i on of some of these data, i n association with environmental f a c t o r s , to explain the population status of the b i r d at Quinsara Lake, Vancouver Island. Most of the l i t e r a t u r e dealing with t h i s genus r e f l e c t s the early phase of ornithology - c o l l e c t , c l a s s i f y and name. U n t i l 1939, references to the blue grouse group (genus Dendragapus) are b r i e f or deal with the bird?s occurrence i n a cer t a i n area. The work of Bent (1932) i s an exception, and includes most of the natural h i s t o r y data on the sooty grouse u n t i l that time. In 1940 Beer, Wing and Tidyman began a study of the blue grouse i n the state of Washington. Their work has given us furt h e r i n d i c a t i o n of the l i f e h istory of the bi r d and p a r t i c u l a r l y data on i t s food habits, brood behaviour and growth. From t h i s research some of the parasites of the blue grouse have been described. Fowle, i n 1942, began a study of the sooty grouse on Vancouver Island. This work i s valuable as a survey of the l i t e r -ature and a contribution to the knowledge of the summer food habits of the species. The material Fowle has gathered on the l i f e h i s t o r y , and parasite-disease relationships of the bird serves as a firm foundation f o r future work. Up u n t i l the time of w r i t i n g , Schottelius 1 study of 1951 i s the l a t e s t report on the genus Dendragapus. 2 As w i l l be appreciated from the l i t e r a t u r e review l i t t l e has been published on the sooty grouse. There i s value then i n the recording and i n t e r p r e t a t i o n of new data pertinent to the bird's biology. Secondly, and perhaps more important, such a l i f e h i s t o r y study i s fundamental to an understanding of the popu-i n l a t i o n ecology of t h i s or any other animal. Thus/presenting t h i s thesis i n two parts, part I i s intended to furnish these basic b i o l o g i c a l data or the c h a r a c t e r i s t i c s of the organism. Some of these data do not r e l a t e d i r e c t l y to the analysis of population dynamics i n part I I . They are included because of t h e i r newness and continuity with d i r e c t l y related data. Once the biology of the organism i s understood and proper study techniques are developed i t becomes the task of a student of populations to examine the factors of the environment and f i n d their effect on animal population. The environmental factors might be broadly c l a s s i f i e d as those of weather or c l i m a t i c , the food supply, space r e l a t i o n s , predators, parasites and disease. Uvarov (1931) suggested a c l a s s i f i c a t i o n of the c l i m a t i c factors a f f e c t i n g the abundance of a t e r r e s t r i a l species. Gener-a l l y , temperature and p r e c i p i t a t i o n , wind, pressure, storms, temperature and r a i n f a l l , temperature and humidity, temperature and l i g h t , and food quantity and q u a l i t y as related to climate are categories of weather a f f e c t i n g an animal population. Kendeigh (1942) studied losses i n the nesting of 51 species of birds and showed that the number of i n f e r t i l e or addled eggs produced by hens was d i r e c t l y related to high and low temperatures. The number of addled eggs produced at medial temperatures was r e l a t i v e l y low as compared to the temperature extremes. As another example, Edminster (1947) reports the deleterious effect of a severe rainstorm on broods of ruffed grouse (Bonasa umbellus). The importance of food as a factor influencing animal populations i s obvious. A r e l a t i o n must exis t between the growth and w e l l being of an i n d i v i d u a l or population and food supply. On the other hand food - animal relationships are among the most d i f f i c u l t to understand. A complexity of physical and b i o t i c factors d i r e c t l y and i n d i r e c t l y influence food quality and quantity. Superimposed upon t h i s s i t u a t i o n are the food requirements of a p a r t i c u l a r animal or animals at any given time i n t h e i r l i f e h i s t o ry and the conditions influencing t h e i r a b i l i t y to forage. As an example a range may provide abundant forage for the adults of a population but be def i c i e n t i n foods f o r the young. Studies on general malnutrition Schneider et a l (1949) have shown that dietary deficiencies generally affect host parasite r e l a t i o n s i n favour of parasites which become more abundant and more pathogenic. Thus the quality and quantity of food and parasitism might operate to effec t a host population. An appreciation of the effects of population density i s fundamental to the understanding of population growth and s i z e . In the case of the f r u i t f l y Drosophila grown i n culture, Robertson and Sang (1944) concluded that fecundity may be reduced by crowding. This occurred, however, only when the food supply was inadequate. MacLagen and Dunn (1936) showed that the female 4 grain weevil Sitophilus would not oviposit at t h e i r maximum rate unless more grains were present i n the culture containers than were a c t u a l l y u t i l i z e d . This indicates more niches might be required f o r a p a r t i c u l a r animal a c t i v i t y than are a c t u a l l y used and presents a new twist to animal habitat r e l a t i o n s . Crombie (1944) has shown that i n cultures of granary insects Rizopertha and Sitotroza, crowding among the larvae r e s u l t s i n competition for space. This i n turn r e s u l t s i n f i g h t i n g , mortality from f i g h t i n g or dispersion. With respect to mammals, Errington (1939) i n a study of the effect of drought i n muskrats (Ondatra), found as t h e i r water areas diminished i n size an increase i n i n t r a s p e c i f i c s t r i f e occurred which resulted i n an increased rate of mortality or emigration from the areas of intense competition. In birds, Nice (1937) argues that t e r r i t o r i a l behaviour can act to l i m i t the number of a given species l i v i n g i n a p a r t i c u l a r area and as she puts i t , "cause surplus birds to go elsewhere". Thus competition f o r space might operate to limi^e( animal and p a r t i c u l a r l y b i r d ^ populations i n a given area. On the other hand from the work of Johnson (1941) on the a t l a n t i c murre (Uria aalge) crowding seems a necessity f o r reproduction. Crowding resulted i n f i g h t s which seemed to i n t e n s i f y the drive to incubate rather than vanquish a neighbour as a competitor f o r space. Predation, whether by animal or man i s generally considered as a factor capable of a f f e c t i n g the population status of a given prey species. As an example, Foerster and Ricker (1941) removed four important predators of the sockeye salmon (Oncorhynchus 5 nerka) i n Cultus Lake B r i t i s h Columbia. With the reduction of the predator populations there was a corresponding increase i n surv i v a l of immature sockeye salmon. The increase of the prey was attributed d i r e c t l y to the planned reduction of the predators. L. Tinbergen (1946) i n an important study of predation by the European sparrow hawk (Accipitor nisus) on the house sparrow (Passer domesticus), the chaffinch ( F r i n g i l l a coelebs), the great t i t (Parus major), and the coal t i t (Parus ater) concluded that the sparrow hawks caused approximately 50% of the summer mortality f o r the house sparrow, 25% for the chaffinch and great t i t s and ne g l i g i b l e percentage f o r the coal t i t s . On the other hand, Err i n g -ton (1937a) admits the removal of prey species by predators, but suggests predation i n general i s e s s e n t i a l l y a "by-product of population rather than a broadly dominant influence on population". The attacks of parasites and disease i n an organism often r e s u l t i n i t s death. A f a m i l i a r example i s the r e s u l t of besubonic plague i n Europe. Parasite host r e l a t i o n s have been a pro f i t a b l e f i e l d f o r mathematical t h e o r i s t s , and several schemes of parasite host i n t e r a c t i o n have been proposed as by Nicholson and Bailey (1935), Lotka (1934), Volterra (1926), and others. Generally several things might happen i n these int e r a c t i o n s , but of interest here i s the conclusion that parasites can t h e o r e t i c a l l y control host numbers. This has been the experience of workers i n the f i e l d of pest insect control where introduced or indigenous parasites are capable of c o n t r o l l i n g host populations. Parasites are regularly found i n natural vertebrate populations yet t h e i r r o l e as a f a c t o r i n population control has seldom been demonstrated. 6 Dymond (1947) considers disease as a non-specific factor cap-able of influencing population decline. In the B r i t i s h I s l e s , the Committee of Enquiry on Grouse Disease (1900) has attributed "die o f f " i n the red grouse (Lagopus acoticus) to an i n t e s t i n a l protozoan occurring i n the chicks and on i n t e s t i n a l nematode occurring i n the adults. Clarke (1937) considered the blood parasite Leucocytozoon a l i k e l y factor causing c y c l i c decline i n the ruffed grouse (Bonasa umbellus) i n Ontario. Green, Larson and B e l l (1939) stressed the importance of shock disease as a factor capable of decimating hare (Lepus americanus) populations. With these examples then, there i s a basis f o r considering parasitism as a possible factor of importance i n the control of vertebrate populations. The environmental factors involving the e f f e c t of climate on an organism are generally considered as density independent. That i s to say, they remove animals from the popula-t i o n i r r e s p e c t i v e of t h e i r abundance. The environmental factors involving the effects of space r e l a t i o n s h i p s , food, predators, parasites and disease are generally considered as density depend-ent. Such factors a f f e c t animals i n the population i n proportion to t h e i r abundance. Changes i n population growth form or s i z e are obviously caused by both physical and b i o t i c f a c t o r s , such as c l i m a t i c extremes i n one case, and food supply i n the other. However, Nicholson (1933) and Smith (1935) contend l a r g e l y on t h e o r e t i c a l grounds that density independent factors operating alone cannot determine and maintain an average population density over a long period of time. As an approach to the study of an animal population the phenomena of mortality, n a t a l i t y and dis p e r s a l can be considered as the response of the organism to a p a r t i c u l a r or p a r t i c u l a r set of environmental circumstances. The response can be measured i n terms of population growth form. The environmental factors climate, food, space, predators, parasites and disease can be considered as the causes a f f e c t i n g the response of the organism i n terms of t h i s population growth form. Thus i t becomes a problem to the student of population dynamics to f i n d the status of a p a r t i c u l a r animal population and then to explain how the environmental f a c t o r or factors are operating on the mortality, n a t a l i t y and dispersal of the animal to produce i t s observed population status. This i s attempted i n a consider-ation of the population dynamics of the sooty grouse at Quinsam Lake. 8 ACKNOWLEDGMENTS Many persons have contributed time and e f f o r t to t h i s study, and to them the author i s deeply indebted. Dr. I. McT. Cowan and Dr. J.R. Adams have been chief advisers. Dr. Adams has i d e n t i f i e d most of the parasites mentioned i n the text and i s continuing with t h i s phase of the work. Mr. G.J. Spencer has i d e n t i f i e d l i c e collected as probably Lagopoceus obscurus and the louse f l y Ornithomyia f r i n g i l l i n a . while Mr. G.P. Holland of Science Service, Ottawa, i d e n t i f i e d the f l e a Ceratophyllus d i f f i n i s . Dr. P.A. Larkin has suffered interminable discussions of the problem as have my colleagues of hut M-30. The shortcomings of t h i s work i n no way r e f l e c t s upon them. In the f i e l d , the assistance of,my advisers, Mr. D.J. Robinson and Mr. R.S. Hayes of the B.C. Game Department, Mr. P. Seaton, Mr. Darryl Rye and Mr. T. Hagemeier, i s g r a t e f u l l y acknowledged. Weather recording equipment was kindly loaned through Dr. L. Robinson of the Dept. of Geography, U.B.C., while some camping gear was provided by the B.C. Game Dept. through Dr. J . Hatter. Mr. H. Laing of Comox granted permission to use his superlative telephoto pictures of male grouse i n F i g . 16 and 20. Mr. E. Harris at Queen's University, Kingston, copied and photographed the drawings presented i n the text. F i n a l l y , I am most pleased to acknowledge the assistance of my wife who i n the f i e l d and laboratory phases of the study assumed the status of a co-worker. 9 BASIC MATERIALS AND METHODS  Time and Place of Study F i e l d work began i n June, 1950, at Quinsam Lake on Vancouver Island. In the middle of August the w r i t e r l e f t t h i s area and spent two weeks at Bald Mountain Game Reserve at Cowichan Lake. A two day v i s i t was made to the Quinsam area i n March of 1951 but i t was not u n t i l May that the study was resumed at Quinsam Lake and continued throughout the summer u n t i l the f i r s t week i n August. F i e l d work began again i n A p r i l 1952 and as i n the previous year terminated early i n August. In 1953 the study area was v i s i t e d i n June and July to provide additional data on the return of banded birds and obtain an estimate of population s i z e f o r that year. During intervening periods, data were analyzed i n the Department of Zoology at the University of B r i t i s h Columbia and i n 1952 at Queen's University, Kingston, Ontario. Financial Support F i e l d work was supported i n the f i r s t year by an N.R.C. grant-in-aid and the B.C. Game Department. The National Research Council financed the study thereafter. During the u n i v e r s i t y a sessions of 1950 and 1951 the writer held/Research Council of Ontario scholarship. This, and f a c i l i t i e s provided by the Univers-i t y of B r i t i s h Columbia made the laboratory phase of the work possible. F i e l d Equipment and Marking Techniques Observations i n the f i e l d were made i n most part with a 6 X 30 binocular. This, along with recording materials, compass, 10 noose and pole, puncture needles, microscope s l i d e s , banding and marking k i t , colour bombs, Sah l i haemometer k i t , 2,000 gramme scale, r u l e , a wool sock, shotgun, coloured shipping tags and several large paper bags made up the f i e l d equipment. In work involving the recognition of animals good captur-ing and marking techniques are of inestimable value. Grouse of both sexes and a l l ages were captured by means of a simple noose and pole device which could be placed over t h e i r heads and then pulled taut. The noose and pole consisted of a ten to eleven foot bamboo cane, with a loop of black house f i x t u r e wire at the t h i n end. The loop passed through two eyelettes and then as a single strand carried to the base of the pole. In clearings where males and females congregate, drive nets were used with some success. These were simply old f i s h nets strung across the c l e a r i n g on 6 foot stakes. Behind the mouth of the nets the mesh was staked to the ground permitting a long sag between front and back. Grouse were driven into the nets, and i n moving into the mesh, became pinned by the long sag. The netting arrangement was too cumbersome to use beyond open clearings. Once captured, a grouse was held i n the wool sock, blood smeared, weighed, examined, marked and f i n a l l y before release the two outer t a i l r e t r i c e s were plucked f o r l a t e r use as age i n d i c a -t o r s . Each b i r d so handled was given a number corresponding to a numbered aluminum B r i t i s h Columbia Game Department band placed on one l e g . In addition, a coloured c e l l u l o i d band or bands were placed on the other leg so that each bird could be i d e n t i f i e d i n 11 the f i e l d on subsequent contact. To furt h e r f a c i l i t a t e t h i s recognition, a b r i g h t l y coloured p l a s t i c square was af f i x e d to the t a i l of each captured b i r d . In some cases a small b e l l was applied to the leg by threading the aluminum band through a clasp at the back of the b e l l . One marking method that worked wel l on birds which con-st a n t l y evaded capture was a simple ink bomb technique. Printer's ink, a carbon substance of bright colour and insoluble i n water, was dissolved i n naphtha gasoline as 1 part ink to 2 parts f l u i d . This s o l u t i o n was poured into globular Christmas tree decorations approximately 3 inches i n diameter, and the decorations then sealed with a f i t t e d No. 5 cork. This i s an improvement over Bendell and Fowle's (1947) method i n which domestic hen's eggs were used as the container. Best r e s u l t s were obtained when the bomb was hurled at a bi r d crouched behind a tree or shrub. In these cases the shattering of the bomb i n the vegetation created a spray of ink which almost covered the b i r d . Red, blue, orange, green and yellow inks were found best, and with these colours, and various regions of the animal inadvertently inked, many d i s t i n c t i v e l y marked birds were obtained. The ink remained fast throughout the summer and, as i n the case of the t a i l cards, was l o s t only i n the subsequent f a l l moult of the feathers. In 1952, tagging with radioactive wing c l i p s was t r i e d as a device to locate nesting hens and cocks on t e r r i t o r i e s when not a c t i v e l y c a l l i n g or hooting. For t h i s experiment standard poultry wing c l i p s were sent to N.R.C. at Chalk River where they 12 were hollowed and f i l l e d with Rubidium 86 of 0.5 mc. a c t i v i t y and a half l i f e of 19.5 days. The procedure was to capture, tag, and release nesting hens when they were feeding i n clearings and then to f ollow t h e i r l i n e of f l i g h t with a Geiger counter u n t i l a nest was located by v i r t u e of i t s r a d i o a c t i v i t y . The technique f a i l e d to locate hens on nests, but succeeded with respect to loca t i n g a s i l e n t cock. I n a b i l i t y to detect rad i a t i o n over 10 feet from the source i s f e l t to be a major cause of f a i l u r e i n the case of the hens. Recording Techniques After a bi r d had been marked i n the f i e l d by bands or otherwise, the point of i n i t i a l or subsequent observation was surveyed. This locating of the point was done by taking compass bearings on previously erected flags or markers placed about the study area. Later, i n the laboratory, simple t r i a n g u l a t i o n placed the f i e l d p o s i t i o n accurately on large scale maps. In most cases a b r i g h t l y coloured p a r a f f i n coated shipping tag was t i e d to the nearest tree of height to permit easy return to a p a r t i c u l a r point, which i n each case had i t s own time and date. A l l observations made i n the f i e l d were l a t e r coded into a f i l i n g and punch card system. This permitted rapid c l a s s i f i c a t i o n and compilation of data f o r analysis and in t e r p r e t a t i o n . These data and methods of handling them w i l l be mentioned again i n l a t e r sections. Autopsy Procedure When a b i r d was collected i n the f i e l d the point where taken was recorded as above. The carcass was placed i n a paper 13 bag and brought to the laboratory f o r examination and autopsy. This included examination of the bag and b i r d f or ectoparasites and moult, a weight record, removal of t a i l feathers for age c r i t e r i a , a smear of heart blood, examination of the coelome and body organs f o r abnormalities, examination and volumetric measure-ment of the l i v e r , spleen, testes or ovaries f o r disease and sexual condition, and f i n a l l y the examination of the crop, stomach and gut f o r food materials and macroscopic parasites. A l l chicks collected were skinned so that plumage development might be described i n d e t a i l at a l a t e r date. In 1951 and 1952 the complete digestive t r a c t s were bundled i n cheesecloth and immersed i n 10 per cent formalin. They were l a t e r examined i n the u n i v e r s i t y laboratory. Other than three gut smears made i n 1950 and the examination of 50 droppings collected at random over the study area, no search was made f o r i n t e s t i n a l microparasites. Data on grouse movements, weight, plumage, parasites and hunter success i n k i l l i n g grouse were supplemented by material obtained at the B r i t i s h Columbia Game Department annual road check of hunters at Campbell River. Hunters were stopped, questioned as to l o c a l i t y hunted, t h e i r bags examined, and i n some cases weights, blood smears and viscera were obtained. This source of data was tapped by the author i n September of 1950 and 1951. Blood smears were f i x e d i n absolute alcohol, then stained i n stock Geimsa diluted 1 part dye to 10 parts d i s t i l l e d water. Each smear was examined under o i l immersion f o r Haemoproteus and then under low power f o r Leucocytozoon Trypanosoma and M i c r o f i l a r i a . A s l i d e was searched f o r one quarter hour before being designated 14 as negative. Quantitative estimates of i n f e c t i o n l e v e l s i n the case of Haemoproteus and Leucocvtozoon were made with the aid of a Whipple counting disc on the basis of random counts of 1,000 red blood c e l l s . Estimates of haemoglobin l e v e l s and number of r.b.c. per cu. mm. of blood were made i n the f i e l d and laboratory. The Sahli haemometer and the Spencer bright l i n e counting chamber and blood pipettes were used f o r these purposes. Ecto and endoparasites when discovered were placed i n phials of 10$ formalin and submitted to the Department of Zoology at U.B.C. f o r i d e n t i f i c a t i o n . Some were sent to Science Service at Ottawa, others were i d e n t i f i e d by the author. Weather Records and Week Numbers A standard Stevenson screen equipped with a recording thermograph, hygrograph, Piche evaporimeter and maximum and minimum thermometer was used to obtain weather data. R a i n f a l l was measured with a standard U.S. Weather Bureau r a i n gauge. To estimate duration of r a i n f a l l d a i l y records were kept i n which r a i n f a l l was expressed as a f r a c t i o n of a 24 hour period. Thus r a i n from midnight to noon would be one half day's r a i n . Weather data are treated as weekly averages with the exception of duration of r a i n which i s a weekly sum. In the analysis of weather records and other data to be met i n the text i t was convenient to divide the study period into weeks and assign each week a number. A p r i l the 13th, the e a r l i e s t date of consistent f i e l d work, i s the a r b i t r a r i l y chosen beginning of the series. I t and subsequent dates are included below. 15 Date Week or Period A p r i l 13 _ 19 1 20 - 26 2 27 - 3 May 3 May 4 _ 10 4 11 — 17 5 18 — 24 6 25 - 31 7 June 1 7 8 8 - 14 9 15 — 21 10 22 - 28 11 29 - 5 July 12 July 6 _ 12 13 13 - 19 14 20 — 26 15 27 - 2 August 16 August 3 9 17 10 — 16 18 17 - 23 19 Vegetational Analyses After f a m i l i a r i t y with the vegetation was "obtained i n 1950, i t was a r b i t r a r i l y c l a s s i f i e d into 6 major types on the basis of shelter value. The l i m i t s of each type were mapped on a scale of 1 inch to 50 feet i n two 36 acre sample p l o t s . This was done by surveying the edges of the various types with compass and tape. Compass bearings were then taken from the map i n various vegeta-t i o n a l types and carried to the f i e l d . The vegetation was sampled along these bearings by yard quadrats at ten foot i n t e r v a l s and 100 foot l i n e intercept method. Sampling was done at the height of vegetational growth. The intercept method was found s a t i s f a c t o r y f o r rapid measurement of shelter value i n the case of trees, shrubs, logs, 16 stumps and herbaceous vegetation such as bracken ( P t e r i s ) • In most cases t h i s shelter vegetation serves as food species, thus i t was included i n the quadrat samples designed to include grouse food plants of lesser size and greater abundance such as hares 1 ear (Hypochaeris) and s a l a l (Gaultheria). The value of a plant as grouse food was taken from f i e l d observation and the studies of Beer (1942, 1948) Fowle (1944) and others. In t h i s treatment of the vegetation approximately half the plant species occurring i n the quadrat samples have been omitted. The shelter value of a plant species was measured as the amount of l i n e intercept or quadrat i t covered at ground l e v e l . The samples were averaged and expressed as a percentage shelter value. Food plants were sampled f o r amount of ground covered, frequency of occurrence and abundance. For ease of comparison these data were averaged, converted to a percentage and expressed i n rankings of cover and frequency a f t e r Oosting (1948) as: 1 - le s s than 5$ of the ground covered 2 - 5 to 25$ » n n n 3 - 25 to 50$ " " " " 4 - 50 to 75% n n n it 5 - 75 to 100$ « !« n n A - the species occurred i n 1 - 20$ of the quadrats B - " » " n 21 - 40$ " " " C - " " " " 4 1 - 60$ " " " D - " " n " 6 1 - 80$ " " " E - " " " " 8 1 - 100$ " " V Abundance of a plant species was measured as the average number of a given species occurring per quadrat. I d e n t i f i c a t i o n of plants has i n most cases been made by the author. Representative c o l l e c t i o n s are at hand and w i l l be preserved i n the herbarium of the Department of Botany, 17 University of B r i t i s h Columbia and the Department of Botany, University of Toronto, One purpose of the vegetational analysis was to enable a c o r r e l a t i o n between the positions i n which grouse were observed and vegetational type. To do t h i s the amounts of each cover type on the two study plots were rated as a proportion of unity. The r e l a t i v e value of each type was then divided into the t o t a l number of grouse observations made i n that type, to produce a fig u r e of grouse u t i l i z a t i o n , expressed as a percentage of t o t a l s i m i l a r observations made i n a l l cover types. This c a l c u l a t i o n made comparable, values of grouse u t i l i z a t i o n f o r each vegetational type occurring i n the study p l o t s . 18 THE STUDY AREA The study area i s situated near Quinsam Lake on an undulating coast p l a i n that slopes east from a height of 600 feet to sea l e v e l at the s t r a i t s of Georgia, F i g . 1. To the west and southwest the land continues to r i s e into the Island mountain ranges. The c i r c l e i n Fig . 1 represents the approximate range of the author, who observed, caught and collected grouse over t h i s area. I t i s ca l l e d the study area. The squares I and I I are two sample plots of 36 acres surveyed and blazed i n 1951. On these, grouse and vegetation were studied i n d e t a i l and from here stems most of the data on behaviour and population s i z e . They are c a l l e d plot I and I I . Plot I I I was established i n 1951 and i s an area where males were shot, to experiment with migration and behaviour. The study area overlaps the region studied by Fowle i n 1943. This was close to the north and south banks of the Quinsam River at Quinsam Lake. The high incidence of blood parasitism he found here, coupled with his b e l i e f that the area was apparently optimum summer grouse range, influenced the decision to continue research i n t h i s l o c a l i t y . 19 THE SPRING AND SUMMER CLIMATE The elimate was recorded to study i t s ef f e c t upon grouse behaviour and the s u r v i v a l of young, especially i n the week of, and a f t e r , hatch. The data are expressed graphically i n F i g . 2, from Table I appended. Generally, 1950, from the l i m i t e d amount of data available f o r that year, was intermediate to 1951 and 1952 with respect to maximum weekly temperatures and days of r a i n . 1951 was a r e l a t i v e l y warm summer with l i t t l e r a i n and associated high rates of evaporation. No r a i n f a l l was recorded a f t e r the 13th week or July 6th and t h i s was general i n the Campbell River area f o r at that time forest closure was enforced by the B r i t i s h Columbia Forest Service. 1952 was recorded as r e l a t i v e l y cool and wet through spring and into early summer as compared to 1950 and 1951. Minimum and maximum temperatures were at t h e i r lowest u n t i l August of that year, while the greatest amount of r a i n , days of r a i n , and lowest rates of weekly evaporation were recorded up u n t i l that month. In August of 1952 l i t t l e r a i n , high temperatures, and high rates of evaporation resulted i n another general forest closure. Thus of the three, 1950 was the only year with a r e l a t i v e l y cool moist August without forest closure. w i t h respect to the effect of climate on the s u r v i v a l of young (to be discussed below) the week of hatch June 15 to 21 (p. BO) and two weeks thereafter are assumed c r i t i c a l . Over t h i s period the three years provide a valuable contrast. This i s u. 90 o 280 3 | 7 0 E <u " 60 50 o 2 40 ->' 4 1950 Y] IT J I I I L . 4 -i 3 o -2 h a. j I i I L c 5 a •a • o 4 -3 -2 -i r J I L 1951 u u i r J I I I I 1 I L _n J I I I I I I I I I L 1 J L J I I L 1952 n L J I \ L J I I L J l_ J I L J I l_ J 1 L 10 -o 8 " £ 6 o > 11 _l I I I I I I L 6 10 14 18 n L r u Ln n -I 1 1 I l_U I 1—1 L 2 6 10 14 18 Fig. 10 14 18 Week of study 2 from Table I. Weolher data and week of study, 1950, 1951, 1952. 19 THE SPRING AND SUMMER CLIMATE The climate was recorded to study i t s e f f e c t upon grouse behaviour and the s u r v i v a l of young, es p e c i a l l y i n the week of, and a f t e r , hatch. The data are expressed graphically i n F i g . 2, from Table I appended. Generally, 1950, from the l i m i t e d amount of data available f o r that year, was intermediate to 1951 and 1952 with respect to maximum weekly temperatures and days of r a i n . 1951 was a r e l a t i v e l y warm summer with l i t t l e r a i n and associated high rates of evaporation. No r a i n f a l l was recorded a f t e r the 13th week or July 6th and t h i s was general i n the Campbell River area f o r at that time forest closure was enforced by the B r i t i s h Columbia Forest Service. 1952 was recorded as r e l a t i v e l y cool and wet through spring and into early summer as compared to 1950 and 1951. Minimum and maximum temperatures were at t h e i r lowest u n t i l August of that year, while the greatest amount of r a i n , days of r a i n , and lowest rates of weekly evaporation were recorded up u n t i l that month. In August of 1952 l i t t l e r a i n , high temperatures, and high rates of evaporation resulted i n another general forest closure. Thus of the three, 1950 was the only year with a r e l a t i v e l y cool moist August without forest closure. ^ i t h respect to the effect of climate on the s u r v i v a l of young (to be discussed below) the week of hatch June 15 to 21 (p. 80) and two weeks thereafter are assumed c r i t i c a l . Over t h i s period the three years provide a valuable contrast. This i s 20 summarized i n the following t a b l e : Weather week 10 to week 12, 1950, 1951, 1952 • 1950 : 1951 : 1952 Av. Minimum temperatures, °F.: > 52, 53,! • 43, 51, 49, Av. R a i n f a l l , c.c. : - ! °' o, . 1 / .1, .1, Total Day's r a i n : :1, 2.5, 0 ! °' 0, 2,! :2.5, 2, 4, Av. Evaporation, c.e. : !l2, 11, 7.: ''4, 5, 3. Thus from the 3 year's records i n the c r i t i c a l chick period, 1952 was cooler by 8 degrees, wetter by .2 c.c. of r a i n that was prolonged over a period of 6 more days than 1951 and 5 more than 1950. F i n a l l y the evaporation rate over t h i s period i n 1952 was 18 c.c. less than i n 1951. 21 THE VEGETATION AS HABITAT Mountain forests of douglas f i r (Pseudotsuga t a x i -f o l i a ) are the primaeval habitat of the sooty grouse. From here they descend i n the spring to mountain meadows and more sparsiey wooded lowlands and breed, Bent (1932). According to B.C. Forest Service records, the Quinsam study area p r i o r to 1925 was mature forest of douglas f i r , western hemlock (Tsuga heterophylla) and western red cedar (Thuja p l i c a t a ) . As such, i t must have been unsuitable breeding range f o r the sooty grouse. After 1925, l i k e much of the east coast of Vancouver Island, the Quinsam area was r a p i d l y logged, and i n the process burned. There are records of logging and burning i n the study area i n 1927 and 1929. F i n a l l y , i n 1933, a severe forest f i r e swept 74,500 acres of logged and mature timber from Menzies Bay on the north, thence i n a swath two miles i n width to Courtenay on the south. In F i g . 1 the l i n e represents the western edge of t h i s burn. In forestry records; f i r e #230, Bloedel, Book 1936-41. Residents of t h i s area report sooty grouse on the Quinsam range p r i o r to 1938. Evidently with the clear cutting of timber and subsequent burning, the region had become suitable summer range f o r grouse which over-wintered i n the higher timbered slopes. What effect i f any the 1938 f i r e had on the Quinsam breeding population i s unknown, but by 1943 the area was i n a condition that Fowle (1944) called apparent optimum summer range f o r the species. He accredited t h i s to the abundance of plant and 22 insect food f o r the adults and chicks. In an attempt to further understand the summer habitat rela t i o n s of the sooty grouse i n the present stages of plant succession at Quinsam Lake, the vegetation was a r b i t r a r i l y c l a s s i f i e d into 6 major shelter types, mapped on plots I and I I , and described. The vegetational types once recognized were then correlated with grouse d i s t r i b u t i o n and a c t i v i t y to discover t h e i r u t i l i z a t i o n . Each shelter type was given a name a f t e r i t s dominant shelter species as follows: F i r Dense F.D. Willow Dense W.D. F i r Open F.O. Willow Open W.O. Bracken Open B.O. Log Open L.O. The shelter types occurring on plot I are representatives of natural burn succession, i . e . , Log Open, Bracken Open, Willow Open and Willow Dense. These types occur on plot I I but here the natural pattern of succession has been altered by large scale replanting of the area and thousands of acres l i k e i t , by the B r i t i s h Columbia Forest Service. While douglas f i r occurs r a r e l y i n unplanted areas, i n planted areas i t i s a major element of the vegetation and therefore i s included i n the shelter type c l a s s i f i c a r t i o n as F i r Dense and F i r Open. A s t a t i s t i c a l description of the shelter types i n terms of ground covered and the amount of each type occurring on the two study plots i s presented i n Table I I . The shelter value of each type i s expressed graphically i n Fig..3 from Table I I . TABLE I I Ground covered by shelter plants i n percent. Shelter type F i r Dense F i r Open Willow Dense Willow Open Bracken Open Log Open Number of 100 f t . samples 5 7 5 4 10 8 Shelter component Av. Range Av. Range Av. Ran^e Av. Range Av. Range Av. . Range Pseudostuga t a x i f o l i a S3 75-90 34 11-51 - - - 2 0-7 S a l i x spp. 3 1-6 4 2-8 82 56-100 50 33-66 5 2-13 2 1-7 Alnus oregona - - 3 0-21 - 1 0-5 4 0-30 1 0-1 Logs and stumps 6 5-9 12 6-21 11 2-28 8 4-13 10 4-40 15 2-41 P t e r i s a q u i l i n a 35 11-60 26 13-36 13 1-5 42 31-56 42 21-63 13 3-28 Lupinus spp. - - - - 8 0-38 1 0-2 19 0-68 - -Vaccinium p a r v i f l o r u s - - 1 1-8 - - - 5 0-23 Rubus pa r v i f l o r u s - - 1 0-2 - - 5 0-28 Amount of each shelter type on plot I and I I i n percent Plot I 0 0 27 30 23 18 Plot I I 7 66 10 1 5 s Fir Dense P. toxitolia Solix spp. A. oregona Logs and P. aguilina Lupinus spp. V. parviflorus R parviflorus stumps s> 1 , Fir Open a) Willow Dense Willow Open P. tOlifoliO Solix spp. A. oregona Logs and stumpsfvX^  P. aguilina Lupinus spp. V. parviflorus R. parviflorus ^ ^ ^ ^ Bracken Open Log Open P. taxi folia Salix spp. A. oregona Logs and stumps P. aguilina Lupinus spp. V. parviflorus R. parviflorus 0 Fig. 3 Average amount of ground covered in percent from Table H Average amount of ground covered in percent by shelter plants in each of the six shelter types 24 Generally, although d i f f e r e n t i n plant component, F i r Dense, Fi g . 4(a) and Willow Dense, F i g . 4(c and d) are s t r u c t u r a l l y a l i k e i n terms of average amount or percentage of ground covered by f o l i a g e and stems. In the same way, F i r Open, F i g . 4(b) i s s i m i l a r to Willow Open, F i g . 4(e and f ) , p a r t i c u l a r l y i n June and l a t e r summer when bracken reaches i t s maximum growth and c o n t r i -butes to the shrub layer. Bracken Open, Fig . 4(g and h) i s a shelter type i n which bracken, along with logs and stumps i s the sole shelter species present. On dry s i t e s bracken i s loosely associated as i n F i g . 4(g)i while on moist s i t e s i t forms a dense stand almost completely covering the ground, F i g . 4 ( i ) . In such cases l u p i n occasionally appears and may i n some cases dominate the bracken as i n F i g . 4 ( j ) . This stand i s t r a n s i t o r y , however, and by early August the bracken again becomes the major shelter plant as the l u p i n s h r i v e l s and drys. Log Open i s the l a s t shelter type of the study p l o t s , and t h i s type, as the name suggests, has logs and stumps as the major shelter elements. Logs and stumps are everywhere at Quinsam Lake. They figure l a r g e l y i n the various cover types, e s p e c i a l l y i n the spring before f o l i a g e has developed. In Log Open type, Fig. 4(k) they remain an important shelter element throughout the year, although here, huckleberry (Vaccinium parv i f l o r u s ) and thimbT,eberry (Rubus parviflorus) make t h e i r greatest contribution as shelter vegetation. Of the shelter types discussed Log Open i s the most F i g . 4(a) F i r dense type 1 F i g . 4(b) F i r open type F i g . 4(c) Willow dense type F i g . 4(e) Willow open type F i g . 4(d) Willow dense, spring aspect • I F i g . 4(f) Willow open, spring aspect h l ? i r d S 0 0^! 1 1^, l n t hfS a n d ° t h e r Ph°tographs i s 4 feet i n Height. Each black or white section i s 1 foot i n length. F i g . 4(g) Bracken open type F i g . 4(h) Bracken open, spring aspect F i g . 4 ( i ) Bracken open type F i g . 4 ( j ) Bracken open type F i g . 4(k) Log open type F i g . 4(1) Sedge open type F i g . 4(m) Clover open type Fig. 4 ( n) A t y p i c a l road F i g . 4 ( 0 ) Quinsam area 1943 (After Fowle 1944) Fi g . 4(p) Quinsam area 1953 25 s i m i l a r to early stages of burn succession as described by Fowle (1944). Since h i s study, the greatest change i n the area as a whole has been the advance of woody vegetation. This i s obvious from a comparison of F i g . 4(o), a 1943 picture of the area by Fowle, with F i g . 4(p), a picture taken i n the same area i n 1953. F i n a l l y mention may be made of two non-shelter types that complete the pattern of vegetational cover on the study p l o t s . Sedge Open, S.O., i s a cover type produced by temporary spring pools i n which the vegetation i s almost exclusively sedge (Carex spp.) with an underlying carpet of moss. F i g . 4(1) i l l u s -trates t h i s type with Willow Dense i n the background. Clover Open, Fi g . 4(m), i s a cover type without shelter value but i n which, Clover (Trifolium spp. and Medicago lupulina) makes up a major portion of the food plants present. Roads are included w i t h i n t h i s type f o r although t h e i r edges are usually Bracken Open the central swath commonly contains two of the three species of clover recorded on the study area. Sedge Open covered less than lfo of each plot while Clover Open covered 2% of plot I and 3$ of plot I I . Table I I I presents a description of food plants i n the shelter types and Clover Open and Sedge Open i n terms of percentage ground covered, frequency of occurrence and abundance. Generally, with respect to ground coverage by shelter species now considered as food plants the table presents s i m i l a r r e s u l t s as obtained by l i n e intercept method. The abundance of 5 willows per quadrat as recorded i n Willow Dense i l l u s t r a t e s the " t h i c k e t " nature of this shelter type. TABLE I I I Description of food species; t r e e s , shrubs and herbs i n each cover type Cover type % ground covered"'- Frequency $2 Abundance3 :FD FO WD WO BO LO CO SO FD FO WD WO BO LO CO SO FD FO WD WO BO LO CO SO Number of yard quadrats :30 40 30 30 60 45 35 5 30 40 30 3 0 60 45 35 5 30 40 3 0 30 60 45 35 5 Food species  Pseudostuga t a x i f o l i a  S a l i x spp. Alnus oregona  P t e r i s a q u i l i n a  Lupinus spp. Ifabjyfell' ;; parviflorus  Vaccinium p a r v i f l o r u s Kubus v i t i i ' o l i u s Gaultheria shallon  Mahonia nervosa  Rosa gymnocarpa Mosses and Lichens Epilobeum sp. Hypochaeris radicata  Hieracium sp. Vi o l a sp. Thu.ja p l i c a t a  Cornus canadensis  Campanula sp. Symphorycarpus alba  V i c i a americana  Linnaea borealis Gramineae Sedge ,Fragaria brachtiata  Trifolium procumbens 1 T r i f o l i u m repens  Medicago lup u l i n a  M i t e l l a breweri  Plantago lanceolata 4 2 1 E C A ^1 <1 <1 1 1 5 3 1 1 1 A A E G A A A A <1 <l 5 2 <1 <i 1 1 1 A A A <1 <1 <i 3 3 2 3 3 2 1 E E B E E C A 7 s 1 5 9 3 1 2 1 3 1 C B C A 6 2 15 <1 1 1 1 2 1 2 A A A D B B ^ 1 <i <1 3 2 2 1 i A A B <i <1 <1 3 2 2 2 2 2 1 E E E E E E C 14 6 6 7 5 6 2 2 2 1 1 2 C B A A C 7 6 < 1 2 4 1 1 1 1 1 A A A A B <1 <1 <1 <1 1 1 1 1 1 1 A A A A A <1 <1 ^1 <1 <1 1 1 1 1 2 3 2 4 C D D D C E D E 1 1 1 1 1 1 A B C B B B <1 <1 2 <1 <1 <1 1 1 1 2 1 1 2 C C D D C C D 4 3 6 14 2 4 38 1 1 1 1 1 1 1 A B A B B C A <1 <1 <1 <1 <1 1 <1 1 1 1 1 1 1 A A A A A A <1 <1 2 <1 <1 <1 1 1 1 1 1 A A A A A <1 <1 <1 <1 <1 1 1 1 1 1 A A A A A <1 <1 <1 a 1 1 1 1 1 A A A A A <1 <1 a <i <i 1 1 1 A A A <1 <1 <i 1 1 1 1 1 1 1 A A E E C A B <1 <1 <1 <1 <i <i l 1 1 1 A A <1 <1 1 1 1 1 1 2 A A D C B E 1 1 1 1 2 5 A C A A B E 1 1 1 1 A A A A <: 1 <1 < i < l 1 1 1 1 A A A A 2 2 <i l 1 2 A C 1 2 A A 1 1 1 1 B A A A 2 <1 <i l 1 1 A A <. 1 c i <i TABLE I I I (continued) 3over type $ ground covered1 Frequency f<£ Abundance^ :FD FO WD WO BO L0 CO SO FD F0 WD WO BO LO CO SO FD FO WD WO BO LO CO SO dumber of yard quadrats :30 40 30 30 60 45 35 5 30 40 30 30 60 45 35 5 30 40 30 30 60 45 35 5 3 l a n t component Blechnum spicans P o l y s t i chum munition-Duff and mineral s o i l 1 4 3 1 1 1 1 1 4 4 4 3 3 4 A E A A A A A E E E E E D C <1 <1 <1 <1 <1 Total number of food species • 22 24 23 21 24 22 19 4 1 - less than 5$ of the ground covered. 2 A _ t h e s p e e i e s occurred i n 1 - 2 0 $ of the quadrats. 2 - 5 - 2 5 $ of the ground covered B - " " " « 2 1 - 4 0 $ " » •« 3 _ 2 5 - 5 0 $ » « n n c _ n n n tt 4 i « 6 0 $ « » « 4 _ 5 0 - 7 5 $ " » " tt D - " " tt n 61-80$ " » » 5 - 7 5 - 1 0 0 $ " " " » E - " » " « 8 1 - 1 0 0 $ " " » Average number occurring per quadrat. to 28 Rubus v i t i f o l i u s a major berry producing plant shows a r e l a t i v e l y constant coverage, frequency of occurrence and abundance, throughout a l l types with the exception of Clover Open and Sedge Open where i t i s not commonly found. I t i s most abundant i n F i r Dense type. Hypochaeris radicata occurs i n a l l types i n approximately the same per cent coverage, and high frequency of occurrence. I t i s most, abundant i n Clover Open type. The plant i s a major food item of the adults. Mosses and lichens occurred commonly i n each type sampled and thus have a r e l a t i v e l y high frequency of occurrence. Duff and mineral s o i l are common and covered a large proportion of the ground i n a l l types sampled. In the remaining majority of food items recorded, there i s a general d i s t r i b u t i o n of the plants irrespective of the shelter type l i m i t s , with a r e l a t i v e l y small amount of ground covered, a low frequency of occurrence, and an abundance less than 1 i n almost every case. I t i s noteworthy that each type, excepting Sedge Open, has approximately the same numbers of food species occurring i n i t . With respect to food plants then, the s i x shelter types are s i m i l a r , a fact which serves to place emphasis on differences found i n the abundance and ground covered by species constituting the shelter types. I f the d i s t r i b u t i o n of grouse i s related to a p a r t i c u l a r shelter type t h i s then suggests the importance of shelter or shelter and food vegetation as a factor influencing t h i s d i s t r i b u t i o n . 29 TOPIC I NATURAL HISTORY  Moult The observations on moult presented here are based on the examination of 356 grouse on the breeding range from A p r i l to September. At least 5 birds were examined i n each week of the three year study period. In September of 1950 and 1951, several hundred grouse i n hunter's bags were examined f o r moult pattern and weight. According to Bent (1932), the moult of chick plumage begins i n July and August and continues into October. The post juvenile moult i s complete except that the outer pairs of prim-aries are retained f o r a f u l l year. Van Rossem (1925) and Swarth (1926) noted that the t a i l r e t r i c e s developed by the chicks i n October were shorter and narrower than those possessed by adult birds going into t h e i r second or l a t e r f a l l . Van Rossem was of the opinion that most of these r e t r i c e s of yearling birds were replaced during the following winter spring and summer. Swarth disagreed with t h i s and could f i n d no feather replacement i n the yearling birds u n t i l a f t e r what he cal l e d t h e i r post-nuptial moult i n the middle of July and l a t e r of t h e i r second year. From the present study the moult i n the young i s as described by Bent and Swarth with the exception that the chicks do not r e t a i n t h e i r chick primary feathers into t h e i r second year. The natal down of June i s replaced by chick body and f l i g h t feathers i n July, which i n turn are added t o , or shed and replaced completely so that by September the young of the year 30 are i n adult plumage with the exception of the r e t r i c e s which are c h a r a c t e r i s t i c a l l y short and narrow. With the exception of the development i n the r e t r i c e s , the moult i n sooty grouse chicks from egg to adult plumage p a r a l l e l s the d e t a i l e d moult pattern described by Bump et a l (1947) for the ruffed grouse (Bonasa umbellus). There are minor differences of colouration between plumage of young bi r d and adult and t h i s i s most noticeable i n males i n t h e i r second year. At t h i s time the plumage of the yearling male i s l i g h t e r and more speckled with white than that found i n older birds. The most important feature of the y e a r l i n g plumage i s , however, the shorter and narrower r e t r i c e s . These can be used as an age c r i t e r i o n on the breeding range to separate yearling males and females from the older adults. The adult birds'" possess larger and wider t a i l r e t r i c e s , obtained i n the moult of th e i r second f a l l . Thus on the breeding range birds with these larger r e t r i c e s are two years of age at least and i n t h e i r t h i r d or l a t e r summer. The two age classes yearlings and adults, of both sexes, begin i n early summer, what Swarth c a l l e d the post-nuptial moult. This moult according to Dwight (1900) i s a complete replacement of body and wing feathers. The adults of two. years or older are replumaged with i d e n t i c a l feathers, while the yearling birds i n the annual moult assume adult plumage. There appears some variance with t h i s basic pattern. 31 Adults and yearlings of both sexes examined i n t h i s study begin moulting by the end of May. At t h i s time the 10th primary i s replaced and by the end of June primaries 9, 8 and 7 are either f u l l y replaced or i n the process of active growth. Body moult begins at t h i s time, usually i n the head and neck and extending over the flanks, back and sides. By the end of July the 6th and 5th primaries are shed and replaced, while the new primaries are f u l l grown and the old s t i l l t i g h t i n t h e i r sockets. Body moult continues with feather shedding and replace-ment. I t i s most noticeable i n the cocks which show a white and black mottled appearance about the neck region. Concommitantly the neck tissues of the male, swollen and deep yellow during A p r i l and May, become t h i n and pale i n colour. The same change i s noted i n the caruncle. The August and September samples indicate the 4th prim-ary i s shed and replaced i n t h i s period with a continuation of body moult. The f i r s t t a i l r e t r i x i s shed by middle or l a t e August, and these are replaced from the outside mediad. In the September shoot, most hens have a completely new t a i l or one nearly replaced. The moult of upper and lower t a i l coverts seems to occur i n association with the r e t r i c e s . At no time i n the body and wing moult are the birds f l i g h t l e s s . An unusual feature i n t h i s pattern i s the absence of wing covert and secondary f l i g h t feather moult. While the ten primaries apparently follow a regular laterad sequence of moult the wing coverts and secondaries do not conform. Only two adults 32 examined showed secondary feather moult and t h i s was e r r a t i c with the 3 r d , 4 t h and 5 t h , of the 12 secondaries being replaced i n one, while the 2nd, 5th, 7 t h and 12th i n the other. Both of these moults were observed i n early August. There exists the p o s s i b i l i t y then, i f a l l feathers are to be annually replaced, that the secondary feathers, wing coverts, and the remaining 3 to 1st primary are l o s t on the winter range. Some l i g h t has been shed on the problem by a June, 1953, examination of two adult males, marked or covered with printers ink i n May, 1952. Since the feathers were inked i n 1952 then replacement of feathers from May, 1952, to June, 1953, would be indicated by ink free parts of the plumage. In both birds, head, neck, body, t a i l and legs, were uncoloured. On the other hand the f i r s t primary was coloured, as were a l l the secondaries except the 3 r d and 12th. Most of the undercovert and overcovert feathers of the wing were unmarked, although the f i r s t row of undercoverts to the secondaries were s o l i d l y dyed. From t h i s evidence i t appears that adult birds do not replace a l l t h e i r plumage i n the post nuptial moult and r e t a i n most of the secondaries, some of the wing coverts and possibly the f i r s t primary f o r more than a f u l l year. Age C r i t e r i a To check and refine the age c h a r a c t e r i s t i c s noted by Van Rossem (1925) the outer p a i r of t a i l feathers of a l l birds examined on the study area were collected and measured f o r t o t a l 33 length. These were compared with the t a i l feathers of chicks or birds of the year sampled from hunter's bags at the Campbell River road check i n September of 1950 and 1951. Although the young at t h i s time resemble the adults s u p e r f i c i a l l y , several ch a r a c t e r i s t i c s can be used, other than the length of t a i l , to accurately i d e n t i f y them as birds of the year. The young usually r e t a i n into September a few juvenile feathers as i n the a x i l l a e or upper t a i l coverts. In the young males, the external tissue of the neck i s not at a l l coloured, thickened or rugose i n nature as i n adult males. In the young of both sexes the posterior edge of the sternum i s incompletely o s s i f i e d and can be e a s i l y bent. F i n a l l y and most c h a r a c t e r i s t i c a l l y , the bursa of Fabricius i s a deep pouch of approximately 1 centimeter i n the young, while i n the adults i t i s reduced to a s l i g h t pocket or scar i n the dorsal surface of the cloaca. The road check sample of yearling t a i l feathers from 15 males and 21+ females and the sample of t a i l feathers taken from 84 male and 121 female grouse on the study area through A p r i l to August are compared graphically i n F i g . 5. Here the average length of the two outer t a i l feathers are placed i n 2 m.m. classes and plotted against t h e i r frequency of occurrence. The s o l i d part of the histograms represents the t a i l feather lengths of yearling b i r d s . The open part i s the contribution of grouse on the breeding range. In the case of males, there i s a clear break between the feather lengths of yearlings and another class representing birds i n adult plumage. From the graph yearling males have outer 26 -24 -•° 20 'a 16 % 12 z 8 " Males Birds of the year, rood check [ | Study orea sample 1 7T / _ ro ro ro ro OI OI 6 i cr> ro i 6> ro ro OI OI CI ro ot ab — J L i ^ ^ oi o< en u en cn * >i 6 " m ib ro oi oo — 6 oi u> cn u> o a> cn -H -J ' oi (O ro ai cb — * - J O O J • ^ ^ J C D C D C O C D ( O < O < £ ' t ro ^ | C B C O C O ( O ( 0 < f o Average outer tail feather length in cm. S O U J I K J P J O I Q ) - i S O U 01 li> rb t i l CD — « S Q U g i K l g ^ ( g — — — r o r o r o o i o i o i * ^ ^ ^ oi oi oi « ai oi -H ~ j - g a > a > o o i o < o ( O Q Average outer tail feather length in cm. Fig. 5. Comparison of average outer tail feather length of adult and yearling grouse 34 t a i l feathers ranging i n length from 13.2 to 15.2 cm. Adult males have outer t a i l feathers ranging i n length from 16.1 to 19.4 cm. With t h i s , 9 out of the 84 cocks examined on the study area can be classed as yearling males. In the case of females, the break between age classes as found i n males i s not clear cut, however, the two groups are s t i l l evident. As a working figure hens were classed as yearlings i f t h e i r average outer t a i l feather length f e l l between 11.7 cm. and 13.4 cm. and as adult hens i f t h i s length f e l l between 13.5 and 16.1 cm. With t h i s , 78 out of the 121 females examined on the study area can be classed as yearling hens. Since the adult t a i l feather i s obtained i n both sexes i n the f i r s t post nuptial moult, then birds with adult t a i l feathers are by hatching time i n June, two years of age or older, and into t h e i r t h i r d or l a t e r year. In t h i s study the term adult refers to t h i s age group. The term yearling, as the name suggests, refers to birds of the previous years hatch which are one year of age by the subsequent hatch and i n t h e i r second year. The term chick or young i s applied to birds between hatching date and the end of September, when they acquire yearling plumage. After a two year old b i r d has attained adult plumage there i s no i n d i c a t i o n that subsequent moults produce longer or shorter t a i l feathers, which would confuse i t s age c l a s s i f i c a t i o n . Once adult, as f a r as feather data goes, i t i s at least two, but may be an unknown number of years older. 35 Weight of Yearlings and Adults A sample of 14 adult males taken at random from a larger f i e l d sample i n A p r i l and May was 1300 * 50 1 grammes i n average weight. A s i m i l a r sample taken i n June and July gave an average weight of 1200 *. 25 grammes. The difference i s s t a t i s t i c a l l y s i g n i f i c a n t (by " t n test) and indicates the males come from the winter range i n greater weight than they a t t a i n i n the summer months. This i s not unusual, the loss i n weight being attributable to the strenuous a c t i v i t i e s of the breeding period. The hens i n A p r i l and May are heavy with eggs, and thus make comparison with t h e i r summer weight less meaningful. In 24 recorded i n t h i s period, the weights ranged between 850 and 1200 grammes. A sample of 20 adult hens weighed i n June and July averaged 850 + 25 grammes. Eight yearling males weighed i n June and July averaged 1100 * 50 grammes. This i s s i g n i f i c a n t l y l i g h t e r than the 1200 * 25 grammes recorded for the adult cocks i n the same period, and an ind i c a t i o n that the yearling males do not a t t a i n adult weight u n t i l after July i n t h e i r second year. Eleven yearling females weighed i n June and July averaged 780 • 25 grammes. This weight i s s i g n i f i c a n t l y l i g h t e r than the 850 2. 25 grammes average weight recorded i n the adult hens over the same period. Thus, as i n the yearling cocks, i t seems l i k e l y that the yearling hens do not a t t a i n adult weight u n t i l a f t e r July of t h e i r second year. ^Standard error of the mean. 36 The Spring Migration Observations on the a c t i v i t i e s of grouse were recorded i n the most part on study plots I and I I , f o r i n these areas most birds of both sexes were handed or marked. The plots were searched as systematically as possible i n a l l hours of the day so that each region was equally investigated. Data on grouse positions within the plots were recorded and these plotted to construct maps of grouse d i s t r i b u t i o n throughout the f i e l d study periods. The maps and associated observations on a c t i v i t i e s then serve as basic material from which, af t e r analysis, some understanding of the mechanics of grouse behaviour can be obtained. L i t t l e i s known of the winter range of the birds on the study area. The distance they t r a v e l , or the d i r e c t i o n they take i n going and coming from i t remain l a r g e l y a matter of speculation. Anthony (1903) has recorded something of the down-ward migration i n Oregon where on the f i r s t of March grouse appeared on the move down from high mountain slopes. In crossing ridges they would glide i n flocks of 12 to 100 birds from one crest to the next. I f they f e l l short the birds would climb on foot to the top of the attempted ridge and then glide again towards the lowlands. He also observed that the largest f l i g h t s seemed to occur at sunrise and sunset, and that the f i r s t sex to reach the lowlands was the male. Eight hours spent on the study area on the s i x t h of March, 1951, produced one observation on a s i l e n t male i n F i r Dense type, where i t may have spent the winter. This and the 37 absence of droppings and tracks i n the snow, s t i l l present on roads, indicated the birds had not yet returned to t h i s portion of the summer range. By A p r i l the 13th on the beginning of the t h i r d year of f i e l d work the study area was populated by grouse of both sexes, which gave good i n d i c a t i o n , p a r t i c u l a r l y i n the case of the males, that they were resident birds. Thus i f the downward migration occurs at the same time each year the birds a r r i v e on the study area between March 6th and A p r i l the 13th. T e r r i t o r i a l Behaviour of the Adult Male Once on the summer range the behaviour of most adult cocks i s c h a r a c t e r i s t i c and f a l l s into the c l a s s i c pattern of t e r r i t o r i a l behaviour as described by Howard (1920), and modified through various studys by Nice (1937, 1941, 1943) on the song sparrow, Timbergen (1939) on the snow bunting, Kendeigh (1941) on the house wren, and others. The males take up and defend area from other males of the species. From within t h i s area or t e r r i t o r y they emit vocal c a l l s or hoots, a word description of the sound. When the positions i n which males are observed hooting are mapped they present a pattern of points representing the hooting s i t e s or stations of each male recorded i n the weeks of f i e l d study. F i g . 6 i s a map of such hooting s i t e s i n plot I. Fi g . 7 represents the observations of plot I I treated i n a s i m i l a r manner. The data are from A p r i l to August, 1953. By a r b i t r a r i l y j o i n i n g up the outermost points a perimeter i s created which 38 contains the maximum size area or t e r r i t o r y over which a given bird was observed hooting throughout the study period. From these maps i t i s clear, that when hooting, each male carries out t h i s a c t i v i t y i n a t e r r i t o r y peculiar to i t s e l f , i t i s isolat e d from other males engaged i n s i m i l a r a c t i v i t y . Thus while the t e r r i t o r i e s observed on the study plots vary i n size i t i s noteworthy that i n few cases do they overlap. In some regions of the plots where hooting males are not adjacent such as F i g . 7 at (4,A) t h i s s i t u a t i o n i s impossible, simply by the lack of a nearby male. In the case of males No. 162 at (14,D), No. 281 (17,J) male (11,1) and male (7,L) the s i t u a t i o n i s most apparent. Despite the close proximity of birds, each i s contained by a perimeter close to, but la r g e l y free from another. The perimeters and contained hooting areas need further q u a l i f i c a t i o n to gain t h e i r true meaning. In some cases they represent the extreme l i m i t s of a given males t e r r i t o r y , i n others, they represent the greatest area over which a hooting male was observed. For analysis of t h i s s i t u a t i o n , hooting observations of males No. 162 (7,L), (11,1), No. 281, and No. 147, F i g . 7, were chronologically arranged and divided into a group of ten, a group of that ten plus another ten, and a group of these 20 plus another ten and so on u n t i l a l l points were u t i l i z e d . When the outermost points of each group was joined on the map, and measured by planimetry the result was an accumulative series of 39 areas over which the b i r d hooted throughout the summer. I f a male was l i m i t e d i n i t s hooting positions over the study period, then at some group of ten points the accumulative area should cease to grow i n s i z e . The r e s u l t s of t h i s analysis are expressed graphically i n F i g . 8 from Table IV appended. Male (11,1) and (7,L) represent birds whose perimeters as a r b i t r a r i l y mapped are the actual l i m i t s of t h e i r hooting areas. This could have been predicted from the map. The inference here i s that t h e i r observed areas correspond to the actual hooting areas u t i l i z e d throughout the summer. On the other hand, males No. 162, No. 281 and No. 147 are birds which throughout the summer, either extended the area over which they hooted, and thus t h e i r map boundaries represent the greatest area i n which they were observed, or f i e l d observation f a i l e d to detect t h e i r true l i m i t s early i n the season. However, whether the areas are r e a l or apparent, there s t i l l remains the w e l l defined l i m i t s between adjacent birds, and any expansion, once the boundary i s met i s away from i t . I t i s not d i f f i c u l t to appreciate how the boundary between two males i s established f o r i n A p r i l f i g h t i n g i s commonly observed. When and where the l i n e i s to be i s another question. In the case of Male (11,1) t h i s area was recorded at near maximum size i n A p r i l , and s i m i l a r l y f o r Male (7,L). Thus the l i m i t s of these birds were determined early i n the spring. From a consideration of the points of A p r i l observation i n F i g . 7, t h i s probably holds f o r a l l the birds i n the plot p a r t i c u l a r l y with respect to the boundary between neighbouring males. 10 30 50 70 90 Number of points 90 " 70 -30 -Mole (7,L) -I L_ 10 30 50 70 90 Number of points Mole No. 281 J — I — i — i i _ 10 30 50 70 90 Number of points Mole (11,1) J l I I L 10 30 50 70 90 Number of points Mole No. 147 J — i — l I I i _ 10 30 50 70 90 Number of points Fig. 8 frbm Table E . Accumulative size of hooting areas and number of observations on five males of plotH. 40 As to where the boundary between hooting cocks might occur, some l i g h t i s shed on t h i s problem by comparing the d i s t r i b u t i o n of hooting males, as indicated by the perimeter of t e r r i t o r i e s , with the d i s t r i b u t i o n of the cover types on each pl o t . F i g . 9(a) superimposed on F i g . 9(b) and F i g . 10(a) super-imposed on F i g . 10(b) f a c i l i t a t e s t h i s comparison on plots I and I I . Each t e r r i t o r y i n F i g . 9(a) includes some Willow Open or Willow Dense type. S i m i l a r l y , i n F i g . 10(a), a l l t e r r i t o r i e s except (6,U) contain either F i r Dense, Willow Dense or both. There appears then, a relationship between lo c a t i o n of t e r r i t o r i e s and the dense vegetational types which would provide concealment f o r a hooting b i r d . I t i s noteworthy that the t e r r i t o r i e s do not conform to the l i m i t s of the cover types, an i n d i c a t i o n that hooting males, once l o c a l i z e d , are not r e s t r i c t e d i n t h e i r movements by the described vegetation. This serves to emphasize the physiolog-i c a l nature of the l i m i t s between adjacent hooting males. When t e r r i t o r i e s are close to a r e l a t i v e l y large area of dense vegetation as i n F i g . 9(a) at (13,D) (19,K) (15,U) and i n F i g . 10(a) at (7,H), they appear to border upon i t . This edge s i t u a t i o n possibly r e f l e c t s a compromise between area i n protective shelter and open areas w i t h i n which hens feed and are e a s i l y seen. With the above considerations when males arrive i n the spring and take up residence on the summer range, i t seems not u n l i k e l y that they select an area or edge of Willow Dense or F i r DENSE E23 FIR DENSE ^ Dense and begin to hoot. Thus the d i s t r i b u t i o n of the vege-t a t i o n would be a primary factor i n creating a d i s t r i b u t i o n of hooting males. Movements from the dense vegetation would extend the l i m i t s of t h i s hooting area and possibly bring the b i r d into contact with another male. At t h i s point a f i g h t might ensue, the outcome which would supposedly f i x a portion of the boundary of eit h e r "males hooting area, or cause one to move to points remote. I t follows from the above, i f a male became l o c a l i z e d close to other males, i t s t e r r i t o r y would be smaller than a male located not so closely to i t s fellows, assuming both birds tended to move out from the o r i g i n a l point of l o c a l i z a t i o n . This apparently i s what has happened on plot I I , F i g . 7 where the number of males about (7,L) and (11,1) has resulted i n r e l a t i v e l y small t e r r i t o r i e s of .7 and 1 acres respectively. The t e r r i t o r i e s of male No. 162 and No. 9, which are free to expand, were both recorded at 2 acres i n s i z e . Thus t e r r i t o r y s i z e appears inversely proportional to density of hooting males. Additional evidence i n support of t h i s conclusion i s found i n comparing t e r r i t o r y size and hooting male density or abundance over the years 1950 to 1953. Once a male has become l o c a l i z e d on a t e r r i t o r y i t returns or "homes" to the same l o c a l i t y i n subsequent years. Thus male No. 9, F i g . 12 (4,D) was banded on t e r r i t o r y i n 1950 and was observed on the same t e r r i t o r y i n 1951, 1952 and 1953. This has been equally true of 46 hooting males, which marked i n one year, i f recorded i n subsequent years were i n t h e i r o r i g i n a l 42 areas, and i n most cases under the same tree, log or stump where captured. With t h i s behaviour, and a low yearly turnover i n adult males (see p.ioi) there has been l i t t l e recorded change i n t e r r i t o r i e s or t h e i r occupancy as recorded over the years 1950 to 1952. This i s shown i n F i g . 11 and F i g . 12 which i l l u s t r a t e the positions of these t e r r i t o r i e s on plots I and I I . Male No. 8 (10,Q) F i g . 12, banded i n 1950, did not return to i t s t e r r i t o r y i n 1952 and was replaced by another male which was subsequently marked. The t e r r i t o r y of the new male was recorded as large as that occupied by the old. This suggests the new and presumed two year old animal was equally successful i n t e r r i t o r i a l establishment as No. 8 which was at least two years of age i n 1950 and at least three i n 1951. Again males No. 162 (13,D), No. 147 (15,R), No. 205 (24,V), No. 132 (21,E) and No. 9 (4,D) a l l at least three or four years of age i n 1951 have shown no s i g n i f i c a n t change i n observed t e r r i t o r y area over the two or three years they have been banded. At the same time there has been l i t t l e change i n the d i s t r i b u t i o n of hooting males about them. The t e r r i t o r y at (16,S) was vacated when male No. 33 banded i n 1950 did not return i n 1951. In 1952 three new t e r r i t o r i e s were recorded at (6,U), (10jW) and (22,V). In F i g . 11 Male No. 13 (11,S) banded i n 1950 returned i n 1951 but was not observed, nor was a new a r r i v a l , on t h i s t e r r i t o r y i n 1952. Male No. 130 (13,0), adjacent i n 1951 expanded i t s t e r r i t o r y i n 1952 and included area once occupied by male 50' F i g . 11 .A / 7 \ 1 : 2! 3 • -' / s ~I43 - _ \ 5 - ; i 111 I, I V I k .L ik r1, il> il Jo DISTRIBUTION OF TERRITORIES AND NESTS 1950 to 1952. PLOT I. NESTS TERRITORIES 1950 A 1950 1951 A 1951 1952 A 1952 • .. .-270" 3 24 25 0 T DISTRIBUTION OF TERRITORIES AND NESTS 1950 to 1952. PLOT H . NESTS TERRITORIES 1950 A 1950 1951 A '951 1952 A 1 9 5 2 43 No. 13; an i n d i c a t i o n that i n 1951 i t was l i m i t e d i n t h i s d i r e c t i o n of movement by the presence of male No. 13. By June of 1953 a s t r i k i n g change had.occurred on Males plot I I , F i g . 12/(11,1), (7,L), (11,Q), No. 147 (17,R), No. 162 (13,C), No. 281 (17,J) and male No. 200 (20,U) were not observed on the study p l o t . Of the seven marked males three were replaced by new birds which occupied the same general area as had males No. 200, No. 147 and (11,1). The t e r r i t o r i e s of (7,L), (11,Q) and No. 162 (13,C) were l e f t vacant or. overlapped by the hooting areas of the new resident males. Male No. 132 (22,C), l i m i t e d i n expansion by Nos. 162 and 281 i n 1952, was recorded hooting i n i t s o r i g i n a l t e r r i t o r y and subsequently over a greater part of the t e r r i t o r i e s of males No. 162 and No. 281 at (12,E), (10,B), (14,B), (21,C) and (17,J). Here then the density of males was decreased, while the observed t e r r i t o r y size increased. The r e c i p r o c a l s i t u a t i o n to that of 1952, observed above, with a greater density of hoot-ing males. Thus t e r r i t o r y size appears to be a density dependent factor that i s inversely proportional to abundance of hooting males. Sexual A c t i v i t i e s of the Adult Male The most apparent sexual a c t i v i t i e s of the adult male are those of hooting, f i g h t i n g and courting. Each a c t i v i t y i s related to the observed positions or movements of the male and thus contribute to the changing or delimited boundaries of t h e i r t e r r i t o r i e s . 44 Hooting i s the major a c t i v i t y of the cock b i r d on i t s t e r r i t o r y . The c a l l or hoot of the sooty grouse i s a series of deep sounds which might be imitated with closed l i p s as, whrum whrm whrm whrm awhrm whrm. Each complete song takes from 3 to 4 seconds. The number of songs per minute varies between 2 and 4 i n steady daytime hooting to as many as 6 per minute i n periods of peak sexual a c t i v i t y when i t appears to gain i n volume. When hooting the male assumes a t y p i c a l stance, Fig.13 i n which the oesophagus i s s l i g h t l y i n f l a t e d and the head, with mouth closed, i s held forward and down near or into the swollen neck region. Each phrase begins with a c o n s t r i c t i o n of the birds body which probably forces a i r through the syrinx creating the sound. There i s no display of body parts or plumage i n what might be termed routine hooting a c t i v i t y . In beginning to hoot, the male does not give the f u l l song. Several of the i n i t i a l phrases occur, then a pause, and a r e p e t i t i o n of the i n i t i a l phrases of the c a l l . Usually a f t e r 4 or 5 of these abortive attempts the f u l l song i s uttered and continued thereafter. I t i s d i f f i c u l t to appraise the distance over which hooting can be heard. At times a hooting male can be accurately located from a distance of 500 feet. Others, apparently produc-ing a muffled or subdued song cannot be heard beyond 100 feet, at l e a s t to obtain an idea of t h e i r whereabouts. There i s no in d i c a t i o n from t h i s study that temperature, r a i n , pressure or wind d i r e c t l y influence the hooting of the male. F i g . 13 Hooting male (After Laing) Fig. 16(a) Fighting posture F i g . 16(b) V i c t o r stance 45 The influence of l i g h t , presence of females, hooting a c t i v -i t i e s of other males, and the physiology of the bird i t s e l f make t h i s issue complicated enough without resorting to the weather as an explanation of song a c t i v i t y or i n a c t i v i t y . In other studies males have been recorded c a l l i n g from high f i r trees i n dense f o l i a g e . The a c t i v i t y i s by no means so l i m i t e d for i n the study area cocks hoot from the ground or some prominence upon i t . Throughout the hours of d i r e c t sunlight males of plot I were recorded i n , or u t i l i z e d almost equally, the cover types, Willow Dense, Willow Open and Bracken Open, with a lesser u t i l i z a t i o n of Log Open, F i g . 14 from Table V appended. None was recorded i n Clover Open type. On plot I I ( i n the same figure) males showed a r e l a t i v e l y high u t i l i z a t i o n of F i r Dense type with observations i n F i r Open, Willow Dense, Bracken Open and Log Open almost equally numerous. Again none was recorded i n Clover Open type. Although frequently recorded i n the open types, males are r a r e l y observed i n d i r e c t sunlight or open canopy i n the daylight hours, and are i n the shelter of a log, shrub or tree when hooting. The shelter value of the dense vegetational types would appear obvious, pa r t i c u -l a r l y in.eary spring aspect when herbaceous vegetation i s not present. Generally, males have regular hooting stations on t h e i r t e r r i t o r i e s and are most frequently recorded at them. As an example male (20,N) F i g . 6 u t i l i z e d t h i s p o s i t i o n as a frequent hooting s i t e , while the clumping of observations i n t h i s figure Plot I 100 c o o N 50 i—i—I r rjd d d d o u. 5 5 CD -J o Clockers Nests Females Males Broods 100 I 50 o Plot II TT~1 Q O Q u: u.' Bd d o o d ?! cd J u O Q u: 3: p d o o 3f ai J d d d d d d d d u; u: j j: cri J u Clockers Nests Females Moles t f b . d d o * $ * o d d m' J u Broods Fig. 14 from Table H. Cover type utilization on plot I and H i 46 as i n F i g . 7 indicates the same s i t u a t i o n i n other males. Fi g , 15 i s a hooting s t a t i o n i n F i r Open of male (22,M) Fig.7. The bird hooted from the dark recess i n the log at the four foot rod. One function of male song from an established t e r r i -tory i s as a mechanism whereby females are attracted to the singing male, Tinbergen (1939) Nice (1943). Females have been frequently observed i n the t e r r i t o r i e s of hooting males but there i s l i t t l e evidence from t h i s study to indicate they were attracted by the song. With the lack of other evidence, and i n view of the work of others, i t seems l o g i c a l to believe that the loud hooting of the male serves as an attractor mechanism and conditions the movements of ph y s i o l o g i c a l l y receptive hens. When males are hooting i t i s unusual to hear adjacent birds c a l l i n g alone. As an example, i n F i g . 7 males No. 162 (13,C), (11,H) and No. 28 (17,J) sang almost simultaneously throughout the breeding period. On the other hand, these males might be s i l e n t while males No. 270 (24,B), No. 143 (16,B), No. 213 (15,E) and (13,G) on plot I F i g . 6 would be a c t i v e l y hooting. When one of an adjacent pair of males i s silenced by an intruder, the other frequently ceases to c a l l . I t usually resumes song when the disturbed male again becomes vocally active. These observations suggest the hooting of one male stimulates another or others to vocal a c t i v i t y . Over a period of f i e l d study hooting males are recorded Fig. 20(b) Nest Fig. 20(c) Destroyed nest 47 away from t h e i r regular song stations so that a larger area i s u t i l i z e d and the distance between adjacent males i s reduced. This dispersed nature of hooting s i t e s , which i n part creates the greatest extent of t e r r i t o r y i s evident i n a l l males studied i n s u f f i c i e n t d e t a i l , Figs. 6 and 7. Twice early i n A p r i l , the author was able to e l i c i t a f i g h t reaction i n a male and cause i t to move towards him. This was accomplished by hiding and imitating the song close to a male. In one instance a bird came rapi d l y towards the sound i n f i g h t i n g posture over a distance of 30 feet. In the second case a male was vigorously courting a female at a distance of 20 feet from the hide. When the author imitated the song, the cock immediately ceased i t s courting display and ran towards the source of sound i n f i g h t i n g stance. Movements of some males on t e r r i t o r y can be simply explained on the basis of an a t t r a c t i o n between closely situated birds as an example male No. 9 (4,C) F i g . 7 hooted i n A p r i l from (2,G) and when c a l l i n g here was heard with another banded male hooting at (E) and 100 feet o f f the p l o t . In June and July when t h i s banded male was no longer heard and had apparently vacated i t s t e r r i t o r y , No. 9 moved to positions (9,C), (7,G) and (7,0) which brought i t closer to males (11,1) and No. 26l (13,0) which were s t i l l vocally a c t i v e . Thus the hooting of males i s not independent but appears to be stimulated by hooting a c t i v i t y of a nearby male or males. I f a tendency f o r hooting males to move together i s r e a l , then hooting between males can also be considered as a 48 factor influencing the extent of t e r r i t o r y or at least p a r t l y the cause of a male's movements upon i t . Considering a new a r r i v a l i n spring t h i s tendency f o r males to hoot together may i n part determine whether i t remains and becomes l o c a l i z e d or moves to places remote. Thus presence of suitable shelter vege-t a t i o n and hooting male or males would be prime environmental factors i n i t i a t i n g t e r r i t o r i a l behaviour. I t may be, once hooting males have attained certain proximity, vocal c a l l s alone are s u f f i c i e n t to prevent continued expansion and resultant overlapping of t e r r i t o r i e s . The hooting of one male would presumably warn the other of i t s presence, and the song could therefore be considered as a form of passive defence. There i s l i t t l e evidence from the present study to permit acceptance or r e j e c t i o n of t h i s conjecture. r i g h t i n g i s an important a c t i v i t y of a t e r r i t o r y hold-ing male and i s associated with a w e l l defined pattern of behaviour. I f a trespassing male should appear w i t h i n the l i m i t s of a male's t e r r i t o r y and show no apparent display, the resident male w i l l at f i r s t begin to adopt the courting display as e l i c i t e d by the presence of a female. He then moves towards the intruder who may suddenly take f l i g h t , stand motionless or move towards the approaching male. In the majority of f i g h t s the outcome seems determined at t h i s point. I f the intruder should stand motionless or perhaps mount a stump or l o g the resident male, a l l traces of courting display gone may run at the intruder with neck out-stretched and head down, i n t y p i c a l f i g h t i n g posture, F i g . 16(a). Immediately the rush begins the 49 intruder takes f l i g h t . I f the resident male does not run towards the intruder by v i r t u e of i t s p o s i t i o n on a log or stump (or f o r unknown reasons), i t then approaches steadily i n f i g h t i n g posture and invariably begins to emit a stacatto series of sounds which might be written as, Mgug gug gug gug gug," as quickly emitted as the above symbols can be pronounced. While thus v o c a l i z i n g , the resident male begins to pace i n a four or f i v e foot oval i n front of the s i l e n t and motionless intruding male or around and beside him on a stump or log. After a period of from 1 to 3 minutes of t h i s , a completed oval ends i n a quick rush at the intruder who thereupon leaves. f i n a l l y , when two males meet, presumably on ground that each recognizes as i t s own hooting area, the outcome i s by no means sure. In such encounters both males pace i n t i g h t ovals with head down, neck out-stretched and emit sounds as described above. P e r i o d i c a l l y they cease the pacing and standing i n front of one another, stretch up t h e i r necks and bodies, then return to the f i g h t i n g posture and pacing. Suddenly they engage, and there follows a vigorous i f not physically harmful melee of pecking, buffeting of wings and downward slashing of feet. Upon breaking the birds again resume pacing and v o c a l i z a t i o n . At times i n pacing, the males peck at debris on the ground although they do not act u a l l y feed. How long the pacing and closing i n physical contact might continue i s a question. Only two such fights.were observed i n t h e i r entirety. In one l a s t i n g 5 minutes a b i r d 50 suddenly broke away from the point of f i g h t i n g , was pursued by the other approximately 15 feet, and there the chase stopped. In t h i s case the pursued male moved away about 100 feet and began to hoot, presumably from within the region i t s t i l l recognized as i t s own t e r r i t o r y . In the second case the contact continued for 25 minutes with actual f i g h t i n g taking up about 1 minute of that time. In t h e i r pacing the two birds became separated by a mound of earth and a small f i r tree. When t h i s occurred the o r i g i n a l i n t e n s i t y of the contact seemed to diminish, and one bi r d began to feed, r u f f l e d i t s feathers, began to preen and then walked into i t s t e r r i t o r y . I t seems l i k e l y that such f i g h t s ( i n which both males play an aggressive role) r e s u l t i n the formation of t e r r i t o r i a l boundaries. When the outcome of a f i g h t has been decided and the intruder or contestant repelled, there generally follows a rapid chase on foot or i n the a i r . The resident male, however, pursues the intruder only as f a r as what appears to be the edge of i t s t e r r i t o r y . Here i t stops or s e t t l e s to the ground. Usually the successful male then adopts what might be termed a v i c t o r stance, F i g . 16(b) i n which i t stands at f u l l height with neck upstretched, and head held i n the d i r e c t i o n taken by i t s opponent. This l a s t s a few seconds a f t e r which time the male begins to hoot. I t i s noteworthy that the song i s only given when the f i g h t i s over and the opponent out of sight. Thus hoot-ing at t h i s time may serve as a warning or indicate the proclam-ation of claimed area by the resident male. 51 Fa i l u r e to obtain observations i n l a t e March and early A p r i l leaves much to be desired f or by t h i s time males appeared to be established on t h e i r t e r r i t o r i e s and boundary disputes between adjacent males were not frequently observed. An apparent boundary dispute was observed between male No. 162 and male No. 281 on A p r i l the 1 4 t h at (15,G) i n F i g . 7- I t i s noteworthy that (15,G) i s on the l i n e drawn f o r the t e r r i t o r y of No. 162 based on i t s recorded hooting positions. S i m i l a r l y i n eight other f i g h t s observed i n A p r i l between adjacent males the disputes i n every case occurred on what was or became the boundary region between the two birds as indicated by hooting stations. Instances of trespassing are more common and are observed throughout the time of t e r r i t o r i a l a c t i v i t y . As an example male No. 132 (22,D) F i g . 7 was observed to f l y from (22,D) to ( 1 2 ,C). S i m i l a r l y male No. 9 flew from (1,D) to . (11,C) and male No. 126 of plot I Fi g . 6 flew from (20,Y) i n Fig . 6 to (12,B) i n F i g . 7 . In each case the males were i n pursuit of females and landed i n the t e r r i t o r y of male No. 1 6 2 . Immediate f i g h t posturing and rushes by male No. 162 repulsed the trespassers almost as soon as they alig h t e d . There i s d i r e c t and i n d i r e c t evidence to suggest f i g h t -ing between males may re s u l t i n the displacement of one. Male No. 132 was f i r s t observed hooting at (10,D) F i g . 7 on A p r i l 2 0 t h of 1 9 5 2 . A l l other males were established about No. 1 3 2 , as i n the f i g u r e , and a c t i v e l y hooting. On A p r i l 22 a f i g h t was 52 observed at (9,G) between male No. 132 and the male of t e r r i -tory (11,H), i n which No. 132 was defeated and chased to approximately (11 ,D). Thereafter No. 132 was recorded hooting on i t s t e r r i t o r y at (23,D) which i t had occupied i n 1 9 5 1 . On plot I, F i g . 6 a male was recorded hooting at po s i t i o n (5,N) i n A p r i l . At the same time a male was heard at (4,K). Subsequently but one male was heard and i n the (4,K) area. This b i r d did not use the o r i g i n a l hooting s t a t i o n of male (4,K). I t seems l i k e l y that the male of (5,N) had moved into the (4,K) t e r r i t o r y and forced the o r i g i n a l resident to places remote. Unfortunately at the time, neither b i r d was marked, a condition which leaves t h i s observation i n question. On plot I I F i g . 7 , a male was marked on A p r i l 1 4 t h , at p o s i t i o n (19,R). Later an unmarked male was captured which used t h i s area throughout the summer as i t s t e r r i t o r y . The marked male of A p r i l 1 4 t h had moved to pos i t i o n (22,J) and occupied t h i s area throughout the rest of the summer. I t would appear from t h i s that the captured male, possibly a l a t e r a r r i v a l , had usurped the p o s i t i o n of the marked male which then s e t t l e d i n a new area. Again t h i s observation i s open to question as the marked male was never recorded hooting i n the (19,R) area and may have been a vagrant at the time. I f hooting behaviour i n part might bring males into contact, f i g h t i n g appears to function as a mechanism by which l i m i t s or boundarys are established, between adjacent males once they have become l o c a l i z e d on an area and begin to hoot. 53 I t i s also a mechanism by which trespassing males are repulsed from an established male's t e r r i t o r y . ^ i ^ n y ^ f i g h t i n g may result i n the displacement of one male causing i t to move to areas remote. The courting a c t i v i t y of the adult male as a prelude to copulation can be considered the prime feature of i t s t e r r i -t o r i a l behaviour. Unlike vocal display, the courting display i s a combination of sound and body and plumage movement. A grouse landing with whirring wings on or near a male's p o s i t i o n usually i n i t i a t e s hooting, plumage and body display and causes the cock to move toward the sound. Females i n movement, when apparently seen by the cock are pursued to the l i m i t of the t e r r i t o r y and i f t h i s i s not an actual boundary, beyond. Such pursuits contribute then to the expanse of t e r r i t o r y . Should the female disappear i n the vegetation or beyond actual t e r r i -tory l i m i t s , the cock ceases pursuit and usually begins or continues hooting presumably to a t t r a c t the female. Should the female remain stationary within a male's t e r r i t o r y , hooting ceases and body and plumage display i s i n t e n s i f i e d as the cock moves towards i t . In f u l l courting display F i g . 17 the oesophagus i s i n f l a t e d which i n part activates the e r e c t i l e feathers of the neck. These open and reveal the thickened and rugose neck tissue which i n the spring and early summer i s an egg yolk yellow. The caruncle dorsal to the eye enlarges, r i s e s and becomes lemon yellow i n colour or sometimes a l i v i d red. The t a i l i s held Fig. 17 Courting display (After Laing) 54 erect and spread while the wings are extended v e n t r a l l y . The male's cloaca puckers and d i l a t e s as i t approaches the female. When 2 to 20 feet from the hen the male drops i t s wings to the ground, and with s t i f f legs and r u s t l i n g primaries, swoops towards her. This movement i s made i n a s l i g h t arc so that i t approaches the hen from one side. At the termination of the rush and almost touching the female i t dips i t s head and emits a loud "whoot" sounding note, a c a l l shorter and higher pitched than the phrases of the song. At times the c a l l i s i n s t a n t l y followed by a squeak or squeal which appears to be the i n s p i r a -t i o n a f t e r the courting note expiration. I f the female should jump, and move away the performance i s repeated. I f she remains, there begins an elaborate posturing with the cock standing motionless beside the female or thrusting one side of i t s i n f l a t e d neck and then the other at her while the body i s jerked upwards and forwards. This posturing may l a s t from 2 to 3 minutes. Gradually the male works behind and places h i s body and hanging wings over the crouching female u n t i l he touches her back. At t h i s point, which i s the closest to copulation that has been observed i n t h i s study, the female jumps forward and moves ra p i d l y away. Again the cock pursues her, or may i f other females are present on the t e r r i t o r y , turn to them. After unsuccessful attempts at copulation with one or several females, the male begins to hoot, s t i l l i n the courting display although now the wings are held to the body. He may mount a log or stump and hoot from here while between c a l l s 55 turning his head, apparently looking i n a l l d i r e c t i o n s . Fa i l u r e to observe actual copulation obscures the meaning of the f u l l courting display. L o g i c a l l y i t would serve as mechanism i d e n t i f y i n g a receptive male to a receptive female, whereupon copulatory movements would ensue. Cowan (personal communication) has observed a copulation i n which coitus occurred immediately a f t e r the males rush and "whoot" note. I t seems l i k e l y then, the r e l a t i v e l y long time observed i n displaying and posturing by the male i s a r e s u l t of an unreceptive condition of the female. On the other hand, the time spent by the male i n posturing would suggest that t h i s , as w e l l as the i n i t i a l phases of the display might function as a mechanism releasing the copulatory response i n a not f u l l y receptive hen. Males, while sexually active, court a l l hens of the species without regard f o r t h e i r age or breeding condition. Thus, whether non-laying, incubating, or with young, hens e l i c i t the same response from the cock. Trespassing cocks whether adult or yearling generally e l i c i t the i n i t i a l phase of the courting display i n which the t a i l i s held erect and spread, the neck i n f l a t e d and the neck feathers d i l a t e d . Hooting cocks frequently respond i n a s i m i l a r manner, when disturbed i n the f i e l d by an observer. Thus i n i t i a l response to the hen or trespassing cock might be considered of a general nature. The completion of the courting display or the change to f i g h t i n g posture might be considered a more s p e c i f i c response to an intruding grouse once i t s sex i s recognized. Since there i s no 56 apparent difference i n the posture of trespassing males as compared to females, i t i s suggested that sex recongition by the male i s based on plumage or size dimorphism or both. The "whoof or courting note i s c h a r a c t e r i s t i c of a male with female, and i s heard at no other time. Although the birds may be out of sight, the sound serves to reveal t h e i r p o s i t i o n as well as in d i c a t i n g when a cock and hen are together. The courting c a l l of a male with a hen appears to cause adjacent males to hoot more vigorously and draw as close to the courting male and female as t h e i r t e r r i t o r y l i m i t s w i l l permit. I t i s at t h i s time that the boundaries between males are most apparent. As an example of the courting c a l l ' s influence on an adjacent male, male ( 12 ,F) was heard with a female at t h i s p o s i t i o n i n Fig . 7 . From the f i g u r e , the point i s on or near the boundary between ( 1 2 ,F) and No. 1 6 2 . The male (12,F) was observed to stand i n f u l l display then turn and run into i t s t e r r i t o r y and begin to hoot. At the same time No. 162 apparently responding to the courting c a l l came running i n plumage and body display from deep i n i t s t e r r i t o r y and proceeded to locate and court the banded female l e f t by male ( 1 2 ,F). She evidently eluded him, or he ceased to follow, f o r he began to hoot at (13,G) the extreme upper edge of hi s t e r r i t o r y . As an example of the male's recognition of i t s t e r r i -t o r i a l boundary and that of another male, No. 162 was heard and seen with a banded female at position ( 14 ,E) i n F i g . 7 . Males 57 No. 281 and No. 132 were hooting at the time. Male No. 162 pursued the hen to (16,G) and then at t h i s position the boundary l i n e , turned back and began to hoot. The banded female continued i n the o r i g i n a l d i r e c t i o n . Near (16,G), male No. 281, the resident of t h i s t e r r i t o r y emerged from under a small f i r where i t had been vigorously hooting, began f u l l display and moved a f t e r the female. Male No. 162 remained hooting at the edge of i t s t e r r i t o r y , s i x t y feet from the banded female and male No. 281. In a s i m i l a r example, male (10,H) was vigorously courting a female on the road i n t h i s position. Sixty feet up from i t male (8,J) was s i t t i n g on a stump at the edge of the road i n plumage and body display. Male (9,1) courted and pursued the hen up the road to (8,1) where he stopped and began to hoot. At t h i s point (8,J) moved from the stump and began to court the female which (10,H) had moved into i t s t e r r i t o r y . Clearly these males recognized how f a r they might go or at least i n what area they retained superiority over t h e i r neighbour with respect to the use of area. This appears to be the purpose of the t e r r i t o r i a l behaviour of the male sooty grouse. The undisputed possession of area, wherein hooting and courting display can function to f u l f i l l i t s reproductive requirements. Thus the t e r r i t o r i e s can be considered mainly as areas of display and courting a c t i v i t y . 58 General A c t i v i t i e s of the Adult Male Most of the daylight hours of A p r i l and May are spent i n hooting so that the male i s l o c a l i z e d and occupied with t h i s a c t i v i t y . Observations on s i l e n t males i n and after t h i s time indicate they do not move f a r from t h e i r t e r r i t o r i e s while sexually active. Thus most or a l l the a n c i l l a r y a c t i v i t i e s of such males are carried out withi n the l i m i t s of these hooting areas. In reacting to an observer cocks as well as hens tend to crouch and "freeze" rather than take f l i g h t . When movement i s made i t i s usually on foot as a slow gait or run. Generally a bird must be s t a r t l e d or hard pressed before i t w i l l f l y ; a rapid beat of the wings and a long f l a t g l i d e r a r e l y more than 20 feet above the ground. The males feed but l i t t l e throughout the day. In l a t e evening there i s a feeding period, when they feed vigor-ously and f i l l t h e i r crops. Vegetable and available seem the only prerequisites f o r a food species, although i f present clovers are taken before other vegetation. From the vegetational analysis there appears to be no shortage of food on the t e r r i t o r i e s of males. This i s obvious from observation i n the f i e l d . No male was observed taking water or g r i t , although the l a t t e r was found i n the crop and gizzard of birds. The frequent occurrence of dust baths i n f i n e sand or r o t t i n g debris, and t h i s material i n feathers would suggest dusting as an a c t i v i t y of the male. Preening and scratching 59 the head region have twice been observed. Males have been frequently found s i t t i n g quietly under a shrub or l o g . This behaviour probably accounts f o r most of t h e i r time when not otherwise active. When roosts have been found they were on the ground and usually at hooting s i t e s . I t seems l i k e l y that unless feeding i n an exposed s i t e , the males cease a c t i v i t y and begin again wherever n i g h t f a l l and daybreak finds them. Seasonal Behaviour of the Adult Male The seasonal behaviour of the adult male can be i l l u s t r a t e d i n several ways. In terms of males recorded per hour per week of the study period as i n F i g . 28(a) there i s a marked trend i n the number of males observed. The observations i n almost every case were on hooting males. Thus from a peak of observed hooting a c t i v i t y i n the f i r s t weeks of the study the number observed per hour declines u n t i l by August they are r a r e l y observed on the study area. In terms of the i n d i v i d u a l males i n a study p l o t , t h e i r change i n behaviour i s related to the numbers observed holding t e r r i t o r y . In A p r i l and May both plot I and I I contained the greatest number of hooting males. On plot I I i n A p r i l , 18 hooting males were recorded, i n May, 16 i n June, 14 and i n July, 6. By the end of July but two males remained a c t i v e l y hooting i n the p l o t . In terms of the d a i l y behaviour of males, the change over the summer i s most s t r i k i n g . In A p r i l and May they are hooting almost constantly from t h e i r t e r r i t o r i e s and do not 60 move f a r from them when s i l e n t . By the end of June and i n July daytime hooting i s sporadic with general hooting heard only i n the morning and evening hours. By the end of July no hooting at a l l i s heard i n the daylight hours, and r a r e l y i n the mornings and evenings. As the males cease to hoot, they no longer remain l o c a l i z e d on t h e i r t e r r i t o r i e s but apparently begin to wander. Thus male No. 132 Fig . 7, l a s t recorded hooting at (21,D) was subsequently observed at (19,1) then at [15,Q) F i g . 6. One apparently wandering adult male was observed to make contact with a female and began to court and hoot. I t was captured but not seen again at t h i s s i t e although l a t e r observed twice at widely separated points on plot I I . Other males, and t h i s i s the usual case i n July and l a t e r , show no reaction to females. As an example male No. 147, F i g . 7 was observed at (12,F) on August 6th. Up u n t i l t h i s time i t had not been observed outside the l i m i t s of i t s t e r r i t o r y at (18,Q). The male was beside a f i r clump within which two females were s i t t i n g i n f u l l view, yet i t did not react to eit h e r . The cessation of hooting and abandonment of t e r r i -t o r i e s and sexual a c t i v i t y are l i k e l y preludes to the a l t i t u d i n a l migration of the cocks. From Fig. 28(a) and a consideration of the numbers of hooting males censused on plot I I from A p r i l to July above, the movement i s not sudden or rapid but apparently begins i n June so that by August males are ra r e l y seen on the study area. Cocks observed i n August have been alone and on 61 the ground. Their necks were t h i n , i n moult, and the caruncle of the eye scarcely v i s i b l e . Five males observed i n t h i s month were off t h e i r t e r r i t o r i e s and three that were banded had moved i n a d i r e c t i o n suggesting a return to the winter range. In searching an underlying mechanism for the seasonal behaviour of the adult male i t i s noteworthy how the decreasing testes volumes of males measured i n each week of the study period, correspond to the events described. F i g . 18 i s a plot of t e s t i s volume of 51 adult males and 5 yearling males against weeks of the study period. The average adult t e s t i s volume of each weeks sample i s plotted f o r each week to produce the curve. The s i m i l a r i t y of the curve i n F i g . 18 to the curves of F i g . 28(a) i s s t r i k i n g . Thus while the a c t i v i t i e s of the male are determined i n part by external f a c t o r s , i t i s l i k e l y the inte r n a l sex physiology as measured here by t e s t i s volume, sets the stage upon which external factors play t h e i r r o l e . The Behaviour of the Yearling Male While over 300 adult males have been observed hooting on t h e i r t e r r i t o r i e s i n the study area but 1 yearling male was so recorded i n the same time. This b i r d and nine others make up the t o t a l number of yearling males observed over the years 1951 to 1953. Of the ten, two were captured on the study plots i n various positions i n A p r i l and May. One yearling male was observed with a female and both moved together. No sexual display was noted i n the male. Of the 2 banded yearlings, one o u S 3 </> V to tt) 0) E 2 3 o > • Volume of adult male testes o Volume of yearling male testes Average volume, yearlings excluded J I i i 5 6 7 8 9 10 Week of summer 14 Fig. 18. Testes volume in c.c. and week of summer 62 was seen twice again i n positions on and o f f plot l l 1,000 feet apart. Thus i t was not apparently l o c a l i z e d to a p a r t i -cular region. The second y e a r l i n g captured was banded i n the t e r r i t o r y of a male at (5,0) F i g . 6 i n 1951. The bi r d was not seen again u n t i l 1953 when i t was located as an adult male hooting on a t e r r i t o r y 600 feet from the point of capture. The observations obtained on yearling males are s i m i l a r to those of adult males a f t e r they have ceased t h e i r t e r r i t o r y holding a c t i v i t i e s ; vocal silence, apparent wandering and no reaction to females. The one yearling male recorded hooting was an exception to t h i s and had evidently attained adult sexual development i n i t s f i r s t year. Another yearling was observed to court and hoot a female which landed and fed on the t e r r i t o r y of male No. 9 F i g . 7. When the hen l e f t the area, the yearling followed and both disappeared. I t was not observed again. Thus with the exception of one hooting yearling and another which was observed i n courting display, yearling males observed on the study area do not manifest the sexual and t e r r i t o r i a l behaviour as found i n the adults. Correlated, and serving to i l l u s t r a t e a rel a t i o n s h i p between adult male behaviour and sexual development, the testes volumes of 5 year-l i n g males have i n each case been less than the testes volumes of adult males measured i n the same week, F i g . 18. 6 3 Spring Migration i n the Yearling Male Generally, the yearling males behave as females p r i o r to hatching time, and are found under the same conditions. In the spring, however, when t h e i r behaviour i s comparable, yearling hens are frequently observed, while yearling cocks but ra r e l y . Thus the small number of yearlings recorded on the summer range i s apparently r e a l , and not caused by t h e i r going unobserved. I t seems u n l i k e l y t h i s i s the true number of yearling cocks i n the population for there i s no apparent reason why the year-l i n g males should die or move out of the study area at a fa s t e r rate than the yearling females to produce the observed d i s p a r i t y i n spring sex r a t i o . The simplest explanation i s that they are not with the summer population of females and adult males but i n places remote, l i k e l y the winter range on the mountain slopes. Wing ( 1 9 4 3 ) has made reference to the "big males" and absence of females observed on the winter range i n the summer. He suggests they are mature males but non-breeders. Beer (personal communication and f i e l d notes) states that while c o l l e c t i n g i n Washington near Lone Frank Pass i n la t e June at 4 , 5 0 0 feet and above, he and his companions observed 5 0 blue grouse and a l l males. Ten birds were collected and each was sexually undeveloped with respect to testes size and neck condition. Beer recognized the p o s s i b i l i t y that the birds were breeding males of the spring which had returned i n June to the winter range, or old males beyond reproductive age that had f a i l e d to make the spring descent. From the l i g h t colour of the plumage and soft texture of the neck tissues, however, Beer 64 concluded the ten birds sampled were a l l immature males hatched i n the preceding year. In t h i s study they are ca l l e d yearling males. These data from the winter range i n summer, coupled with the observations made i n the study area indicate that the observed absence of yearling males from the breeding range i s caused by t h e i r f a i l u r e to make a downward migration i n the spring a f t e r hatch. Thus most males leaving the summer range as chicks do not make the downward migration u n t i l t h e i r second spring a f t e r hatch, and by t h i s time, i n adult plumage. From t h i s , and the absence of t e r r i t o r i a l and sexual behaviour the yearling males observed on the study area, i t i s l i k e l y the spring migration, as well as sexual and t e r r i t o r i a l behaviour i n the male i s related to sexual development. Spring Behaviour of the Female Although Anthony (1903) suggests the females arrive on the summer range l a t e r than the cocks, there i s no corrobor-ative evidence from t h i s study. As i n the case of the males, by the e a r l i e s t date of f i e l d i n v e s t i g a t i o n , both sexes appeared to be established on the summer range. Although more yearl i n g hens make the descent than yearling cocks, there exists the p o s s i b i l i t y that they too remain i n numbers on the winter range over the f i r s t year. The reported absence of females on the winter range i n summer, the breeding behaviour of the yearling hens which resembles that of 65 the adults, and the apparently f u l l numerical contribution of yearling females to the population on the study area suggests, however, the yearling females descend to the lowlands i n t h e i r f i r s t spring a f t e r hatch. P r i o r to hatching of the young and between early morning and l a t e evening which are times of intense a c t i v i t y , the observation of hens i n the f i e l d i s lar g e l y a matter of chance. Unlike the hooting cocks, the hens make no sound or display to reveal t h e i r positions. They are usually observed singly and s i t t i n g under a shrub or log. At times two hens are seen together and t h i s most often i n the spring months. On one occasion as noted above, a yearling male was observed with a hen. These observations might indicate some tendency i n the hens to make the downward descent together, or a more in t e r e s t i n g s i t u a -t i o n wherein yearling males and females remain with the mother female overwinter and descend with her i n the spring. Such a condition might i n part explain the migration of the few sexually undeveloped yearling males observed i n the study area. Too few data are available to make these suggestions anything but specula' t i v e . In the case of hens together i t i s necessary to c o l l e c t both to make accurate age i d e n t i f i c a t i o n . This has never been done. Unlike the cocks the adult and yearling hens do not occupy and defend t e r r i t o r y on the summer range. From f i e l d observations females move over r e l a t i v e l y large areas p r i o r to incubation and hatch. F i g . 19 i s a map of the observed positions 0 1 2 3 4 5 6 7 8 9 10 II 12 13 14 15 16 17 18 19 20 21 22 23 ]_9 ! PREHATCH DISTRIBUTION OF SEVEN FEMALES AS RELATED TO NESTS AND MALE TERRITORIES PLOT n No 125 • .No 15 ® No 285 • " 350 Q " 164 © " 34 a •• 292 O 66 of marked females without young on plot I I i n A p r i l and May of 1 9 5 2 . largest observed range was that of female No. 125. I t was noted over approximately 20 acres, including area o f f the p l o t . From the distances between observations on other hens i n the same f i g u r e , i t seems l i k e l y that movements of t h i s extent are not unusual. This r e l a t i v e l y large range of the female makes i n t e r -pretation d i f f i c u l t . Marked hens are observed frequently enough to suggest they are resident, or become l o c a l i z e d on an area p r i o r to la y i n g and incubating eggs. Females No. 1 2 5 , No. 3 4 and No. 15 were not observed with young at any time yet were observed on or near plot I I throughout the summer as apparent residents. Again, any tendency f o r surviving females to return to the same area i n subsequent years i s obscured by t h e i r r e l a t i v e l y large movements. Thus f a i l u r e to observe a hen banded the preceding year does not necessarily indicate death or the abandonment of the area i n which i t was banded. Five hens marked p r i o r to the hatch on plot I I i n 1950 were observed on the plot i n 1951. Three of- these hens and 5 banded i n 1951 were observed on the plot i n 1952. This suggests that as with cocks, the hens return to the same area i n subsequent years. Unlike the cocks, the hens then move independently over a r e l a t i v e l y large area which might be ca l l e d a home range. What factors r e s u l t i n the movements of hens p r i o r to incubation i s largely a matter of speculation. As i n the males the requirements f o r general a c t i v i t i e s such as feeding, dusting, 67 preening and positions i n which to s i t probably account f o r some of them. On the study area, from F i g . 1 4 , hens i n plot I show a tendency to u t i l i z e Willow Dense and Willow Open shelter types while the greatest u t i l i z a t i o n i s of Clover Open food type, that i s to say, the roads and small clover f i l l e d c lear-ings. On plot I I from the same f i g u r e , F i r Dense and Willow Dense types are u t i l i z e d most, with Clover Open, as on plot I, frequently used. From t h i s i t would seem factors influencing the d i s t r i b u t i o n of females p r i o r to incubation were i n part concealment found i n shelter vegetation, and preferred food found i n Clover Open type. The u t i l i z a t i o n of the open types i s most pronounced i n the early morning and l a t e evening, when the hens move a c t i v e l y to raads and other open areas and feed. Three observations have been made on hens i n or near standing water. Once a diving beetle (dytiscidae) was observed i n the crop of a collected hen. Other than t h i s , there i s no evidence from t h i s study that free water i s important i n the existence of the female. I t seems l o g i c a l to believe that the hen when gravid with eggs should under concommitant physiological stimulus respond to the hooting of a male or males and seek them out. I t i s note-worthy that the home range positions, as observed i n hens, p r i o r to being observed with young, are i n no way related to a p a r t i -cular male's t e r r i t o r y , F i g . 1 9 , S u ch females appear to move f r e e l y about and i n so doing l i k e l y come into contact with as 68 many males as t h e i r home range includes. With the lack of other data on the mating behaviour of the female and from the courting reaction of the cock while i n breeding condition i t i s l i k e l y that sooty grouse of both sexes are promiscuous of breeding habit. Nesting Behaviour of the Female The description of nesting behaviour i s based l a r g e l y on the autopsy of 22 hens. At leas t f i v e were taken each week of the period May 4th to June 1st. These data are supported by information from hens captured, examined and palpated i n the f i e l d . Two hens collected i n l a t e A p r i l had undeveloped ovaries with no apparent ova, the oviduct was s i m i l a r l y i n a c t i v e . By the f i r s t week i n May, ova were apparent i n numbers from 3 to 5 i n the hens sampled with the oviduct thickened and enlarged. By the second week i n May, the f i r s t shed ovarian f o l l i c l e s were observed i n d i c a t i n g the hens had begun to deposit eggs. Two hens captured i n the f i e l d i n t h i s time had palpable eggs i n t h e i r oviducts. In the t h i r d week of May maturing ova were s t i l l v i s i b l e with the shed f o l l i c l e counts increasing. At t h i s time hens were f i r s t observed with a developing brood patch. By the end of May a l l production of ova had ceased, and counts of shed f o l l i c l e s had reached a maximum. Birds taken a f t e r t h i s time had complete brood patches. From t h i s i t appears" that the production of ova begins 69 i n l a t e A p r i l and early May and continues while the eggs are l a i d from the second to l a s t week of May. The brood patch i s i n c i p i e n t as the eggs are deposited and becomes f u l l y developed at the cessation of laying a c t i v i t y and the beginning of incubation. The brood patch i s an area between the legs from the base of the furcula to a centimeter anterior to the vent, devoid of contour feathers and with the s k i n thickened and vascularized. This i s evidently an adaptation providing greater warmth to the eggs from incubating hens. One hundred nesting hens and hens with broods examined showed a w e l l formed brood patch, thus i t serves as an indicator of incubating or breeding a c t i v i t y . The r a p i d i t y with which the ovary shrinks af t e r the brood patch i s formed i s worthy of note. In a l l hens sampled, once the brood patch was developed, ovarian a c t i v i t y had ceased and the ovary returned to non-breeding s i z e . This would suggest that once incubation had begun a destroyed clutch would not be replaced. The number of eggs l a i d i s an important s t a t i s t i c that i s d i f f i c u l t to obtain because of the concealed nature of nests. As a best estimate of egg production the few data from nests are supported by counts of shed f o l l i c l e s and ripening ova i n hens shot during the nesting season. A shed f o l l i c l e or a r i p e ovum does not necessarily mean an egg has been or w i l l be deposited i n a nest. This, however, i s not considered an important source 70 of error. °ix nests of adult hens discovered i n the study area, averaged 6 eggs per nest with a range of 5 to 7. Nests of year-l i n g hens have not been found, although hens of t h i s age class have been observed with brood patches and with young. 'On the basis of ripe ova and shed f o l l i c l e counts 9 yearling hens collected i n May produced an average clutch of 4 eggs. Thirteen adult hens collected i n the same period and examined i n a si m i l a r manner produced an average clutch of 5 eggs. There i s no s t a t i s t i c a l l y s i g n i f i c a n t difference (by " t " test) between these two averages which suggests on the basis of ri p e ova and shed f o l l i c l e counts the productivity of nesting adult and yearling hens i s s i m i l a r . With t h i s , and the data from s i x nests, the average clutch s i z e l a i d by nesting hens i n the study area appears to be 6 eggs or possibly lower. This figure agrees with the l i t e r a t u r e , Fowle (1943), Bent (1932) and others. There are few data from t h i s study which might be c l a s s i f i e d as laying behaviour i n the female. Most observations on the hens i n daylight hours f i n d them s i t t i n g under logs or trees, not unlike t h e i r behaviour at a nesting s i t e . On May 20th of 1952 a nest was located at the base of a f i r at (13,M) F i g . 19. I t held 5 eggs which were cold and r a i n wetted. The eggs were covered with debris and almost completely covered by lower branches of the f i r . The nest was a shallow depression i n dead Pte r i s stems and Gaultheria leaves which were not used i n a 71 constructive manner. No female was observed i n the v i c i n i t y -then, nor on the second day when the nest was v i s i t e d . On May 22nd the female was on the nest, and again when v i s i t e d on the 2 3 r d . On the 2 4 t h the hen was observed feeding at 0345 hours at (10,C) F i g . 1 9 . The nest was inspected and contained 6 warm eggs. Thus i n the i n t e r v a l of four days she had l a i d one egg, the s i x t h and l a s t , f o r from t h i s time on incubation was i n progress. I t i s noteworthy that the female was not observed on the nest u n t i l incubation had begun and probably moved over i t s home range u n t i l l o c a l i z e d by laying and incubating a c t i v i t i e s . The absence of the hen from the nest at 0345 hours i s also worthy of note, f o r t h i s time i s within the morning a c t i v i t y period and w i l l be mentioned again below. When incubation i s i n progress, t h i s nest, as others observed, became more bowl shaped, approximately 6 inches i n diameter and 2 to 3 inches i n depth below the rim. The arrange-ment of debris as well as the presence of feathers i n the nest suggested some construction. The feathers are probably those shed or plucked from the hen's ventral surface i n the formation of the brood patch. One of the s t r i k i n g features of the nesting behaviour of the female sooty grouse i s the selection of open vegetation for the nest s i t e , Fig. 1 4 . Of the shelter types i n plots I and I I , Log Open and Bracken Open were the most frequently u t i l i z e d . 72 Nests were not found i n the dense shelter types, although intensive search was made i n these areas to discover them. In the open types, the nests are usually covered by logs, f i r branches or shrubs, F i g . 20(a) and (b). This cover i s completed by the body of the incubating female. The nests found i n plot I and plot I I over the 3 year study period were mapped to determine t h e i r r e l a tionship to the t e r r i t o r i e s of hooting males. This i s i l l u s t r a t e d i n Figs. 11 and 12. Some nests are within the t e r r i t o r y of a hooting male and some are without, there i s no apparent r e l a t i o n s h i p . More-over, the nesting behaviour of hens i s not apparently influenced by the males except as she might make contact with them i n her movements to and from the nest. Thus with the exception of copul-ation and i t s preliminaries the two sexes are independent of one another on the breeding range. The description of incubation behaviour i s based on v i s i t s to, and $ hours of observation on, 3 nests i n plot I I . Time spent at nests did not include a l l hours of the day, there-fore, the data are fragmentary. Further, the almost complete concealment of hens on nests made observation d i f f i c u l t . The eggs- i n the three nests were marked with pencil and t h e i r positions noted. On subsequent v i s i t s they had been rearranged and turned i n the nest, presumably by the hen. Whether t h i s i s by accident or design i s a question. In 34 nest v i s i t s i n daylight hours the females were observed o f f nest 6 times, thus most of the daylight hours are spent incubating. One nesting female observed from a hide i n 73 the day, was never recorded f a r or long from her nest. She would c i r c l e the nest at approximately 30 feet, feed and dust. Three such s a l l i e s were recorded, each l a s t i n g ten minutes. One was at 1100 hours, the other two at 1430 and 1500. The absence of droppings about nesting s i t e s suggests l i t t l e use of the immediate area of the nest. On the other hand, droppings may not be voided i n the precincts. In 15 nest v i s i t s during early morning and l a t e evening periods of a c t i v i t y , females were recorded o f f nest 9 times. This r e s u l t i s supported by the number of females with brood patches noted along the roads and i n the open types during these periods. When observing two hens at the nest, both were observed to make evening f l i g h t s . In. the case of one, she emitted soft quavering notes, then suddenly moved and took f l i g h t from the nest at (11,0) F i g . 19. She returned i n 14 minutes from same d i r e c t i o n towards the nearest road i n which she had flown. On a r r i v i n g she landed with s i l e n t wings w i t h i n a foot of the . nest and immediately disappeared into the surrounding vegetation. Another hen was observed to land s i l e n t l y w i t h i n 20 feet of her nest at the completion of a morning and an evening f l i g h t . The silence of f l i g h t i s noteworthy for i t has already been noted above that the whirring of wings i s s u f f i c i e n t to begin the courting display of the male and cause i t to move toward the sound. Thus landing with or without sound might function as a mechanism f o r the a t t r a c t i o n of the cock or the concealment from i t . i 74 In the p o s i t i o n of an observer on a road or i n a clearing of the study area the commencement of the evening and morning a c t i v i t y i s marked by the sound of wings i n f l i g h t and the c a l l s of the male and female. While i n f l i g h t , or taking of f during the a c t i v i t y periods, hens have been heard to emit a qua qua quaaaa sounding c a l l . From watching hens i n f l i g h t , movements of 5 0 0 feet are not uncommon. Hen No. 125, F i g . 19 was recorded i n 1951 at distances of 200 to 5Q0 feet from i t s nest located over the Quinsam River. She was observed feeding at (12,B), (13,M) and (10,B) on plot I I . Hen No. I 6 4 nesting at (11,0) was observed on the road at (8,J), while hen No. 285 with nest at (14,M) was observed at (16,K) and (10,D) i n the same figu r e . As many as three banded hens have been observed i n one evening i n a p a r t i c u l a r area of Clover Open or Bracken Open with one or none observed the next. Again as many as 9 hens have been observed over a p a r t i c u l a r section of road i n the evening a c t i v i t y period, with but one observed i n the same area i n the morning period. Thus i t does not seem l i k e l y that the same distance or d i r e c t i o n i s taken by the hen each time a f l i g h t or ground movement from the nest i s made. After a r r i v i n g at the roads or open areas by f l i g h t or walking, the hens begin to feed and move about completely exposed. As i n the case of the males almost everything vegetable i s consumed although Trifolium^Medicago and Hypochaeris are selected when present. The foraging of hens i s often interrupted by the 7 5 courting a c t i v i t y of the cocks p a r t i c u l a r l y i f the feeding area i s on the t e r r i t o r y of a sexually active male. Within a hal f hour a l l a c t i v i t y ceases as the hens move back to t h e i r nests or darkness f a l l s . While feeding or upon a r r i v i n g i n open areas hens have been observed to preen, dust, chase one another and defecate. In dusting the hen usually pushes her bare ventral surface into earth or gravel i n one or two quick motions and continues feed-ing. On one occasion antagonism was noted between hens feeding i n an open area. One, a banded hen, p e r s i s t e n t l y chased a second which appeared with her on two consecutive mornings. Perhaps t h i s i s a means by which a female separates i t s e l f from previous years young s t i l l i n consort. At a l l other times hens moved and fed independently of t h e i r fellows. Grouse scats are frequently found on the study area and can be recognized as single, caecal and clocker droppings, Fig. 2 1 . The clocker dropping i s up to ten times the size of a single scat and wound as the c o i l s of an elongated spring. Four incubating hens have been observed to deposit a clocker dropping upon a l i g h t i n g i n open areas during morning or evening a c t i v i t y . The Committee on the Enquiry into the Grouse Disease ( 1 9 1 1 ) mentions the clocker as a dropping voided by incubating hens. With the above evidence and from common poultry knowledge, the dropping when found, can be used as an i n d i c a t i o n of the presence of an incubating hen. In F i g . 1 4 , clocker droppings have been c l a s s i f i e d as F i g . 24(b) Defence display of female Fi g . 24(c) Defence display of female 76 to vegetational type. This i n turn r e f l e c t s the u t i l i z a t i o n of these types by incubating hens. The droppings are con-centrated i n the open cover types with the greatest number i n Clover Open. This i l l u s t r a t e s the r e l a t i v e importance of these areas as feeding grounds and suggests also that defecation does not take place u n t i l the feeding ground i s reached. In nesting and feeding during incubation, the hens u t i l i z e the open types to the almost complete exclusion of dense vegetation. Periods of intense morning and evening a c t i v i t y were observed from the e a r l i e s t date of f i e l d observation, before and aft e r the period of incubation. Non-breeding yearling hens and hens with brood patches but never observed with broods, p a r t i c i -pated i n the a c t i v i t y . Thus the morning and evening movements or f l i g h t s are apparently made by incubating and non-incubating hens. As hatching occurs, however, the number of females observed along roads and i n open types diminishes u n t i l by the middle or end of June i t i s unusual to observe or hear a hen engaged i n morning and evening feeding a c t i v i t y . The Diurnal A c t i v i t y Rhythm To i l l u s t r a t e the diurnal a c t i v i t y rhythm of male and female grouse two periods of f i e l d study were selected, A p r i l 13 to May 15th and May 16 to June 5th. In these periods a l l sights and sounds of grouse were recorded i n sample half hours between 0300 to 2400 standard time, as the observer moved over the study pl o t s . The number of grouse observations were then expressed as per h a l f hour of the 0300 to 2400 day i n the two periods. 77 Sight, i s the observation of birds i n f l i g h t or on the ground, while sound refers to the number of males heard hoot-ing, beat of wings, sound of f i g h t s , c a l l s of females, or the peculiar "whoot" note given when a male i s courting a female. The result s of t h i s a c t i v i t y analysis are presented graphically i n F i g . 2 2 from Table VI appended. In both periods the two a c t i v i t y peaks of each day, which correspond to the morning and evening hours of 0 3 0 0 to 0 5 0 0 and 1 9 0 0 to 2 2 0 0 , are obvious. The greatest part of t h i s a c t i v i t y i s as a re s u l t of the females appearing and foraging on or near the t e r r i t o r i e s of males and subsequently being courted by them. Thus the large contribution of males with females to the a c t i v i t y columns. However, hooting i s more general at t h i s time and i n part explains the peaks. From 0 5 0 0 to 1 9 0 0 or 2 0 0 0 there i s a lesser but steady hooting a c t i v i t y over the study area with the sound of males with females often heard, although les s frequently than i n the morning or evening hours. . In comparing the two periods i t w i l l be observed that a c t i v i t y begins l a t e r i n the morning and ends e a r l i e r i n the evening i n period A p r i l 1 3 to May 5 . The morning and evening peaks are shifted accordingly. Some of the precision with which a c t i v i t y begins and r i s e s to a peak i s l o s t i n using the r e l a t i v e -l y large number of days i n each period. While the peaks of a c t i v i t y appear to occur over two hours of the morning or even-ing i n the figure i n any given day they l a s t but 1 0 to 3 0 minutes. Again, i n the middle of A p r i l , morning a c t i v i t y begins with the 10 12 14 16 18 20 22 24 Hours Fig. 22 from Table 21. Grouse activity and time of day in the periods April 13 to May 15, May 16 to June 23. 78 peak between 0430 and 0500 and the evening peak between 1900 and 1 9 3 0 . In l a t e June a c t i v i t y begins with the morning peak between 0300 and 0330 and the evening peak between 2130 to 2 2 0 0 . In the evenings a c t i v i t y quickly subsides af t e r the short period of f l y i n g , feeding, courting and vigorous hooting so that the area i s s i l e n t u n t i l the morning hours. In each of the two periods the morning peak shows the least spread i n time, which would suggest i t was of shorter duration, or intense a c t i v i t y lasted longer i n the evening. From f i e l d observation t h i s appears to be the case. In the f i e l d one can predict the beginning of evening a c t i v i t y i n any given day from the measurement of l i g h t i n t e n s i t y . A General E l e c t r i c type DW-68 exposure meter was used to measure l i g h t i n foot candles, and i n so doing, held d i r e c t l y into the open sky. Light i n t e n s i t y , according to time of day, f a l l s i n a c h a r a c t e r i s t i c manner, with a rapid and steep drop at sunset which gradually f l a t t e n s out to produce a negative exponential curve, with a long t a i l . The reverse i s true at sunrise. The curve i s nearly asymptotic at the i n t e n s i t y of 2 foot candles and t h i s slowly drops to 1 , the lowest l i g h t value measureable, over a period of 15 minutes to half an hour depending on atmospheric conditions. Each day at 4 to 2 foot candles evening a c t i v i t y begins, and continues past 0 foot candles on the l i g h t meter. The cessa-t i o n of evening a c t i v i t y i s not as precise and occurs as hens 79 move from on or near the t e r r i t o r i e s of males. Hooting continues, becomes sporadic and then ceases at darkness wel l beyond 0 l i g h t i n t e n s i t y as recorded on the exposure meter. In the morning hours a c t i v i t y begins before there i s a reading on the l i g h t meter and continues u n t i l 2 to 4 foot candles a f t e r which the sights and sounds of morning a c t i v i t y r a p i d l y cease. Most of peak a c t i v i t y i s a t t r i b u t a b l e to the females i n t h e i r morning and evening movements. When t h i s behaviour ceases i n l a t e June and July, however, the cocks s t i l l conform to the d a i l y rhythm with peak hooting a c t i v i t y i n the morning and evening hours, although they may remain s i l e n t throughout the day. This continues as long as they hold t e r r i t o r y . The precision with which the a c t i v i t y peaks occur, t h e i r timing with respect to hour of day, t h e i r tendency to become e a r l i e r and l a t e r as the season progresses and the predictable nature of the evening a c t i v i t y at 2 to 4 foot candles suggests that a changing l i g h t i n t e n s i t y or low l i g h t i n t e n s i t y are factors influencing t h i s phenomenon. Since morn-ing a c t i v i t y ends and evening a c t i v i t y begins at 2 to 4 foot candles i t would appear that low l i g h t i n t e n s i t y was important. In the hens, low l i g h t l e v e l s would o f f e r a compromise between s u f f i c i e n t i l l u m i n a t i o n f o r e f f i c i e n t a c t i v i t y , yet not enough to make t h e i r movements i n open vegetation dangerous. The cocks are apparently influenced by s i m i l a r l i g h t l e v e l s , independent of the behaviour of hens, which i n spring serves to in t e n s i f y t h e i r a c t i v i t y . 80 ' Time of Incubation and Hatch In the case of two recorded nests the hatching dates were June 7 t h and June 1 6 t h . The period of incubation was recorded for but one nest. For t h i s i t was 24 - 25 days. According to Bent (1932) 18 to 24 days have been recorded as the incubation period. rp xo f i n d the week of peak hatch, the number of week old broods observed per.hour per week i n the f i e l d were plotted against weeks 6 to 16 i n 1 9 5 0 , 1951 and 1 9 5 2 . At one week of age the s i z e , plumage and behaviour of the chick are character-i s t i c and can be used as aging c r i t e r i a . After one week and l a t e r , no absolute scale to accurately age sooty grouse chicks e x i s t s . A t o t a l of 40 week old broods were observed; 8 i n 1 9 5 0 , 15 i n 1951 and 17 i n 1 9 5 2 . The results of t h i s analysis are presented graphically i n F i g . 23 from Table VII appended. Time of hatch appears to be spread over the same number of weeks i n each year's sample, with no apparent s h i f t i n time of peak hatch. Thus the observed differences i n weather of the three years did not apparently aff e c t time of peak hatch. Each year, p a r t i c u l a r l y i n 1 9 5 2 , r e l a t i v e l y l a t e hatches have been observed i n week 13 and 1 4 , i . e . the second and t h i r d week of July. This may indicate clutch destruction p r i o r to incubation and subsequent relaying. Over the three years, from F i g . 2 3 , 8 0 $ of the week old broods observed per hour have hatched i n the weeks 9 , 10 and 1 1 , or June 8 t h to June 2 8 t h . Week 10 or June 15 to June 21 i s taken as the week of peak hatch. Then i n aging chicks on the Week of study Fig. 23 from Table 3ZLT. Number of week old birds observed per hour for week 6 t h to I6,h, 1950, 1951,1952. 81 basis of weeks of age from week 10, 80$ of the time t h e i r actual age should be within plus or minus 1 week of that period. Behaviour of the Female and Brood With the completion of incubation and hatch a s t r i k -ing change occurs i n the behaviour of the female as she becomes the centre of brood organization. Generally a female with young i s observed i n the open, crouched on some prominence such as a log or stump while the chicks move and feed about her. Observa-tions on broods of week old young suggest that i n the early stages of chick development the female remains on the ground, presumably i n a better position to brood. The chicks at t h i s age are never found f a r from the female, distances of ten feet are unusual. They are unable to f l y and when disturbed scatter i n d i f f e r e n t directions over the ground. Some remain motionless af t e r a short movement, others t r a v e l as f a r as t h i r t y f eet. I f a log or other shelter i s near they w i l l u t i l i z e t h i s , pressing themselves f l a t i n or under the object. I t i s i n the f i r s t week of brood l i f e that the defence display of the female i s f i r s t observed. I t i s also most vigorous at t h i s time. Upon discovery of a brood, and often before the observer r e a l i z e s there i s a brood i n the v i c i n i t y the female rushes at the intruder with erected neck feathers, dragging wings and fanned t a i l , F i g . 2 4 (a)(b)(c). The rush i s invariably accompanied by a loud hissing sound and hard clucking. I f further i n t r u s i v e movement i s not made, the attacks cease and the hen 82 r e t i r e s to a distance of ten to f i f t y feet and s i t s a l e r t upon a prominence. In the i n t e r v a l the chicks have usually vanished. I f a chick i s captured or attempts are made at capture, the attacks of the hen mount i n violence, and often she w i l l beat her wings about the i n t r u d e r 1 s head i n rushes from the ground or nearby stump. Twice hens have been caught by hand as they closed with the observer. The chicks when captured have a d i s t i n c t i v e " d i s t r e s s " c a l l or signal which might be expressed as a s h r i l l peeeeeeer. I t r i s e s i n i n f l e c t i o n and i s repeated frequently. This again e l i c i t s a violent response from the female which rushes at the source of sound. Often adjacent females with broods w i l l respond to t h i s c a l l and f l y two or three hundred feet to j o i n i n the general confusion. At two to three weeks of age the young have begun to develop f l i g h t feathers and can f l y twenty feet or more. At t h i s stage they are found farther from the female which by now i s usually observed crouched upon a stump or l o g . Upon disturbance the hen clucks what i s apparently a "warning" note for at i t s sound the active chicks cease movement and a l l appear aler t e d . At close contact with an observer the hen or a chick w i l l f l u s h , whereupon the majority of the brood takes wing. In f l u s h i n g , the hen invariably clucks the "warning" signal and r e t i r e s f i f t y to several hundred feet. The chicks f l y i n a l l d i r e c t i o n s , do not hide, but land i n trees and on stumps at varying distances from the point of disturbance. Upon capture of a chick the " d i s t r e s s " c a l l ensues with the rapid return and defence reaction of the female. 83 As i n younger birds, there folloxvs a period of silence varying from 5 to 15 minutes. Afte r t h i s time the f i r s t chick i s heard to c a l l . The signal i s not unlike the " d i s t r e s s " note but with a d i f f e r e n t i n f l e c t i o n . I t might be expressed as peeerwee, which i s repeated again and again. With t h i s s i g n a l , the female either utters the "warning" signals or begins a d i s t i n c t i v e chatter which might be termed the "come i n c a l l " . Generally, the presence of an observer i s related to the "warning note", and with i t s sound the c a l l i n g of chicks or chick i s immediately silenced. I f the "warning note" i s not given the c a l l -ing of the chicks increases i n frequency and volume as several begin s i g n a l l i n g . The note seems to regroup the young f o r they begin to move together over the ground and through the a i r . One chick observed at 300 feet from the o r i g i n a l point of fl u s h i n g was observed to drop from a tree i n which i t was perched and move toward a c a l l i n g chick as soon as i t began to s i g n a l . I f the female takes no part i n the organization at t h i s time, the chicks eventually regroup and c a l l together from a log or prominence. Usually, at the f i r s t chick s i g n a l , i f the sharp "warning" cluck i s not given, the hen begins a "come i n c a l l " a series of chattering, caterwauling phrases which sounds as 'queeeeer tau tau tau! I t i s not unlike the sound of a wire clothesline being rotated around i t s spools. With t h i s , the chicks move towards the hen i n her new s i t e or at the old , and as they approach her, and the brood reorganizes, t h e i r c a l l i n g s cease. 84 In observing undisturbed broods i n the f i e l d , other sounds from hen and chicks have been recorded that remain larg e l y a mystery. They probably contribute to the organiza-t i o n of the brood and i t s movements. Observations i n the f i e l d indicate that the hen feeds l i t t l e i n daylight hours but takes some food i n the evening. Feeding i n addition to s i t t i n g , dust bathing and preening appear to constitute her d a i l y a c t i v i t i e s . The chicks on the other hand are voracious feeders and are most frequently observed taking food i n one end and passing the residue out the other. The young were observed to feed on plants and animals l i s t e d as food items by Fowle (1944), Beer (1947) and others. Invertebrates of a l l kinds are consumed as we l l as succulent f r u i t s and smaller vegetation, such as Trifolium flowers' and leaves and Gaultheria flowers. In f i v e observations on roosting young, they were on the ground and under the hen. This might have been expected i n these cases f o r the broods were from 1 to 2 weeks old. I t seems l i k e l y that as the young are fledged brooding becomes unnecessary and thus the roosting habits might change. Generally, the broods appear to remain intact through-out the f i r s t f i v e weeks of chick l i f e , although observations on two or three hens and t h e i r young i n close proximity are often made. In two cases s o l i t a r y hens have been observed with chicks of markedly d i f f e r e n t sizes i n t h e i r broods, an i n d i c a t i o n that s h u f f l i n g or at least chick adoption occurs during t h i s time. 85 By the end of July or at approximately eight weeks of age the chicks have well developed, i f not f u l l grown, r e t r i c e s and wing feathers and are strong i n f l i g h t . They forage on a l l types of vegetation u t i l i z e d by the adults, although unlike them, invertebrates are s t i l l taken. The clear high pitched c a l l s of the young appear now to be lowered i n tone and are often garbled into a clucking sound. The female exhibits l i t t l e of her former defence reaction when disturbed and usually flushes with the young. She s t i l l remains on stumps and logs throughout the day as apparent coordinator of the brood. Wing (1944) reported that the brood organization of blue grouse begins to break down i n l a t e July and s h u f f l i n g of young from one brood to another takes place. Similar observa-tions on the breakdown of brood organization were made i n the 1950 study period from the middle July and l a t e r . Within t h i s time, i n 128 observations on broods, 37 were records i n which the t y p i c a l brood organization had been changed. In 27 of these cases, two or three hens were associated with from 10 to 20 young which were observed to intermingle. In 6 cases but a single female was observed with from 7 to 15 chicks. F i n a l l y i n 4 instances from 1 to 4 chicks were observed alone. Contact between broods i s apparently brought about by t h e i r feeding a c t i v i t i e s , however, the reaction of one hen and chicks to the c a l l s of another hen or chicks cannot be dismissed as a contributing factor. I t seems reasonable that as a brood 86 moves about feeding i t would become temporarily l o c a l i z e d i n an area of good food supply. Other broods engaged i n the same a c t i v i t y might become l o c a l i z e d i n the same area producing a brood communism. There i s no evidence to suggest the hen recognizes her own chicks or t h e i r number and thus i n the breaking up of the feeding group hens might be found with any number of the o r i g i n a l band. This, i f true, might explain the broods of 7 to 15 chicks observed with a single female, or more than one female to a brood. In 1 9 5 1 and 1952 observa-tions suggesting brood disorganization were not made. Both July and August of these years were d r i e r than the same months i n 1950, and t h i s may have been a factor influencing brood movements. The moist summer of 1950 delayed desiccation of the vegetation. This i n turn provided areas of good food supply within which the broods fed and intermingled. The reverse was true i n 1951 and 1952. I f this explanation i s correct i t suggests a summer's climate influences brood organization through i t s effect on food vegetation. Movements of the Female and Brood Analysis of movements of hens with young i s based on the banding and subsequent observation of 2 5 hens with broods i n 1950. The observational period was a r b i t r a r i l y divided into the three months, June, July and August. The observed positions of the hens i n these months were plotted on a map of the study area, Fig. 2 5 . In t h i s i l l u s t r a t i o n each hen with brood i s represented by a symbol, while the number beside the symbol 87 represents the month i n which they were observed. The arrows indicate the shortest l i n e and i t s d i r e c t i o n to or from consecutive observations on a given hen. Generally, the observed range of the female and brood i s larger than the home range as observed i n hens p r i o r to incubation. There i s , however, a great amount of v a r i a t i o n i n the observed hen and brood ranges. Hen (20,D) was not observed outside of plot I i n June and July. She and her young had an observed range less than 2 0 acres. In the same months hen and brood (19,K) moved to (3,J) a map distance of approximately | mile. Again, hen (19,K) was observed on or near plot I over the three months, and as contrast hen a.nd brood ( 2 5 , 1 ) observed i n June were recorded at ( 5 , 1 ) i n August, another straight l i n e movement on the map of over a i mile. Thus the observed movements of females with young vary considerably with map distances up to a g mile recorded between some observations. Factors that influence the movements of the hen and brood on the summer range are mostly a matter of speculation. There i s no apparent re l a t i o n s h i p between age of young and brood range. Free water and adult males s i m i l a r l y bear no apparent relationship to the movements of the hen and brood, although sexually active males w i l l court a hen with young occurring on i t s t e r r i t o r y . The open vegetational types are u t i l i z e d most frequent-l y by the hen and brood, Fig. 14. Thus Clover Open ranks f i r s t ss i n u t i l i z a t i o n , with Log Open and Bracken Open next, but much less i n value. The shelter types Willow Dense and F i r Dense are used but l i t t l e . The u t i l i z a t i o n of open types would appear related to the feeding a c t i v i t i e s of the chicks, f o r i t i s along the edges of the roads and i n openings that invertebrates and succulent plant materials occur i n quantity. In these cover types the ground i s r e l a t i v e l y open, permitting the chicks freedom of movement and an exposure to sunshine not found i n the dense shelter types of f i r and willow. Since the open types, Olover Open, Bracken Open and Log Open are important as habitat f o r the hen and brood the d i s t r i b u t i o n of these types i s probably a major factor influencing t h e i r move-ments on the summer range. rhe d i r e c t i o n i n which the family groups moved i n 1950 show no general tendency of movement towards the higher eleva-tions which are to the l e f t and bottom l e f t of the f i g u r e . Thus over the months studied what could be c a l l e d migrational move-ments were not observed. I f t h i s i s true, migration occurred af t e r the month of August i n 1950. In support of t h i s conclusion the number of broods observed per hour per week i n July and August of 1950 remained r e l a t i v e l y constant, F i g . 28(c). On the other hand, from the same figure, there has been an apparent drop i n the number observed per hour per week af t e r week 14 (mid July) i n the years 1951 and 1952. '^h±s suggests that move-ment from the lowlands had begun or a greater brood loss occurred i n July and a f t e r of 1951 and 1952 as compared to 1950. 89 As mentioned above, 1951 and 1952 were relatively-dry summers which brought about rapid desiccation of the food vegetation. In turn, t h i s probably influenced the movements of the broods and resulted i n an early a l t i t u d i n a l migration. This seems the best explanation to the observed drop i n broods seen per hour and suggests that weather through i t s effect on food vegetation conditions the a l t i t u d i n a l migration of hens with young. Some l i g h t i s shed on the problem of f a l l brood migration by the information obtained from hunters on banded birds bagged. The positions i n which banded hens or young were shot are plotted on a map of the Quinsam region i n Fig. 26. A l l but one of the birds were taken on the 6th of September i n 1950. The hen i n the upper r i g h t region of the point cluster i s the one exception to t h i s and was shot on September 16th i n 1952. In the case of two chicks and a hen which was with a brood when shot, there i s no apparent a l t i t u d i n a l migration. During the time between banding and the hunt i n the second week of September, they apparently had moved distances comparable to the range of broods i n June to August. This suggests that complete migration from the study area between August and September 16th does not occur. There i s a wide movement evident i n 3 of the banded bi r d s , two hens with broods, and a lone chick. In each case movement has been towards higher land, although the directions taken have not been the same. I f these l i n e s of t r a v e l are 90 projected to the nearest highlands as an assumed winter range, grouse inhabiting the study area as summer range would over-winter at distances of nine miles apart. In t h i s respect the upward movement resembles a dispersal rather than a migration of uniform d i r e c t i o n . Since hens once l o c a l i z e d on the summer's range appear to return to the same region of the lowlands i n subsequent years they would converge upon i t from the highland winter range. I f t h i s be true, i t suggests the summer range i s a p a r t i c u l a r area, while the winter range occurs as a general area spread over the upland regions. Sex Ratio and weight Development i n the Young In 138 chicks shot at random over the period June 1 5 t h to August 1 5 t h i n 1951 and 1 9 5 2 , 70 were males, 68 were females. There i s no s t a t i s t i c a l l y s i g n i f i c a n t difference (by Chi-square test) between these two figures which indicates the sex r a t i o i n chicks was apparently 5 0 : 5 0 over the period studied. The data on weight were obtained i n the study area, and at the road check st a t i o n i n 1 9 5 0 , 1951 and 1 9 5 2 . Chicks collected or captured were weighed for t o t a l weight and these weights, c l a s s i f i e d as to sex, were averaged f o r each week from week of peak hatch (June 15 to June 2 1 s t ) . The hunter sample provided weights i n week 23 (Sept. 16) and i n week 21+ (Sept. 2 3 ) . The average weights and t h e i r confidence l i m i t s at the 9 5 $ l e v e l are plotted against week of age i n F i g . 27 from Table VIII append-ed. After age 8 weeks or week 1 7 , few data were available Fig. 27 from Table "VTTT Weight development of chicks 91 from the study area u n t i l the hunter k i l l of age 14 and 15 weeks i n week 23 and 2 4 . Thus between these times the averages are l i k e l y i n error. The r e l a t i v e l y large road check sample, on the other hand, provides a good estimate of weight i n week 23 and 2 4 . No s t a t i s t i c a l l y s i g n i f i c a n t difference i s observed between the weight of male and female chicks to 9 weeks of age. At 14 weeks of age the males are s i g n i f i c a n t l y heavier than the females. At 15 weeks of age the males have attained 884 ±. grammes while the females are 724 I. 35 grammes. Both weights are lower than those recorded f o r y e a r l i n g males and females on the study area i n spring and summer. I f a best straight l i n e i s drawn through the points i t s slope represents an average weekly growth rate. In the males t h i s i s approximately 60 grammes per week and i n the females approximately 50 grammes per week. These values are comparable to the growth rates calculated for blue grouse chicks i n Washing-ton by Wing et a l (1944). They found the growth rates to be 66 grammes per week i n males and 59 grammes per week i n females. The greatest error i n the ca l c u l a t i o n of growth rate r e s u l t s from the i n a b i l i t y to accurately age chicks. Thus i n lumping the weights of chicks collected i n any given week v a r i a t i o n i n hatching date i s ignored. This error doubtlessly contributes to the large f i d u c i a l i n t e r v a l observed i n some samples. The use of chick weights obtained over the three years of study i s not considered a major source of error. A sample of 18 weights taken at the road check i n 1951 was tested against a s i m i l a r ^95% confidence l i m i t . 92 sample obtained i n 1952. The difference between the two averages (by n t f l test) was not s t a t i s t i c a l l y s i g n i f i c a n t . Assuming environmental effects constant over the growth period of the two samples, t h i s r e s u l t would indicate l i t t l e d i f f e r -ence i n hatching date i n 1951 and 1952, and support the same conclusion drawn from a comparison of peak hatch i n the two years. The L i f e History Study as a Basis f o r the Analysis of Population Dynamics At t h i s point the information presented as l i f e h i story may be culled f o r data necessary f o r an understanding of population dynamics. I t i s e n t i r e l y possible that s o c i a l behaviour plays a role i n influencing population.size. Thus the t e r r i t o r i a l behaviour of the male sooty grouse should be considered i n t h i s respect. Here i s a s o c i a l phenomenon which obviously spaces sexually active males. There i s evidence to suggest t e r r i t o r i a l f i g h t i n g between males might r e s u l t i n the displacement of one. Thus space f o r t e r r i t o r y might be a factor l i m i t i n g the number of males resident i n the study plots and i n turn s t a b i l i z e the population therein. Observational evidence indicates t h i s i s not the case at Quinsam Lake. This conclusion i s supported by experimental evidence discussed below (p. 113 ). From observational data, the majority of males were expanding t h e i r t e r r i t o r i e s throughout the summer. There i s no reason to believe that any t e r r i t o r y studied was at i t s minimal size or a further contraction of perimeter would cause the 93 resident male to vacate. Moreover, areas suitable f o r t e r r i t o r i e s were vacant and areas once occupied by sexually active males were vacated and not reoccupied. i n subsequent years. A good example of the l a t t e r point occurred i n the loss of 7 males and replacement of but 3 on p l o t I I i n 1953 (p. 43)* Defence of t e r r i t o r y was not observed i n the females, thus t h i s can be dismissed as a factor influencing hen popula-t i o n s . There i s the p o s s i b i l i t y , however, that mating behaviour might l i m i t the number of successful matings.. I f monogamy were the rule the smallest number of the one sex would determine the number breeding. The evidence suggests the sooty grouse are promiscuous. Thus the s o c i a l behaviour of either sex does not have a d i r e c t bearing on population control. The average clutch size of each age class i n the population i s an important s t a t i s t i c i n the c a l c u l a t i o n of productivity. A knowledge of the sex r a t i o i n the young permits a c a l c u l a t i o n of the number of each sex produced from a given clutch. This i s important i n t h i s population study f o r yearling males are absent from the study area and t h e i r abundance must be inferred from the number of yearling females present. I f the chick sex r a t i o i s equal and each sex suffers equal mortality t h e i r calculations based on one sex should hold for the other. Another category of l i f e h i s t o r y information permits the development of sound techniques of population study rather than bearing d i r e c t l y on population control. Possibly the most important are c h a r a c t e r i s t i c s of the bird which lend themselves 94 to accurate census techniques. The t e r r i t o r i a l behaviour of the male permits an accurate census by sample plot method. Males holding t e r r i t o r y on the plots are counted as an estimate of t h e i r abundance. A knowledge of the r e l a t i v e l y wide and random movement of the females before nesting permits the use of the Lincoln index as a method of censusing t h i s sex. I f an absolute or r e l a t i v e estimate of numbers i s to be made then an observer must understand the conditions influencing h i s day to day or month to month counts. Thus periods of incubation, a c t i v i t y and migration must be appreciated and t h e i r effect upon counts taken into consideration. In the c a l c u l a t i o n of age structure i n the population c r i t e r i a of age are of f i r s t importance. The age c r i t e r i a as developed, can be used to i d e n t i f y yearlings and adults. The r e l a t i v e number of yearlings to adults i n the population i s a crude s t a t i s t i c . I t i s nevertheless invaluable as i t gives more than anything else an i n d i c a t i o n of the contribution made by the chicks of a previous spring to the summer population. The r a t i o of yearlings to adults can be used as one i n d i c a t i o n of popula-t i o n growth form. Mo r t a l i t y rates are essential f o r the understanding of population dynamics. In t h i s study, mortality rates are based on the yearly turnover i n adult banded males although banded males were never found dead. The "homing phenomenon" i n adult males occurs with such r e g u l a r i t y that a f a i l u r e to return to a 9 5 p a r t i c u l a r t e r r i t o r y i n a subsequent year can be taken as an indi c a t i o n of death. In the c a l c u l a t i o n of chick mortality with age, the average date of hatch i s important as a st a r t i n g point. Then average brood sizes are plotted against time to produce a death rate or rate of decrease of average brood si z e . I f t h i s i s done, are repeated counts of the same brood a l i k e l y source of error? I f brood counts are made i n June i s the same population being counted i n August or has the June group moved beyond the study area? Questions of t h i s kind can be p a r t i a l l y answered from a knowledge of brood movements. These appear to be at random over the study area with movements up to a ha l f mile recorded. There i s no i n d i c a t i o n of a migration u n t i l l a t e i n August. Thus brood counts made over the study area and into August seem v a l i d samples of the brood s i z e population i n t h i s region. As i n censusing the adults, the factors influenc-ing brood counts should be appreciated and weighed. Whether the chicks hide or f l u s h , group or disperse, remain i n t a c t i n family groups or shuffle a l l profoundly af f e c t count data. Ignorance of these and other pertinent l i f e h i s t o r y phenomena would re s u l t i n a meaningless population analysis. 96 TOPIC I I . POPULATION DYNAMICS  Population Size and Status Three methods were used to determine the size of the adult and yea r l i n g grouse population i n the study area. A f i r s t method consisted of counting the number of t e r r i t o r i e s on plots I and I I . This i n turn provided a count of sexually active adult males (p. 37). The plot data f o r 1950 are incomplete and not considered here. The following table summarizes the result s f o r 1951, 1952 and 1953: j Number of sexually active males 1 Plot . 1951 ; 1 1952 1 1953 : I : 14 ; : 12 : 12 : I I : : 16 : 18 : • 14 : ! Total ] 3 0 : : 3 0 : ! 26 There i s no s t a t i s t i c a l l y s i g n i f i c a n t difference (by chi-square) between the t o t a l numbers of sexually active males on the two study plots over the three years. Averaging the t o t a l s and d i v i d i n g by 72, the acreage of the two study plots the f i g u r e of .40 males per acre i s obtained. For a gallinaceous b i r d t h i s density i s high i n the extreme. A count of the resident hens on the study plots i s more d i f f i c u l t to obtain by v i r t u e of t h e i r r e l a t i v e l y large home range (p. 6 5 ) . Assuming presence on plot I I as an i n d i c a t i o n of of residence there, a count of marked hens was made p r i o r to hatch-ing time. This figure i s supported by an estimate of resident hen 97 numbers i n the same period by means of the Lincoln index, Lincoln (1930). The technique seems applicable i n the case of the hens as some are marked and other experimental conditions are f u l f i l l e d , Ricker (1948). Data f o r both census techniques were obtained from observation of hens wi t h i n the boundaries of plot I I . The following table summarizes the r e s u l t s : ! Number of resident hens p r i o r to hatch on plot I I I Actual count, marked hens 1 ; 1951 1 1952 1 20 ; 22 | Lincoln index estimate and \ 95% confidence l i m i t s * ; ; 28, 19-44 . ; 27, 20-40 C a l c u l a t i o n s made afte r Adams (1951). As with t e r r i t o r i a l males there i s no difference between the numbers of resident females on plot I I i n the period p r i o r to hatch i n 1951 and 1952. Since the author found i t impossible to mark a l l the females encountered on plot I I , the actual count figures are low. The Lincoln index values are taken as best estimates, and provide an average hen density forl951 and 1952 on plot I I of .78 hens to the acre. Again, as i n the males, an extremely high density. In comparing the average number of 17 males on plo t I I i n 1951 and 1952 with the average number of 28 females resident p r i o r to hatch i n the same time and area, i t w i l l be observed the 98 sex r a t i o i s i n the favour of females as 1.6 to 1. This s i t u a -t i o n r e f l e c t s the absence of y e a r l i n g males from the breeding population on the summer range and supports the conclusion reached above (p. 64) that y e a r l i n g males do not descend from the winter range i n t h e i r f i r s t spring a f t e r hatch. A second census method was based upon the number of birds observed per hour per week i n the f i e l d . Census hours were daylight periods from 0800 to 2000 hours. In t h i s time the a c t i v i t y of birds was r e l a t i v e l y uniform (p. 77). The observer t a l l i e d separately, males, females and females with broods, then divided the t o t a l number observed per week by the number of hours spent i n the f i e l d f o r that week. The r e s u l t s are expressed graphically f o r the year 1950 to 1953 i n F i g . 28 (a)(b) and (c) from Table IX appended. F i g . 2#(a) presents the males observed per hour of each week spent i n the f i e l d . I t indicates the r e l a t i v e abundance of t h i s sex over 4 years as well as the seasonal trend i n observed population size on the summer range (p. 59). Generally, the curves show no difference i n r e l a t i v e abundance that might be interpreted as a change i n male numbers over the four years. The v a r i a t i o n i n the years, p a r t i c u l a r l y i n weeks 1 to 5 can be attributed to v a r i a t i o n i n the a c t i v i t i e s of males and the observer. F i g . 28(b) presents i n the same way as i n the males, the r e l a t i v e abundance of females observed alone. Observations on such hens are l a r g e l y a matter of chance as any bias favouring discovery, 3 0 2 4 6 8 10 12 14 16 18 20 Weeks Fig. 28(b). Females observed per hour per week and weeks from April i3th. £ Fig. 28(c). Females with broods observed per hour per week and weeks from April 13 th. Data from table IX 99 such as the hooting a c t i v i t y of the male, does not occur. In t h i s respect the census technique i s better suited as a r e l a t i v e estimate of hen abundance. The r e s u l t s of the hen per hour census indicate no r e a l change i n r e l a t i v e abundance over the years studied. There i s a downward trend over each year which r e s u l t s from the hatching of the young after week 10 (p. 80) and the departure of broodless females from the summer range. Fig . 28(c) i l l u s t r a t e s the r e l a t i v e abundance of hens with chicks over the four years. Again the v a r i a t i o n observed i n the curves i s not considered i n d i c a t i v e of a r e a l change i n numbers, u n t i l week 15 i n 1950 as compared to 1951 and 1952. I t was suggested above (p. 89) that the observed drop i n these years reflected an e a r l i e r migration i n 1951 and 1952 or a delayed migration i n 1950. A t h i r d census technique was based on an estimate of the r e l a t i v e abundance of clocker droppings found on the study area i n the years 1951 and 1952. This i n turn r e f l e c t s the r e l a t i v e abundance of incubating hens (p. 75). A l l clocker droppings were t a l l i e d and the t o t a l f o r each year was divided by the number of hours spent i n the f i e l d i n each year af t e r the f i r s t dropping was found. The r e s u l t s are presented i n the following table: ;Relative abundance of incubating hens as ;indicated by clocker droppings ' Hours i n f i e l d : : 1951 : 1952 • : 311 : 222 : Clockers found : : 104 : 62 : Clockers per hour : . 3 3 : . 2 8 100 The variation observed i n the number of dockers found per hour i s not considered significant. The results of this census suggest no change had occurred i n the relative abundance of incubating hens on the study area i n the years 1951 and 1952. The results of a l l census methods used are in accord and indicate the status of males, females and females with broods was unchanged over the years 1950 to 1953. Thus i n the period studied, these components of the sooty grouse population at Quinsam Lake have remained stable i n numbers or their increase or decrease has not been detected. Each census method has i t s limitations. In counting t e r r i t o r i a l males, birds which abandon territory early i n the year are not recorded unless censused appropriately. This situation i s l i k e l y the cause of the variation i n numbers of males on plot II i n 1953. Males hooting at the plot edges create a problem, for i n this method, often one observation determines whether they are i n or out of the plot. In this study, a l l terri t o r i e s touching the plot boundaries were counted. A count of males based on terriroties ignores the number of adult or yearling males not holding territory. This error i s corrected i n part, by the inclusion of a l l males observed per hour on the study area as i n the second census method. This method, as the clocker count, i s limited mostly by the irregular activities of the observer for any change i n study technique from day to day influences the number and kind of observations made. The Lincoln 101 index method of determining hen density i s biased by the e movements of the females which l i k e l y extended byond the l i m i t s of the plot i n which the technique was used. I f , however, movement of banded and unhanded hens into the census area equalled movement out, a not u n l i k e l y condition, then some of t h i s error would cancel. If the grouse population, as censused, i s stable then one or a combination of two conditions would e x p l a i n i t s status. The b i r t h rate equals the death rate and emigration equals immigration. The b i r t h rate i s greater or les s than the death rate and emigration or immigration r e s u l t i n population s t a b i l i t y . With t h i s , an explanation of the observed population status can be obtained from the consideration of mortality, productivity, emigration and immigration i n the study population. M o r t a l i t y i n the Adults M o r t a l i t y i n adult males was calculated from time of banding i n the spring and summer to time of observation the following spring. Since adult t e r r i t o r i a l males are r e a d i l y observed and return to the summer range each year (p. 41) a percentage return can be calculated. I f non-returning males are assumed dead, the value represents a percentage s u r v i v a l . The number of males banded each year i n the study area and t h e i r return i n subsequent years i s summarized i n the following t a b l e : 102 : Return of adult males each year a f t e r banding : : 1950 : 1951 ! 1952 : 1953 : [No. Banded ; : 19 ; [ No. returned! : 1 2 : ;No.returned ' : 9 ; No. returned : 6 !No. banded \ : 15 : 'No. returned : 1 4 | No. returned : 7 [No. banded ., : 8 !No.returned : 5 As a best estimate of yearly return i n the adult t e r r i -tory holding males, the return figures f o r each year are added, and expressed as a percentage of the numbers banded, i . e . 29 ^_i2 +- 9 H-15 -T14 X- \ ^ e return. Assuming non-returning males dead, the value represents a 69$ yearly s u r v i v a l or a 31$ yearly death or turnover rate i n the t e r r i t o r i a l adult male. The i n d i v i d u a l variates suggest a r e l a t i v e l y uniform mortality rate i n the adult males p a r t i c u l a r l y i n the case of the 1950 sample followed through 3 years. Since the samples contain several year classes i t would appear death 5 - occurred independent of age. Farner (1952) has shown a tendency i n birds towards uniform mortality rates which do not vary extensively with age a f t e r a juvenile period of higher mortality. This i s true of the sooty grouse. In the case of the adult females, which are not l o c a l i z e d as the adult males on t e r r i t o r y , f a i l u r e to observe a hen cannot be taken as i n d i c a t i o n of i t s death. Further, most of the females banded were captured when with chicks and thus probably f a r from 103 t h e i r home range p r i o r to hatch (p. 87). The chance of observ-ing such hens the following spring i s less than that of observ-ing the few hens banded on t h e i r prehatch range. With the lack of other data the yearly turnover i n adult females i s assumed to be as found i n adult males - 31$. M o r t a l i t y Factors i n the Adults What factors operate to remove the adult males and females from the population i s l a r g e l y unknown. In the case of marked adult males, none was found dead on i t s t e r r i t o r y , rather the plot populations remained unchanged throughout the spring and summer except as affected by what i s taken as the abandonment of t e r r i t o r y at the cessation of sexual a c t i v i t y (p. 59). Some mortality occurs on the .summer range and i t i s worthy of mention here. Over the years 1950 to 1952 the remains of 7 adult birds and one yearling have been found i n the study area. From animal sign at the remains, fox (Vulpes fulva) and an avian predator could be involved. In the spring of 1952 a fox and two pups were discovered by a den i n the edge of an old railway embankment. The ground i n and about the den was l i t t e r e d with grouse remains. These were c l a s s i f i e d on the basis of feather colour and shape as the parts of 12 adult males and 3 adult females. This would suggest that fox predation i s heavier on the males than females, an observation i n accord with the r e l a t i v e ease of l o c a t i n g and capturing hooting males. The Quinsam area i s hunted f o r grouse and b l a c k - t a i l e d 104 deer (Odocoileus columbianus). Accordingly, human predation might be a factor contributing to adult and chick mortality. In the case of the adult males, hunting has l i t t l e or no effect on t h i s population component by v i r t u e of t h e i r upward migration which occurs i n August and weeks before the opening of the grouse season i n September (p.60). Thus i n 204 adult birds sampled at random at the Campbell River road check i n 1950 but 4 were males. In the case of the adult females and chicks which bear the brunt of the shoot, human predation i s more e f f e c t i v e . There i s no clear i n d i c a t i o n , however, that the ent i r e female with brood population bears a uniform k i l l . There i s the p o s s i b i l i t y that as with the males, some hens and young escape hunter preda-t i o n by an upward migration i n August. For t h i s analysis, however, l e t us assume that a l l banded females are subjected to uniform hunting pressure, and a l l banded hens are reported. The second condition i s a l i k e l y assumption supported by the checking of most hunters of the Quinsam area during the periods of greatest harvest. The following table summarizes the data on banded hens shootable to banded hens shot f o r the three year study period: : No. hens banded and shot i n each study year : : Year ; : No. banded : No. shot : % shot : 1950 \ 61 i 2 : 3 : 1 9 5 1 : : 27 : 0 : : 0 : 1952 : 20 : 0 : 0 105 From t h i s , i t would appear the loss to hunting was neg l i g i b l e and a minor f a c t o r contributing to the assumed 31$ yearly turnover of the adult hens. This conclusion i s supported by a consideration of the sex r a t i o i n the summer range. I f the shoot were having a great ef f e c t on the adult and yearling male;, component of the population, one would expect a disproportionate sex r a t i o on the breeding range i n favour of adult males which escape the harvest and have a 69$ winter s u r v i v a l . A s mentioned above, the sex r a t i o i n the years 1951 and 1952 on plot I I was i n favour of the females as 1.6 to 1. Parasitism and disease does not appear a major mortality factor i n the adults and yearlings, at least on the summer range. This statement i s based upon the examination of 174 blood smears taken from shot or captured birds and 103 autopsies. The sample, obtained over the years 1950 to 1952 i n the spring and summer months, f a i l e d to reveal any pathogenicities or effects attributable to parasite i n f e s t a t i o n . The r e s u l t s of the parasite survey i n adults and yearlings are presented i n Table X. Dispharynx nasuta, Plagiorhyncus formosus (occurring i n chicks), Yseria sp., Ceratophyllus d i f f i n i s and Lagopoceus  obscurus are new host records f o r the genus Dendragapus. The percentage and degree of i n f e c t i o n with Dispharynx and Table X Parasites of Adult and yearling grouse examined at Quinsam Lake data of 1950, 1951, 1952. Parasite : Site » :Number • • :Number S % :Degree of i n f e c t i o n : found :examined :infected \ infected Haemoproteus sp. blood 174 169 97 1-500 per 1,000 r.b.c. Leucocytozoon sp. blood 148 85 1-2 per 1,000 r.b.c. Trypanosoma sp. blood 134 77 1-20 per smear M i c r o f i l a r i a sp. blood 139 80 1-25 per smear Quadruple Infections 99 57 Dispharynx nasuta stomach 103 4 4 1-6 #(Cheilospirura spinosa gizzard 23 22 1-5 (Yseria sp. gizzard Rhabdometra n u l l i c o l l i s (?) in t e s t i n e 40 39 1-20 Ascaridia bonasae in t e s t i n e 14 14 1 Plagiorhync^us formosus intestine 0 0 0 Ceratophyllus d i f f i n i s external 11 11 1-4 Lagopoceus obscurus external 39 38 1-300 Ornithomyia f r i n g i l l i n a external 2 2 1-2 These nematodes, maeroscopically a l i k e , were not d i f f e r e n t i a t e d i n autopsies. C. spinosa i s the more commonly occurring form. A new species of Yseria i s yet to be described and named by Dr. J.R. Adams. 107 Plagiorhynqus i s i n extreme contrast with i n f e s t a t i o n s of these worms i n the chicks and w i l l be mentioned again. The 4 cases of Dispharynx i n f e c t i o n observed i n the table were from 3 yearlings and 1 adult b i r d . The degrees of i n f e c t i o n with Haemoproteus. Leucocytozoon and Ornithomyia recorded i n the table must be regarded as best estimates obtained by counting techniques l i k e l y i n error. What effect parasitism might have on the adults once i n the highlands and under greater c l i m a t i c stress i s an i n t e r e s t -ing question. With the lack of other evidence from the summer range, i t seems l i k e l y the greater part of the 31$ yearly mortality recorded i n the adult males, and assumed f o r adult females, occurs on the winter range. Here, predation, or some combination of predation, weather, and d e b i l i t a t i o n through disease might act to produce a major portion of the observed yearly turnover. M o r t a l i t y i n the Chicks M o r t a l i t y i n the chicks or young of the year was studied i n terms of decrease i n brood size from the time of nesting, u n t i l the middle of August i n each study year. Time of hatch was taken as June 15th to June 21st or i n the 10th week (p. 80). The number of chicks observed i n each brood was t a l l i e d and an average brood size calculated f o r each week. F i g . 29 from Table XI appended i s a graphic presentation of the r e s u l t s from the years 1950 to 1952. • • 1950 -O- O- 1951 • O — — O - 1952 10 12 14 16 18 Week of study 2 9 from Table 21.Weekly average brood size and weeks. Data of 1950, 1951 and 1952 108 S t a t i s t i c a l analysis (simple analysis of variance) indicates no s i g n i f i c a n t difference i n the weekly averages of the three years from week 10 to week 16. Byieek 17, however, the averages of 1950 are at variance with the averages of 1951 and 1952. As noted above (p. 86), i n August of 1950, unlike 1951 and 1952, a tendency towards brood disorganization was observed i n the hens and young. Under these conditions i t became impossible to accurately count the progeny of any one female. Thus the data of weeks 17 - 19 i n 1950 are not considered here. In each year the average brood s i z e increased from week 10 to a high at weeks 11 and 12. In the f i r s t week a f t e r hatch some chicks escape detection, p a r t l y through the v i o l e n t d i v e r t -ing action of the female, and p a r t l y by remaining motionless, or darting under logs and debris. By week 12 the chicks tend to run and f l u s h r e a d i l y when the brood i s discovered (p. 82), thus accurate counts are possible. With t h i s , and the above consider-ation of 1950 data there i s a pronounced drop i n brood s i z e from the calculated average clutch size of 6 eggs per hen (p. 70) to approximately 2 chicks per hen at the l a s t dates of f i e l d observation. A 67% decrease i n brood s i z e . This mortality or loss of productivity per hen i s ac t u a l l y greater than 67$, f o r i n counting the chicks of hens with broods, females that have l o s t a l l , or never had young, go u n t a l l i e d . I t i s not possible to consider the number of lone hens seen as a brood s i z e of 0, f o r females with chicks are much more r e a d i l y observed by nature of t h e i r brood behaviour and reaction to the chick d i s t r e s s c a l l . I 109 As an estimate of the number of unproductive females and females which lose a l l young on the study area, the census date" of F i g . 28(b) from Table IX appended, were used i n the following manner. Assuming a l l lone females observed per hour i n weeks 1 to 14 to be resident females and that lone females are as r e a d i l y observed i n the spring weeks as i n the summer, then the average number of lone females observed per hour i n week 1 to 6, to the average number of lone females observed per hour i n week 10 to 14, i s a r a t i o of females on the range i n spring to unproductive females and females which have l o s t a l l young, on the range i n summer. The periods 1 to 6, and 10 to 14 were selected for several reasons. One was to remove any bias created by nesting hens i n the approximately 3 weeks of incuba-t i o n (p. 80). This a c t i v i t y would remove them from the lone hen population and bias the r a t i o i n favour of productive hens. This tendency would again occur a f t e r week 14 f o r there i s i n d i c a -t i o n from the graph and the behaviour of the males, that a f t e r t h i s time, unproductive hens and hens having l o s t a l l t h e i r chicks leave the summer range. From the data of 1950 to 1952, the average number of lone females observed per hour i n week 1 to 6 i s .55* The average number of lone females observed per hour i n week 10 to 14 i s .22, a figure representing the number of unproductive hens and hens 22 of t o t a l brood loss on the study area a f t e r the hatch. Thus -s-^j or 40$ of the females are without young and t h i s i n the weeks of the summer up to and including the 14th or to July 19th. 110 I f females were l o s i n g a l l t h e i r chicks as the summer progressed, one would expect an upward trend i n the number of females observed alone per hour. Again r e f e r r i n g to F i g . 28(b) fo r the weeks 10 to 14, t h i s does not occur. I t would appear then 1+0% of the females lose t h e i r brood early i n the season, as by nest predation, or a l t e r n a t i v e l y are unproductive. Another explanation i s that hens, once made broodless, leave the summer range. I f t h i s i s the case the true r a t i o of lone hens i n spring to lone hens i n summer would be smaller with a subsequent decrease i n productivity. With the above considerations, i t i s possible to consider i n terms of chick mortality and hen breeding success the productivity of the grouse population on the study area. This i n turn can be integrated with data on adult mortality, numerical s t a b i l i t y and chick s u r v i v a l , to explain the population status of the grouse at Quinsam Lake. In a t h e o r e t i c a l 100 hens on the study area i n spring, by week 14, 40$ are broodless. By week 19, the remaining 60% of the hens have broods of 2 chicks. Thus 100 hens have produced by week 19, or the end of August, 120 chicks. I f now, 31% i s taken as the winter turnover i n the 100 hens, by the following spring, assuming no further chick mortality and with the 50:50 sex r a t i o observed i n the young (p. 90), the hen population should consist of 129 b i r d s , 60 yearlings and 69 adult hens. A condition i n whieh the yearlings make up 1+7% of an I l l increasing hen population. The s i t u a t i o n would be s i m i l a r i n the males. Over the four year study period, as concluded above, the population of females and adult males i n the study area has remained stable, with no increase or decrease observed. To determine the proportion of yearlings i n the hen population 66 hens were shot at random, before incubation had begun, i n the years 1951 and 1 9 5 2 . The r e s u l t s of the sampling are summarized below: Proportion of ye a r l i n g hens to adult hens i n spring Year : Sample size : •No. yearlings : % yearlings 1951 : : 25 J 6 ! ! 24 1952 : ! 41 : 11 i : 27 Total : \ 66 ! 17 : 26 From t h i s , the number of yearling hens occurring on the summer range i s not the predicted 4 7 $ but closer to the 31% winter turnover assumed to occur i n the hens of a year or more older. Thus to maintain the observed stable population and produce an expected 31% yearling hen class i n t h i s population 1+7% of the 120 chicks surviving t© week 19 must die between t h i s time and the following spring, migrate to regions remote, or do some combination of both. Indirect studies on migration suggest a 47% mortality occurs i n the chicks between week 19 and the follow-ing spring. This i s supported by a consideration of chick mortality f a c t o r s . 112 From observations on the breeding adults i t was shown that t h i s portion of the population returns each year to the same l o c a l i t y of the summer range, u n t i l presumed dead (p. 41). No direct evidence exists to show that the young of t h i s l o c a l -ized breeding population return to the l o c a l i t y of b i r t h . A t o t a l of 37 chicks wass banded i n the study area i n 1950 and 1951. None was recorded on the summer range i n subsequent years. One explanation f o r t h i s , other than emigration, would be the large mortality occurring i n chick l i f e before and a f t e r hunter predation. As another explanation, i n banding chicks, they could not be ringed u n t i l large enough to hold the bands. This was at 4 to 5 weeks of age. From the movements of females with young (p. 86) such chicks caught and banded might be up to one h a l f mile from the nest, a condition making t h e i r discovery near the hatching s i t e u n l i k e l y even i f , as adult males, they became l o c a l i z e d and conspicuous on t e r r i t o r y . Nice (1937) has shown that yearling song sparrows (Melospiza melodia) tend to return to the l o c a l i t y of b i r t h . This has been demonstrated i n other, but not a l l , banded b i r d studies. Nice (op. c i t . ) also suggests that on the return of the young song sparrows i f some fac t o r such as space be l i m i t i n g , they move on to new locations. Assuming that sooty grouse young return to the region of t h e i r b i r t h there i s no apparent reason why they should leave i t , or at l e a s t why immigration into the study area from other places should not occur. This seems most obvious i n the case of breeding hens f o r which food, protective cover and nesting s i t e s are i n abundance at Quinsam Lake. 113 Moreover, no behaviour mechanism has been observed i n the hens which might l i m i t t h e i r density i n a given area, f o r unlike the cocks they do not occupy and defend t e r r i t o r y . Moffat (1903) Nicholson (1933) Nice (1937) and others have stressed the importance of t e r r i t o r i a l behaviour i n male birds as a mechanism capable of l i m i t i n g population size i n a given area. Stuart and Al d r i c h (1951) attempted to eliminate the breeding male population from several sample s t r i p s i n a spruce-fir f o r e s t . As quickly as one male was shot, however, another took i t s place. They concluded from t h i s that most of the t e r r i t o r y niches were occupied before shooting began and the rapid replacement of new males indicated a " f l o a t i n g " population of birds which had l o s t i n the competition f o r space to other members of t h e i r species. They agree with Nice (op. c i t . ) who states, " I t ( t e r r i t o r y ) ensures that there w i l l be no crowd-ing and no overpopulation since surplus birds must go elsewhere". From the study of marked males on plot I and I I , there i s no clear i n d i c a t i o n that t e r r i t o r i a l behaviour i s l i m i t i n g the present male population s i z e , producing a surplus male population or creating an emigration pressure. To further test t h i s condition, i n May of 1952, 16 hooting males were removed from a sample area, plot I I I , F i g . 1. Two banded males were l e f t i n the plot as "inducers", with the b e l i e f that t h e i r hoot-ing would influence members of a " f l o a t i n g " population to s e t t l e . In no case was an emptied t e r r i t o r y reoccupied i n that year. The two banded birds remained throughout the summer as the only 114 resident males. In June of 1953 plot I I I was recensused. One banded male was replaced and 3 new a r r i v a l s occurred on the area i n regions where t e r r i t o r i e s had not been recorded i n the years 1950 to 1953. On the basis of 18 males i n the plot i n 1952, a 31% turnover and a stable population, the number of new a r r i v a l s was predicted as 6. As noted above, 4 occurred. This l e f t 13 suitable t e r r i t o r y "niches" vacant. I f then, sooty grouse young do home, there appears no ba r r i e r preventing t h e i r f u l l numerical contribution to the study area population, or as an a l t e r n a t i v e , immigration i s apparently unobstructed. With the lack of other evidence on the movements of young p r i o r to t h e i r l o c a l i z a t i o n as breeding birds on the summer range i t would appear a fu r t h e r 47% mortal-i t y occurs i n the chicks that survive the period from nest to week 19, and t h i s before the following spring. Thus the population status observed at Quinsam Lake can be explained as a condition wherein -40% of the females are unproductive or lose a l l young. 60% of the females lose 4 out of 6 or 67% of t h e i r young i n the summer months. The surviving young have a 47% f a l l and winter mortality which reduces t h e i r numbers to a l e v e l that equals the 31% yearly loss observed i n the older age classes and re s u l t s i n the observed stable population. With these data, the population dynamics of the sooty 115 grouse at Quinsam Lake can be summarized i n a l i f e table and survivorship curve drawn from i t , Table XII, begins the l i f e table with a t h e o r e t i c a l 1,000 eggs i n the nest. The f i r s t loss i s from broodless females, which may have l o s t a l l t h e i r young or been unproductive. S t r i c t l y speaking, the loss of eggs through unproductive hens occurs before or without nest-ing and should not be considered here. Since non-productivity i n the hens i s a minor loss of young (to be discussed below) and f o r the sake of s i m p l i c i t y , i t i s considered here. Other than t h i s the table i s orthodox i n structure. F i g . 30 i s drawn from Table XII and can be c a l l e d a survivorship l i n e . I t i s a negatively skewed rectangular curve or a concave J i n shape. This r e f l e c t s the production of a large number of eggs by a single female with extremely heavy mortality i n the ea r l y stages of l i f e . According to Hickey (1952) the only approach to t h i s negatively skewed curve thus f a r reported f o r birds i s found i n Deevey fs (1947) reanalyses of Nice's (1937) work on the song sparrow. Burkitt (1926) gives a formula f o r c a l c u l a t i n g the average length of l i f e of an animal given the condition where the number of surviving young equals the number of adults that die yearly. I f a b i r d l i v e s n years then there die i birds. n I f the yearly turnover of adult grouse i s 31$ with the number dying each year equalling the number of surviving young then .31 = i or n * 3.2 years as the average length of l i f e of a n grouse once i t has reached yea r l i n g age. 116 Table XII L i f e table f o r the sooty grouse at Quinsam Lake ' : : x : Ix Ti 2l qx J Primary data :Survivors:(age i n years):(Cohort : dx : ( i n %) : : •- :of 1.000 : :  Eggs of 100 females 600 0 1,000 Complete brood loss 360 600 4 0 0 40 Summer chick l o s s 120 198 402 67 F a l l to spring loss 63 1 105 93 47 31% adult winter loss 43 1-2 72 33 31 2-3 50 22 3-4 34 16 4-5 23 11 5-6 16 7 6-7 11 5 7-8 8 3 8-9 6 2 9-10 4 2 10-11 3 1 11-12 2 1 12-13 1 1 1 3 - 1 4 0 0 1. l x , number l i v i n g at beginning of each age i n t e r v a l . 2. dx, number dying w i t h i n the age i n t e r v a l . 3. qx, the rate of mortality i n per cent. 1000 b K 800 c > 0) .o E 3 600 400 200 h Fig. 30 from Table TK 6 8 10 12 Age in years ( x) A survivorship curve for the sooty grou 117 M o r t a l i t y Factors i n the Chicks The l i f e table calculations begin with the supposition that each female on the summer range lays 6 v i a b l e eggs. There exists the p o s s i b i l i t y that some females do not l a y or i n so doing produce non-viable or addled eggs. Either condition might explain the 40$ broodless females observed i n the study area. As an analysis of t h i s s i t u a t i o n i n the spring of 1951 and 1952, 61 hens were shot or captured at random, aged and examined f o r breeding condition. The r e s u l t s are l i s t e d below i n tabular form: Breeding hens i n each age class i n per cent Age : Class : :Number in:Breeding c r i t e r i o n : :sample of:and number of hens: : 61 hens :classed by i t : : No. : :breed-: ing : $ : ibreedf-ing.: Yearling ; : 13 • :Brood patch 2 : :Ripe ova 2 : :Shed f o l l i c l e s 5 : : 9 1 : 70 Adult : 48 • :Brood patch 7 : :Ripe ova 5 :Shed f o l l i c l e s 34 : * \ 4 6 : i 9 6 ! There i s a s t a t i s t i c a l l y s i g n i f i c a n t difference (by c h i -square test) between the number of yearling and adult,hens engaged i n breeding a c t i v i t y . On the basis of t h i s sample, 70$ of the yearling hens and 96$ of the adult hens are productive. I f then, yearlings make up approximately 26$ of the hen popula-t i o n then i n 100 hens on the spring range 18 are breeding yearlings and 71 are breeding adults. In another way, 89$ of the females i n the study area are breeding or productive birds. This s i t u a t i o n r e f l e c t s i n the r e l a t i v e numbers of each age class found with broods. In sampling hens with young 118 i t i s assumed that each age class i s as l i k e l y to lose nests and young and each i s sampled without bias. From the above calcu l a t i o n s , a f t e r the hatch the r a t i o of yearlings with chicks to adults with chicks should be 18 to 71 or .25. In 1951 and 1952, 48 females were shot or captured when with broods. Of these, 9 were yearlings and 39 were adult hens, a r a t i o of 9 to 39 or .23, a deviation from the expected r a t i o which i s not s t a t i s t i c -a l l y s i g n i f i c a n t (by chi-square t e s t ) . I f 89% of the hens on the summer range are productive, or 11% unproductive, then non-productivity alone does not explain the 40% hens observed without broods and indicates most loss., of young occurs a f t e r the eggs are l a i d . Data on the number of addled or i n f e r t i l e eggs l a i d by nesting hens are meagre. Of the nests found i n the study area but 3 yielded data on addled eggs. In other cases, while addled eggs may have been l e f t i n the nest a f t e r the remainder had hatched, they could have been destroyed or carried away by predators before discovery. In the 3 nests mentioned, 1 egg i n a clutch of 6, 2 i n a clutch of 7 and 2 i n a clutch of 4 were addled. From studies on gallinaceous birds by Bump et a l (1947) Patterson (1952) and others, i n f e r t i l i t y has not been a major f a c t o r i n chick l o s s . While t h i s unexplained phenomenon may help decrease the brood siz e by a chick or two, i t i s not considered a sole factor creating brood l o s s at Quinsam Lake. 119 Nest desertion and/or predation appears a r e l a t i v e l y -large mortality factor i n young grouse p r i o r to hatch. This conclusion i s based upon the fate of 36 nests discovered over the three year study period. Of the 36 nests only 6 were found p r i o r to successful hatch or destruction. The remaining nests were c l a s s i f i e d as to a successful or unsuccessful hatch on the basis of s h e l l fragments i n and around the nest. Thus desertion of the nest might have occurred before depradation. In the 6 nests mentioned above, 2 were l o s t through predation, rather than nest desertion. S i m i l a r l y a l l unsuccessful nests have shown evidence of predation. With the lack of other data, i t seems l i k e l y that most nest f a i l u r e i s as a d i r e c t r e s u l t of predation rather than desertion. In the sample of 36 nests 9 or 25% were apparently l o s t through depredation. This f i g u r e , while not high i n comparison with other studies, i s probably greater than the actual nest destruction. When a nest has been destroyed the eggs are broken and scattered about i n a manner that aids i n the i d e n t i f i c a t i o n of the predator and the discovery of the nest, F i g . 20(c). In a successful hatch the s h e l l s are pipped c h a r a c t e r i s t i c a l l y and remain within the nest structure, s t i l l p a r t l y hidden by logs and vegetation. There i s no doubt that these successful nests are l e s s often found than the unsuccessful, a condition that introduces into the c a l c u l a t i o n an unknown bias i n favour of nest destruction. I d e n t i f i c a t i o n of nest predators i n the study area i s 120 based on circumstantial evidence. Bump et a l (1947) describe and i l l u s t r a t e nests of ruffed grouse destroyed by various animals. On t h i s basis, and from faeces, h a i r feathers and odour at the destroyed nests an attempt was made to i d e n t i f y the predator. In the 9 observed cases of nest depredation, 1 appeared to be the r e s u l t of fox, 4 fox or raccoon (Procyon l o t o r ) , 1 raven (Corvus corax) and 3 unknown. From the above considerations, non-productivity, nest desertion and depredation do not explain the 40$ broodless females observed on the study area. Nor do these mortality factors explain the drop i n brood size i n week 10 to week 19 i n 1950, 1951 and 1952. Clearly, both conditions are a r e s u l t of mortality i n the young a f t e r hatch. The pattern of chick death as i l l u s t r a t e d i n F i g . 29 has been s i m i l a r over the years 1951, 1952 and early 1950, with a downward trend from week 11 and 12 to week 19, the end of f i e l d observation. The gap i n r e l i a b l e data on brood size between time of hatch and the t h i r d week of age leaves much to be desired. It might be assumed the trend begins at 6 eggs i n the nest and follows the same "slope" of mortality as i n the older age classes. On the other hand, conditions peculiar to s u r v i v a l i n early chick l i f e might be acting to remove young birds from the population and cause a sudden drop to what i s observed as maximum brood size i n week 11 and 12. Addled eggs or a s i c k l y chick per brood which perishes shortly a f t e r the hatch might be considered i n t h i s respect. 121 Beer (1943), Fowle (1944) and others report blue grouse chicks to be insectiverous i n diet u n t i l about ten days of age when they begin to take vegetable food. While plant material i s obviously p l e n t i f u l at Quinsam Lake, a shortage of acceptable invertebrates might exi s t and t h i s , caused by or associated with inclement weather, might remove week old chicks from the broods. I t i s noteworthy, however, that the decrease i n brood size continues beyond the 12th week despite the fact that the chicks by t h i s time are on an adult d i e t . Inclement weather per se, or i n association with food shortage, might r e s u l t i n the death of week old grouse, p a r t i c u -l a r l y i f some chicks are separated from the hen and brood. Assuming other mortality factors constant, however, the r e l a t i v e l y cool wet spring recorded i n 1952 (p. 20) appears to have had no markedly deleterious effect on brood size as compared to 1950 and 1951. This seems so from a comparison of average brood sizes over the three years, which f a i l to show a s t a t i s t i c a l l y s i g n i f i -cant difference from week 11 to week 16. Predation doubtlessly removes chicks from the broods i n the f i r s t week of hatch and a f t e r . I t i s d i f f i c u l t , however, to reconcile the loss of 2 or even 1 chick per brood to predation i n the early stages of l i f e . On the other hand, human predation during the hunting season i s an apparent cause of chick mortality. Road check data of 1950 (Taylor, unpublished B.C. Game Report, 1950) indicated chicks formed a minimum of 80% of the t o t a l bag checked i n 1950. Thus f o r every 1 hen, approximately 4 chicks are 122 taken i n the f a l l harvest. I f the hunter success i n taking females i n 1950 to 1952 i s averaged as 1% then t h i s would suggest k% of the chicks are shot. In 1950 and 1951, 37 chicks were banded and released. Assuming the i n t a c t sample present on the summer range p r i o r to the harvest, an u n l i k e l y assumption, the number shot as to number banded would give some i n d i c a t i o n of hunter success. Of the 37, 3 or 8$ were shot and reported by hunters. From t h i s , and the above, there i s no i n d i c a t i o n that predation, human or otherwise, i s a major mortality factor i n the chicks on the summer range. Within t h i s patchwork of possible but uncertain mortal-i t y factors parasitism and disease begin to appear as environmental factors capable of c r i p p l i n g and k i l l i n g chicks. Table X I I I summarizes the parasites found i n chicks collected from week 10 to week 19 i n the years 1950 to 1952 at Quinsam Lake. The data are from 89 chicks smeared f o r blood examination and 107 chicks autopsied f o r v i s c e r a l parasites. Not included i n the table i s the record of one t i c k (Ixodes auritulus) removed from the head of a chick examined at the 1950 road check i n Campbell River. In the 1950 study period b a c t e r i a l infections occurred i n 10 out of a sample of 60 chicks examined i n the f i e l d . The infections were apparently caused by mechanical i n j u r y to the feet and other body parts with subsequent b a c t e r i a l invasion. No cases were recorded i n 1951 and 1952. Comparing Table X I I I to parasitism recorded i n the adults Table X I I I Parasites found i n chicks from 1 to 9 weeks of age. Quinsam Lake data of 1950, 1951 and 1952. Parasite *>. » •> » : Site :Number : found :examined • : Number :infected :infected rDegree of i n f e c t i o n Haemoproteus sp. blood 89 59 66 1-50 per 1,000 r.b.c. Leucocytozoon sp. blood 34 38 .. -1 per 1,000 r.b.c. Trypanosoma sp. blood 18 20 1-10 per smear M i c r o f i l a r i a blood 0 0 0 T r i p l e Infections 5 6 Dispharynx nasuta stomach 107 68 64 1-430 ^(Cheilospirura spinosa (Yseria gizzard gizzard 11 10 1-2 Rhabdometra n u l l i c o l l i s ( ? J i n t e s t i n e 22 21 1-20 Ascaridia bonasae 'intestine 4 4 1 Plagiorhynous formosus int e s t i n e 53 50 1-33 Ceratophyllus d i f f i n i s external 0 0 0 Lagopoceus obscurus external 21 20 1-50 Ornithomvia f r i n g i l l i n a external 7 7 1-2 #Th ese nematodes, macroscopically a l i k e , were not d i f f e r e n t i a t e d i n autopsies. _C. spinosa i s the more commonly occurring form. 123* and yearlings, Table X, several differences w i l l be noted. Generally, with the same sampling reservations as noted i n the case of the adults, the number and degree of i n f e c t i o n s are lower i n the chicks. This i s more apparent than r e a l since the chick sample includes week old young. These animals, although possibly parasitized may not show detectable stages of parasites and thus introduce a bias not found i n the older age classes i n favour of non-parasitized. F i g . 31 from Table XIV appended, i s a graphic presentation of the p a r a s i t i c i n f e s t a -tions observed i n chicks with age. The data were obtained from samples taken each week of the study i n 1950 to 1952 from week of peak hatch. Thus v a r i a t i o n i n the date of hatch i n any one sample i s an obvious source of error i n t h i s treatment as w e l l as the small sample sizes i n each week. Lumping data i s not considered a serious error as the samples of each year have been comparable, Bendell ( i n manuscript). As i t might be expected the number of infections with most parasites increases as the chicks age. This i s evident from a consideration of the i n f e c t i o n trends of Haemoproteus. Leucocytozoon. Dispharynx. Plagiorhyncps and perhaps of Rhabdometra. In these parasites number of hosts infected i n l a t e r chick l i f e equals or exceeds the figure f o r the adults and year-l i n g s . M i c r o f i l a r i a was apparently absent from the blood of chicks over the period studied. A most s t r i k i n g and noteworthy difference between chick and adult parasitemia i s observed i n the occurrence of Haemoproteus Leucocytozoon Trypanosoma Dispharynx Cheilospirura •and Yser ia Rhabdometra Ascaridia Plagiorhynqys J L J c I I - O I I I I L -I—lo I 2 3 4 5 6 7 8 9 Age in weeks Fig. 31 from Table I E . Age and infections in chicks 124 Dispharynx and Plagiorhyncus as common parasites of the young. The 4 Dispharynx infections recorded i n Table X occurred i n 3 yearlings and 1 adult b i r d with the l e v e l of i n f e c t i o n from 1 - 6 worms. Plagiorhyncus was not found i n adult or yea r l i n g grouse. In the chicks at 4 to 5 weeks of age 87 - 94$ were infected with Dispharynx and 67 - 73$ were infected with Plagiorhvncus. In t h i s age group, 53 - 73$ of the chicks examined carried both worms, Table XlV appended. Dispharynx and Plagiorhynyis were the most damaging parasites encountered during the study. According to " both S i n i t s i n (1929), Cram (1931 bVworms are vectored by isopoda, a common item i n the diet of chicks. Within the chicks Dispharynx occurs i n the stomach or proventricuius and here causes obvious le s i o n s . In severe infestations of 100 - 300 worms, the soft stomach i s diseased and p r o l i f e r a t e d into long fibrous shreds. This and profuse quantities of mucus occur i n the stomach lumen creating a b a r r i e r to food passage. The worms themselves are found i n t h i s t i s s u e , or embedded i n the glands of the stomach, which are i n most cases devoid of secretion. The stomach often enlarges to four times i t s healthy size and i s streaked and blotched with red inflamma-t i o n as compared to i t s normal l i g h t grey or beige colour. The acanthocephalan Plagiorhyncfeis has i t s habitat i n the lower small i n t e s t i n e of chicks and while not associated with as great a host reaction as recorded i n the ease of Dispharynx s t i l l creates obvious t i s s u e damage. The worm 125 generally occurs with i t s head of spines embedded i n the i n t e s t i n a l w a l l . Twelve cases have been observed where the gut was perforated and the worms free i n the coelome or under the i n t e s t i n a l mesentery. In such cases b a c t e r i a l i n f e c t i o n from gut to coelome l i k e l y occurred. Generally the gut tube i s constricted and thrown into a t i g h t c o i l about the s i t e of acanthocephalan i n f e c t i o n with apparent blockage of the i n t e s t i n e . c h i c k s with severe infe c t i o n s of Dispharynx and Plagiorhync ;us or Dispharynx alone, are emaciated, weak and easily caught i n the f i e l d . Their body organs, especially the kidneys appear blanched and pale, while the i n t e s t i n e i s f i l l e d with a slimy l i q u i d and gas. Five young grouse were collected i n the study area, apparently near death from the ravages of these worms. Observations on one are as follows: "July 9, 2130, 350°S, 60OF, female and brood of 3 observed i n Log Open two chicks f l u s h , 1 remains near female which clucks and moves slowly away with s l i g h t neck display. Attempt capture of remaining chick with noose, stroke head, back and t a i l with noose, and then move i n and capture chick by hand. Prepare to band i t f o r release and note extremely le t h a r g i c responses, place i t i n bag, i t remains motionless on i t s side". In every respect t h i s behaviour was a t y p i c a l from what i s usually experienced i n capturing and banding apparently healthy chicks (p. 82). An estimate of % haemoglobin i n the 126 blood by S a h l i technique and the number of red blood c e l l s per cu. mm. of blood was 45% and 1,200,000 per cu. mm. respectively. Both figures are about h a l f that recorded i n apparently healthy young, Table XV appended. The lung, l i v e r and kidneys of the chick were pale i n eolour, the stomach was inflammed and swollen, the i n t e s t i n e was f l u i d f i l l e d and acanthocephalans were v i s i b l e i n the gut lumen. The diseased stomach yielded 150 Dispharynx and the i n t e s t i n e 17 acantho-cephalans one of which was i n the coelome of the b i r d . What converts an i n f e c t i o n with Dispharynx or Dispharynx and Plagiorhyncus into a l e t h a l condition i s unknown. Edminster (1947) considers 20 - 30 Dispharynx capable of a f f e c t i n g the health of ruffed grouse while more may prove f a t a l . He designates t h i s parasite a major pathogen when i t occurs. Infections with 50 and more Dispharynx and 1 to 5 acanthocephalans are commonly encountered i n chicks shot as apparently healthy. F i g . 32 i l l u s t r a t e s the frequency of occurrence of Dispharynx infections recorded i n 112 chicks collected i n the study area. Perhaps a 10 worm i n f e c t i o n would be l e t h a l i n young chicks while 50 worms i n older birds would have no e f f e c t . The s i t u a t i o n i s made more complex by introducing the effects of host resistance, other parasites, weather and food supply as additional variables. One or a combination of these factors might t i p the balance of a Dispharynx i n f e c t i o n from recovery to death. 60 -0 - 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 + Number of worms Fig. 32. Distribution of infections with Dispharynx in 106 chicks autopsied at Quinsam Lake. Data of 1950 to 1953 1 2 7 The pathogenicity of Dispharynx and Plagio rhyncus infections cannot be doubted. There remains to be shown a c o r r e l a t i o n between chick mortality and parasite attack. The downward trend i n average brood s i z e from week 12 has been noted above. I t i s worthwhile to consider the variates i n each week's average brood size as an explanation of the observed drop. F i g . 33 i l l u s t r a t e s the frequency of brood size occurrence f o r weeks 10 to 19 i n 1950 to 1952. I t i s noteworthy that beginning with week 12 the figures change shape so that by week 14 a brood size of 1 i s the modal class and remains a r e l a t i v e l y common brood size thereafter. The frequent occurrence of 1 chick per brood suggests that t o t a l loss of chicks occurs and r e s u l t s i n broodless hens. This occurrence of low brood sizes i n the study area correlates with the b u i l d up of Dispharynx and Plagiorhyn-qus infections i n terms of per cent young infected and average number of worms per i n f e c t i o n with each week of age, F i g . 34 from Table XVI appended. After the 14th week there appears a downward trend i n the number of chicks infected which might r e f l e c t the removal of heavily infected birds from the population, a developing age immunity i n the young, or both. Nevertheless, i n a sample of 16 chicks obtained at Quinsam Lake i n September of 1950 and 1951, 12 were infected with 1 to 300 Dispharynx. while 6 were infected with from 5 to 9 acanthocephalans, an i n d i c a t i o n that these parasites are carried onto the winter range. 20 16 12 8 -4 Week 12 1 2 3 4 5 6 7 20 I6h 12 8 4 Week 17 I 2 3 4 5 6 7 20 -16 -12 -« *-•O 4 " o '— o Week 13 2 3 4 5 6 7 2 or 16 12 Week 18 1 2 3 4 5 6 7 28-24 20 o 16 12 8 ». 4 -0 -O E Week 14 j i I 2 3 4 5 6 7 20 • 6 12 8-Week 19 I I V/YZ2 i i I 2 3 4 5 6 7 20 16 12 8 4 Week 15 j i 1 2 3 4 5 6 7 1950 data Histograms comparing brood sizes for weeks 12 - 19. Data of 1950, to 1952. 20 16 F 12 8 4 Week i6 - l L I 2 3 4 5 6 7 Brood size Dispharynx 100 100 4 5 6 7 Age, weeks 100 80 T3 a> o 60 a> 3« 4 0 20 10 Plagiorhyncus % infected average no. of worms 100 80 | o i o 60 w a> E 40 1 v o> o at 20 < 12 4 5 6 7 8 9 10 Age, weeks 13 14 15 16 17 18 19 Week of study Fig. 34 from Table XEL . % infection, average number of worms per infection and age of chicks. Data of 1950 to 1952. 128 With t h i s , and i n view of the 8 9 $ productivity of the hens, the doubtlessly high estimate of nest destruction and the apparently n e g l i g i b l e effect of predation i t seems l o g i c a l to conclude that the parasites Dispharynx and Plagiorhyncus are important as chick mortality f a c t o r s . They would explain i n most part the 4 0 $ broodless hens and the 6 7 $ chick l o s s recorded on the summer range. Moreover, i t seems l i k e l y under conditions of winter stress, chicks carrying these parasites would suffer greater mortality than the older age classes. This was calculated at 4 7 $ between f a l l and spring as compared to a 31$ yearly turnover i n the older b i r d s . Thus, as causal agents of extreme chick mortal-i t y , Dispharynx and Plagiorhyncus can be considered as major factors effecting population siz e and s t a b i l i t y on the study area. k-D i s t r i b u t i o n of Dispharynx and Plagiorhyncus I f disease plays a major r o l e i n population control on the study area, it.seems worthwhile to speculate on i t s importance as a population control i n other regions. The study area, as already mentioned, i s representative of 7 4 , 5 0 0 acres once under climax forest, now logged and burned. Since t h i s entire area i s i n the same stages of plant succession and w i t h i n the known range of sooty grouse i t i s l i k e l y that conditions operating over the larger area are s i m i l a r to those found at Quinsam Lake. Certainly i f Dispharynx and Plagiorhyncus 129 are present i n numbers, the wide range of chicks before and i n migration (p. 87, 89) would f a c i l i t a t e i n d i s p e r s a l of the parasites, given the necessary intermediate hosts. Since sooty grouse are hunted over the Quinsam region and beyond, i t was possible through the cooperation of hunters to obtain viscera of young grouse taken i n various l o c a l i t i e s . The l o c a l i t i e s sampled and the presence or absence of Dispharynx and Plagiorhyndjus are l i s t e d i n Table XVII. F i g . 35 i s a map of the d i s t r i b u t i o n of these two parasites over the sampled area. From t h i s , i t appears Dispharynx occurs over the e n t i r e 74,500 acre burn, and l i k e l y Plagiorhyncus i f enough samples had been taken. This d i s t r i b u t i o n of the two pathogens suggests they may be operat-ing as population controls i n other regions than Quinsam Lake or at least over the 1938 burn. On the other hand, a r e l a t i v e l y large sample of 31 young shot i n the Campbell Lake region i n 1952 was negative f o r both Dispharynx and Plagiorhyncus. This i s a logged region and i n 1951 was severely burned. Thus the absence of the two parasites may mean that the area never was infested, or the f i r e of 1951 destroyed the isopod intermediate hosts. Clearly, however, the parasite ecology of t h i s region i s quite d i f f e r e n t than that at Quinsam Lake, and other popula-t i o n controls must be operating, or w i l l operate, to remove grouse by death or emigration. With t h i s difference i n environmental factors a f f e c t i n g a species over a r e l a t i v e l y 130 Table XVII D i s t r i b u t i o n of Dispharynx and Plagiorhyncus in f e c t i o n s from hunter k i l l e d young. September 1951, 1952. L o c a l i t y :Map :No. • • :Sample : Size : Dispharynx :Infected: % • k-: Plagiorhyncus : Infected: Jo Boot Lake 1 6 2 1 Upper Campbell Lake 2 6 0 0 Camp 5 3 7 1 0 Roberts Lake 4 3 3 0 Sayward 5 2 0 0 Middle Campbell L. 6 31 0 0 0 0 Ladore F a l l s Dam 7 4 1 0 Mohun Lake 8 7 2 1 Iron River Road 9 1 1 1 Quinsam Lake 10 16 12 75 4 25 Constitution H i l l 11 2 2 2 approx. scale l" = 10 miles Fig. 35 from Table Z S H . Distribution of Dispharynx and Plagiorhyncus based on hunter killed young 1950,1951. Logged and burned in, and prior to, 1938 ( Bloedel fire no. 230,1938) r~| Study area O Hunter sample, negative Q Hunter sample, Dispharynx # Hunter sample, Dispharynx and Plagiorhyncus Numbers refer to locality in table 131 small portion of i t s known range, i t i s d i f f i c u l t to accept the suggestion of Leopold (1933) Wing (1943) and Fowle (1944) that the sooty grouse are c y c l i c , at least as investigated i n t h i s study. The evidence suggests one must look f o r populations, each responding to the environmental conditions of i t s p a r t i c u l a r l o c a l i t y . 132 DISCUSSION The abundance of sooty grouse i n the study area doubtlessly r e f l e c t s the s u i t a b i l i t y of the vegetation on i t s summer and winter range. From a consideration of the habits of the males they apparently have a wide environmental tolerance. Thus males are observed hooting or/sexually active i n dense stands of douglas f i r or beside a log i n near minimum of shelter vegetation. The hens on the other hand, show a marked selection of open vegetation f o r feeding, nesting and when with chicks. Fowle (1944) did not record the intense f l i g h t s and feeding a c t i v i t y of the hens i n early morning and l a t e evening. Since the Quinsam area at the time of his study was i n an e a r l i e r stage of burn succession, there i s the suggestion then, that the changing environment has resulted i n a change i n behaviour of the hens. As plant succession advances i t seems l i k e l y that the breeding hens with a r e l a t i v e l y narrow environmental tolerance w i l l be the population component f i r s t affected. This may r e f l e c t i n a f a i l u r e to breed, nest, or successfully r a i s e young. Thus the stable population as observed now at Quinsam Lake seems destined to dwindle and disappear, primarily as a r e s u l t of the ecology of hens. The occurrence of Plagiorhyncus and Dispharynx as new host records coupled with t h e i r abundance and pathogenicity leads to further speculation. Both parasites are common. 133 ^ispharynx has a cosmopolitan d i s t r i b u t i o n and occurs i n the ruffed grouse, crow (Corvus brachyrhyncos), robin (Turdus  migratorius) and other birds, Coble (1945). Plagio rhyncus occurs i n old world avifauna, and P. formosus has been recorded from the rob i n i n Alaska, Van Cleave and Williams (1951). I f the f a i l u r e of Beer (1944) and Fowle (1944) to f i n d the two pathogens i s r e a l , then t h i s may indicate the sooty grouse has acquired these parasites i n r e l a t i v e l y recent times. The extreme host reaction would tend to support t h i s conclusion, f o r i n long host parasite associations, each member becomes adapted to the other and both l i v e together more or less harmoniously. Assuming Dispharynx and Plagiorhyncus endemic i n the ruffed grouse and robin p r i o r to man's logging and burning, then the stage i s set f o r a new host parasite r e l a t i o n -ship involving the sooty grouse. With a tremendous increase i n numbers by v i r t u e of the new range made ava i l a b l e , the chances of host parasite contact through the isopod vector are increased accordingly, u n t i l i f necessary, a sooty grouse form of Dispharynx and Plagiorhyncus becomes established, ^hua a change i n population size has resulted i n the introduction of a new environmental factor a f f e c t i n g the sur v i v a l of the species. As plant succession i n e v i t a b l y reclaims the new summer range to climax f o r e s t , the sooty grouse must retreat to a more primaeval habitat of the higher timbered slopes and mountain meadows beyond the range of the ruffed grouse and robin. Dispharynx and Plagiorhyncus would now be i s o l a t e d i n 13k the sooty grouse. Granted the necessary intermediate hosts and assuming genetic mutation, or natural selection or both would occur i n the newly established forms, t h i s ecological i s o l a t i o n would f u l f i l l the f i r s t r e q u i s i t e of speciation. 135 SUMMARY AND CONCLUSIONS 1. A population of sooty grouse (Dendragapus obscurus  fuliginosus) has been studied on i t s summer range over the years 1950 to 1953. 2. Sooty grouse chicks by September of t h e i r f i r s t year are i n plumage s i m i l a r to the adults with the exception of shorter and narrower t a i l r e t r i c e s . The annual post nuptial moult follows a recognizeable pattern with the replacement of wing t a i l and body feathers. There i s evidence that annual wing feather moult i s not complete i n adult b i r d s . 3. As c r i t e r i a of age, yearling males have outer t a i l feathers ranging i n length between 13.2 and 15.2 cm. The outer r e t r i c e s of adult male birds of 2 years and older, range between 16.1 and 19.4 cm. Yearling females have outer t a i l feathers ranging i n length between 11.7 and 13.4 cm. The outer r e t r i c e s of adult females range between 13.5 and 16.1 cm. 4. A sample of 14 adult males i n spring averaged 1300 • 50 g. i n weight. A simi l a r summer sample averaged 1200 * 25 g. A sample of 20 adult hens weighed i n the summer averaged 850 • 25 g. 5. Eight y e a r l i n g males and 11 yearling females weighed i n June and July averaged 1100 ± 50 g. and 780 • 25 g. respectively, an i n d i c a t i o n that yearling males and females do not a t t a i n adult weight u n t i l a f t e r July of t h e i r second year. 136 6c L o c a l i z a t i o n , i s o l a t i o n and vocal display on an area with w e l l defined boundaries between adjacent males are features c h a r a c t e r i s t i c of t e r r i t o r i a l behaviour i n the adult male. 7. Te r r i t o r y size as determined i n t h i s study might be r e a l and represent the maximum area over which a given b i r d hooted throughout a study period, or apparent and represent the maximum area over which a given b i r d was observed to hoot. 8. There appears a rel a t i o n s h i p between the lo c a t i o n of t e r r i -t o r i e s and the dense vegetational types which would provide concealment f o r a hooting b i r d . No rela t i o n s h i p was found between t e r r i t o r y l i m i t s and the l i m i t s of the described vegetational types. T e r r i t o r i e s contain open areas i n which hens feed and are e a s i l y seen as well as dense shelter vegetation. 9. Adult males exhibit a "homing" behaviour i n returning to t h e i r previous year fs t e r r i t o r i e s i n subsequent springs. 10. T e r r i t o r y s i z e appears to be a density dependent factor which i s inversely proportional to abundance of hooting males. 11. The males i n daylight hours show a r e l a t i v e l y high u t i l i z a -t i o n of F i r Dense type with the remaining shelter types less frequently used. 12. The hooting a c t i v i t y of a male appears to be stimulated by that of adjacent males and hooting possibly influences i t s 137 movements contributing to the extent of t e r r i t o r y . The presence of hooting males and suitable shelter vegetation might be considered as factors i n i t i a t i n g t e r r i t o r i a l behaviour. 13. Fighting appears to function as a mechanism by which t e r r i -t o r i a l boundaries between adjacent males are established and trespassing males are repulsed. I t may result i n the displacement of one male by another. 14. Theoretically the f u l l courting display would serve as a mechanism i d e n t i f y i n g a receptive male to a receptive female. The i n i t i a l stage of the courting display i s a response of a general nature. I t may become the f u l l courting display or the f i g h t i n g posture depending upon a more s p e c i f i c response at sex recognition. Sex recognition i s apparently made through plumage or size dimorphism or both. 15. The purpose of t e r r i t o r y appears to be i n the undisputed use of area wherein hooting and courting display can function to f u l f i l l the reproductive requirements of the male. T e r r i t o r i e s can be considered mainly as areas of display and courting a c t i v i t y . 16. There i s a marked seasonal behaviour i n the adult male i n terms of t e r r i t o r i a l behaviour, sexual a c t i v i t y , and migration from the summer range i n June to August. There appears a r e l a t i o n between these phenomena and a decrease i n testes volume. 138 17. Yearling males do not manifest the sexual and t e r r i t o r i a l behaviour as found i n the adult male, and are apparently vagrants on the summer range. The r e l a t i v e l y small testes volume observed i n yearling males appears correlated with these phenomena. 18. Most males leaving the summer range as chicks do not make the downward migration u n t i l t h e i r second spring a f t e r hatch. The migration i n the male appears related to sexual development as measured by testes volume. 19. As the cocks, the hens appear to return to the same area of the summer range i n subsequent years. Unlike the cocks they move independently over a r e l a t i v e l y large area which might be called a home range. 20. Hens p r i o r to incubation showed tendency to u t i l i z e the dense vegetational types and Clover Open which would provide shelter and food respectively. 21. It i s l i k e l y that sooty grouse of both sexes are promiscuous of breeding habit. 22. The production of ova apparently begins i n l a t e A p r i l and early May, and continues while the eggs are l a i d from the second to the l a s t week of May. The brood patch i s apparent-l y i n c i p i e n t as the eggs are deposited and becomes f u l l y developed at the cessation of l a y i n g a c t i v i t y and the begin-ning of incubation. 23. The average clutch size l a i d by nesting hens appears to be 6 eggs or possibly lower. On the basis of r i p e ova and shed f o l l i c l e counts the productivity of nesting adult and yearling hens i s s i m i l a r . 24. The open vegetational types are u t i l i z e d f o r nest s i t e s , 25. Morning and evening movements of the hens are part of a we l l defined diurnal a c t i v i t y rhythm of the grouse i n the study area. Light i n t e n s i t y up to 4 foot candles appears to be a factor influencing the r e l a t i v e l y intense a c t i v i t y of morning and evening as compared to the remainder of the day. 26. The variations i n climate as recorded i n 1950, 1951 and 1952 had no apparent effect on time of peak hatch. Over the three years 80$ of the hatch occurred between June 8th and June 28th. June 15th to June 21st i s taken as the week of peak hatch. 27. There i s a marked change i n hen behaviour as she becomes the centre of brood organization. Signals from the hen and chicks are factors i n early brood organization and chick behaviour. 28. Brood organization and chick behaviour change with age. In July and a f t e r of 1950 brood disorganization occurred. I t i s suggested a summer's climate, through i t s effect on food vegetation, influences brood organization. 140 2 9 . The observed movements of females with young vary con-siderably with map distances up to £ mile recorded between observations. 3 0 . The open vegetational types are u t i l i z e d most frequently by the hen and brood. This habitat preference appears related to the a c t i v i t i e s of the chicks. 3 1 . The a l t i t u d i n a l migration of the hens with young began a f t e r August i n 1950 and i n July of 1951 and 1 9 5 2 . I t i s suggested a summer's climate through i t s effect on food vegetation conditions the a l t i t u d i n a l migration of hens with young. 3 2 . A sample of 13# chicks collected over the period June 15 to August 15 i n 1951 and 1952 was equal i n sex r a t i o . 3 3 . Over the period June 15 to September 23 the average growth rate of young males was 60 grammes per week, and young females 50 grammes per week. 3 4 . Over the years 1950 to 1953 sexually active males, females and females with broods have Remained stable i n numbers, or t h e i r increase or decrease has not been detected. 3 5 . The yearly turnover i n adult males i s 3 1 $ or a yearly s u r v i v a l of 6 9 $ . I t i s assumed the same i n adult females. The average length of l i f e of a sooty grouse once i t has reached y e a r l i n g age i s calculated as 3 . 2 years. 36. The population status observed at Quinsam Lake can be explained as a condition wherein 40% of the females are unproductive or lose a l l young, 60% of the females lose 4 out of 6 or 67% of t h e i r young i n the summer months. The surviving young have a 47% f a l l and winter mortality which reduces t h e i r numbers to a l e v e l that equals the 31% yearly loss i n the older age classes and r e s u l t s i n the observed stable population. 37. 70% of the yearling hens and 96% of the adult hens on the study area are breeding hirds. 38. Dispharynx and Plagiorhync Aus are important chick mortality factors and explain i n most part the 40% broodless females and 67% brood decrease observed i n the study area. These parasites l i k e l y produce a further mortality on the winter range and contribute to the 47% f a l l to spring mortality calculated f o r the chicks. Disease, caused by Dispharynx and Plagiorhyncus can be considered a major factor e f f e c t -ing population size and s t a b i l i t y on the study area. 39. 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J. Anim. Ecol. 2:132-178. and V.A. Bailey 1935. The balance of animal populations. Part I. Proc. Zool. S o c , London, 1 9 3 5 : 5 5 1 - 5 4 8 . Oosting, H.J. 1 9 4 8 . The study of plant communities. W.H. Freeman and Co. San Francisco. Patterson, R.L. 1 9 5 2 . The sage grouse i n Wyoming. Wyoming Game and Fish Commission, Sage Books Inc. Denver. Robertson, F.W. and Sang, J.H. 1 9 4 4 . The ecological deter-minants of population growth i n a Drosophila culture. I. Fecundity of adult f l i e s . Proc. Roy. S o c , London, s.B. 1 3 2 : 2 5 8 - 2 7 7 . 145 Ricker, W.**. 1948. Methods of estimating v i t a l s t a t i s t i c s of f i s h populations. Indiana University Publica-t i o n , Science Series No. 15. Schneider, H.A. 1949. Influence of n u t r i t i o n i n experimental i n f e c t i o n . Bact. Rev. 13:99-134. Schottelius, B.A. 1951. Studies on blue grouse (D.O. p a l l i d u s swarth) i n the Methow Valley of Washington. M.S. Thesis, State College of Washington, Pullman, Washington. Smith, H.S. 1935. The rol e of b i o t i c factors i n the determina-t i o n of population d e n s i t i e s . J. Econ. Entom. 28: 873-898. Stewart, R.E. and John W. A l d r i c h 1951. Removal and repopula-t i o n of breeding birds i n a spruce-fir f o r e s t community. Auk 68:471-482. Swarth, H.S. 1926. Report on a c o l l e c t i o n of birds and mammals from the A t l i n region, northern B r i t i s h Columbia. Univ. C a l i f . Pub. i n Zoo. 30:51-162. Taylor, E.W. 1950. Report on Vancouver Island blue grouse harvest, 1949-1950. Unpublished B.C. Game Report. Tinbergen, L. 1946. De sperwer a l s roofvijand van zangvogels. Ardea 34:1-213. Tinbergen, N. 1939. The behaviour of the snow bunting i n spring. Trans. Linn. Soc. New York, 5:l»-94. Uvarov, B.D. 1931. Insects and climate. Trans. Entom. S o c , London, 79:1-247. Van Cleave, H.J. and R.B. Williams 1951. Acanthocephala from passerine birds i n Alaska. J . Parasit. 37:151-159. Van Rossem, A.J. 1925. F l i g h t feathers as age indicators i n Dendragapus. I b i s 12:417 -422. Volterra, Vito 1926. V a r i a z i o n i e f l u t t u a z i o n i del numero d'i n d i v i d u i i n specie animali conviventi. Mem. Accad. L i n c e i , 2(6):31-113. Wing, L. 1943. B l u e grouse. Am. For. 49:58-59, 96. , J . Beer and Wayne Tidyman 1944. Brood habits and growth of blue grouse. Auk 61:426-440. 1947* Seasonal movements of the blue grouse. N.A. Wild. Conf. 12:504-511. Table I Weather data. Weekly Records. 1 9 5 0 , 1 9 5 1 , 1952, 1 9 5 3 . Year 1 Week No. • : i : 2 ! 3 : 4 ! 5 : 6 : 7 : s: : 9 : ; 1 0 : I I ! 1 2 : 1 3 ! HI 15: 1 6 ! 17*. 1 8 : 19 1950 Av. Temp. °F. 69 68 59 72 64 69 76 65 65 65 Av. Max. 78 79 68 85 77 80 86 78 77 79 Av. Min. Av. Rain c.c. Day's Rain 0 1 2 . 5 0 2 . 5 1 2 2 1 .5 Av. Evap. c.c. 1951 Av. Temp. °F. 57 56 65 66 72 70 72 64 73 69 61 67 Av. Max. 60 64 64 73 67 74 81 77 75 73 77 76 75 71 80 Av. Min. 41 47 44 47 51 46 52 53 54 54 51 53 53 51 53 Av. Rain c.c. . 2 .1 .1 0 0 0 0 a . 2 0 0 0 0 0 0 Day's Rain 3 2 1 0 0 0 0 2 1 0 0 0 0 0 0' Av. Evap. c.c. 4 4 7 9 4 12 11 7 6 4 8 7 1952 Av. Temp. °F. 51 2 2 45 52 61 59 61 61 55 58 62 60 76 69 63 73 71 67 58 Av. Max. 60 60 53 58 69 65 70 66 62 65 69 64 87 77 67 84 84 82 71 Av. Min. 42 35 35 38 47 46 44 41 44 43 51 49 51 51 50 51 53 52 44 Av. Rain c.c. 0 0 . 5 . 1 0 . 1 . 1 . 1 . 1 . 1 . 1 . 1 0 0 . 1 0 0 0 0 Day's Rain 0 0 4 2 . 5 0 3 1 . 5 3 . 5 2 . 5 2 4 0 0 2 0 0 0 0 Av. Evap. c.c. 5 7 4 5 5 4 7 11 6 4 5 3 11 10 4 9 8 4 4 1953 Av. Temp. °F. 61 56 60 62 66 60 Av. Max. 73 67 70 74 77 70 Av. Min. 49 45 51 49 56 50 Av. Rain c.c. Day's Rain 3 1 .5 1 1 2 1 .5 A'v. Evap. c.c. Table IV Number of observations and accumulative area units of 5 males of plot I I Male No. 162 : Male (7,L) : Male (11,1) : Male No. 147 : Male No. 781 No. : Acc. :No. : Acc. : •No. : Acc. : No. Points: Acc. :No. : Acc. Points : Area x :Points : Area :Points : Area : Area : Points : Area 10 : 13 : 10 : 10 : 10 : 12 : 10 : 11 : 10 ! : 12 20 : ! 23 : 20 : : 13 : 20 : 18 , : 20 ! : 16 i : 20 : ! 16 30 : : 24 \ 30 i : 15 : 30 i t 19 : - 22 : : 30 ! : 29 40 : 25 i 40 1 15 ; 40 :  20 : 50 '. i 3 1 50 . \ 16 60 ! i ' 3 1 i 70 I 43 i 80 ; 43 ! xTo convert to acres multiply by . 0 5 . Table V Cover type and u t i l i z a t i o n on plots I and I I Clockers ! Nests ! Females \ Males \ 'Females with broods Type No. : U t i l - : % U t i l - : No. : U t i l - :% U t i l - " : No. : U t i l - : % U t i l - : No. : U t i l - :% U t i l - : : No. : U t i l - :% U t i l -•noted : i z a - : i z a t i o n :noted : i z a - : i z a t i o n : noted : i z a - : i z a t i o n •noted : i z a - r i z a t i o n : noted : i z a - r i z a t i o r : t i o n x : : tion • :tion : :tion Z ; :tion • Plot I : F.D. F.O. W.D. : 6 22 1 : : 0 0 0 : : 20 74 16 ! 62 230 27 : 5 19 2 _ W.O. • 6 20 1 : : 2 7 12 : 19 63 14 : 91 300 35 . : 12 40 5 £ B.O. : 47 2 0 4 11 r 5 22 35 : 8 35 8 : 50 220 26 :  16 70 8 P L.O. : 13 72 4 " : 6 33 53 « 6 33 7 : 19 105 12 : : 12 67 8 ^ CO. : 31 1550 83 : 0 0 0 : : 5 250 55 : 0 0 0 • : 13 650 77 Plot I I F.D. 1 14 1 : 0 0 0 : 32 460 42 : 56 800 60 : : 2 29 3 F.O. • 13 20 2 : • 11 17 11 : 40 61 5 : 90 135 10 : 43 65 7 W.D. • 3 30 3 : 0 0 0 : ' 25 250 22 :  21 210 16 : 5 50 5 W.O. 0 0 o • : 0 0 0 : 0 0 0 : : 0 0 0 : 0 0 0 B.O. 4 80 9 : 4 80 50 : 1 20 2 : : 5 100 7 : 5 100 11 L.O. : 8 100 12 : : 5 62 39 • : 2 25 2 : ' 8 100 7 : 11 137 14 CO. : 19 633 73 : 0 0 0 : • 9 300 27 :  0 0 0 : 17 566 60 xNumber noted divided by proportion of vegetational type on each plot^Table I I ) . (iv) Table VI Grouse a c t i v i t y and time of day i n the periods A p r i l 13 to May 1 5 , May 16 to June 5 Time : A p r i l 13 - May 15 May 16 - June 5 of day i£ hrs:Males :Other:Males •.Other :£ hrs.rMales :Other:Males rOther : i n rwith :activ -cwith ractiv-: i n rwith ractiv--rwith ra c t i v -(standard) -: f i e l d : f e - : i t y :females : i t y : f i e l d : f e - : i t y :females : i t y males • • :per £ :per £ males •> * :per £ :per £ • • * :hour rhour • rhour rhour 0230 0 3 0 0 : : 2 0 0 0 0 : : 2 0 0 0 0 0300 0330 : : 2 0 0 0 0 : : 3 2 14 . 7 5 0330 0400 . : 2 1 8 . 5 4 : 6 38 30 6 5 0400 0430 ' : 5 10 23 2 5 : • 2 1 9 . 5 5 0430 0500 : : 4 56 67 14 17 : 1 0 5 0 5 0500 0530 • : 3 10 7 3 2 : 1 0 3 0 3 0530 0600 . : 2 0 4 0 2 : 1 0 5 0 5 0600 0630 • : 2 0 10 0 5 : 1 0 2 0 2 0630 0700 : : 1 1 3 1 3 1 2 0 0 0 0 0700 0730 : : 2 0 9 0 5 . : 2 0 1 0 .5 0730 0800 • : 2 0 6 0 3 : 6 3 21 . 5 3 0800 0830 . : 8 4 2 4 .5 3 : 10 0 22 0 2 0830 0 9 0 0 : 14 0 45 0 3 : 1 15 1 24 . 1 2 0900 0930 : 21 7 67 . 3 3 : 16 1 29 .1 2 0 9 3 0 1000 : 19 10 55 . 5 3 ' • 15 3 23 . 2 2 1000 1030 : 21 20 58 1 3 :  16 2 31 . 1 2 1030 1100 . : 22 17 71 . 8 3 : ' 15 0 24 0 2 1100 1130 • : 19 3 60 . 2 3 : : 10 12 17 1 2 1130 1200 : 16 10 43 . 6 3 : • 8 3 19 . 4 2 1200 1230 . 18 6 48 .3 3 : : 4 0 18 0 5 1230 1300 . : 18 0 43 0 2 : : 2 0 5 0 3 1300 1330 , : 19 7 65 . 3 3 • : 4 2 18 . 5 5 1330 1400 : 14 1 49 . 1 3 : ' 4 0 5 0 1 1400 1430 : 13 2 38 . 2 3 • 6 4 14 . 7 2 1430 1500 : 11 0 31 0 3 : . 7 0 5 0 .7 1500 1530 • 13 1 44 .1 3 : : 9 2 15 . 2 2 1530 1600 : 12 1 20 . 1 2 : : 11 0 19 0 2 1600 1630 • 13 0 19 . 0 1 : : 10 0 18 0 2 1630 1700 : 14 10 27 .7 2 : 8 0 19 0 2 1700 1730 : 10 5 31 . 5 3 : • 6 0 16 0 3 1730 1800 : 6 1 7 . 1 1 : 5 4 11 1 2 1300 1830 : 4 0 13 0 3 : 2 3 5 1 3 1330 1900 : 2 0 9 0 4 : 2 0 8 0 4 1900 1930 : 5 19 22 4 5 : 5 0 15 0 3 ! 1930 2000 : 12 67 74 6 6 : 6 1 19 . 2 3 2000 2030 : 16 122 134 8 9 : 16 153 117 3 7 2030 2100 : • 7 10 27 1 4 J 16 144 166 3 10 2100 2130 : 2 0 0 0 0 :  13 94 103 7 9 2130 2200 : 2 0 0 0 0 • 2 9 14 4 7 2200 2230 : 2 0 0 0 0 : : 2 0 0 0 0 2230 2300 : 2 0 0 0 0 . • 2 0 0 0 0 Table VII Number of week-old broods observed per hour i n weeks 6 to 16, 1950, 1951, 1952. 1950 : : No. : :Hrs. in:week- : No. i 1951 » •> » •> :Hrs. i n : No. : week-: No. : : 1952 : : No. : ;Hrs. in:week- : No. Week . f i e l d : old : :broods: per hour : : f i e l d : old : per ' : :broods:hour ; f i e l d : old : :broods: per hour 6 - - 15 0 0 : : 19 0 0 7 j - - - : 27 0 0 ! : 20 0 0 8 ; - - : 33 2 .06 : : 6 0 0 9 : 25 1 .04 i 32 5 .16 ! ! 23 4 .17 10 : 32 2 .06 : : 22 5 .23 : i 13 4 .30 11 : 24 4 .17 ! 22 2 .09 ! 20 2 .10 12 j 26 0 0 : 24 0 0 '. : 16 0 0 13 i 28 1 .04 ' 27 1 .04 : : 27 4 .11 14 ! • 29 0 0 I : 37 0 0 • : 20 3 .05 15 : 24 0 0 - - - : 12 0 0 16 I 33 0 0 : : 7 0 o : 17 0 0 (vi) Table VIII Weight development with age i n 224 chicks, 1950, 1951, 1952. Week Age :Sample: weeks: size : Males, average weight:Sample:Fjemales, average and 95% c o n f i - : size : weight and 95% . dence l i m i t : : confidence l i m i t 10 1 9 38 ± 16 gms. 3 34 113 gms. 11 2 10 42 i 9 n 12 66 • 22 n 12 3 11 104 i 15 n 10 1 0 5 t 3 7 tt 13 4 10 189 t 55 « $ 130 1 17 tt 14 5 7 260 i 106 9 207 - 44 n 15 6 13 250 t 50 n 15 230 i 29 ft 1 6 7 11 283 i 95 n 9 293 1 46 n 17 8 14 394 ±66 n 11 361 ± 80 n 18 9 2 515 + 221 n 3 460 *112 n 19 10 3 573 t387 n - - -20 11 - - - - - -21 12 - - - - - -22 13 - - - - - -23 14 14 825 i 88 tt 14 632 •• 20 ft 24 15 20 8 8 4 £ 48 20 724 t 35 n Table IX Males, females, and females with broods observed per hour per week i n study area, 1950 to 1953. Week : : 1950 ; 1951 : : 1952 j 1953 of : ;Cen- :Males :Fe- :Broods : Cen- :Males :Fe- :Broods: Cen- :Males :Fe- :Broods ,Gen- :Males : Fe- :Broods study :sus : per :males : per : sus : per :males : per : sus : per :males : per : :sus : per males : per :hours:hour : per :hour : hours:hour : per :hour : hours :hour : per :hour : hours:hour : per :hour i n • • :hour • i • i i n * :hour * t » i : i n thour • 4 » i i n : :hour • • : f i e l d • • * • f i e l d » * • • i • : f i e l d • • f i e l d : • • • 1 ! • 18 1.03 . 5 6 0 : 2 : 39 2 . 2 . 5 5 0 : 3 : 29 2 . 7 .41 0 4 ! 19 1 . 6 . 3 7 0 : 38 2 . 6 . 6 1 0 5 : : 32 1 .5 . 6 6 o : . 28 2 . 5 . 5 8 0 , H * 6 15 2 . 1 . 4 8 o ; : 19 2 . 2 . 7 0 0 7 : 27 1 .3 . 4 9 : 20 1 .5 . 3 9 0 8 : 0 ; 33 1 . 4 .31 . 0 6 i : 6 1 .3 . 6 6 0 ; 3 1 .5 0 0 9 : 25 1 . 0 . 6 8 0 : 32 1 .2 . 2 8 .06 : 23 1 . 4 . 3 1 .13 : : 18 1 .7 .11 . 0 6 10 : 32 1.1 . 3 8 .06 : ; 22 . 9 5 .23 . 4 5 : : 13 1 . 8 . 0 8 . 0 8 : n l . o 0 . 1 0 11 ; 24 1.1 . 2 6 . 2 5 \ 22 . 7 9 . 0 9 . 8 7 : ; 20 1 .5 . 5 1 . 2 0 ! 9 1 .3 0 . 5 9 12 • '> 26 1 . 0 . 2 3 .19 24 .71 . 2 1 . 2 5 : 16 1 . 4 . 3 2 . 3 8 0 13 = . 28 . 4 7 .11 .75 ; : 27 .15 . 19 .41 « 27 . 9 6 .15 . 5 6 : : 20 . 8 8 . 2 5 1 .1 14 ' ; 29 .41 . 2 1 . 7 9 : : 38 . 2 7 . 0 8 . 6 7 ; ; 20 . 6 7 . 2 6 . 9 2 ' 15 . ' 24 . 2 1 . 16 . 8 8 , : o : 1 2 . 4 9 0 . 4 9 16 ; 33 . 3 0 . 2 7 . 8 1 i ! 7 0 0 . 2 9 ! : 17 . 12 . 0 6 .53 ' 17 « : 22 .14 .14 1 .3 : : 33 0 0 . 1 8 ; : 10 . 3 . 3 . 3 18 : 31 0 0 1 .3 : 0 > 0 19 : 3 0 0 3 . 1 . ( v i i i ) Table XI Average weekly brood s i z e s , f o r the three-year study period. 1950 ! 1951 » 1952 Date :Week: : No. :Aver-:broods rage : :size : No. rbroods > * :Aver-:age :size : No. :Average rbroods: size • • • * June 15 - 21 10 3 1.7 14 2.5 9 3.3 22 - 28 11 6 4.0 19 3.3 5 3.2 2 9 - 5 12 7 2.7 12 4.3 11 3.3 July 6 - 12 13 21 2.9 21 3.6 14 2.6 13 - 19 14 25 2.4 2 5 2.6 28 • 1.9 20 - 2 6 15 19 2.4 - - 6 2.5 27 - 2 16 55 2.7 4 2.7 18 2.1 Aug. 3 9 17 28 3.2 11 1.8 9 2.0 10 - 16 18 44 3.2 - - 13 1.5 17 23 19 9 3.8 7 1.7 Table XIV Age and infections i n chicks. Lumped data 1950, 1951, 1952. Age, weeks 1 : 2 : 3 : 4 : 5 1 6 ' . 7 : 8 : 9 : : A H ages Sample size ! 11 : io : io : . i i . 6 : . 12 . 7 : . 9 : 13 : 89 Infected :No, ; % • » • • :No.: % • :N0, • 8 % : Not • :* fo ' • % s :No, I % :No. : % ; :No. * • • fo :No.: 4, \ k * • * m m : No. : # Haemoproteus 2 18 6 60 8 80 7 64 4 66 5 42 7 100 9 100 11 85 59 66 Leucocytozoon 0 0 0 0 2 20 4 35 3 50 3 25 5 72 7 78 10 77 34 38 Trypanosoma 1 9 3 30 4 40 1 9 0 0 3 25 2 29 2 22 2 15 18 20 M i c r o f i l a r i a 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Sample size • : 14 \ 13 ! \ 15 ; : 15 ! : io : : 21 1 ; 9 : ; o : \\ 109 Infected • :No. ; % •No!: No. \ fo :No. No.: :No.: % : » » :No.: % ' tNo. • • fo : :No.: : :: No. • • fo Dispharynx 2 14 4 40 6 46 13 87 14 94 7 70 17 81 5 56 68 64 Cheilospirura) Yseria j 0 0 0 0 0 0 2 13 1 7 0 0 6 29 2 22 - - 11 10 Rhabdometra 0 0 0 0 1 8 4 27 2 13 1 10 9 43 5 56 22 21 Ascaridia , 0 0 0 0 0 0 0 0 1 7 1 10 1 5 1 11 _ _ 4 4 Plagiorhyncus 2 14 3 30 6 46 10 67 11 73 6 60 11 50 4 45 - - 53 50 Ceratophyllus 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Lagopoceus 0 0 0 0 5 38 4 27 0 0 5 50 6 29 1 11 — _ 21 20 Ornithomyia 0 0 0 0 0 0 0 0 3 20 0 0 2 11 2 22 — — 7 7 (x) Table XV $ Haemoglobin l e v e l s of 2 5 adult grouse by S a h l i haemoglobino-meter. 100, 85, 91, 83, 73, 85, 73, 90, 75, 90, 93, 108, 95 85, 88, 100, 68, 90, 95, 80, 78, 70, 86,1 C8, 75. Arithmetic mean 87$ $ Haemoglobin l e v e l s of 25 grouse chicks by Sah l i haemoglobino-meter.  70, 85, 7 2 , 95, 88, 83, 80, 88, 83, 80, 79, 90, 70 82, 8 4 , 80, 80, 93, 80, 62, 80, 82, 70, 75, 80. Arithmetic mean 80$ Number of r.b.c. per cu. m.m. of blood i n 2 adult grouse 2,080,000 2,040,000 Number of r.b.c. per cu. m.m. of blood i n 5 grouse chicks 1 week of age - 1,800,000 over 2 weeks of age - 3,360,000 1,800,000 2,680,000 2,560,000 Volume i n c.c. of l i v e r s from 39 adult grouse 19, 27, 19, 29, 20, 20, 22, 25, 18, 18, 20, 18, 18. 18, 20, 19, 16, 30, 20, 20, 28, 28, 22, 26, 17, 22. 18, 24, 13, 20, 23, 20, 20, 13, 12, 20, 16, 18, 20. Volume i n c.c. of spleens from 39 adult grouse 1.3, 0.8, 1.5, 2.0, 1.0, 3.0, .5, 1.0, 4.0, 3.0, 0.8, 1.0, 1.0. 1.5, 1.5, 2.0, 2.5, 2.0, 0.5, .75, 1.0, 1.2, 1.0, 1.0, 1.0, 1.0. 0.5, 1.5, 2.5, 2.0, 2.0, 0.5, 2.0, 3.0, 1.0, 1.0, 0.5, 1.0, 1.5. Table XVI Age ^ f chicks, percent infected, and i n f e c t i o n l e v e l s with Dispharynx and Plagior- hyncus. Lumpted data, 1951 and 1 9 5 2 . Age, weeks : i : 2 1 3 \ 4 1 5 : 6 : 7 : 8 Sample size : 14 : 10 : 13 : ; 15 : 15 : 10 : : 21 : 9 No. infected with Dispharynx 2 4 6 13 14 7 17 5 % i n f e c t i o n 14 40 46 87 94 70 81 56 Average No. worms per i n f e c t i o n Range 2 ( 1 - 2 ) 6 (2-14) 42 ( 1 2 - 1 0 0 ) 60 ( 1 3 - 2 0 0 ) 44 ( 2 - 1 3 6 ) 27 (2-50) 86 ( 1 - 4 3 0 ) 69 ( 2 - 1 7 5 ) No. infecte^d with Plagiorhyncus 2 3 6 10 11 6 11 4 % i n f e c t i o n 14 30 46 67 73 60 50 45 Average No. worms per i n f e c t i o n Range 1 ( 1 - 2 ) 1 (1) 11 ( 3 - 3 3 ) 8 ( 3 - 2 0 ) 5 ( 1 - 1 3 ) 4 ( 1 - 9 ) 12 ( 1 - 4 7 ) 10 ( 7 - 1 5 ) No. infected with both parasites 1 1 6 8 11 4 10 4 % i n f e c t i o n 1 1 46 53 73 40 48 44 

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