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UBC Theses and Dissertations

Population fluctuation and changes in the quality of rock ptarmigan in Alaska Theberge, John B. 1971

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POPULATION FLUCTUATION AND CHANGES IN THE QUALITY OF ROCK PTARMIGAN IN ALASKA by JOHN B. THEBERGE B.Sc.A., U n i v e r s i t y of Guelph, 1964 MSc , U n i v e r s i t y of Toronto, 1966. t h e s i s submitted i n p a r t i a l f u l f i l l m e n t of the requirements f o r the degree of DOCTOR OF PHILOSOPHY i n the Department of Zoology We accept t h i s t h e s i s as conforming to the r e q u i r e d standards THE UNIVERSITY OF BRITISH COLUMBIA 1971 In p r e s e n t i n g t h i s t h e s i s in p a r t i a l f u l f i l m e n t o f the requirements f o r an advanced degree at the U n i v e r s i t y of B r i t i s h Columbia , I agree that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r re ference and study . I f u r t h e r agree t h a t permiss ion fo r e x t e n s i v e copying o f t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the Head of my Department o r by h i s r e p r e s e n t a t i v e s . It i s understood that copying o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l ga in s h a l l not be a l lowed wi thout my w r i t t e n p e r m i s s i o n . Depa rtment of ^The U n i v e r s i t y o f B r i t i s h Columbia Vancouver 8 , Canada ABSTRACT This study attempts to explain changes i n abundance of rock ptar-migan (Lagopus mutus) at Eagle Creek, Alaska. I t includes an analysis of population data c o l l e c t e d from 1960 to 1969, and a t e s t of an hypothesis: that there were no d i f f e r e n c e s i n the q u a l i t y ( s u r v i v a l , growth, behaviour) of rock ptarmigan chicks between years that influenced spring d e n s i t i e s . Spring d e n s i t i e s fluctuated between 1960 and 1969, reaching peaks i n 1962 and 1968'. This was the r e s u l t of an o r d e r l y and generally syn-chronous change i n the loss of b i r d s (primarily juveniles) i n winter, accompanied by changes i n the production of young. Both acted.together • i n most years to either increase or decrease numbers. Each contributed • approximately equally to changes i n t o t a l annual l o s s . Changes i n the production of young were p r i m a r i l y caused by p a r a l l e l changes i n both cl u t c h sizes and nest f a i l u r e s . Population regulation by d i r e c t e x t r i n s i c c o n t r o l appeared u n l i k e -l y . Other than weasel predation on nests, no environmental factor external to the population i t s e l f appeared s u f f i c i e n t to explain changes i n winter loss of juveniles or c l u t c h s i z e l o s s , or t h e i r synchrony. These r e s u l t s suggested that some i n t e r n a l process within the population must have been important i n changing the abundance of partmigan. I tested the aforementioned hypothesis i n 1967, 1968, and 1969 by examining chicks both i n the wild, and i n c a p t i v i t y . S u r v i v a l , growth, and behaviour of chicks a l l varied between years. Changes i n s u r v i v a l were apparently determined by u n i d e n t i f i e d parental influences (genetic or p h y s i o l o g i c a l ) rather than by the d i r e c t influence of the environment. Growth rates were s i m i l a r between years i n c a p t i v i t y , but not i n the wild, suggesting that environmental influences must have had some e f f e c t . However, neither the changes i n s u r v i v a l of chicks i n summer, nor i n growth rates, could be implicated i n a l t e r i n g subsequent spring breeding d e n s i t i e s . Levels of agonistic and aggressive behaviour i n successive cohorts of aviary chicks d i f f e r e d . In the s i m i l a r environment of the aviary each year, these behavioural changes were a t t r i b u t e d to undetermined parental influences (genetic or p h y s i o l o g i c a l ) . These changes i n aggressive-agon-i s t i c behaviour o f f e r the best p o s s i b l e explanation of changes i n the. population parameters most important i n a l t e r i n g spring breeding densities.. TABLE OF CONTENTS Page ABSTRACT . . . . . . . . . . . . . i TABLE OF CONTENTS . i i i LIST OF TABLES . • . . . . . . v i LIST OF FIGURES X ACKNOWLEDGEMENTS . . . xv PART I. INTRODUCTORY TOPICS INTRODUCTION 1 HISTORY OF ROCK PTARMIGAN RESEARCH IN ALASKA . . . . . 6 STUDY AREA . . . . . . . . . .. . . . . . . . . 7 LIFE HISTORY OF ROCK PTARMIGAN . . . . . . . . . . .10 PART I I . POPULATION FLUCTUATIONS . .; • METHODS . . . . . .... . . . . . . . . . . - I? RESULTS . ' . . . . . . - . . . . 15 Breeding Population . . . . 1 5 Losses Throughout the Year 15 CONCLUSIONS . . . . . . , . - 25 PART I I I . CHANGES IN SURVIVAL, GROWTH AND BEHAVIOUR OF ROCK PTARMIGAN CHICKS METHODS . . . . . 27 RESULTS . . '• . . . . . . 30 Survival of Chicks i n Summer 30 F i e l d 30 Aviary . . . •.. 35 Conclusions ' . 37 Page Growth of Chicks . . . . .. . . . ' . . . . . 38 F i e l d . . . . . . . . . 3 8 Aviary 46 Organ Weights . . . . . . . . . . . 49 Conclusions . . . 5 3 Behaviour i n Summer . . . 5 3 F i e l d . . • . . . . . . . . . . . . . 55 Aviary . . . . . . . 63 Conclusions 73 PART IV. DISCUSSION 74 Population regulation by d i r e c t e x t r i n s i c control . . . 7 4 Population regulation by changes i n the q u a l i t y of the stock . . . . . . . . . . . . . . . . 87 SUMMARY 106 APPENDICES I. TECHNIQUES OF INCUBATION, HOUSING, AND REARING ROCK PTARMIGAN CHICKS . . . . . . 109 I I . MEASURING AGONISTIC AND AGGRESSIVE BEHAVIOUR IN CAPTIVE ROCK PTARMIGAN CHICKS . . . 113 I I I . MAINTENANCE, EXPLORATORY, AND GENERAL ACTIVITY AND THEIR POSSIBLE RELEVANCE TO CHICK VIGOUR . . . . 121 IV. FOOD, PREDATION, AND DISEASE IN RELATION TO SURVIVAL OF CHICKS IN SUMMER . . . . . 130 V. DIFFERENCES IN HABITATS USED BY ROCK PTARMIGAN BROODS IN 1967,1968, AND 1969 . . . . 139 VI. CAUSES OF AVIARY MORTALITY . . 144 VII. GROWTH RATES MEASURED BY WEIGHT-FOOT RATIOS . . . 147 VIII. CHARACTERISTICS OF GROWTH OF ROCK PTARMIGAN CHICKS . . . 149 Page IX. MEASURES OF COHESIVE BEHAVIOUR IN WILD ROCK PTARMIGAN BROODS 155 X. BROODMATE PECKING AND SOCIAL HIERARCHY IN CAPTIVE ROCK PTARMIGAN CHICKS . . . . . 159 XI. TEMPERATURE AND SNOWFALL DATA COLLECTED AT FAIR-BANKS, ALASKA BETWEEN 1960 & 1969 . .' . 163 XII. PATTERNS OF PIGMENT ON NINTH WING PRIMARY OF ROCK PTARMIGAN - A NATURAL TAG . . . . . 164 XIII. ADDITIONAL DATA ON.AGONISTIC AND AGGRESSIVE BEHAVIOUR IN CAPTIVE ROCK PTARMIGAN CHICKS . . . 166 XIV. PHOTOGRAPHS . . . . . 170 LITERATURE CITED . . . . . . . . 178 BIOGRAPHICAL INFORMATION LIST OF TABLES .. TABLE 1. Numbers and age r a t i o s of rock ptarmigan i n spring at Eagle Creek, Alaska 17 TABLE 2. Changes i n numbers of rock ptarmigan at Eagle Creek, Alaska, from 1960 to 1969 . . . . . . . . . . IB TABLE 3. Per cent s u r v i v a l of chicks to eight weeks of age, i n the aviary. Sample sizes are i n brackets . . . . . 3 6 TABLE 4. Survival of chicks to two weeks of age i n c a p t i v i t y and i n the wild i n Scotland, i n 1968 . . . . ,. . ••. 3,9 TABLE 5. Survival of chicks to two weeks of age i n c a p t i v i t y and i n the wild i n Scotland, i n 1969 39 TABLE 6. Weights (grams) of wild juvenile rock ptarmigan i n September . . . . . . . . . . 40 TABLE 7.< Wing lengths (centimeters) of wild j u v e n i l e rock ptarmigan i n September . . . . . . . . . . . . 40 TABLE 8. Stored body f a t of wild juvenile rock ptarmigan i n September (mgs. of f a t per gram body weight) . . . . 42 TABLE 9. Comparison of adrenal gland weights of wild juvenile rock ptarmigan i n September 1967, 1968, 1969 (mgs. per gram body weight) . . . . ; 52 TABLE 10. Comparison of testes weights of wild juvenile rock ptarmigan i n September 1967, 1968, 1969 (mgs, per gram body weight) . . . . . . . . . . .52 Page TABLE 11. Comparison of adrenal weights i n captive rock ptar-migan i n l a t e August with low agonistic scores against those with medium or high scores (mgs. per gram body weight) . . . . . .54 TABLE 12. Defense of nests by ptarmigan hens i n 1967, 1968, 1969 58 TABLE 13. Comparison of rea c t i o n of brood hens and chicks to disturbance i n 1967, 1968, 1969 . . . . . . . . 58 TABLE 14. Comparison of the reaction of chicks from y e a r l i n g and adult hens to disturbance by observer 61 TABLE 15. Brood movements from hatch to mid August (s t r a i g h t -l i n e distance), compared over f i v e years 61 TABLE 16. Comparison of stored body f a t of captive juvenile rock ptarmigan r a t i n g low i n ago n i s t i c behaviour against those r a t i n g medium or high (mgs. f a t per gram body weight) . . . . . . . . . . . . 69 TABLE 17. Comparison of changes i n winter s u r v i v a l of juve n i l e s , and c l u t c h s i z e , with snowfall i n early and l a t e winter .76 TABLE 18. Comparison of changes i n winter loss of juve n i l e s , i and c l u t c h s i z e , with temperature i n the f a l l - t o -spring period 79 TABLE 19. Densities of male rock ptarmigan i n spring i n experimentally hunted and unhunted (control) popu-l a t i o n s . . . 82 Page TABLE 20. Weights of wild f a l l j u v e n ile rock ptarmigan possess-ing d i f f e r e n t patterns on ninth primaries . . . . 92 TABLE 21. Aggressive and ago n i s t i c rank of captive Alaskan rock ptarmigan chicks during summer compared with the following March . . . . . . 96 TABLE 22. Aggressive rank of captive S c o t t i s h rock ptarmigan juveniles i n f a l l compared with the following Spring . . . , . . . 96 TABLE 23. Agonistic behaviour shown by rock ptarmigan chicks towards strange chicks . . . . 116 TABLE 24. Agonistic and aggressive behaviour shown towards t h e i r mirror image by i n d i v i d u a l rock ptarmigan chicks i n i s o l a t i o n . . . . . . . . . . . . . . 118 TABLE 25. E f f e c t s of age on maintenance and exploratory a c t i - ' v i t y i n captive rock ptarmigan chicks (acts per minute of observation) . . . . . 124 TABLE 26. Analysis of crop contents of rock ptarmigan chicks * one to six days of age . . . . . . . . . . . 131 TABLE 27. Per cent of broods found from hatch to early August i n various plant associations . . . . . . . . 141 TABLE 28. Per cent of broods found at d i f f e r e n t heights on h i l l s 141 TABLE 29. Comparison of concealment of chicks when approached by observer i n 1967, 1968, 1969 . . . . . . . . 142 TABLE 30. Distance from observer at which brood hens flushed i n 1967, 1968, 1969 155 TABLE 31. Distance brood hens flew upon encounter with observer i n 1967, 1968, 1969 . . . . . . . . . . . . 155 TABLE 32. Distances flown by brood hens upon release, in 1968 and 1969 . . . . . . . . . . . . . . . . 156 TABLE 33. Defense of broods by hens i n 1967, 1968, 1969 . . . 156 TABLE 34. Distances from hens that rock ptarmigan hid when encountered by observer i n 1967, 1968, 1969 . . . .157 TABLE 35. Distances from observer.at which chicks flushed ' ' * • i n 1967 and 1969 . . . . . . . . . . . . . .157 TABLE 36. Distances chicks flew upon encountering observer i n 1967 and 1969 . . . . . . . . . . . . . 158 TABLE 37. Number of captive rock ptarmigan chicks with low, ., medium, and high agonistic ratings i n 1967, 1968, ; 1969 . ' . . . . . . . . . . . . . . . . . . . . 166 TABLE 38. Number of captive rock ptarmigan chicks with low, and medium plus high agonistic scores, from hens of d i f f e r e n t ages . . 167 TABLE 39. Weights of captive rock ptarmigan chicks r a t i n g low, medium, and high i n ago n i s t i c behaviour . . . . . 168 TABLE 40. Number of captive rock ptarmigan chicks with low, medium, and high aggressive ratings i n 1967, 1968, 1969 .169 LIST OF FIGURES FIG. 1. Map of Alaska. Arrow points to the Eagle Creek study area . . . . . . 8 FIG. 2. The Eagle Creek study area. Map shows 100 foot contour l i n e s . . . . . . . J 9 FIG. 3. Numbers of rock ptarmigan i n May on 15 square miles at Eagle Creek, Alaska, from 1960-69 . . . . . . . 16 FIG. 4. The r e l a t i o n s h i p of various losses (k to k,.) to t o t a l o 5 annual loss (K) of rock ptarmigan at Eagle Creek, J ..• Alaska . . . . . . . . . . . . . . . . . . . 19 FIG. 5. The r e l a t i o n s h i p of j u v e n i l e , and yearling-adult l o s s of rock ptarmigan i n winter at Eagle Creek, Alaska from 1960 to 1969 . . . . ', . . . . . . . . .21 FIG. 6. The r e l a t i o n s h i p of losses i n winter between sexes i n ; ju v e n i l e , and y e a r l i n g - a d u l t rock ptarmigan . . . . . 23 FIG. 7. The r e l a t i o n s h i p between summer loss of chicks and preceeding numbers of chicks plus adults at hatch . . . 24 FIG. 8. The r e l a t i o n s h i p between winter loss of juvenile rock ptarmigan and preceeding f a l l numbers .26 FIG. 9. Comparison of changes i n s u r v i v a l of wild chicks to eight weeks with differences i n mean, temperature and r a i n f a l l at. Eagle Creek. Weather data are for the week following the mean hatch date, and the month of July . . 32 FIG. 10. Comparison of changes i n chick s u r v i v a l to eight weeks with di f f e r e n c e s i n temperature and r a i n f a l l at F a i r -banks (representative of Eagle Creek). Weather data are for the week following the mean hatch date, and ; the month of July . . . . . . . . . . . . . 33 FIG. 11. Comparison of weights of wild rock ptarmigan chicks i n 1967, 1968, 1969 . . . . . . . . . . . . 43. FIG. 12. Comparison of wing lengths of wild rock ptarmigan chicks . . . . .44 FIG. 13.- Comparison of weight of captive rock ptarmigan chicks housed indoors i n 1967, 1968, 1969 . . . . . . . 4 7 FIG. 14. Comparison of wing lengths of captive rock ptarmigan chicks housed indoors i n 1968, 1969 . . . . . . . 4 8 FIG. 15. Comparison of weights of captive rock ptarmigan chicks that l i v e d eight weeks with those which did not . . . 50 FIG. 16. Per cent of brood hens showing strong brood cohesion when disturbed by observer, i n 1967, 1968, 1969 . . . 56 FIG. 17. Per cent of chicks showing strong brood cohesion when disturbed by observer, i n 1967, 1968, 1969 . . . . .60 FIG. 18. Comparison of the agonistic behaviour, ratings between years of captive rock ptarmigan chicks 65 FIG. 19. Comparison of the agonistic behaviour ratings (medium and high ratings combined) of rock ptarmigan chicks coming from adult and y e a r l i n g hens . . . . . . . 67 Page FIG. 20. Comparison of mean weights of captive rock ptarmigan chicks r a t i n g low, medium, and high i n agonistic behaviour . .68 FIG. 21. Comparison of the aggressive behaviour ratings between years of captive rock ptarmigan chicks . 7 1 FIG. 22. Comparison of per cent of f a l l juveniles possessing various pigment patterns on ninth primaries, with per cent found the following spring . . . . . . . . 91 FIG. 23. Comparison of per cent of captive rock ptarmigan , chicks with medium and high maintenance a c t i v i t y ratings i n 1967, 1968, 1969 . . . . . . . .. . .123 FIG. 24. Comparison of per cent of captive rock ptarmigan chicks with low, medium, and high exploratory a c t i v i t y r a tings i n 1967, 1968, 1969 126 FIG. 25. Comparison of per cent of captive rock ptarmigan chicks on t h e i r feet i n 1967, 1968, 1969 . . . . . 128 FIG. 26. Relationship between number of cestodes and weight of juvenile rock ptarmigan . . . 134 FIG. 27. Relationship between number of cestodes and f a t of juvenile rock ptarmigan i n September . . . . ' . . .135 FIG. 28. Relationship between number of trematodes and weight , of juvenile rock ptarmigan i n September . . . . . .136 FIG. 29. Relationship between number of trematodes and f a t of juvenile rock ptarmigan i n September . . . . . .137 Page FIG. 30. Comparison of weights of wild rock ptarmigan chicks with s p e c i f i c foot lengths . . . . 148 FIG. 31. L o g i s t i c curve of weight-gains of captive rock ptar-migan chicks shown by actual weight, and by s t r a i g h t -l i n e transformation using l o g i s t i c conversion factors . . 150 FIG. 32. Instantaneous r e l a t i v e growth rate for f i r s t 3.5 days of l i f e of captive rock ptarmigan chicks . . . . . 151 FIG. 33. Comparison of weights of male and female captive rock ptarmigan chicks . . . . . . . . . . . .' 152 FIG. 34. Comparison of wing lengths of male and female captive rock ptarmigan chicks . . . . . . . . . ... .153 FIG. 35. Broodmate pecking by captive rock ptarmigan chicks, compared between years . . . 160 PHOTOGRAPHS FIG. 36. Male rock ptarmigan i n spring i n predominantly white winter plumage 170 FIG. 37. Female rock ptarmigan brooding chicks . . . . . . 170 FIG. 38. Female rock ptarmigan being f i t t e d with a radio transmitter . . . . . . . . . . . . . . 171 FIG. 39. Locating hens on nests, and t r a c i n g brood movements was f a c i l i t a t e d by telemetry . . . . . . . . . 171 FIG. 40. Birds were captured with a long-handled net . . . . 172 FIG. 41. Typ i c a l rock ptarmigan habitat at Eagle Creek, Alaska 172 Page FIG. 42. South-facing slopes (on l e f t ) on the study area were treed, and r a r e l y used by rock ptarmigan 173 FIG. 43. Graminoid vegetation on a high saddle, a habitat often used by rock ptarmigan broods 173 FIG. 44. A t y p i c a l rocky h i l l top 174 FIG. 45. Lower slope, with higher vegetation (Betula nana) . . .174 FIG. 46. Indoor aviary, with 4-tiered brood-unit pens v i s i b l e . . . . . . . . 175 FIG. 47. Outdoor pen, i n which chicks were housed i n 1969 . . . 175 FIG. 48. Ptarmigan eggs i n an incubator . . . . . . 176 FIG. 49. Agonistic and aggressive behaviour was measured by presenting chicks with t h e i r own mirror-image . . . .176 FIG. 50. Growth of rock ptarmigan chicks . . . . . . . . .177 ACKNOWLEDGEMENTS This research was done under the supervision of Dr. J . F. Bendell. For his guidance throughout the study, I express my appreciation. Other members of the Dept. of Zoology, U n i v e r s i t y of B r i t i s h Columbia, who acted i n an advisory capacity were Dr. I. McT. Cowan, Dr. J . M. Taylor, Dr. H. Nordan, and Dr. H. D. Fi s h e r . The thesis was also c r i t i c a l l y reviewed by Dr. Stonehouse and Dr. C. J . Walters. The study was made po s s i b l e , f i n a n c i a l l y and l o g i s t i c a l l y , through the courtesy of Dr. R. B. Weeden, Alaska Department of F i s h and Game,. Fairbanks. Dr. Weeden i n v i t e d and welcomed my p a r t i c i p a t i o n i n research he had i n i t i a t e d i n 1960. He made a v a i l a b l e his extensive population data for my analysis i n Part II of t h i s t h e s i s , and for presentation by . me at the XV O r n i t h o l o g i c a l Conress i n Holland, September 1970. I thank him most s i n c e r e l y for his help. The aviary phase of t h i s study was made pos s i b l e by Dr. G. C. West, I n s t i t u t e of A r c t i c Biology, U n i v e r s i t y of Alaska. He provided; f a c i l i t i e s , funds and constant help. I also wish to thank Dr. R. Di e t e r i c h , Veterinarian at the I n s t i t u t e of A r c t i c Biology who gave w i l l i n g l y of much time to help solve aviary problems. In the f i e l d I had much help, foremost from my wife, Mary, who was,a f u l l time a s s i s t a n t i n a l l years, working far i n excess of normal hours each day. She prepared the tables and fi g u r e s , edited, and provided much encouragement i n the f i n a l stages of preparation of the t h e s i s . Among the many others who worked with me i n the f i e l d , J . A. :McGowan, Alaska Department of F i s h and Game deserves s p e c i a l mention. In the f i n a l two summers, he was p r i m a r i l y responsible f or c o l l e c t i n g the popu-l a t i o n data used here. Dr. A. Watson, Nature Conservancy, Banchory, Scotland, r a i s e d ptarmigan chicks i n 1968 and 1969 i n Scotland as part of the study, providing data on s u r v i v a l and behaviour. His advice during the early stages of the study was also most h e l p f u l . F i n a n c i a l a i d came from many agencies: Alaska Department of F i s h and Game, National Research Council of Canada, I n s t i t u t e of A r c t i c Biology, at the Un i v e r s i t y of Alaska, A r c t i c I n s t i t u t e of North America, A r c t i c and Alpine Research Committee at the U n i v e r s i t y of B r i t i s h Columbia. Personal support was provided by scholarships from the Canadian W i l d l i f e Service, U.S. W i l d l i f e Management Institute', and Un i v e r s i t y of B r i t i s h Columbia. To a l l these, I express my sincere thanks. PART I. INTRODUCTORY TOPICS INTRODUCTION This study attempts to explain.the changes i n abundance of rock ptarmigan (Lagopus mutus) at Eagle Creek, Alaska, from 1960 to 1969. The information may have general a p p l i c a t i o n , since rock ptarmigan e x h i b i t c y c l i c (non-random) fluctuations i n abundance c h a r a c t e r i s t i c of many northern species (Keith, 1963). I t does have value i n helping understand mechanisms of population control i n at l e a s t t h i s one species, l i v i n g i n a northern habitat r e l a t i v e l y unaltered by man. Few studies of population regulation i n vertebrates have delineated exact causation of- changes i n abundance, po s s i b l y because numbers of . animals i n a population are subject to a vast number of b i o t i c and a b i o t i c factors. The r e s u l t has been the development of an array of hypotheses, which can be categorized as e x t r i n s i c - c o n t r o l brouqht about p r i m a r i l y by changes in the environment of the population, or i n t r i n s i c - control brought about p r i m a r i l y by changes within the population i t s e l f i n an environment that has a r e l a t i v e l y constant e f f e c t on the population. The former, e x t r i n s i c c o n t r o l , may be accomplished e i t h e r by the d i r e c t action of the environment, or by i t s i n d i r e c t action expressed by a l t e r i n q the q u a l i t y ' o f the stock. These categories are not n e c e s s a r i l y mutually exclusive, but provide a rough framework for discussion. Direct e x t r i n s i c control o f f e r s the simplest explanation of changes in animal numbers, as i t implies a simple causal c o r r e l a t i o n between numbers and some environmental factor. Predation, for example, may d i r e c t l y influence prey d e n s i t i e s , as. demonstrated e s p e c i a l l y in undisturbed ungulate populations (Murie, 1944, Mech, 1966, Pimlott, 1967). Applied to c y c l e s , the well-known lynx-snowshoe hare f l u c t u a t i o n s (Moran, 1953) docu-ment a predator-prey o s c i l a t i o n i n which the predator may have influenced prey numbers. Disease i s also implicated as a d i r e c t determinant of animal num-bers, and described i n reference to cycles i n B r i t i s h grouse (Lovatt, 1911), snowshoe hare (MacLulich, 1937), and Wisconsin r u f f e d grouse (Dorney and Kabat, 1960). While predation and disease have been implicated i n the c o n t r o l of animal numbers, many populations fluctuate i n the absence of s i g n i f i c a n t m o r t ality from e i t h e r of these causes. Consequently, no general theory currently e x i s t s i n v o l v i n g predation or disease. But, food and climate are environmental factors common to a l l species. For both of these, general theories e x i s t , each theory suggesting that i t embodies the p r i n c i p l e mech-anism of population regulation. Andrewartha and Birch (1954) believe that changes i n c l i m a t i c factors account, i n general, f o r changes i n animal abun-dance and d i s t r i b u t i o n . The l i m i t a t i o n on population increase imposed by . food i s r a r e l y reached because of "density-independent m o r t a l i t y " due to weather. Lack (1954, 1966) states that populations are c o n t r o l l e d by food supply, which provides the "density-dependent" f a c t o r necessary for popula-t i o n regulation. Food p r i m a r i l y a f f e c t s m o r t a l i t y of j u v e n i l e s , and only to a l e s s e r extent, reproduction. •Lauckhart (1957) suggests that nutrient cycles i n plants caused population cycles i n animals. P i t e l k a (1964) sug-gests that lemming (Lemmus trimucronatus) cycles were caused by f l u c t u a t i o n s i n nutrient composition of plants. Some studies i n d i c a t e that food may work i n d i r e c t l y , by a l t e r i n g the q u a l i t y of the stock, so making i t s e f f e c t f e l t over a longer period or at a l a t e r date, or even.in a l a t e r generation. Siivonen (1957) found that the quantity.and q u a l i t y of food a v a i l a b l e before egg-laying determined the s u r v i v a l of chicks i n Finnish Tetraonidae. Lack (1968) states that i n a l l nidifugous species (which includes rock ptarmigan), food available to the female before or during egg-laying a f f e c t s population l e v e l s by determining clutch s i z e . • In contrast to e x t r i n s i c methods of population c o n t r o l , i n t r i n s i c hypotheses attempt to explain population regulation where no environmental factor appears t o . c o r r e l a t e with changing numbers. From basic work.of Selye (1946), C h r i s t i a n (1950) suggested that at high d e n s i t i e s , physiolo-g i c a l stress (adrenopituitary exhaustion) caused increased mortality.and decreased reproduction, and brought animal numbers down. In 1957, he.1:' modified t h i s to include an e f f e c t on the v i a b i l i t y of subsequent generations (Christian and Lemunyan, 1957), making i t a more f e a s i b l e explanation;for cycles, where decreases continue even a f t e r numbers are r e l a t i v e l y low. Chitty (1960, 1967) proposes that changes i n the density and behaviour of animals a l t e r mutual interference; t h i s i n turn influences genetic selec-t i o n , and subsequent reproduction and s u r v i v a l in the next generation. This array of possible mechanisms of population regulation opens many avenues of approach to studying any p a r t i c u l a r species. Of fundamental importance, however, i s an adequate understanding of the basic biology and l i f e h i s t o r y of the species. This was provided for Alaskan rock ptarmiqan (see " L i f e History") i n p r i o r studies. This information must be. supported with data on population processes - changes i n reproduction and mortality. Documentation of numerical change was the p r i n c i p l e aim of the Alaska Department of Fish and Game's long-term study of rock ptarmigan at Eagle Creek, i n i t i a t e d i n 1960. These data were made ava i l a b l e to me by R. B. Weeden. They were c o l l e c t e d on a 15 square mile study area (henceforth known as the "Eagle Creek study area") i n c e n t r a l Alaska. Each year, counts were made of breeding b i r d s i n spring, composition (sex and age) of adults ' i n summer, and broods i n f a l l . As w e l l , annual p r o d u c t i v i t y was.determined from a sample of nests. These data were analyzed with the objective of i d e n t i f y i n g the most important parameters causing f l u c t u a t i o n s in spring breeding d e n s i t i e s . This forms Part II of the thesis.. I set up the hypothesis that: There are no d i f f e r e n c e s . i n the q u a l i t y ( s u r v i v a l , growth,, behaviour) of rock.ptarmigan between years that, influence spring d e n s i t i e s . This was tested during three summer f i e l d sessions, ;1967, 1968, 1969. This hypothesis was formed p a r t i a l l y from evidence that d i r e c t control of numbers in f l u c t u a t i n g species by any environmental variable r a r e l y provided an explanation of population regulation (Keith 1963).- Also, research on other Lagopus populations pointed to differences i n the q u a l i t y of the stock i n both v i a b i l i t y and behaviour that appeared important to population regulation - in willow ptarmigan (Lagopus lagopus a l l e n i ) (Bergerud, in press), red grouse (Lagopus lagopus scoticus) (Jenkins, 1963,. Jenkins, et_ al_., .1963, Jenkins, et aJL. , 1967), and S c o t t i s h rock ptarmiqan (Watson, 1965). The hypothesis was tested through both aviary and f i e l d studies. Aviary studies, while making possible a more d e t a i l e d assessment of q u a l i t y , , also gave i n s i g h t i n t o whether q u a l i t a t i v e differences were due to the immediate environment of chicks, or parental influences (genetic or physio-l o g i c a l ) . The environment of the aviary was maintained as constant as p o s s i b l e , so eliminated as a v a r i a b l e . Any differences observed i n the q u a l i t y of chicks could then be a t t r i b u t e d to parental influences. Test of t h i s hypothesis forms Part III of the t h e s i s . , HISTORY OF ROCK PTARMIGAN RESEARCH IN ALASKA Buckley (1954) evaluated ptarmigan numbers between 1850 and 1952 i n Alaska from questionnaire data and harvest records of the U.S. Fis h and W i l d l i f e Service and Alaska Game Commission. Between 1850 and 1924 scanty reports showed merely that ptarmigan numbers fluctuated, and were too few to delineate any p e r i o d i c i t y . Better data between 1925 and 1952 indicated that ptarmigan harvests by hunters .were high between 1932 and 1935, 1942 and 1944, and i n the early 1950's or roughly every ten years. DeLeonardis (1952) and Roberts (1963) and the Alaska Cooperative W i l d l i f e Research Unit reported on ptarmigan at Eagle Creek i n the 1950's. Numbers peaked i n 1953-54, and declined r a p i d l y u n t i l 1959. In I960, Weeden began an intensive study of population dynamics of rock ptarmigan. at Eagle Creek. He had previously, studied habitat differences between rock and willow ptarmigan at Eagle Creek (Weeden, 1959). Weeden (1965) reported that numbers increased u n t i l 1962, a f t e r which they began to drop once again. He published a serie s of papers describing facets of t h e i r l i f e h i s t o r y (Weeden, 1961a, 1964, 1966, 1968, 1969).' The study, of population dynamics by the Alaska Department of Fish, and Game i s continuing as i s a study of n u t r i t i o n a l aspects of ptarmigan i n e arly spring by the Alaska Cooperative W i l d l i f e Research Unit. STUDY AREA The study area consists of 15 square miles of t y p i c a l r o l l i n g a r c t i c -alpine tundra in c e n t r a l Alaska (Fig. 1 and 2). Tundra vegetation i s con-tinuous except for some deeply-cut stream v a l l e y s and some south-facing slopes with sub-alpine vegetation, such as spruce (Picea glauca) and willow (Salix spp.). Elevations vary from 2600 to 4400 feet. H i l l tops are covered p r i m a r i l y with mountain avens (Dryas octopetala) and fragmented rock ( s c h i s t ) ; mid slopes with birch (Betula nana) and willow normally l e s s than 12 inches.high, sedges and grasses; lower slopes with b i l b e r r y (Vac- cinium uliginosum), b i r c h , and willow sometimes up to 15 feet i n height. During the breeding season, rock ptarmigan occupy a l l but v a l l e y bottoms and south-facing slopes where vegetation exceeds approximately three feet in height (Weeden, 1959). . . . The climate i s continental subarctic. P r e c i p i t a t i o n i s l i g h t , nor-mally less, than 15 inches per year. The f r o s t free period usually extends from e a r l y June to mid August. . Winter temperatures are often extremely \ cold, f a l l i n g to minus 60 degrees Farenheit on occasion. (See Appendix XI for a d d i t i o n a l pertinent weather data.) Human a l t e r a t i o n s of rock ptarmigan habitat on the study area include a gravel road with several short spur roads and a few overgrown ditches used i n past placer gold mining operations. FIG. 1. .. Map of Alaska. Arrow points to the Eagle Creek study area. FIG. 2. The Eagle Creek study area. Map shows 100 foot contour l i n e s . LIFE HISTORY The basic biology and l i f e h i s t o r y of rock ptarmigan i s well docu-mented (Salomonsen, 1939; DeLeonardis, 1952; Watson, 1956; Roberts, 1963; Weeden, 1959, 1963). In Alaska, t e r r i t o r i a l behaviour, beginning i n l a t e March, leads to a spacing of birds over the a v a i l a b l e tundra habitat. A l -though reported to be monogamous (Weeden, 1959), I o c c a s i o n a l l y observed, males mating with mote than one female. Females appear to wander, not con-f i n i n g their, movements to s t r i c t t e r r i t o r i a l boundaries. • A l l hens mate, :,as none were found without a brood patch. Eqgs are l a i d i n late May or early June, and hatch about 21 days a f t e r the onset of incubation. Reproduction schedules vary with yearly differences i n phenologic progression (flowering dates of a r c t i c p lants, Weeden, 1968). Hatch occurs, within narrow l i m i t s of nine to 15 days. Unsuccessful hens rarely, re-nest, but j o i n cocks in loose flocks on the ridge tops. Chicks are brooded during the f i r s t three to f i v e days of l i f e , and remain with the hen through July. By early. August,, broods begin to form f l o c k s , and are l a t e r joined by cocks and unsuccessful hens. Most birds are i n these flocks by mid September. During winter, sexes segregate, most cocks remaining in flocks on the tundra, hens forminq flocks at lower elevations i n t a i g a vegetation (Weeden, 1964). Neither sex undertakes long migrations, conforming to rock ptarmigan elsewhere (excep-tions being to and from B a f f i n Island (Salomonsen,' 1939), and when at peak numbers at Greenland (Salomonsen, 1950). C y c l i c f l u c t u a t i o n s of approximately 10 years p e r i o d i c i t y are docu-mented in rock ptarmigan i n Iceland (Gudmundgson, 1960), Greenland (Braestrup, 1941), Scotland (Watson, 1965), and p r i o r to t h i s study i n Alaska (Buckley, 1954). The present study has not gone on long enough to confirm a nori-i • •  random p e r i o d i c i t y s p e c i f i c a l l y at Eagle Creek; ptarmigan numbers here have, however, fluctuated. PART II POPULATION FLUCTUATIONS This section i d e n t i f i e s the most important parameters causing changes i n spring breeding numbers, an e s s e n t i a l step to understanding population regulation. METHODS Five censuses were conducted e^ch year between l a t e May and ea r l y August (Weeden, 1965). Males were counted i n l a t e May. Dire c t counts were within.5%.of the actual number of males (Weeden, 1965). This accuracy was made possible by t h e i r conspicuous d i s p l a y f i g h t s , and habits of perching on elevations, plus the open t e r r a i n . Detailed census techniques were rep-orted previously, as were methods of trapping, banding, and age determination (Weeden, 1965). P r o d u c t i v i t y data each year were based on the average sample of 18 nests. We have no evidence that human disturbance, which was r e l a t -i v e l y constant each year, af f e c t e d production, which was extremely v a r i a b l e . Data were c o l l e c t e d from 1960 to 1969 p r i m a r i l y by Alaska Depart-, ment of Fis h and Game personnel, under the supervision of R. B. Weeden.; Age classes used throughout are: Chicks hatch to f a l l , when they a t t a i n a f u l l set of white post-juvenal primaries. Juveniles - f a l l to spring birds previously chicks. Yearlings - f i r s t breeding spring to end of summer, when they a t t a i n t h e i r second set of white primaries. Adults - a l l birds older than yearlings^ With the aim of i d e n t i f y i n g the p r i n c i p l e cause of fl u c t u a t i o n s i n spring numbers I have assembled these data i n a "key-factor a n a l y s i s " (Var-l e y and'Gradwell, I960; Southwood, 1966). A se r i e s of "mortality f a c t o r s " c a l l e d "loss f a c t o r s " here) was c a l c u l a t e d for each year. Each loss factor applied to a s p e c i f i c period or event, such as loss of chicks i n summer, and was the difference between the number of birds before and a f t e r i t s action. Census data were f i r s t converted to logarithms, to make loss factors, additive (Blank, e_t aJ. , 1967) . . Loss factors were compared i n d i v i d u a l l y to t h e i r sum. This sum, . c a l l e d . " t o t a l loss", represents a l l the i n d i v i d u a l losses through-out the year, in c l u d i n g changes, i n n a t a l i t y (clutch s i z e ) . With t h i s tech-nique,, a graphical comparison i s possible to assess the part played.by each i n d i v i d u a l l o s s in'determining t o t a l .loss each year. Changes,in t o t a l loss explain f l u c t u a t i o n s i n spring numbers, as they incorporate a l l possible v a r i a b l e s that might influence spring numbers. In general, when t o t a l loss i s high, spring numbers w i l l be low, and vice versa. But i n some years t h i s was not true. This i s simply because i n c a l c u l a t i n g t o t a l l o s s one s t a r t s out with a d i f f e r e n t number of birds each spring, and i f one begins with a l o t more one year than another, one can have greater t o t a l l o s s and s t i l l end up with more birds the next spring. This observation does not a l t e r the v a l i d i t y of the key f a c t o r analysis. The various losses were: , -k =. the amount by which mean clutch s i z e i n any. year f a i l e d to achieve-o the maximum mean observed during the study, k^ = h a t c h a b i l i t y loss (eggs f a i l i n g to hatch i n successful nests). k = losses from nest f a i l u r e (nest predation and desertion). + k^ + k^ = production loss. ' k^ = losses of chicks from-hatch to August, k^ = losses of adults and ;yearlings from mid May to August. k_ = losses of b i r d s i n winter (late August to mid Mav). K = t o t a l l o s s , the sum of k• , k n, k„, k., k ., k_. , o . l . 2 3 4 b I prefer, to use the term "loss f a c t o r s " instead of the N more usual "mortality f a c t o r s " . In some cases, (loss of birds i n winter) disappearance may have included emigration as well as death. 1 Although the Eagle Creek study, area was representative of many miles of. s i m i l a r habitat, warranting the assumption that emigration equalled immigration, unequal movements may have taken place to l e s s suitable ptarmigan habitat,, u n t i l d i s p e r s a l c a n , , , be measured, or evidence found that, i t r e s u l t s i n death, as i n S c o t t i s h red grouse (Jenkins e_t al_., 1963) winter loss means dispersion and death. Direct evaluation of adult and y e a r l i n g loss in summer was not pos-sible.. Between 2% and 5% of spring b i r d s were actually, found dead each year, but carcasses were undoubtedly missed. Adult and y e a r l i n g loss was a r b i t r a r i l y f i xed at 10% of spring numbers. Si m i l a r small losses of adults, and yearlings i n summer were estimated at 7% in S c o t t i s h rock ptarmigan (Watson, 1965), and 4% i n Newfoundland willow ptarmigan (Bergerud, i n press). From 1960 to. 1963, age r a t i o s were not as accurate as l a t e r (Weeden, 1965). An aging technique used l a t e r , based on pigment c h a r a c t e r i s t i c s of outer reminges . (Bergerud, et- ^1, , 1963) was 98% accurate :(Weeden and Watson, 1967). ; : . RESULTS Breeding Population Spring numbers at Eagle Creek increased, for at least two consecutive years to 325 birds in 1962, f e l l for three years to 126 b i r d s , rose for three years to 235 b i r d s , and f e l l again i n 1969 (Fig. 3). Numbers include yearlings (birds hatched the previous breedinq season) and older bird? of , both sexes. Age r a t i o s varied, the proportion of yearlings present increasing and decreasing in p a r a l l e l with spring d e n s i t i e s (Table 1). The c o r r e l a t i o n c o e f f i c i e n t (r = 0.59, n = 10) was hot quite s i g n i f i c a n t at the 95% l e v e l . Sex r a t i o s , however, were quite constant, the extremes being 0.98 . males to .1 female and. 1.16 males to 1. female. . Losses Throughout the Year Loss factors (k's) were calculated from the logarithms of population data presented i n Table 2. Total l o s s , K, shown i n the right-hand column, was, as mentioned, the sum of a l l i n d i v i d u a l k's for each year. I t was checked by c a l c u l a t i n g the diff e r e n c e between the logarithms of "maximum p o t e n t i a l eggs l a i d plus adults" (in column 3)', and "number of birds the following spring (in column 8), and a r r i v i n g . a t the same values. , In F i g . 4, k values are qraphed for v i s u a l comparison with changes • in t o t a l l o s s . Both winter l o s s , k r, and production l o s s , k. + k..-+ k_, o 0 1 2 varied In p a r a l l e l with changes i n t o t a l l o s s , that i s , both correlate with. TABLE 1. ' Numbers and age r a t i o s of rock ptarmigan i n spring at Eagle Creek, Alaska Year Numbers . i n spring Increase (+) or decrease (") between years Per cent yearlings Increase (+) or decrease (-) between, years . 1960 163 57 1961 269 + . 67 + 1962 325 + 71 + 1963 271 - ; 69 1964 209 30 -1965 . 126 26 1966 157 + 62 + 1967 198 + 71 . + • 1968 235 • . 69 1969 218 — - 56 Year Spring numbers Maximum potential .' eggs laid, plus adults Actual .:number eggs laid plus adults Number of f e r t i l e eggs plus adults Number of eggs that • hatch plus adults Number, of chicks plus adults in August Number of birds, the. following spring Total loss (K) (difference between logs, of column 3 and density next spring)- -1960 1961. 1962 1963 1964 1965 1966 1967 1968 1969 163 269 325 271 209 126 157 198 235 218 838 1484 1720 1441 1109 666 832 1098 1270 1163 . b ~ 778 1268 1410 1116 869 582 832 1088 1098 901 766 1208 1355 1090 783 559 819 1070, 979 .778 663 1069 890 724 538 473 655 879 741 576 476 944 760 590 474" 411 477 591 585 471 269 325 271 209 126 157 198 235 218 204° .493 .660 .803 .839 . .944 .628 .623 .670 .765 ~ .756 loss values"in any year are the differences between the logs, of columns indicated below. k_ and k„ -••3. 4-.(separated by applying per cent contributed by each) ^Calculated from the maximum mean clutch size of 9.0 eggs, in 1966. 3k = clutch size loss; k, = hatchability loss; k„ = nest failure; k„ = summer chick loss; k„ = summer adult ,o . 1 J 2 3 . 4 loss; k = winter loss. 5 '102 males counted. Female numbers not obtained but sex ration considered 50:50. LU =>• _I co co O 1.0 0.8 0.6 0.4 0.2 0 0.2 K k 0 +kf-k 2 0.2 0 0.2 0 0.2 0 ,i,-..„' , i SUMMER CHICK LOSS SUMMER ADULT LOSS NEST FAILURE LOSS CLUTCH SIZE LOSS HATCHABILITY LOSS 1960 '61 '62 YEAR FIG. 4. The r e l a t i o n s h i p of various losses (k to kj.) to t o t a l annual loss (K) of rock ptarmigan at Eagle Creek, Alaska, t o t a l loss with highly s i g n i f i c a n t c o r r e l a t i o n c o e f f i c i e n t s (r = .85, n = 9) for winter, loss correlated with t o t a l l o s s , and r = .92, n = 9 for pro-duction loss correlated with t o t a l l o s s . In terms of p r e d i c t i n g changes in' numbers, therefore, both winter loss.and production loss are "key fa c t o r s " . In addition, the magnitude of change between years in winter loss and production loss was very s i m i l a r . In four years, change i n winter loss exceeded change in production l o s s , and i n f i v e years the reverse was true, C l e a r l y then,'both winter loss and,production loss were involved i n causing v a r i a t i o n s i n t o t a l loss., and almost equally so. Separate from any connection.with .change.-in- t o t a l loss between years, winter loss was the most important factor• e s t a b l i s h i n g mean, loss' over the 10 years. In each year i t accounted f o r most pi" the t o t a l loss (Fag. 4). Over the 10 years, 59% of t o t a l loss occurred.in t h i s period-Winter loss covered the period between late August to mid May, thus incl u d i n g t h e period of low i n t e n s i t y f a l l t e r r i t o r i a l behaviour which,..; , although observed (Weeden, 1962) , was not d i r e c t l y studied. I t also included most of the spring t e r r i t o r i a l period. Any density adjustments r e s u l t i n g from t e r r i t o r i a l behaviour, therefore were included i n t h i s segment of lo s s . Two components contributed to winter l o s s : juvenile l o s s , and adult and y e a r l i n g l o s s . Variations i n juvenile l o s s generally p a r a l l e l e d v a r i a -tions i n t o t a l winter loss (Fig. 5). This p a r a l l e l was not as marked when ye a r l i n g and adult loss was compared, with t o t a l winter l o s s . The magnitude of v a r i a t i o n between years i n juvenile loss was greater than i n y e a r l i n g and adult loss i n a l l but one year. Therefore, changes i n winter loss 1960-'61 '61- '62 '62- '63 '63- '64 *64-*65 '65- '66 '66-'67 '67- '68 *68'69 YEAR FIG. 5. The r e l a t i o n s h i p of juvenile, and yearling-adult loss of rock ptarmigan i n winter at Eagle Alaska from 1960 to 1969. . r e s u l t e d p r i m a r i l y from changes i n juv e n i l e l o s s . Losses i n both sexes of juveniles were s i m i l a r i n most years (Fig. 6). Among yearlings and adults, s l i g h t l y more v a r i a t i o n between the sexes occurred. The mean l e v e l of winter loss was pr i m a r i l y determined by juvenile l o s s . In F i g . 5, juvenile l o s s i n winter greatly exceeded yearlinqs and adult loss i n a l l years. To summarize winter l o s s , juvenile birds were .primarily responsible for both chanaes i n winter loss between years, and the mean l e v e l of winter loss over the 10 years. Both sexes of juveniles contributed equally. Turning to production l o s s , two components, clutch size loss. an(3 nest . f a i l u r e , varied i n p a r a l l e l i n most yea,rs (Fig. 4) - small clutches normally accompanied by high nest losses, and vice versa. In magnitude, of. v a r i a t i o n , c l u t c h - s i z e loss and nest loss were, very s i m i l a r . These two components, therefore, were about equally responsible for v a r i a t i o n s i n production l o s s . H a t c h a b i l i t y loss was much less important. Changes in clutch size were not due to the changing age r a t i o of hens. In f i v e years when s u f f i c i e n t nests were found to compare clutch sizes of yearlings and adult hens t t h e i r means were always within a maximum of 0.9 eggs from each other, whether mean clutch sizes were low (6.5, eggs) or high (9.0 eggs). . ' Production, loss contributed to changing subsequent.spring numbers because i t was not l a t e r counteracted by density-dependent mortality; neither summer chick loss nor winter loss c o r r e l a t e d with density (Fig. 7 and F i g . o JUVENILE FEMALES © JUVENILE MALES A ADULT & YEARLING FEMALES A ADULT & YEARLING MALES 1960*61 '61- '62 *62'63 '63- '64 '64- '65 ' 6 5 5 6 '66- '67 '67- '68 '68- '69 YEAR FIG. 6. . The relationship of losses in winter between sexes in juvenile, and yearling-adult rock ptarmigan. 3.1 _ 3.0 O © y 2.9 3= O cc 1 2.8 © © g 2.7 2.6 e 25 0 .02 .04 .06 .08 .10 .12 .14 16 LOG. OF CHICKS PLUS ADULTS AT HATCH FIG. 7. The r e l a t i o n s h i p between summer loss of. chicks and preceeding numbers of chick plus adults at hatch. 8), that i s , when production loss was hiah, subsequent loss of chicks or , juveniles was not correspondingly low, and vice versa. Loss of chicks in. the summer, k^, bore no r e l a t i o n to changes i n t o t a l loss (Fig. 4), and numerically was of l i t t l e consequence. CONCLUSIONS Fluctuations i n abundance of rock ptarmigan at Eagle Creek from 1960 to 1969 were the r e s u l t of an'-orderly and generally synchronous change i n winter loss and.production loss, both acting i n most years to eit h e r increase or decrease numbers. Each of these contributed approximately equally to v a r i a t i o n s . i n t o t a l l o s s . Variations i n production loss were p r i m a r i l y caused by clutch size losses and nest losses, which varied i n p a r a l l e l most years to e i t h e r increase or decrease numbers. Mean loss of ptarmigan over the 10 years was pr i m a r i l y established by winter l o s s . Mean winter l o s s , i n turn, was p r i m a r i l y determined by loss of juveniles. UJ > co C O O .50 LU AO 9 .30 o .20 .10 2.5 2.6 2.7 2.8 2.9 LOG. OF SEPTEMBER POPULATION 3.0 FIG. 8. The r e l a t i o n s h i p between winter loss of juve-n i l e rock ptarmigan and preceeding f a l l numbers. PART I I I . CHANGES IN SURVIVAL, GROWTH, AND BEHAVIOUR OF ROCK PTARMIGAN CHICKS This section provides evidence to t e s t the hypothesis that: there are no differences i n the q u a l i t y ( s u r v i v a l , growth, behaviour) of rock ptarmigan chicks between years that influence spring d e n s i t i e s . This hypothesis i s relevant to the. findings that the key f a c t o r s , causing changes i n spring numbers, namely winter los s of juveniles and • > production l o s s , varied i n p a r a l l e l between years (Part I I ) . A possible explanation of these p a r a l l e l changes i s that basic q u a l i t a t i v e differences between years e x i s t i n the stock. Such q u a l i t a t i v e d i f f e r e n c e s may show up i n i t i a l l y i n chicks, e s p e c i a l l y i f the differences o r i g i n a t e from an i n -herent component, and hence are part of a b i o l o g i c a l make-up. Inherent differences i n q u a l i t y of s i g n i f i c a n c e to f l u c t u a t i o n s i n numbers form part of both Chitty's (1960, 1967) and C h r i s t i a n and Davis' (1964) hypotheses of- population regulation. As well, inherent differences. are suggested i n other Lagopus studies (Watson.and Moss, i n press a), as w i l l be discussed. An assessment of q u a l i t a t i v e differences i s .made i n t h i s Part. The s i g n i f i c a n c e of these differences to population regulation is d i s -cussed i n Part IV. METHODS. The q u a l i t y of chicks was assessed i n both the f i e l d and i n an aviary, from mid May to l a t e August'in 1967, 1968,.and 1969. During t h i s , •period, the population rose and f e l l again, as described i n Part I I . 1 Eggs and young chicks were c o l l e c t e d from areas adjacent but. continuous with the Eagle Creek study area, and the q u a l i t y of chicks was compared i n the constant indoor aviary environment. As w e l l , the q u a l i t y of chicks was assessed i n the field., to a s c e r t a i n i f inherent changes found i n chicks i n the aviary appeared in wild stock. Aviary studies were conducted at the U n i v e r s i t y of Alaska, at Fairbanks, 100 miles from Eagle Creek, p r i n c i p a l l y i n a c o n t r o l l e d envir-onment room. . This room was held between 70° and 80°F, and was l i g h t e d continuously except for.a dark period between 22:30 and 01:30 hours. Eggs were incubated i n Humidaire Model 10 standard s t i l l - a i r incubator's. Also, chicks were brought in, at less than four days of age. Each brood was housed separately i n the indoor aviary. In addition, i n 1968 and 1969-, broods were housed together i n . large outdoor pens to. see i f g u a l i - . t a t i v e differences appeared under more natural conditions'. Methods of handling were standardized. Techniques of incubation, housina, and rearing are described i n Appendix I (Techniques of Incuba-tion,. Housing, and Rearing of Rock Ptarmigan Chicks). Each chick was weighed and measured at l e a s t twice a week. Measurements were: length of foot (tarso-metatarsus and longest phalange exclusive of n a i l ) ,, and lenqth of wing (carpo-metacarpus and longest primarv feather). Behaviour of each chick, categorized as a g o n i s t i c and aggressive,. was rated d a i l y . D e t a i l s and j u s t i f i c a t i o n of techniques of measuring these behaviours are i n Appendix II (Measuring Agonistic, and Aggressive Behaviour i n Rock Ptarmigan Chicks). Other behaviour was also measured d a i l y , but did not prove important i n t e s t i n g the hypo-thesis'. These, are discussed i n Appendix II (Maintenance, Exploratory, and General A c t i v i t y and Their Possible Relevance to Chick V i g o r ) . F i e l d studies involved the c o l l e c t i o n of chicks and eggs for the aviary. This was f a c i l i t a t e d by telemetry, hens being instrumented p r i o r to incubation. Later, during d a i l y general searching, data were recorded on the s i z e , l o c a t i o n and behaviour of broods. Birds were captured with long-handled hoop nets, and weighed and measured, as i n the aviary, and banded. We colour-marked the feet of very young chicks, and the wings of adults. This f i e l d work was conducted by crews of two men, one crew ; operating i n 1967, two crews a l t e r n a t i n g between f i e l d and aviary i n 1968 and 1969. In addition, one crew of Alaska Department of F i s h and Game personnel, who were co-operating i n t h i s study, was operating i n the f i e l d each year. Each crew was accompanied by trained pointing dogs.; The Alaska Department of F i s h and Game crew provided spring census data, information on adult age and sex r a t i o s , and other popula-t i o n parameters, as noted i n Part I I . They also c o l l e c t e d some chick measurements, and provided me with a sample of juve n i l e s c o l l e c t e d each September from an adjacent area for p h y s i c a l comparison. In 1968 and 1969, A. Watson, Nature Conservancy, Banchory, Scot-land, r a i s e d rock ptarmigan and red grouse chicks which he c o l l e c t e d as eggs, as part of a co-operative arrangement with t h i s study. This was done to compare information on the causes of mor t a l i t y of chicks i n summer. S t a t i s t i c a l s i g n i f i c a n c e , where mentioned, always r e f e r s to at le a s t the 95% confidence l e v e l . RESULTS S u r v i v a l of Chicks i n Summer Changes i n the s u r v i v a l of w i l d c h i c k s i n summer were r e l a t i v e l y unimportant to chanqes i n subsequent s p r i n g numbers (Part I I ) . However s e l e c t i o n may take p l a c e i n the summer th a t a l t e r s the l a t e r v i a b i l i t y of the j u v e n i l e cohort or i t s subsequent prod u c t i o n , the key f a c t o r s to p o p u l a t i o n change. This would be true i f change i n s u r v i v a l of c h i c k s was determined p r i m a r i l y by v a r i a t i o n s i n the environment. Hence, sur-v i v a l of c h i c k s was s t u d i e d to determine whether i t changed because of v a r i a t i o n s i n the environment or i n the inherent g u a l i t v of the stock;. F i e l d Each summer, chick s u r v i v a l was c a l c u l a t e d as the d i f f e r e n c e ' between the mean number of c h i c k s per brood a t hatch (determined from a sample of nests) and brood counts made i n l a t e J u l y and e a r l y August (Part I I ) . S u r v i v a l v a r i e d from 60% i n 1967 to 74% i n 1968 and 74% i n 1969. 1967 s u r v i v a l was w e l l below the 10 year average of 76%, whereas i n 1968 and 1969 s u r v i v a l was very c l o s e to t h i s average. I was unable to document when lo s s e s of c h i c k s occurred, as e a r l y counts l i k e l y underestimated brood s i z e s ; some c h i c k s which h i d were not found. I f t h i s p o p u l a t i o n f o l l o w e d the p a t t e r n of other g a l l i f o r m s , most of the m o r t a l i t y occurred w i t h i n the f i r s t two to three weeks a f t e r hatch. To determine i f s u r v i v a l of c h i c k s was i n f l u e n c e d by post-hatch weather, I c o l l e c t e d temperature and r a i n f a l l data on the study area i n 1967, 1968, and 1969. Data from only one other year, 1964, were a l s o a v a i l a b l e . Based on t h i s scant four years, changes i n mean d a i l y temper-ature and r a i n f a l l during the week immediately f o l l o w i n g the mean hatch date, as w e l l as during J u l y , d i d not p a r a l l e l changes i n c h i c k s u r v i v a l to the end of J u l y ( F i g . 9). However, weather data c o l l e c t e d at Fairbanks by the U.S. Weather Bureau allowed a 10 year comparison w i t h summer chick s u r v i v a l . Fairbanks weather data were, r e p r e s e n t a t i v e of. Eagle Creek, i n s p i t e of a d i f f e r e n c e i n e l e v a t i o n of 2500 f e e t and a sep a r a t i o n of 100 miles (Haugen, et a l . , i n p r e s s ) . F i g . 10 shows-again t h a t changes bet-ween years i n mean d a i l y temperature and r a i n f a l l immediately post-hatch, as w e l l as during J u l y , d i d not p a r a l l e l changes i n summer c h i c k s u r v i v a l . The best p a r a l l e l w i t h chick s u r v i v a l was provided by mean temperatures . immediately post-hatch up to 1965. However, a f t e r t h a t they departed r a d i c a l l y from each other. C o r r e l a t i o n c o e f f i c i e n t s f o r chick, s u r v i v a l , r e l a t e d to temperature f o r the week post-hatch (r=0.37) and f o r the summer (r=0.33) were not s i g n i f i c a n t . S i m i l a r l y , c o e f f i c i e n t s f o r chick, s u r v i v a l r e l a t e d to r a i n f a l l f o r the week post-hatch (r=0.13) and f o r the summer (r=0.43) were not s i g n i f i c a n t . N e i t h e r d i d a combination of temperature and r a i n f a l l c o r r e l a t e : w i t h chick s u r v i v a l . M u l t i p l e c o r r e l a t i o n c o e f f i c i e n t s f o r the week .post-hatch (R=0.39) and f o r the summer (R=0.58) were not s i g n i f i c a n t , d e s p i t e a suggestion one gets from F i g . 10 t h a t s u r v i v a l was best i n c o l d wet summers. I conclude t h a t d i f f e r e n c e s i n summer s u r v i v a l of rock ptarmigan chicks at Eagle Creek were not g r e a t l y i n f l u e n c e d by weather c o n d i t i o n s 50 I—- i i _ i i i 1964 1967 1968 1969 YEAR FIG. 9. Comparison of changes in survival of wild chicks to eight weeks with differences in mean temp-erature and r a i n f a l l , at Eagle Creek. Weather data are for the week following the mean hatch date, and the month of July. 3.0 R 5 0 I960 1961 1962 1963 1964 1965 1966 1967 1968 1969 YEAR FIG. 10. Comparison of changes i n chick s u r v i v a l to eight weeks with differences i n temperature and r a i n f a l l at Fairbanks (rep-resentative of Eagle Creek). Weather data are for' the week following the mean hatch date, and the month of J u l y . a f t e r hatch. Furthermore, ptarmigan adjust t h e i r nesting a c t i v i t i e s to differences i n spring weather, as measured by the phenology of flowering dates of representative plants (Weeden, 1968). This acts to reduce the v a r i a b i l i t y i n the spring weather to,which nestinq ptarmicran otherwise would be exposed. Late hatching chicks i n 1964 (average hatch date J u l y 1) survived equal]y well as early hatching chicks i n 1961 (average hatch date June 19), so the f a c t that breeding a c t i v i t y was timed to weather did not influence summer chick s u r v i v a l . Other e x t r i n s i c or environmental v a r i a b l e s that might d i r e c t l y influence summer chick s u r v i v a l are food, predation, and disease. These are dealt with i n d e t a i l i n Appendix IV (Food, Predation, and Disease, i n Relation to Survival of Chicks i n Summer). The main conclusions i n thi s Appendix are that chicks eat a v a r i e t y of vegetation and inverte-brates, of which there i s always abundant supply. Predators were not; common enough to account for chick m o r t a l i t y . Disease was uncommon. Analyses were made of habitats used by broods each year to see i f t h i s influenced chick s u r v i v a l . These are described i n Appendix V (Differences i n Habitat used by Rock Ptarmigan Broods i n 1967, 1968, 1969). The use of d i f f e r e n t habitats may a l t e r a number of environmental factors - food q u a l i t y , predation, parasites. However, r e s u l t s i n d i - : cate that although there were dif f e r e n c e s between vears i n per cent, of broods found i n "mixed" vegetation associations, i n height on h i l l , and i n densitv of cover, s u r v i v a l i n the wild was i d e n t i c a l i n 1968 and ; 1969. I conclude, therefore, that changes i n brood locations were of l i t t l e consequence to changes i n summer chick s u r v i v a l . In summary, no evidence was found that changes i n environmental variables account for. changes i n summer chick s u r v i v a l , although such an analysis can v i r t u a l l y never be considered complete. This suggests the possible importance of changes i n inherent v i a b i l i t y , the a l t e r n a t i v e cause of changes i n summer chick s u r v i v a l . Aviary In the constant conditions of an indoor aviary, d i f f e r e n c e s i n s u r v i v a l of chicks between years are taken to r e f l e c t d i f f e r e n c e s i n the inherent v i a b i l i t y of chicks. Survival to eight weeks of age i n the indoor aviary v a r i e d from 33.2% i n 1967, to 83.1% i n 1968, and 73.0% i n 1969 (Table 3). The l a t t e r two years were, not s i q n i f i c a n t l y d i f f e r e n t from each other. Two classes of chicks made up the indoor.aviary: those hatched i n incubators (incubator c h i c k s ) , and those hatched i n the wild and brought to the aviary at less than four days of age ( f i e l d c h i c k s ) . Both survived poorly i n 1967. In 1968 and 1969 s u r v i v a l was better and s i m i l a r (Table 3). In 1968 and 1969, chicks were rai s e d i n an outdoor aviary as w e l l . Almost a l l were hatched i n the wild and brought to the aviary at less than four days (outdoor c h i c k s ) . Although housing was not i d e n t i -c a l (Appendix I ) , and weather was an added v a r i a b l e , the per cent s u r v i v a l was s i m i l a r i n the two years; 53.6 and 59.1 r e s p e c t i v e l y (Table 3). The three classes of'aviary chicks; incubator chicks, f i e l d TABLE 3. Per cent s u r v i v a l of chicks to eight weeks of age, i n the aviary. Sample sizes are i n brackets 1967 1968 1969 Incubator c h i c k s 3 26.3(19) 81.3(64) 73.6(53) b . F i e l d chicks 35.5(62) 100.0( 7) 70.6(17) Total indoor chicks 33.2(81) 83.1(71) 73.0(70) c Outdoor chicks - 53 .6.(41). 59.1(22) 'Incubator chicks were hatched i n incubators and housed indoors. F i e l d chicks were hatched i n the wild and were brought to the aviary at <4 days of age and housed indoors. Outdoor chicks were same as f i e l d chicks but housed indoors. chicks, outdoor chicks, therefore showed s i m i l a r i t i e s i n . t h e i r patterns of s u r v i v a l between years. T o t a l l e d over the three years, however, a lower percentage of outdoor chicks, 56%, and f i e l d chicks, 48%, survived than incubator chicks, 76%. This lower s u r v i v a l of outdoor and f i e l d chicks was p r i m a r i l y because many did not feed i n c a p t i v i t y ; 79% of the outdoor chick m o r t a l i t y and 56% of the f i e l d chick m o r t a l i t y took place within the f i r s t four days, and chicks had totally empty d i g e s t i v e t r a c t s . These chicks a l l experienced a rough four hour t r i p from the field., and were placed i n a t o t a l l y d i f f e r e n t environment from that which they had experienced i n the. wild. -Aviary m o r t a l i t y , other than that associated with not feeding, was due to a number of causes, discussed i n Appendix VI (Causes of Aviary M o r t a l i t y ) . . v Conclusions ,' In the aviary, chick s u r v i v a l to eight weeks was low i n 1967,; higher and s i m i l a r i n 1968 and 1969. This pattern of summer chick s u r v i v a l was the same as found i n the wild. Summer chick s u r v i v a l Aviary Wild 1967. low low 1968 high high 1969 . high high Since no environmental f a c t o r could be i d e n t i f i e d to explain changes i n chick s u r v i v a l i n the wild, I conclude these changes must have been p r i m a r i l y due to the changes i n inherent v i a b i l i t y . The s i g n i -ficance of t h i s conclusion to the o r i g i n a l hypothesis w i l l be discussed i n Part IV. A s i m i l a r conclusion can be drawn from rock ptarmigan and red grouse r a i s e d i n Scotland i n 1968 and 1969. Chick s u r v i v a l was better i f eggs came from moors which had good chick s u r v i v a l i n the wild (Tables 4 and 5). This observation had also been made i n 1963 for red grouse (Jenkins, et a l . , 1963). There i s evidence, therefore, that the conclu-sion that chick s u r v i v a l i s pre-determined by inherent v i a b i l i t y of chicks, may apply to more than a l o c a l population of ptarmigan. Growth of Chicks The growth of chicks may have aff e c t e d spring numbers by deter-mining the physical c h a r a c t e r i s t i c s of birds entering the c r i t i c a l winter period. I therefore assessed various p h y s i c a l c h a r a c t e r i s t i c s of chicks -t h e i r growth rate (weight, wing length) and s i z e of adrenal glands and testes. F i e l d In 1968, juvenile males and females shot i n September were s i g n i f i c a n t l y l i g h t e r than i n 1967 or 1969 (Table 6). C o l l e c t i o n s were made adjacent to Eagle Creek as well as by hunters at Eaqle Creek. Birds were s i m i l a r i n age each year, as mean hatch dates only varied by four days. Males were s i g n i f i c a n t l y heavier than females i n a l l years, also evident in.'Table 6. TABLE 4 . Survival of chicks to two weeks of age i n c a p t i v i t y and i n the wild i n Scotland, i n 1968 C a p t i v i t y Wild Species Location Underlying rock Number hatched Proportion reared (%) Young reared ' per adult Red grouse Kerloch base - poor. 14 86 1.2 Rock ptarmigan Cairngorms base - poor 14 29 0.0 Rock ptarmigan Lochnagar 17 41 0.4 . • Rock ptarmigan Cairnwell base - r i c h 14 57 1.5 Reproduced from "Grouse Research i n Scotland, 13th Progress Report 1969", page .29. Courtesy A. Watson. TABLE 5. Survival of chicks to two weeks of age i n c a p t i v i t y and i n the wild i n Scotland, i n 1969 Species Location Underlying rock C a p t i v i t y Wild Number hatched Proportion reared (%) Young reared per adult Red grouse Cairnwell base - r i c h 18 33 1.3 Rock ptarmigan Cairngorms base - poor 18 17 0.2 Rock ptarmigan Cairnwell base - r i c h . 18 . 44 1.0 . TABLE 6. Weights (grams) of wild juvenile rock ptarmigan i n September Males Females 1967 1968 1969 1967 1968 1969 Mean 443.8 395,3 454.7 408.5 363.1 414.1 • 95 Per cent Confidence l i m i t (+) 11.5 9.8 11.3 16.1 6.7 10.6 Standard error (+) .5.9 4.9 5.4 8.2 3.4 5.2 ' Sample s i z e 41 82 21 37 100 29 TABLE 7. Wing lengths (centimeters) of wild juvenile rock ptarmigan i n September Males Females 1967 1968 1969 1967 1968 1969 Mean 18.7 18.2 18.7 18.1 17.4 18.0 95 Per cent Confidence l i m i t s (+) .2 .2 .2 .2 .2 .2 Standard error (+) .1 .1 .1 .1 .1 .1 Sample siz e 32 24 21 23 25 28 As w e l l , 1,968 juveniles of both sexes had shorter wings (Table 7) , and again males were c o n s i s t e n t l y larger than females. Amount of stored body f a t was compared i n these b i r d s . Fat l y i n g i n a band at the point where the crop met the breast ( p e c t o r a l i s major muscle) was used as an index of t o t a l stored bpdy f a t . Four centimeters of t h i s band on each side of the midventral l i n e were stripped o f f and weighed. Data presented as weight of f a t per gram body weight r e f l e c t the same r e s u l t s as a comparison of the absolute weights of the f a t . 1968 juveniles had l e s s stored body f a t (0.25 mgs. per gram body weight) than those i n 1967 (0.38) or 1969 (0.29) (Table 8). This was s t a t i s t i -c a l l y s i g n i f i c a n t between 1967 and 1968., not quite so between 1968 and 1969. As sexes d i d not d i f f e r from one another i n t h i s respect, they were combined. To understand why 1968 juveniles were l i g h t e r and smaller, growth curves, constructed from chicks banded throughout the summers, were com-pared. (Figs. 11 and 12). These curves s u f f e r from my i n a b i l i t y to age chicks accurately, the X axis being "number of weeks a f t e r peak of hatch" rather than age. Aging by time of molt of juvenal primaries (Zwickel and Lance, 1966) was not possible because v a r i a t i o n s between, chicks introduced a greater variance than dating from the peak of hatch, as discovered from known-age aviary chicks. As well, slow-growing chicks often molted l a t e r , meaning I would i n c o r r e c t l y age s i m i l a r slow-growing chicks i n the wild rather than detect d i f f e r e n c e s i n , growth ra t e s . Likewise, using length of developing juvenal primaries TABLE 8. Stored body f a t of wild juvenile rock ptarmigan i n September (mgs. of f a t per gram body weight) 1967 1968 1969 Mean .38 ' .25 .29 95 Per cent Confidence l i m i t s (+) .08 .05 .06 Standard error (+) .04 • .02 .03 Sample siz e . ... 38 41 . 4 8 CD 240 210 180 150 120 90 60 30 A '31-T 5 I1 o 1967 • 1968 A 1969 3-H h-4—I 1-5—1 I-6-H WEEKS AFTER PEAK OF HATCH H-7-FIG. 11.. Comparison of weights of wild rock ptarmigan chicks i n .1967, 1968, 1969. FIG. 12. Comparison of wing lengths of wild rock ptarmigan chicks. (Zwickel and Lance, 1966) or t o t a l wing length (Bergerud, et a l . , 1963) was not possible for the same reason. Growth data for wild chicks are presented as weekly means,'which are more d e s c r i p t i v e than the more commonly used regression l i n e s . The comparison of wild chick weights throughout the three summers i s n o t a b l e f o r the lack of consistent r e l a t i o n s h i p i n the weekly means (Fig. 11). However, by the seventh week (late J u l y ) , 1968 chicks began to f a l l behind, being s i g n i f i c a n t l y l i g h t e r th^n 1967 chicks. In the eighth week, they were farther behind, although not s i g n i f i c a n t l y l i g h t e r . Sample sizes were much smaller, however, leading to wider confidence l i m i t s . Therefore, the previously discussed l i g h t weight of juveniles i n September 1968 i n the wild, was apparently due to a lag i n l a t e summer. The same lag was not evident i n growth of wings (Fig. 12). Per-haps v a r i a t i o n s i n the time of molt affected wing length to mask t h i s - l a g , or perhaps the lag occurred a f t e r early August. A f i n a l comparison of growth i n wild chicks was made by p l o t t i n g foot length against weight. As variances were very large, t h i s method added l i t t l e . I t i s described i n Appendix VII (Growth Rates Measured by Weight-Foot Length Ratios). To summarize, wild juveniles i n September i n 1967 and 1969 were verv s i m i l a r i n weight, wing length, and stored body f a t ; j u v e n i l e s i n September 1968 weighed l e s s , had shorter wings, and less stored body f a t . Weight curves indicated that chicks i n 1968 lagged behind 1967 and 1969 chicks i n l a t e summer. Aviary I compared the growth r a t i o s of chicks i n 1967, 1968, and 1969 i n the constant conditions of the indoor aviary to determine whether inherent differences were involved i n d i f f e r e n c e s i n growth rates observed i n the wild. Growth curves were constructed by measuring and averaging each' ; parameter of growth (weight, wing length, foot) for chicks each week.' Where measurements were not made at exactly weekly i n t e r v a l s , they were cal c u l a t e d by i n t e r p o l a t i o n of i n d i v i d u a l growth curves constructed by a computer. C h a r a c t e r i s t i c s of growth of rock ptarmigan chicks are des- : cribed i n Appendix VIII, with that t i t l e . Growth curves treated incubator chicks and f i e l d chicks together, and sexes together. J u s t i f i c a t i o n i s given i n Appendix VIII. At seven weeks of age, indoor aviary chicks i n 1968 and 1969-cohorts both average 350 grams (Fig. 13). At six weeks, the l a s t measure for 1967 chicks, there was no s i g n i f i c a n t d i f f e r e n c e i n the weight of the three cohorts (Ficr. 13) . Since no differences i n weight were obvious i n the aviary chicks i n l a t e summer, inherent factors were l i k e l y not res-ponsible for the.differences i n the weight of juveniles found i n the wild i n September between years. S i m i l a r l y , F i g . 14 suggests that wing lengths of aviary chicks i n 1968 and 1969. did not d i f f e r , leading to the same conclusion as for 300 250 GO E 200 CD £ 150 100 50 f 1 o 1967 @ 1968 A 1969 ! I hatch i — 3 — i • t—4-AGE (weeks) - 5 - H ^ 6 -FIG. 13. Comparison of weight of captive rock ptarmigan chicks housed indoors i n 1967, 1968, 1969. H - 3 - . r - 4 -AGE (weeks) FIG. 14. Comparison of wing lengths of captive rock ptarmigan chicks housed indoors i n 1968 and 1969. weight, although data are fewer. From two to s i x weeks of age, aviary chicks i n 1968 were s i g n i f i -cantly heavier than i n 1967 or 1969 (Fig. 13). This appeared to have l i t t l e b i o l o g i c a l s i g n i f i c a n c e , neither r e s u l t i n g i n heavier aviary chicks at the end of the summer, nor r e l a t i n g to early aviary chick s u r v i v a l -s u r v i v a l of chicks i n 1967 was much poorer i n 1969, but weights i n those years were not d i f f e r e n t . Further confirming that t h i s e arly d i f f e r e n c e i n mean weekly weights of aviary chicks d i d not influence s u r v i v a l was the s i m i l a r i t y i n weights of chicks that l i v e d the f u l l eight weeks with chicks that died (Fig. 15). The growth analvsis of aviary chicks, therefore, i d e n t i f i e d no inherent factor that would help account for the differences i n growth found i n the wild. Organ Weights Evidence.that enlarged adrenal glands and i n h i b i t e d testicular' devel-opment accompany hiqh d e n s i t i e s or aggression has been reported i n a number of studies of rodents ( C h r i s t i a n and Davis, 1964, 1966) and Davis (1964). I examined the adrenal glands and testes of j u v e n i l e ptarmigan shot i n September to determine i f behavioural or density d i f f e r e n c e s r e f -lected i n the weights of these organs. Adrenal, and testes weights i n birds have received s u r p r i s i n g l y l i t t l e study, when so many studies have reported on these organs i n mammal populations. Murton (1967), however, reported.that subordinate wood-pigeons (Columba palumbus), had enlarged 200 150 CO E ro 100 50 o CHICKS THAT LIVED © CHICKS THAT DIED 5+ 55 AGE (weeks) FIG. 15. Comparison of weights of cap-t i v e rock ptarmigan chicks that l i v e d eight weeks with those which d i d not. Data, one week before death were exclu-ded. adrenal glands, and Neave and Wright (1968) found adrenal weights heavier i n dense than i n sparse populations of r u f f e d grouse. In Table 9 the weights of adrenal glands o f w i l d j u v e n i l e p t a r -migan are compared between years. In a l l y ears, b i r d s were shot i n the f i r s t week i n September, so were very s i m i l a r i n age. I t was t h e r e f o r e unnecessary t o convert weights to "standardized means", a technique neces-sary f o r comparing animals at d i f f e r e n t stages of development (Chitty> 1961; Krebs, 1964). For each b i r d , weights o f the two adrenals were averaged and expressed as mgs. per gram body weight. No s i g n i f i c a n t d i f f e r e n c e s e x i s t e d f o r males between 1967, 1968, and 1969. Adrenals i n females i n 1967 were l i g h t e r than i n 1968 or 1969. This d i f f e r e n c e was s i g n i f i c a n t between 1967 and 1968. The l a r g e r adrenals i n females i n 1968 d i d not appear t o c o i n -c ide w i t h peak d e n s i t i e s or aggression. D e n s i t i e s o f b i r d s i n September on the study area were comparable i n 1968 (585 b i r d s ) and 1967 (591 b i r d s ) . There was no evidence t h a t aggression was highest i n 1968, to be discussed under "Behaviour i n Summer". In Table 10, t e s t e s weights of these same j u v e n i l e s are compared between years. Testes were s i g n i f i c a n t l y heavier ( r e l a t i v e to body weight) i n 1969 than 1967 or 1968. However, t h i s does not i n v e r s e l y c o r r e l a t e with changes i n adrenal weights i n males. Inverse c o r r e l a t i o n s have been found i n s t u d i e s o f s t r e s s by B a i l e y (1966) and those reviewed by Davis (1964). I conclude, t h e r e f o r e , t h a t i f any d i f f e r e n c e s i n s t r e s s occurred i n f a l l among w i l d j u v e n i l e rock ptarmigan, they d i d not manifest themselves TABLE 9. Comparison of adrenal gland weights of w i l d j u v e n i l e rock ptarmigan i n September 1967, 1968, 1969 (mgs. per gram body weight) Males Females Weight 1967 1968 ] .969 1967 1968 1969 Mean .028 .029 027 .026 .032 .029 95 Per cent Confidence l i m i t s ( + )• .003 .003 002 .002 .003 .002 Standard e r r o r (+) .001 .001 0.01 .001 .002 .001 Sample s i z e 25 22 • • ] .9 14 .23 25 TABLE 10. Comparison of t e s t e s weights of w i l d j u v e n i l e rock ptarmigan i n September 1967, 1968, 1969 (mgs. per gram body weight) Weight 1967 1968 1969 Mean .020 .021 .026 95 Per cent confidence l i m i t s (+) .004 .003 .001 Standard e r r o r (+) .002 .001 .001 Sample s i z e 16 18 18 by changes i n adrenal or t e s t e s weights. The adrenal weights of s e l e c t e d a v i a r y b i r d s were a l s o measured, to determine i f a g o n i s t i c behaviour c o r r e l a t e d w i t h adrertal s i z e . Adre-n a l weights of a v i a r y b i r d s that r a t e d "low" i n a g o n i s t i c behaviour were compared w i t h those who ra t e d "medium" or "high" (Table 11). A g o n i s t i c behaviour included a strong aggressive component. Behaviour w i l l be discussed subsequently under "Behaviour i n Summer". B i r d s were k i l l e d i n mid August. No s i g n i f i c a n t d i f f e r e n c e was found i n adrenal weights f o r low or medium/high c a t e g o r i e s of a g o n i s t i c behaviour. Conclusions . Wild j u v e n i l e s i n September 1968. weighed l e s s , had sh o r t e r wings, and l e s s stored body f a t than i n 1967 or 1969. The l i g h t e r weight was apparently due to a l a g i n l a t e summer. No s i m i l a r l a g occurred i n the weight curve of 1968 ch i c k s r a i s e d i n the a v i a r y . T h i s . i n d i c a t e s that environmental i n f l u e n c e s were probably r e s p o n s i b l e f o r the l a g . No evidence was found e i t h e r i n the w i l d or a v i a r y that adrenal or t e s t e s weights of j u v e n i l e s i n f a l l r e f l e c t e d changes i n d e n s i t y or aggression. Behaviour i n Summer As w i t h s u r v i v a l and growth of c h i c k s i n summer, f o r behaviour to greatly, i n f l u e n c e s p r i n g d e n s i t i e s of ptarmigan a t Eagle Creek i t must somehow a f f e c t e i t h e r winter l o s s of j u v e n i l e s or production (Part I I ) . This s e c t i o n presents a catalogue of behav i o u r a l changes observed i n both TABLE 11. Comparison of adrenal weights i n c a p t i v e rock ptarmigan i n l a t e August w i t h low a g o n i s t i c scores a g a i n s t those w i t h medium or high scores (mgs. per gram body weight) Adrenal weight Low A g o n i s t i c Rating Medium and High A g o n i s t i c . Rating Mean .031 .030 95 Per cent Confidence l i m i t s . (+') .003 .005 Standard e r r o r (+) .002 .002 Sample s i z e 20 10 th e f i e l d and a v i a r y i n the summers of 1 9 6 7 , 1 9 6 8 , and 1 9 6 9 . The s i g n i -f i c a n c e of these changes i s assessed i n . P a r t IV. F i e l d Behaviour of c h i c k s and hrood hens, was recorded i n two s i t u a t i o n s : The f i r s t , d i s t u r b e d behaviour, was t h a t shown i n response to a "predator" s i t u a t i o n of man and dog. I t provided a measurement of cohesion w i t h -i n broods and hen aggression. The second was undisturbed behaviour, confined to a c t i v i t i e s of broods as u n i t s , unaffected by our presence. Cohesive behaviour of hens w i t h i n broods was measured as: 1) Distance from observer at which hens f l u s h e d . 2) Distance hens flew upon encountering observer. 3) Distance hens flew a f t e r being, banded. , 4) Brood defense bv hens. Brood hens were a r b i t r a r i l y r a t e d as showing strong cohesive bond w i t h broods i f they: 1) Waited u n t i l the observer was w i t h i n 20 f e e t before f l u s h i n g , .2) Flew 50 f e e t or l e s s upon encountering observer. 3) Flew 50 f e e t or l e s s a f t e r being banded. 4) Made a strong e f f o r t to f e i g n i n j u r y and lead the observer away, or attacked the" observer. Cohesion i n brood hens changed, between years ( F i g . 1 6 ) . S i g n i - . f i c a n t l y more hens allowed the observer, to come w i t h i n 20 f e e t i n 1 9 6 9 than i n e a r l i e r years. Upon encountering an observer, hens fle w a s i g n i -f i c a n t l y s horter d i s t a n c e i n 1 9 6 9 than i n 1 9 6 7 . A f t e r being banded they 1969 100 R ° 50 1968 100 ,-50 -NO DATA 1967 FIG. 16. Per cent of brood hens showing strong brood cohesion when d i s t u r b e d by observer, i n 1967, 1968, 1969. Types of mea-surements are: 1. Hens not f l u s h i n g u n t i l ob-server c l o s e ( w i t h i n 20 feet) 2. Hens f l y i n g short d i s t a n c e (50 f e e t or l e s s ) upon en-countering observer. 3. Hens f l y i n g short d i s t a n c e (50 f e e t or l e s s ) upon r e l e a s e a f t e r banding. 4. Hens which showed strong brood defense behaviour (week one and two a f t e r hatch). flew a s h o r t e r d i s t a n c e i n 1969 than i n 1968 but not s i g n i f i c a n t l y so. Brood defense was not s i g n i f i c a n t l y d i f f e r e n t , although i n the f i r s t two weeks a f t e r hatch, the per cent of hens r a t i n g poor increased from 25 to 43 to 53 i n 1967, 1968, and 1969 r e s p e c t i v e l y . A f u l l e r treatment of these data i s presented i n i n d i v i d u a l t a b l e s f o r each measure of cohesion i n Appendix IX (Measurements of Cohesive Behaviour i n Wild.Rock Ptarmigan Broods). In q e n e r a l , t h e r e f o r e , hens showed p r o g r e s s i v e l y greater cohesion, or w i l l i n g n e s s to stay w i t h Chicks when distu r b e d , from 1967 to 1968 to 1969 ,(Pig. 16) . Brood cohesion i n hens, measured i n the wavs mentioned, i s at l e a s t to some deqree r e l a t e d to aggression. W i l l i n g n e s s to stay w i t h the c h i c k s may r e f l e c t the r e s u l t of a " f i g h t or f l i q h t " d e c i s i o n made when faced w i t h an i n t r u d e r . F l u s h i n q d i s t a n c e s and d i s t a n c e s flown by hens e l e c t i n g to " f i g h t " were minimal. In a d d i t i o n , aggressive behaviour i n hens was measured at nests. This was done by measuring the d i s t a n c e hens allowed the observer before l e a v i n g the nest, the d i s t a n c e she stayed while the observer was at the nest, and the strength of any attack behaviour d i r e c t e d towards the observer before hatch. A f t e r t h a t , most hens i n a l l years reacted a q g r e s s i v e l y towards the observer. Although sample s i z e s are s m a l l , r e s u l t s i n d i c a t e t h a t aqqression at nests became p r o g r e s s i v e l y stronqer (Table 12). • Brood cohesion was a l s o measured i n c h i c k s . When encountered by TABLE 12. Defense of nests by ptarmigan hens i n 1967, 1968, 1969 1967 1968 1969 Poor Per cent 37.5 37.5 0 Number of hens 3 3 0 Moderate Per cent 37.5 62.5 25.0 .Number of hens ' 3 5 3-E x c e l l e n t Per cent 25.0 0 75.0 Number of hens 2 0 9 TABLE 13. Comparison of r e a c t i o n of brood hens and ch i c k s t o disturbance i n 1967, 1968, 1969 Hens Chicks 1967 1968 1969 1967 1968 1969 Run Per cent Number of b i r d s 30.4 7 55.8 29 24.1 14 6.4 19 48.7 56 17.9 38 -Remain s t i l l Per cent Number of b i r d s .14.1 3 11.5 6 20.7 . 12 2.1 6 10.4 12 5.7 12 F l y Per cent Number of b i r d s 55.5 13 32.7 17 55.2 32 91.5. 272 40.9 47 76.4 162. . an observer, very young c h i c k s e i t h e r h i d and remained m o t i o n l e s s , or ran. A f t e r about 14 days, c h i c k s flew as w e l l . Measures of cohesion were: 1) Distance from hen that c h i c k s h i d when encountered by observer.' 2) Distance from observer a t which c h i c k s f l u s h e d . 3) Distance c h i c k s flew upon encountering observer. Chicks t h a t e i t h e r h i d w i t h i n 10 f e e t of hens, waited u n t i l the observer was .within 20 f e e t before flushing,- or flew 50 f e e t or less., were considered showing strong brood cohesion. Brood cohesion i n c h i c k s changed between years (F-ia.. 17). Chicks h i d s i a n i f i c a n t l v c l o s e r to hens i n 1969 than i n 1967, and d i d not f l y as f a r . The di s t a n c e c h i c k s allowed the observer before f l u s h i n g d i d not vary s i g n i f i c a n t l y . F u l l data on c h i c k cohesion are presented i n t a b l e form i n Appendix IX. Hens and c h i c k s d i s t i n c t l y avoided f l u s h i n g i n 1968, when approached by an observer or doqs. This d i d not g r e a t l y a f f e c t brood cohesion, as b i r d s s t i l l d i s p e r s e d , but. by running r a t h e r than f l y i n g . With hens,;only 33% flushed i n 1968 compared w i t h 55% i n both 1967 and 1969 (Table 13). With c h i c k s , only 41% f l u s h e d i n 1968 compared w i t h 92% and 76% i n 1967 and 1969, r e s p e c t i v e l y (Table 13). Chick data a p p l i e d only a f t e r approximately 14 davs post, hatch, when f l i g h t was p o s s i b l e . In both 1968 and 1969,j c h i c k s accompanying a d u l t hens f l u s h e d s i g n i f i c a n t l y more o f t e n than those accompanying y e a r l i n g hens, suggesting d i f f e r e n t p a r e n t a l i n f l u e n c e s (Table 14). ; Turning to undisturbed behaviour, an assessment of how f a r broods 50 0 100 y so DC LU Q_ 0 100 L969 NO DATA 1968 50 1967 FIG. 17. Per cent of c h i c k s showing strong brood cohesion when d i s t u r b e d by observer, i n 1967, 1968, 1969. Types of measurement are: 1. Chicks t h a t h i d w i t h i n 10 f e e t of hen when encount-ered by observer. 2. Chicks not f l u s h i n g u n t i l observer w i t h i n 20 f e e t -3. Chicks f l y i n g 50 f e e t or l e s s when encountered by observer. TABLE 14.. Comparison o f the r e a c t i o n of c h i c k s from y e a r l i n g and a d u l t hens to disturbance by observer 1968 1969 Chicks from y e a r l i n g hens Chicks from a d u l t hens Chicks from y e a r l i n g hens Chicks from a d u l t hens Run Per cent Number of c h i c k s 71.9 28 . 1 6 . 7 4 54.6 ' 18 5.3 2 Remain s t i l l Per cent Number of c h i c k s 7.7 ' 3-20.8 . 5 9.1 3. 2.6 1 F l y Per cent Number of c h i c k s 20.4 8. 62.5 15 36.3 12 92.1-35 TABLE 15. Brood movements from hatch to mid August ( s t r a i g h t - l i n e d i s t a n c e ) , compared over f i v e years Approximate d i s t a n c e moved (feet) 1960 1961 1967 1968 1969 Short term (10 days or l e s s ) Number of broods Mean d i s t a n c e : Standard e r r o r 17 1065 245.0 9 761 239.4 6 1343 997.8 6 2050 497.6 6 976 280.7 Medium term (11 to 20 days) . Number of broods Mean d i s t a n c e Standard e r r o r 4 1238 526.1 18 600 161.4 6 981.7 360.0 5 2940 .643.7 5 1032 384.8' Long term (> 20 days) Number of broods Mean d i s t a n c e Standard e r r o r 11 2050 682.6 14 1860 616.7 2 1950 650.0. 2 4200 200.0 2 1720 920.0 moved was obtained by r e s i g h t i n a colour-marked hens, recapture of marked c h i c k s , and use of telemetry. Movements were broken down i n t o short-term (10 days or l e s s ) , medium (11 to 20 days) , and long-term l>20 days). D i s -tances moved were, measured as s t r a i g h t l i n e s between two capture or s i g h t i n g l o c a t i o n s . This o b v i o u s l y r e s u l t e d i n lower than a c t u a l v a l u e s , but t h i s b i a s i s considered constant. In one extreme case, i n 1969, a hen wearing a t r a n s m i t t e r , w i t h f i v e c h i c k s , was at one time 2 3/4 m i l e s from i t s nest, but i n e a r l v August moved back to w i t h i n 1000 f e e t of the nest. Radioed hens, d i s t u r b e d more f r e q u e n t l y than other hens, d i d not move any qreater d i s t a n c e s . Two hens w i t h r a d i o s spent a l l of J u l y w i t h i n 1000 f e e t of t h e i r n e s t s , d e s p i t e p e r i o d i c capture and release, of t h e i r c h i c k s . Table.15, which summarizes brood movements, i s supplemented by data c o l l e c t e d i n 1960 and 1961 (Weeden, 1961b, 1962). For medium and long-term p e r i o d s , broods moved s i g n i f i c a n t l y f a r t h e r i n 1968 than other years (Table 15). Broods normally j o i n together i n f l o c k s i n eary August (Weeden, 1959). Before t h a t , althouqh broods mav encounter each o t h e r , .with sub-sequent brood mixinq, hens.normallv Continue to lead a d i s t i n c t qroup of c h i c k s . In 1968, f l o c k i n a of broods occurred e a r l i e r (beginning 19 days a f t e r mean hatch date) than i n 1967 (23 days) or 1969 (35 days). In -1960, Weeden (1961b) reported the f i r s t brood f l o c k 47 days a f t e r the mean hatch date. As w e l l as f l o c k i n g e a r l i e r , the number of f l o c k s seen i n J u l y was much grea t e r i n 1968 (11) than 1967 (3) or. 1969 (5). To summarize, the behaviour of w i l d broods d i f f e r e d between years. Broods became p r o g r e s s i v e l y more cohesive - i n four of the seven measures, b i r d s i n 1969 were s i g n i f i c a n t l y more cohesive than i n 1967; i n two mea-sures cohesion was a l s o stronger but not s i g n i f i c a n t l y so; i n the remaining one, no c l e a r d i f f e r e n c e was found. Brood cohesion i n hens was p a r t l y r e l a t e d to aggression. An. a d d i t i o n a l measure of aggression i n hens was defense of nests, which appeared to p r o g r e s s i v e l y increase in s t r e n g t h from 1967 to 1968 to 1969, but sample s i z e s were s m a l l . And f i n a l l y , f o l l o w i n g a d i f f e r e n t p a t t e r n , i n 1968 broods moved f a r t h e s t , f l o c k e d e a r l i e s t , and both hens and c h i c k s f l u s h e d l e s s o f t e n . These changes i n behaviour may have occurred because of e n v i r o n -mental d i f f e r e n c e s , or d i f f e r e n c e s w i t h i n the b i r d s themselves. To • i n v e s t i g a t e d i f f e r e n c e s w i t h i n the b i r d s , behaviour was assessed i n the a v i a r y . A v i a r y A v i a r y behaviour s t u d i e s concentrated p r i m a r i l y on a s s e s s i n g changes i n aggression, as t h i s aspect of behaviour has been i m p l i c a t e d i n chanqing numbers i n other Lagopus s t u d i e s , -Each brood was presented w i t h a m i r r o r f o r f i v e minutes each dav throughout the summer. The behaviour d i r e c t e d to t h e i r image was observed and .recorded. Behaviour d i r e c t e d towards the m i r r o r i n v o l v e d e x p l o r a t o r y a c t s such as cocking head, l o o k i n g , and g e n t l e pecking. More i m p o r t a n t l y , i t i ncluded a sequence of behaviour - run up to the m i r r o r , v i o l e n t peck at the, image, and run away. These three a c t s were considered a g o n i s t i c , -as they included elements of both " f i g h t and f l i g h t " . One f u r t h e r act was considered wholly aqgressive: "shadow-boxing", being a r a p i d l a t e r a l head movement, accompanied by pecks and sometimes foot s c r a t c h i n g at the m i r r o r . Head feathers were e r e c t . Normally shadow-boxina was seen i n the context of a g o n i s t i c a c t s , but s i n c e i t sometimes occurred alone, i t was analyzed s e p a r a t e l y , . A g o n i s t i c and aggressive behaviour, measured as d e f i n e d , were viewed as two semi-independent methods of measuring e s s e n t i a l l y the same -, i n t e r n a l l y aroused s t a t e of the c h i c k . Two of the a c t s c a t e g o r i z e d under a g o n i s t i c behaviour, namely run up and v i o l e n t peck, can be considered aggressive. A g o n i s t i c scores f o r c h i c k s , summed over the e i g h t weeks, c o r r e l a t e d w i t h aggressive scores (r = 0.65). . D e t a i l s of methods, and t h e i r v a l i d i t y i n measuring a g o n i s t i c and aggressive behaviour are found i n Appendix I I (Measuring A g o n i s t i c , and Aggressive Behaviour i n Captive Rock Ptarmigan C h i c k s ) . A g o n i s t i c Behaviour. - I n d i v i d u a l scores f o r c h i c k s , i n acts per minute of o b s e r v a t i o n , were t o t a l l e d over the summer, and c a t e g o r i z e d as: Low = 0 to .09 acts per minute Medium = .1 to .19 acts per minute High = .2 and greater acts per minute Tabular data supporting the f i g u r e s that f o l l o w are presented i n Appendix X I I I ( A d d i t i o n a l Data on A g o n i s t i c and Aggressive Behaviour i n Captive Rock Ptarmiqan C h i c k s ) . The p r o p o r t i o n of h i g h l y a g o n i s t i c b i r d s i n the a v i a r v increased from 1967 to 1968 to 1969 ( F i g . 18). This was not q u i t e s t a t i s t i c a l l y 80 70 60 50 i— L U o 40 30 20 10 I L U Q . AGE 1&2 WEEKS 1967 1968 1969 AGE 3 & 4 WEEKS 1967 1968 1969 YEAR MEDIUM AGONISTIC RATING HIGH AGONISTIC RATING AGE 5, 6, 7, & 8 WEEKS 967 968 969 i CTl Ul I FIG. 18. Comparison of the a g o n i s t i c behaviour r a t i n g s between years of c a p t i v e rock ptarmigan c h i c k s . Data are broken i n t o three age groups. s i q n i f i c a n t between 1967 and 1968, but was between 1968 and 1969. As noted i n F i g . 18, a g o n i s t i c behaviour changed w i t h age, i n c r e a s i n g through the t h i r d and f o u r t h weeks, and waning t h e r e a f t e r ; hence analyses were separ-ated i n t o age p e r i o d s . The s i g n i f i c a n t increase between 1968 and 1969 was mainly due to an increase i n a g o n i s t i c behaviour of c h i c k s from a d u l t hens ( F i g . 19), which, although marked i n a l l three age p e r i o d s , was s t a t i s t i c a l l y s i g n i -f i c a n t only i n the o l d e s t age p e r i o d , when c h i c k s were f i v e weeks and o l d e r . There was a l s o an increase i n a g o n i s t i c behaviour i n c h i c k s from y e a r l i n g hens, but i t was not as great ( F i g . 19). D a i l v d i f f e r e n c e s were observed i n a g o n i s t i c behaviour of i n d i -v i d u a l c h i c k s . Environmental v a r i a b l e s ; time of t e s t i n g , l e n g t h of time a f t e r feeding or handling, d i d not r e l a t e to these d i f f e r e n c e s . Despite d a i l y d i f f e r e n c e s , however, most c h i c k s soon showed tendencies towards e i t h e r r e a c t i n g to or i g n o r i n g the m i r r o r . The d i f f e r e n c e s between c h i c k s , when t o t a l l e d over the summer, were not r e l a t e d to sex, or p o s i t i o n i n hatch r e l a t i v e to brood mates.; Neither d i d scores r e l a t e to the p h y s i c a l w e l l - b e i n g of c h i c k s (other than those c h i c k s v i s i b l y d i s a b l e d , which were excluded from a n a l y s e s ) . Growth ra t e s d i d not d i f f e r s i g n i f i c a n t l y i n c h i c k s w i t h high or low a g o n i s t i c r a t i n g s ( F i g . 20). Stored body f a t , although gr e a t e r i n c h i c k s r a t i n g medium and high than low i n a g o n i s t i c behaviour, was not s i g n i f i c a n t l y d i f f e r e n t (Table 16). A g o n i s t i c scores i n the f i r s t week of l i f e f o r • chicks, t h a t subsequentlv d i e d , or those t h a t l i v e d throughout the summer, o CHICKS FROM ADULT HENS • CHICKS FROM YEARLING HENS 100 AGE 1&2 WEEKS 80 60 40 20 J _L AGE 3&4 WEEKS AGE 5, 6, 7 & 8 WEEKS 1968 1969 1968 1969 YEAR 1968 1969 FIG. 19. Comparison of the a g o n i s t i c behaviour r a t i n g s (medium and high r a t i n g s combined)of rock ptarmigan c h i c k s coming from a d u l t and y e a r l i n g hens. 350 300 250 & 200 i— C3 5?' 150 100 50 o LOW AGONISTIC SCORE © MEDIUM AGONISTIC SCORE A HIGH AGONISTIC SCORE hatch -2-H - 3 ^ H-4-AGE (weeks) FIG.. 20. Comparison of mean weights of cap t i v e rock ptarmigan c h i c k s r a t i n g low, medium, and high i n a g o n i s t i c behaviour. TABLE16. Comparison of stored body f a t of c a p t i v e j u v e n i l e rock ptarm-igan r a t i n g low i n a g o n i s t i c behaviour against those r a t i n g medium or high (mgs. f a t per gram body weight) Fat weight Low a g o n i s t i c r a t i n g Medium and high a g o n i s t i c r a t i n g Mean .3391 .6398 Confidence l i m i t s (+) .1198 .5293 Standard e r r o r (+) .0577 .2238 Sample s i z e 23 8 Four centimeters on each side of the midventral l i n e , of a linear-shaped f a t depot between the crop and p e c t o r a l i s major muscle, were used as an index of t o t a l stored body f a t . d i d not appear d i f f e r e n t . D i f f e r e n c e s i n a g o n i s t i c behaviour were apparent between broods as w e l l as between c h i c k s . For example, i n brood 1, 1969, 79% of the i n d i -v i d u a l scores c a l c u l a t e d f o r each time p e r i o d were i n medium or high a g o n i s t i c c a t e g o r i e s , compared w i t h only 15% i n brood 8. D i f f e r e n c e s between broods d i d not r e l a t e to the number of c h i c k s , whether the brood hatched e a r l y or l a t e , or whether the brood c o n s i s t e d of egg c h i c k s or f i e l d c h i c k s . Age of parent i n 1969., however, d i d i n f l u e n c e brood scores, as discussed. However, c h i c k s from both y e a r l i n g and a d u l t hens increased i n a g o n i s t i c behaviour ( F i g . 19). Therefore, age of parent d i d not wholly account f o r . t h e d i f f e r e n c e between years i n a g o n i s t i c scores. I conclude, t h e r e f o r e , t h a t the increase i n p r o p o r t i o n of agon-i s t i c c h i c k s between years was not the r e s u l t of sampling b i a s . Since the increase i n p r o p o r t i o n of a g o n i s t i c c h i c k s occurred i n a constant e n v i r o n -ment, i t must have had i t s source i n pre-hatch d i f f e r e n c e s i n the stock. Aggressive Behaviour. - Aggressive behaviour was r a t e d from "shadow-boxing" i n f r o n t of the m i r r o r , as. discussed. I n d i v i d u a l scores f o r c h i c k s , t o t a l l e d over the summer, were ca t e g o r i z e d as: Low = 0 to .049 acts per minute Medium = .05 to .099 a c t s per minute High = .10 and g r e a t e r a c t s per minute The p r o p o r t i o n of h i g h l y aggressive c h i c k s increased from 1967 to 1968 to 1969 ( F i g . 21). This was s t a t i s t i c a l l y s i g n i f i c a n t between 1967 and 1968, but not a u i t e s i g n i f i c a n t between 1968 and 1969. Tabular data MEDIUM AGGRESSIVE RATING 80 70 60 50 40 °~ 30 -20 -HIGH AGGRESSIVE RATING o or 10 L967 L968 YEAR L969 FIG. 21. Comparison of the aggressive behaviour r a t i n g s between years of ca p t i v e rock ptarmigan c h i c k s . are i n Appendix XIII. Data were not broken down in t o age periods, as aggressive behaviour d i d not wane very markedly with age. Individual variables previously assessed that may have influenced agonistic behavioural scores, were not re-assessed here, because of the c o r r e l a t i o n between agonistic and aggressive behaviour. As with agonistic behaviour, I conclude that the increase i n proportion of aggressive chicks between years had i t s source i n pre-hatch V. differences i n the stock\ A c t i v i t y of chicks. - Besides measuring agonistic and aggressive behaviour, scores were kept on 11 other behavioural acts. These were l a t e r i n t e r -preted and grouped into three categories: maintenance a c t i v i t y , explor- ; atory a c t i v i t y , and general a c t i v i t y . These are discussed i n Appendix III (Maintenance, Exploratory, and General A c t i v i t y and t h e i r Possible Relevance to Chick Vigour). The observation made was that changes in. these types of behaviour between years d i d not p a r a l l e l each other, or agonistic or aggressive behaviour. This has relevance i n removing the p o s s i b i l i t y that changes i n agonistic and aggressive behaviour merely r e f l e c t e d vigour of chicks - healthy stock responding to the mirror, and unhealthy stock not responding. Lack of vigour, i f a f f e c t i n g behaviour, would l i k e l y lower a l l categories. However, when exploratory and main-tenance a c t i v i t y both were lowest i n 1969 (Appendix I I I ) , agonistic and aggressive behaviour were highest. . Broodmate pecking. - One add i t i o n a l measurement of behaviour was made, broodmate pecking. This appeared to be more exploratory than aggressive. I t did not c o r r e l a t e with aggressive behaviour shown towards the image i n the mirror. Broodmate pecking i s discussed i n Appendix X (Broodmate Pecking and S o c i a l -Hierarchy i n Captive Rock Ptarmigan Chicks). Conclusions Wild broods became progressively more cohesive (less w i l l i n q to flee.from observer) from 1967 to 1968 to 1969. This was p a r t l y due to increasing aggression i n hens. In 1968, broods moved fa r t h e r , flocked, e a r l i e r , and both hens and chicks flushed l e s s often. In the aviary, the proportion of a g o n i s t i c and aggressive chicks increased progressively from 1967 to 1968 to 1969. This was not a r e f l e c -tion, of vigour. I t was apparently due to undetermined parental differences between years. PART IV DISCUSSION In t h i s s e c t i o n I leave a d e s c r i p t i o n of what has happened to both the p o p u l a t i o n (Part I I ) , and q u a l i t y of c h i c k s (Part I I I ) , and d i s c u s s how t h i s i n f o r m a t i o n may e x p l a i n p o p u l a t i o n r e g u l a t i o n at Eagle Creek. The r e s u l t of the a n a l y s i s of p o p u l a t i o n data i n d i c a t e d t h a t f l u c -t u a t i o n s i n abundance from 1960 to 1969 were the r e s u l t of an o r d e r l y and g e n e r a l l y synchronous change i n w inter l o s s and p r oduction l o s s . These were of approximately equal importance to changes i n t o t a l l o s s . V a r i a -t i o n s i n w i nter l o s s were p r i m a r i l y caused by j u v e n i l e b i r d s , w i t h sexes c o n t r i b u t i n g e q u a l l y . V a r i a t i o n s i n p r oduction l o s s were p r i m a r i l y caused by p a r a l l e l changes i n c l u t c h s i z e l o s s and nest f a i l u r e s . Winter l o s s of j u v e n i l e s was the most important l o s s . i n determining the mean l o s s of ptarmigan over the 10 years. Any complete e x p l a n a t i o n of changes i n abundance of rock ptarmigan at.Eagle Creek must e x p l a i n : 1) The high and v a r i a b l e l o s s of j u v e n i l e s i n w i n t e r , 2) The s i m i l a r l o s s i n the sexes of j u v e n i l e s i n w i n t e r , even though they spend most of t h e i r time i n q u i t e d i f f e r e n t h a b i t a t s , . 3) The p a r a l l e l changes i n c l u t c h s i z e , nest f a i l u r e , and winter l o s s . I w i l l f i r s t examine p o p u l a t i o n r e g u l a t i o n by d i r e c t e x t r i n s i c c o n t r o l , exerted by changes i n the environment of the p o p u l a t i o n . Then I w i l l i n v e s t i g a t e the r o l e s of the changes i n q u a l i t y of the stock which . were found (Part I I I ) . P o p u l a t i o n Regulation by D i r e c t E x t r i n s i c C o n t r o l Examination of the i n f l u e n c e of changes i n the environment on w i nter l o s s i s complicated by l a c k of continuous y e a r l y o b servation during the winter period (late-August to early May). However, conclusions may be drawn from miscellaneous observations. Lack of food was not causing any apparent s i g n i f i c a n t l o s s of ptarmigan i n winter. During the winter, both sexes feed p r i m a r i l y on b i r c h buds (Weeden, 1969), which are abundant i n an absolute sense i n both tundra and taiga, habitats. Neither did r e l a t i v e abundance of food a f f e c t winter l o s s , as suggested for microtines by P i t e l k a (1958), as the number of' birds entering the winter period was not r e l a t e d to winter los s (Part I I , F i g . 8 ) . Snow apparently d i d not l i m i t food a v a i l a b i l i t y , as i n the taiga habitat many dwarf b i r c h shrubs p r o j e c t above maximum snow l e v e l s . On the tundra, where most males wintered, had snow l i m i t e d a v a i l a b i l i t y , -disproportionate mortality i n males and females would have r e s u l t e d . This was not observed (Part I I , F i g . 6). In September and October, and again i n A p r i l and May, when both sexes are on the tundra breeding grounds, changes i n snowfall d i d not c o r r e l a t e with winter loss (Table 17). (Actual weather data are i n Appendix XI). As w e l l , changes i n snowfall i n A p r i l and May did not c o r r e l a t e with subsequent c l u t c h sizes (Table 17). Snowfall i n spring and f a l l , therefore, d i d not influence either winter loss or production. Prolonged i c i n g of vegetation may have l i m i t e d food a v a i l a b i l i t y , and McGowan (1969) described l e t h a l e f f e c t of one such ice-storm i n . c e n t r a l Alaska i n January ,1968 on r u f f e d grouse (Bonasa  umbellus) and sharp-tailed grouse (Pedioecetes p h a s i a n e l l u s ) . However, prolonged i c i n g (over four days) occurred i n only one other winter, 1962-63 (McGowan, 1969) . Hence, such conditions, although l i k e l y k i l l i n g p tar-migan, are not s u f f i c i e n t to explain observed winter l o s s . . TABLE 17. Comparison of changes i n winter s u r v i v a l of j u v e n i l e s , and c l u t c h s i z e , w i t h s n o w f a l l i n e a r l y and l a t e w i n t e r 3 Winter Changes i n s u r v i v a l of j u v e n i l e s from . f a l l to s p r i n g Change i n mean amount of snow on ground Mean c l u t c h s i z e f o l l o w i n g s p r i n g E a r l y winter Late winter 1961-'62 b + + -'62-'63 c + - + -'63-'64 - - -'64-'65 - - - same '65-'66 + + + + '66-'67 + - + + •67-'68 - same - -'68-'69 - same - -Calendar dates of season i n t e x t . Decrease from previous year. Increase from previous year. In summer, rock ptarmigan eat a wide v a r i e t y of v e g e t a t i o n (Weeden, 1969), of which there i s abundant supply. A d e c l i n e of Newfoundland w i l l o w ptarmigan took place w i t h no evidence of food shortage (Bergerud, i n p r e s s ) . Lack (1954) concluded that food shortage was not the cause of d e c l i n e s i n g a l l i n a c e o u s b i r d s . Rather, he suggested an i n d i r e c t r o l e f o r food through a predator s h i f t , to be mentioned l a t e r . D eclines of f l u c t u a t i n g small mammal populations have been reported w i t h no evidence of food shortage (Krebs, 1964; Krebs and DeLong, 1965; Rausch, 1950). This evidence from other species or populations does not argue f o r c o n d i t i o n s a t Eagle Creek. I t only dem-ons t r a t e s t h a t d e c l i n e s i n other species can take place without food shortages. We have no assessment of d i f f e r e n c e s i n q u a l i t y of food. Lauck-h a r t (1957) proposed that animal c y c l e s r e s u l t e d from inherent c y c l e s - i n the n u t r i t i o n of p l a n t s . The l a t t e r r e s u l t from the p e r i o d i c b uild-up and l o s s of n u t r i e n t s through the well-known seed-cycles of many tre e s and shrubs. Baker (1950) l i s t e d b i r c h , the main food of rock ptarmigan i n w i n t e r , as having a good seed crop every two or three years. This c y c l e i s too s h o r t to c o r r e l a t e w i t h Alaskan rock ptarmigan f l u c t u a t i o n s . Lauckhart's b e l i e f t h a t the i n t e r a c t i o n of two or more seed-cycles i n d i f f e r e n t t r e e species could cause much longer animal c y c l e s seems unten-able here, w i t h no evidence t h a t ptarmigan shift to other p l a n t species i n w i n t e r . Kimmins ( i n press) proposed t h a t "the n u t r i t i v e q u a l i t y of p l a n t s i s seen as a necessary but not s u f f i c i e n t determinant of c y c l i c p o p u l a t i o n f l u c t u a t i o n s . . . ." This p o s s i b i l i t y makes i d e n t i f i c a t i o n of the r o l e o f n u t r i t i o n d i f f i c u l t , as d i r e c t c o r r e l a t i o n s between n u t r i t i o n and a n i -mal numbers may be masked by other v a r i a b l e s . However, Moss (1969) c o r r e -l a t e d moors w i t h high phosphorus i n heather (Calluna v u l g a r i s ) w i t h high breeding d e n s i t i e s and good breeding success i n red grouse. The p o s s i b l e importance o f n u t r i t i o n a l q u a l i t y of food cannot be r u l e d out without-d i r e c t study. I could i d e n t i f y no component o f weather as s u f f i c i e n t to e x p l a i n changes i n w i n t e r l o s s of j u v e n i l e s . Crusted snow increased exposures t o cold, of Wisconsin r u f f e d grouse (Dorney and Kabat, 1960) by preventing t h e i r burrowing i n i t . Above average w i n t e r temperatures apparently caused these snow c o n d i t i o n s . Above average temperatures are l e s s l i k e l y to cause s i m i l a r snow c o n d i t i o n s i n c e n t r a l A l a s k s , as temperatures r a r e l y approached the m e l t i n g p o i n t during mid wi n t e r (November, December, January, February). The i n t e r i o r b a s i n o f Alaska,, which i n c l u d e s t h i s area, i s "the most ext-ensive r e g i o n of extremely low mean wi n t e r temperatures i n the United S t a t e s " ( S t r e t e n , 1969). No s i g n i f i c a n t c o r r e l a t i o n e x i s t s between mean d a i l y temperatures i n mid winter and l o s s o f j u v e n i l e s (r=0.52, n=9) :(Table 18) even though changes i n mid wi n t e r temperature g e n e r a l l y p a r a l l e l e d changes i n wi n t e r l o s s of j u v e n i l e s . Weather data are given i n f u l l i n Appendix XI. L o c a l v a r i a t i o n s i n temperature l i k e l y caused d i f f e r e n c e s between the two h a b i t a t s due to the common presence of strong termperature i n v e r s i o n s ( S t r e t e n , 1969). Wind played l i t t l e r o l e i n magnifying exposure to c o l d as i t i s very l i g h t i n c e n t r a l A l a s k a . Extremes i n mean v e l o c i t y f r o 1960 to 1969, during November, December, January, and February were small -TABLE 18. Comparison of changes i n winter l o s s of j u v e n i l e s , and c l u t c h s i z e , w i t h temperature i n the f a l l - t o - s p r i n g p e r i o d 3 Winter Changes i n s u r v i v a l of j u v e n i l e s from f a l l to s p r i n g Mean d a i l y temperatures Autumn Mid winter Spring Mean c l u t c h s i z e f o l l o w i n g s p r i n g 1961-'62 '62-'63 •63-'64 '64-'65 •65-*66 •66-'67 '67-'68 •68-'69 same + + same Calendar dates of season i n t e x t . Decrease from previous year. 'Increase from pervious year. 2.4 to 3.7 miles per hour. Periods of p o t e n t i a l stress may occur when ptarmigan s h i f t from summer to winter d i e t s i n September, and again when they s h i f t back to summer d i e t s (May) (Weeden, 1969). Table 18 shows that changes i n mean d a i l y temperatures then did not c o r r e l a t e with changes i n winter loss of ju v e n i l e s . Although I was unable to i d e n t i f y any component of winter weather s u f f i c i e n t to cause changes i n loss of juve n i l e s , I cannot completely eliminate weather as important, i n the absence of data on crusti n g of snow. The possible influence of weather on cl u t c h sizes i s reduced since ptarmigan adjusted t h e i r breeding a c t i v i t y to seasonal variations,, as mentioned i n Part I. Late hatching d i d not a l t e r c l u t c h s i z e ; the l a t e s t and e a r l i e s t years had mean c l u t c h s i z e s of 6.6 and 6.5 eggs res-p e c t i v e l y . Snowfall i n A p r i l and May d i d not c o r r e l a t e with changes i n cl u t c h s i z e , as mentioned. Neither d i d spring temperatures c o r r e l a t e with c l u t c h s i z e (Table 18). I therefore could i d e n t i f y no c l e a r r e l a -tionship between changes i n c l u t c h s i z e and weather. Hunting i n f a l l appeared to have no depressing e f f e c t on subse-quent spring numbers. D e t a i l s w i l l not be presented here, except to r e i t e r a t e p r i n c i p l e conclusions from annual game b i r d reports of the Alaska Department of F i s h and Game. Conclusions are based on band returns and f a l l removal experiments: 1) , Hunters i n f a l l removed approximately 20% of resident adult and year-l i n g males, 5% adult and y e a r l i n g females, and 6% j u v e n i l e s . Adult and y e a r l i n g males were t h e r e f o r e most v u l n e r a b l e to hunting. Their 20% removal represented about h a l f t h e i r l o s s between August and May. Loss of 6% of j u v e n i l e s , represented only approximately 10% of t h e i r t o t a l winter l o s s . That sex r a t i o s were equal each s p r i n g i n d i c a t e d t h a t e i t h e r replacement of males took p l a c e , or females were more s u s c e p t i b l e to other causes-of m o r t a l i t y . Bergerud ( i n press) suggests that female w i l l o w ptarmigan are i n t r i n s i c a l l y l e s s v i a b l e than males during p o p u l a t i o n d e c l i n e s . Latham (1947) concluded from t e s t s w i t h c a p t i v e b i r d s t h a t i n monagamic spe c i e s , females were l e s s able to withstand c l i m a t i c extremes than males. 2) Most hunting was confined to a s t r i p on each s i d e of the Steese High- . way, which b i s s e c t s the study area. In each s p r i n g but one, d e n s i t i e s there were s l i g h t l y g reater than i n more remote areas, but p a r a l l e l changes occurred i n a l l s e c t o r s . The exception was 1968, when, f o r the only time during the study, hunters were able to shoot at Eagle Creek i n A p r i l . In . that year, p o p u l a t i o n d e n s i t i e s along the highway were lower than i n sur-rounding areas. Carcasses of l e g a l l y and i l l e g a l l y taken b i r d s were found. Thus, whereas f a l l hunting seems not to reduce s p r i n g d e n s i t i e s , prolonged s p r i n g hunting may. i 3) A g r e a t e r p r o p o r t i o n of y e a r l i n g males was found on the hunted s e c t o r than on more remote s e c t i o n s , while female age r a t i o s remained s i m i l a r . . Hunting t h e r e f o r e , apparently a f f e c t e d age r a t i o s of males. 4) Removal of 40% of b i r d s present i n f a l l on a 5 square m i l e p l o t near Eagle Creek, i n both 1967 and 1968, r e s u l t e d i n p a r a l l e l changes i n popu-l a t i o n d e n s i t y the f o l l o w i n g s p r i n g as on a c o n t r o l p l o t and at Eagle Creek (Table 19). A f t e r three years of removal, d e n s i t i e s on the experimental TABLE 19. D e n s i t i e s of male rock ptarmigan i n s p r i n g i n experimentally hunted and unhunted (control) p o p u l a t i o n s Area Year C o n t r o l Experimental (unhunted) (40% f a l l removal i n 1967, 1968, 1969) (4 square miles) (5 square miles) . 1967 15 1968 24 25 1969 20 24 1970 20 23 'Males per square m i l e . and c o n t r o l areas were very s i m i l a r (Table 19). E i t h e r f a l l hunting l o s s e s were compensated f o r by a r e d u c t i o n i n other l o s s e s i n w i n t e r , or b i r d s immigrated onto hunted areas from surrounding areas, which counteracted the e f f e c t s of f a l l hunting. I am not sure which took p l a c e . In c o n c l u s i o n , hunting i n f a l l d i d not depress d e n s i t i e s , i t s only c l e a r e f f e c t being t o increase the p r o p o r t i o n of y e a r l i n g males i n the subsequent breeding p o p u l a t i o n . S i m i l a r l y , f a l l hunting was reported as having a n e g l i g i b l e e f f e c t on d e n s i t i e s i n s p r i n g i n S c o t t i s h red grouse (Jenkins, 1963), and Newfoundland w i l l o w ptarmigan (Bergerud and Huxter, 1969), and other g a l l i f o r m e s . Between four and seven per cent of b i r d s disappearing i n winter-were a c t u a l l y found dead each s p r i n g . As mentioned p r e v i o u s l y , the d e n s i t y of b i r d s a t the beginning of w i n t e r , and winter l o s s showed no c l e a r r e l a -t i o n s h i p . Whatever the proximate cause of winter l o s s , i t was not d i r e c t l y l i n k e d to the d e n s i t y of bird's e n t e r i n g the winter p e r i o d . Most common predators on rock ptarmigan i n winter were g y r f a l c o n s (Falco r u s t i c o l i s ) , red foxes (Vulpes f u l v a ) , and to a l e s s e r extent marten (Martes americana), great-horned owls (Bubo v i r g i n i a n u s ) , snowy owls (Nyctea scandiaca) and golden eagles (Aquila chrysaetos) (Weeden, 1965) . A l l but marten.and great-horned owls l i v e i n both h a b i t a t s occupied by rock ptarmigan i n w i n t e r and so could have caused m o r t a l i t y i n both sexes. In 1954, Lack hypothesized t h a t predators turn to and cause d e c l i n e s i n galliformes after declines in the dominant rodent, t h e i r primary food. However, northern micro tine fluctuations character i s r i c c i i i y ars ox s::,ur'"-r periodicity (Elton, 1942; Siiv o n e n , 1954 ; Krebs, 1964) than rock ptarmigan. Lack withdrew t h i s hypothesis (Lack, 1966) p a r t l y on evidence by Buckley (1954) that a peak population of varying hare (Lepus americanus) i n Alaska i n 1947 was out of phase with Alaskan rock ptarmigan. S i m i l a r l y , my casual observations showed that varying hare numbers adjacent to the Eagle Creek area were higher i n 1969 than i n the preceeding years, even though ptarmigan had begun to d e c l i n e , further confirming Lack's a l t e r e d opinion. Too few birds k i l l e d by predators were found to assess changes i n predation, and no information e x i s t s on changes i n predator numbers. Therefore, no conclusions can be drawn as to the r o l e predation played on ptarmigan numbers i n winter. Predation was not considered important i n ptarmigan declines i n Iceland (Gudmundsson,- I960), Newfoundland (Bergerud, i n press; Mercer, 1969), or Scotland (Watson, 1965). Nest f a i l u r e , a main determinant of production l o s s , was primar-i l y due to predation on eggs. Over the 10 years,, i n 81% of nest where no chicks hatched, eggs were e i t h e r removed or mutilated. The remaining 19%, classed as deserted by the hen, contained unmutilated eggs. Desertion was r e l a t i v e l y unimportant compared to i t s much higher occurrence (67.% of nest f a i l u r e s ) i n Newfoundland willow ptarmigan (Bergerud, i n p r e s s ) . Weasels (Mustela erminea) were the p r i n c i p l e nest predators (Weeden, 1965), as they were i n Newfoundland (Bergerud, i n p r e s s ) . Their numbers were not measured. High l e v e l s of nest predation were associated with declines (Part I I , F i g . 4), and perhaps were due to changes i n predator-prey r a t i o s . These r a t i o s could have varied either because of increasing weasel numbers, or conversely, decreasing ptarmigan numbers. When ptarmigan numbers• decreased, i f weasel numbers remained constant, more predators would be present per ptarmigan nest. Hence, nest p r e d a t i o n might increase as p t a r -migan numbers f a l l . In t h i s case, nest p r e d a t i o n i s a r e s u l t , or a symptom of ptarmigan d e c l i n e s , r a t h e r than an independent c a u s a l v a r i a b l e . Weasel numbers might be expected to stay up i n the face of ptarmigan declines-, only i f a b u f f e r food species were a v a i l a b l e . Many small mammal species are present (Manville and Young, 1965), although nothing i s known of t h e i r f l u c t u a t i o n s i n abundance a t Eagle Creek. , However brought about, nest p r e d a t i o n d i d apparently i n f l u e n c e subsequent s p r i n g numbers, as i t was not l a t e r counteracted by.density dependent s u r v i v a l of c h i c k s i n summer, or of j u v e n i l e s i n w i n t e r ; t h a t -i s , when nest l o s s e s were high, subsequent s u r v i v a l was not correspond-i n g l y good, and.vice versa (Part I I , F i g s . 7 and 8 ) . P a r a s i t e s harboured by Alaskan rock ptarmigan are reported on by Babero ( 1 9 5 3 ) , . J e l l i s o n and Neil a n d (1965), S t a b l e r , e t a l . (1967), Anvik (1969) , and A l l e n (1969). These i n c l u d e four species of cestodes, three nematodes,, two trematodes, and three types of blood p a r a s i t e s . With the exception of cestodes b l o c k i n g and causing inflammation of the small i n t e s t i n e i n four b i r d s ( A l l e n , 1969), no evidence e x i s t s t h a t par-a s i t e s were d i s a b l i n g b i r d s . The most common helminth, Brachylaima fus--c a t a , v a r i e d between 26 and 220 per b i r d i n f a l l of 1968. Helminths d i d not a f f e c t body weights or amounts of st o r e d f a t (Appendix I V ) . Although p a r a s i t i s m cannot be discounted completely u n t i l monitored throughout f l u c t u a t i o n s , we have no evidence t h a t i t had any d i s a b l i n g i n f l u e n c e on ptarmigan. S i m i l a r l y , Watson (1965) and Jenkins (1963) reported t h a t p a r a s i t e s , p r i m a r i l y T r i c h o s t r o n g y l u s sp., d i d not a f f e c t the c o n d i t i o n of S c o t t i s h . rock ptarmigan or red grouse r e s p e c t i v e l y . High incidence of i n f e c t i o n w i t h cestodes and nematodes i n bobwhite q u a i l (Colinus v i r g i n i - , anus) i n e a r l y winter d i d not i n f l u e n c e body weight (Robel and Linderman, 1966). ptarmigan i n Newfoundland and Iceland had low l e v e l s of p a r a s i t e s which were not considered.important t o p o p u l a t i o n d e c l i n e s .(Bergerud,. i n press; Watson, 1965 from pers. comm., F. Gudmundsson). Summarizing the evidence f o r e x t r i n s i c c o n t r o l by a. simple and d i r e c t r e l a t i o n s h i p between the environment and ptarmigan numbers, no f a c -t o r , other than weasel pr e d a t i o n on nests was i d e n t i f i e d t h a t caused e i t h e r changes i n winter l o s s , or p r o d u c t i o n , or t h e i r synchrony. Changes i n winter l o s s of j u v e n i l e s were not due to food abundance or hunting, and s u p e r f i c i a l evidence suggests t h a t weather and p a r a s i t i s m were a l s o unimportant. Preda-t i o n and food q u a l i t y were not assessed. Changes i n c l u t c h s i z e s were apparently not i n f l u e n c e d by s p r i n g weather. Such an assessment of d i r e c t e x t r i n s i c c o n t r o l as t h i s can never be considered complete. As w e l l , most s t u d i e s , i n c l u d i n g t h i s one, have examined environmental f a c t o r s i n d i v i d u a l l y , which although simple, may be u n r e a l i s t i c because of p o s s i b l e " p l u r a l i t y of causes" ( C h i t t y , 1967). Changes i n numbers may be the r e s u l t of a combination of e x t r i n s i c f a c t o r s , each one perhaps, c o n t r i b u t i n g to changes, but not s u f f i c i e n t t o e x p l a i n t o t a l change by i t s e l f . However, i t i s d i f f i c u l t t o conceive of any environmental f a c t o r acting, d i r e c t l y on ptarmigan t h a t would create the synchrony i n p o p u l a t i o n parameters t h a t occurred here, e s p e c i a l l y as these parameters acted not only a t d i f f e r e n t times of the year, but i n v o l v e d both production and l o s s . The synchrony was more l i k e l y due to a b a s i c u n d e r l y i n g v a r i a b l e , such as the q u a l i t y or type of b i r d s i n successive p o p u l a t i o n s . P o p u l a t i o n Regulation by Changes i n the Q u a l i t y of Stock Changes i n the q u a l i t y of stock.may o f f e r an e x p l a n a t i o n of popu-l a t i o n r e g u l a t i o n of ptarmigan at Eagle Creek, as suggested i n the foregoing d i s c u s s i o n . This was i n v e s t i g a t e d by t e s t i n g . t h e hypothesis: there are no d i f f e r e n c e s i n the q u a l i t y of c h i c k s between years t h a t i n f l u e n c e sub-sequent s p r i n g d e n s i t i e s . In P a r t I I I changes i n q u a l i t y were i d e n t i f i e d . These are summarized below: • ' , 1967 1968 1969 Wild c h i c k s u r v i v a l A v i a r y c h i c k s u r v i v a l Wild j u v e n i l e weights Wild j u v e n i l e wing lengths Wild j u v e n i l e stored body f a t Wild c h i c k growth r a t e s low high . . high high low high Wild j u v e n i l e adrenal weights Wild brood movements, f l o c k i n g , f l y i n g low . high low Wild j u v e n i l e t e s t e s weights Wild c h i c k brood cohesion Wild hen cohesion and aggression A v i a r y c h i c k a g o n i s t i c behaviour A v i a r y c h i c k aggressive behaviour low low high low medium high In assessing which, i f any, of these changes i n q u a l i t y may be important i n a l t e r i n g subsequent s p r i n g d e n s i t i e s , one must remember that to be s i g n i f i c a n t , they must i n f l u e n c e winter l o s s of j u v e n i l e s , or subsequent production. Chick s u r v i v a l may have i n d i r e c t l y i n f l u e n c e d l a t e r s u r v i v a l of j u v e n i l e s . I f a v a r i a b l e amount of environmental s e l e c t i o n of c h i c k s took place i n d i f f e r e n t summers, the l a t e r v i a b i l i t y and hence s u r v i v a l of the j u v e n i l e cohort may have been a l t e r e d . However, I found t h a t changes i n the inherent v i a b i l i t y of c h i c k s , as measured i n the a v i a r y , provided a b e t t e r e x p l a n a t i o n of changes i n the w i l d c h i c k l o s s i n summer, than d i d any environmental v a r i a b l e (Part I I I ) . The c o n c l u s i o n was drawn that the environment appeared to have a r e l a t i v e l y constant e f f e c t on the chicks.. This e l i m i n a t e s an i n d i r e c t e f f e c t t h a t c h i c k s u r v i v a l might have had on winter l o s s of j u v e n i l e s . The c o n c l u s i o n that c h i c k s u r v i v a l i s pre-determined by p a r e n t a l c o n t r i b u t i o n s i s not unique i n t e t r a o n i d s t u d i e s . Siivonen (1957) sug-gested that the v i a b i l i t y , and hence e a r l y s u r v i v a l of t e t r a o n i d c h i c k s i n F i n l a n d was determined by pre-hatch f a c t o r s . This has been confirmed i n other s t u d i e s i n v o l v i n g comparisons of s u r v i v a l i n c a p t i v e and w i l d stock - r u f f e d grouse (Bump, e t a l . ' , 1947), red grouse (Jenkins, et a l . , 1965), blue grouse (Zwickel and B e n d e l l , 1967), partridge (Southwood, 1967). As mentioned, experiments w i t h S c o t t i s h red grouse and rock ptarmigan, as an aspect of t h i s study, a l s o i n d i c a t e d t h a t c h i c k m o r t a l i t y r e l a t e d b e t t e r to pre-hatch c o n d i t i o n s than changes i n the environment of c h i c k s . As mentioned i n P a r t I I , even though summer ch i c k l o s s was q u i t e minor compared w i t h winter l o s s , i t had a small i n f l u e n c e on subsequent s p r i n g numbers. Only under one c o n d i t i o n could summer l o s s be meaningless; i f i t were counteracted by winter l o s s a c t i n g i n reverse (or i n other words, i f winter l o s s was d e n s i t y dependent). However, i t was not d e n s i t y depend-ent (Part I I , F i g . 8 ) . Summer chick, s u r v i v a l was i d e n t i f i e d as art important component o f p o p u l a t i o n change i n three other long-term Lagopus st u d i e s - S c o t t i s h red grouse (Jenkins, e t a l . , 1967), S c o t t i s h rock ptarmigan (Watson, 1965), and Newfoundland w i l l o w ptarmigan (Bergerud, i n p r e s s ) , but not i n Choate's (1963) four year study of w h i t e - t a i l e d ptarmigan (Lagopus l e u c u r u s ) . Among Tetraonidae, i t s importance appears to vary; Zwickel (1965), a f t e r reviewing t h e . r o l e of e a r l y m o r t a l i t y , s t a t e d ". . . the r o l e of these l o s s e s ( e a r l y m o r t a l i t y ) i n the r e g u l a t i o n of l e v e l s of breeding populations i s a r a t h e r moot p o i n t . " • To conclude, I i d e n t i f i e d changes i n the inherent v i a b i l i t y of c h i c k s , expressing themselves i n the w i l d by a l t e r i n g the s u r v i v a l of c h i c k s i n the summer. However, t h i s was only a r e l a t i v e l y minor determinant of. subsequent breeding numbers. Although p r o v i d i n g evidence to r e f u t e my o r i g i n a l hypothesis t h a t there are no d i f f e r e n c e s i n the q u a l i t y of c h i c k s between years that i n f l u e n c e s p r i n g d e n s i t i e s , the i n f l u e n c e of changes i n summer ch i c k s u r v i v a l was s m a l l . v Weight gains of w i l d rock ptarmigan c h i c k s i n l a t e summer of 1968 lagged behind those of 1967 and 1969, r e s u l t i n g i n s i g n i f i c a n t l y l i g h t e r j u v e n i l e s i n September.1968 (Part I I I ) . 1968 j u v e n i l e s a l s o had the s h o r t e s t wings and l e a s t stored body f a t . The 1968 cohort i n the winter p e r i o d experienced a 67% l o s s , which was s l i g h t l y higher than t h a t experienced the previous winter by the 1967 j u v e n i l e cohort (61%). These f a c t s might suggest t h a t the p h y s i c a l c o n d i t i o n of the 1968 j u v e n i l e cohort a f f e c t e d t h e i r l o s s i n w i n t e r . However, other evidence suggest t h a t s t a t i s t i c a l l y s i g n i f i c a n t d i f f e r e n c e s i n the weight of j u v e n i l e s i n September of•t h e magnitude observed between years (11% to 13%), d i d not i n f l u e n c e w i n t e r • l o s s . In both 1967 and 1968, I c l a s s i f i e d f a l l j u v e n i l e s shot by hunters on the ba s i s of p a t t e r n of pigment on t h e i r n i n t h primary f e a t h e r . These p a t t e r n s are i l l u s t r a t e d i n Appendix X I I (Patterns of Pigment on Ni n t h Wing Primary of Rock Ptarmigan - A N a t u r a l Tag). Y e a r l i n g s the f o l l o w i n g s p r i n g were a l s o c l a s s i f i e d , and the r a t i o of pigment types compared w i t h the r a t i o s i n the same cohort as j u v e n i l e s the previous f a l l . F i g . 22 shows th a t there was l i t t l e d i f f e r e n c e i n f a l l and s p r i n g r a t i o s , i n d i c a t i n g t h a t s u r v i v a l i n winter was uniform among pigment types. However, although a l l groups survived the winter e q u a l l y w e l l , i n September 1967 j u v e n i l e males w i t h a type two pigment p a t t e r n were s i g n i -f i c a n t l y l i g h t e r than j u v e n i l e males i n two other pigment groups (Table 20). D i f f e r e n c e s i n weight were 31 and 32 grams, or 7%. F i g . 22, Diag. A shows that these groups su r v i v e d the winter e q u a l l y w e l l . . . S i m i l a r r e s u l t s were found the f o l l o w i n g winter (Table 20). In September 1968, j u v e n i l e males w i t h a type three pigment p a t t e r n were 30 grams (7%) and 40 grams (10%) l i g h t e r than males i n two other pigment groups. Again, these groups survived i n winter e q u a l l y w e l l ( F i g . 22 - Diag. B) . That they survived e q u a l l y w e l l i n d i c a t e s t h a t weight d i f f e r e n c e s of t h i s magnitude, which were s i m i l a r to those p r e v i o u s l y described between y e a r l y 50 r-40 30 N o m L U o. 20 10 0 F A L L 0 SPRING 1 I 1 1 2 3 4 PIGMENT TYPE DIAG. A. J u v e n i l e males i n F a l l 1967 (89 b i r d s ) and as y e a r l i n g s i n Spring 1968: (36 b i r d s ) 60 r-50 40 ° 30 UJ Q_ 20 10 0 m 1 VIZ 1 2 PIGMENT 3 TYPE DIAG. C. J u v e n i l e females i n F a l l 1967 (7.2 b i r d s ) and as y e a r l i n g s i n Spring 1968 (52 bi r d s ) Y 1 2 3 4 PIGMENT TYPE DIAG. B, J u v e n i l e males i n F a l l 1968 (112 b i r d s ) and as y e a r l i n g s i n Spring 1969 (34 b i r d s ) 1 2 3 4 PIGMENT TYPE DIAG. D. J u v e n i l e females i n F a l l 1968 (143 b i r d s ) and as y e a r l i n g s i n Spring 1969. (46 b i r d s ) FIG. 22. Comparison of per cent of f a l l j u v e n i l e s possessing v a r i o u s pigment patt e r n s on n i n t h p r i m a r i e s , w i t h per cent, found the f o l l o w i n g s p r i n g . TABLE 20. Weights of w i l d f a l l j u v e n i l e rock ptarmigan possessing d i f -f e r e n t pigment p a t t e r n s on n i n t h primary feathers Weight f o r pigment types Males Females Sept. 1967 Sept. 1968 Sept. 1967 Sept. 1968 Type 1 Mean 457.4— 409.9- 374 .8 Confidence l i m i t s (+) 28.5 16.8 35.2 Standard e r r o r 12.5 a 7.9 14.4 Sample s i z e 10 16 3 7 Type 2 Mean 425.8_ 402.3 a 442.7 358.7 Confidence l i m i t s (+) Standard e r r o r 17.7 8.3 20.1 9.7 20.2 8.9 20.2 9.4 Sample s i z e 17 24 10 14 Type 3 Mean a 369.3_ 383.3 357.4 Confidence l i m i t s (+) 35.6 57.6 21.6 Standard e r r o r (+) 15.4 20.8 9.7 Sample s i z e 3 9 5 11 Type 4 Mean 456.9_ 379.9 j 404 .5 361.8 Confidence l i m i t s (+) 23.0 21.6 28.9 9.6 Standard e r r o r 10.3 10.4 13.7 4.8 Sample s i z e 11 23 19 53 weights s i g n i f i c a n t l y d i f f e r e n t . j u v e n i l e cohorts, were meaningless to winter s u r v i v a l . Mercer (1969) found decreasing October weights of w i l l o w p t a r m i -gan i n Newfoundland during a p o p u l a t i o n d e c l i n e . However, m o r t a l i t y i n winter was not p r o g r e s s i v e l y worse. He suggested t h a t weight, r a t h e r than a cause of the d e c l i n e , was a symptom, r e f l e c t i n g v i g o r . Growth r a t e s of m i c r o t i n e s i n d e c l i n i n g populations were reported as poor by Krebs . (1964, 1966). Newson and C h i t t y (1962) reported t h a t d e c l i n i n g p opulations of Microtus c o n s i s t e d of a mixture of animals w i t h i n h e r e n t l y good and poor growth r a t e s . My r e s u l t s i n the a v i a r y d i d not r e v e a l any inherent d i f f e r e n c e s i n growth r a t e s of cohorts of c h i c k s i n • the d e c l i n i n g p o p u l a t i o n of rock ptarmigan. The cause of the l a t e summer la g i n growth r a t e s of 1968 c h i c k s i n the w i l d i s not known. Environmental v a r i a b l e s t h a t may i n f l u e n c e weight i n c l u d e food a v a i l a b i l i t y (Robel and Linderman, 1966) , photoperiod ( K i r k p a t r i c k , 1957), p a r a s i t i s m (MacLulich, 1937), and disease (Green, 'et a l . , 1943). None of these could be i m p l i c -ated here; summer food, as mentioned, was always abundant, photoperiod was the same each year, p a r a s i t e l e v e l s d i d not r e l a t e to body weights, and there was no evidence of disease on autopsy of b i r d s . Food q u a l i t y may have d i f f e r e d i n 1968, to cause a l a t e summer l a g i n weight gains - vege-t a t i o n appeared somewhat d e s s i c a t e d i n l a t e summer due to high temperatures and low r a i n f a l l (part I I I , F i g . 9 ) . However, whatever the cause of the reduced growth r a t e i n l a t e summer of 1968, t h i s reduced r a t e apparently played no r o l e i n s u r v i v a l e i t h e r of c h i c k s or j u v e n i l e s . Regarding organ weights, w i l d j u v e n i l e females i n 1968 had l a r g e r adrenal glands than i n other years. However, t h i s d i d not c o i n c i d e w i t h peak f a l l d e n s i t i e s o r aggression, as expected i f i t were a s s o c i a t e d w i t h b e h a v i o u r a l stress. ( C h r i s t i a n and-Davis, 1964). N e i t h e r d i d a v i a r y c h i c k s who r a t e d d i f f e r e n t l y i n a g o n i s t i c behaviour show any d i f f e r e n c e s i n s i z e of adrenal glands. I cannot conclude, however, t h a t d i f f e r e n c e s i n hormone l e v e l s between w i l d cohorts or a v i a r y c h i c k s d i d not e x i s t , s o l e l y on the b a s i s of weight of adrenals. Although i n c r e a s e d s e c r e t i o n s of androgens o r ; g l u -cocortocoids'may cause increased adrenal weight ( C h r i s t i a n and Davis, 1966), adrenal h i s t o l o g y may change without weight change (Myers, pers. comm.). I can conclude only t h a t s t r e s s r e s u l t i n g from e i t h e r d e n s i t y o f aggres-sion, was not apparent i n the weights o f . a d r e n a l s i n w i l d or a v i a r y juve-n i l e s . The p r o p o r t i o n of a g o n i s t i c and aggressive c h i c k s , increased, among a v i a r y c h i c k s from 1967 to 1968 to 1969. In the constant a v i a r y environment, t h i s must have been determined by pre-hatch i n f l u e n c e s . U n f o r t u n a t e l y , no 'direct measure was found to determine i f changes i n aggression expressed i n the a v i a r y were expressed i n the w i l d as w e l l . Changes i n brood cohesion c o r r e l a t e d w i t h changes i n a v i a r y a g o n i s t i c and aggressive behaviour, over the three years. However, there i s only i n d i r e c t evidence that brood cohesion may have, a c t u a l l y i n v o l v e d aggression in. c h i c k s This evidence i s based on e l i m i n a t i o n of, a more probable cause of the change i n brood cohesion, namely v i g o r of c h i c k s . Unhealthy c h i c k s , i n theory, might not f l u s h as r e a d i l y or f l y as f a r . But, i n 1968 when brood cohesion was greater than i n 1967, brood movements were longer and s u r v i v a l both i n the w i l d and i n the a v i a r y was much b e t t e r . However, without d i r e c t e v i -dence, I cannot be sure t h a t brood cohesion i n c h i c k s was a measure o€ aggression. Even i f aggression had been i d e n t i f i e d i n w i l d c h i c k s , to be s i g -n i f i c a n t to p o p u l a t i o n change, i t must c a r r y over to somehow i n f l u e n c e l a t e r winter l o s s of j u v e n i l e s and subsequent p r o d u c t i o n , ft test was made to see i f aggression, as r a t e d i n the summer i n a v i a r y c h i c k s > was r e l a t e d to aggres-s i o n d i s p l a y e d the f o l l o w i n g s p r i n g . Table 21 compares the order of f i v e c h i c k s ranked f o r both a g o n i s t i c and aggressive behaviour throughout ,the: summer,.with t h e i r order the f o l l o w i n g March. Their order i n March was determined by aggression shown towards each other when food was s u p p l i e d i n a very l i m i t e d space. The s i m i l a r i t y i n rank as c h i c k s , and as s p r i n g j u v e n i l e s approaching the breeding season, suggests t h a t aggression I, measured during the summer was l i k e l y c a r r i e d i n t o the important winter p e r i o d . Strengthening t h i s c o n c l u s i o n are s i m i l a r r e s u l t s w i t h S c o t t i s h rock ptarmigan r a i s e d by A. Watson, Nature Conservancy, Banchory, Scotland, i - • as p a r t of t h i s study. B i r d s were ranked i n the f a l l of 1968 and again the f o l l o w i n g s p r i n g . Ranks were determined by observations of s o c i a l i n t e r -a c t i o n s . Table 22 shows a c l o s e s i m i l a r i t y i n males, l e s s c l o s e but s t i l l s i m i l a r i n females. I n j u r y , a c c i d e n t and temporary removal are a l l known to a f f e c t dominance h i e r a r c h i e s i n p o u l t r y ( A l l e e , 1951). That i d e n t i c a l orders d i d TABLE 21. Aggressive and a g o n i s t i c rank of c a p t i v e Alaskan rock p t a r m i -gan c h i c k s during summer compared w i t h the f o l l o w i n g March Chick Sex Summer Aggressive Rank Summer A g o n i s t i c Rank Aggressive Rank F o l l o w i n g Spring 1 C ' 1 2 1 11 G 2 1 3 8 C . 3 3 4 11 I. 4 4 2 ... 2 B ' . 5 5 5 TABLE 22. Aggressive rank of c a p t i v e S c o t t i s h rock ptarmigan j u v e n i l e s i n F a l l compared w i t h the f o l l o w i n g Spring Males Females F a l l Spring F a l l Spring aggressive rank aggressive rank aggressive rank aggressive rank 1 . ' 1 1 1 2 2 1 2 ' • 2 5 1 8 4 6 4 3 5 3 4 4 5 4 4 7 . 7 6 8 5 not appear e i t h e r i n Alaska or Scotland, t h e r e f o r e , i s not s u r p r i s i n g . The s i m i l a r i t y , however, shows t h a t aggressive - a g o n i s t i c behaviour shown by c h i c k s and f a l l j u v e n i l e s could express i t s e l f the next s p r i n g . In the a n a l y s i s of p o p u l a t i o n data (Part I I ) , s p r i n g t e r r i t o r i a l behaviour f e l l w i t h i n the winter p e r i o d . Perhaps aggression i n the w i l d i s not expressed by c h i c k s , r a t h e r i s dormant u n t i l b i r d s approach t h e i r f i r s t breeding season. I t may f u r t h e r also, r e f l e c t on ,the behaviour of these b i r d s as brood hens. My measure of aggression i n w i l d brood hens hinged p a r t l y on the assumption t h a t cohesive behaviour of hens ( f l u s h i n g d i s t a n c e , d i s t a n c e flown) r e f l e c t e d . a g g r e s s i o n . As evidence t h a t t h i s was t r u e , when hens reacted a g g r e s s i v e l y towards the observer they feigned a t t a c k r a t h e r than f l e d , s o . f l u s h i n g d i s t a n c e and d i s t a n c e flown were minimal. Strength of brood defense was a c t u a l l y measured and found r e l a t i v e l y constant. This measure,.however, was s u b j e c t i v e , and I place l i t t l e confidence i n i t , as many observers were i n v o l v e d i n r a t i n g i t over the three years. An a d d i t i o n a l measure of aggression i n hens, i n defense of t h e i r nests was l e s s s u b j e c t i v e as a l l measurements were made by myself. Although sample s i z e s were s m a l l , hens appeared to defend nests more v i g o r o u s l y from 1967 to 1968 to 1969. Mercer (1969). found t h a t w i l l o w ptarmigan brood hens became pro-g r e s s i v e l y more aggressive i n a d e c l i n i n g p o p u l a t i o n . Watson (1965) reported that male rock ptarmigan were more aggressive during p o p u l a t i o n d e c l i n e i n Scotland.. Changes between years i n aggression i n a d u l t s has t h e r e f o r e been documented i n other Lagopus s t u d i e s . Three questions must be answered before the f u l l s i g n i f i c a n c e of changes i n behaviour to p o p u l a t i o n r e g u l a t i o n at Eagle Creek can be ans-wered: 1) HOw might changes i n aggression a l t e r l o s s i n winter? 2) How might changes i n aggression account f o r the p a r a l l e l changes i n .clutch s i z e and nest f a i l u r e ? , 3) ,How are changes i n aggression caused? Dealing w i t h 1), e x c l u s i o n of p o t e n t i a l breeders from the breeding grounds by the aggressive behaviour of t e r r i t o r i a l holders has been recorded i n red grouse (Watson and J e n k i n s , 1968),.Australian magpie (Gymnorhjna t i b i c e n ) ( C a r r i c k , 1963), song sparrow (Melospjza melodia) (Tompa, 1962). This i s d i s t i n c t from the a l t e r n a t i v e , r o l e of t e r r i t o r i a l behaviour to ; space animals over a v a i l a b l e h a b i t a t , p r o v i d i n g undisputed areas f o r p a i r -formation, and s u c c e s s f u l mating. In t h i s case, no surplus b i r d s were created, as demonstrated i n blue grouse (Dendragapus obscurus) (Bendell and E l l i o t t , 1967) , and r u f f e d grouse (Bonasa umb ;ellus) (Dorney and Kabat, ' 1960), and t e r r i t o r i a l behaviour d i d not l i m i t breeding numbers. However, i n the case of red grouse, A u s t r a l i a n magpie, and song sparrows, p o t e n t i a l breeders were forced onto sub-marginal h a b i t a t where they f a i l e d to repro-duce, e i t h e r because of f a i l u r e to mate, or death. In these cases, the > aggression a s s o c i a t e d w i t h t e r r i t o r i a l behaviour a c t u a l l y l i m i t e d numbers. In S c o t t i s h rock ptarmigan, a l s o , Watson (1965) concluded t h a t surpluses were created and e x p e l l e d , as i n red grouse. However, h i s evidence .was i n d i r e c t , based on the d i s c o v e r y t h a t b i r d s disappeared suddenly j u s t at. the onset of t e r r i t o r i a l behaviour, a feat u r e of the populations where aggre-s s i o n created a s u r p l u s . More aggressive red grouse (Jenkins, et_ a l . , 1963) and S c o t t i s h rock ptarmigan (Watson, 1964) claimed l a r g e r t e r r i t o r i e s . Therefore, the higher the p r o p o r t i o n of aggressive b i r d s i n the p o p u l a t i o n , the lower the d e n s i t y . Myers (1966), a l s o found t h a t aggressive. A u s t r a l i a n r a b b i t s a l s o claimed l a r g e r t e r r i t o r i e s . That surpluses appear to be created i n two other Lagopus popula-t i o n s a t l e a s t suggests i t s p o s s i b i l i t y here. However, no d i r e c t study has been made o f s t h e f a l l - t o - s p r i n g p e r i o d . ' • I f i n rock ptarmigan a t Eagle Creek, aggression acted i n a s i m i l a r way, to create l a r g e r t e r r i t o r i e s and hence a doomed s u r p l u s , one would p r e d i c t t h a t winter, l o s s would increase a s . p r o g r e s s i v e l y more aggressive cohorts competed f o r t e r r i t o r i e s each s p r i n g (The "winter p e r i o d " , l a s t i n g from l a t e August to e a r l y May., in c l u d e s the p e r i o d of t e r r i t o r i a l beha-viour) . Winter l o s s d i d increase when the more aggressive 1968 c h i c k cohort entered the breeding p e r i o d : Chick Cohort Aggression Winter Loss , 1967 low low 1968 higher higher Data over a longer time span are needed t o confirm a r e l a t i o n s h i p between aggression and winter l o s s , as w e l l as d i r e c t o b s e r v a t i o n to see i f aggression i s i n f a c t l i m i t i n g d e n s i t i e s . Wynne-Edwards's (1962) examples of e x c l u s i o n of c e r t a i n members from a p o p u l a t i o n as the r e s u l t of e p i d i e c t i c d i s p l a y s o f f e r s another pos s i b l e method i n which aggression might have worked i n the winter p e r i o d . E p i d i e c t i c d i s p l a y s can be d i s t i n c t from t e r r i t o r i a l behaviour, and oper-ate when the animals are i n f l o c k s . In f a l l , rock ptarmigan form f l o c k s , and.aggressive behaviour has been observed then (Weeden, 1962). Perhaps such behaviour represents e p i d i e c t i c d i s p l a y , r e s u l t i n g i n the e x c l u s i o n of some b i r d s . Again,, the winter p e r i o d needs d i r e c t study. , C h i t t y (I960, 1967) suggested t h a t animals i n a R e c l i n i n g popula-t i o n are i n h e r e n t l y both more aggressive and l e s s v i a b l e . . His hypothesis b r i e f l y i s : at high d e n s i t i e s , mutual i n t e r f e r e n c e lowers reproduction and causes s e l e c t i o n of aggressive i n d i v i d u a l s , but these are l e s s v i a b l e a g a i n s t environmental c o n t i n g e n c i e s , and numbers f a l l u n t i l low enough that lowered mutual i n t e r f e r e n c e reduces s e l e c t i o n f o r aggressive i n d i -v i d u a l s , at which time numbers r i s e again. I d i d not find that aggressive chick, cohorts i n the a v i a r y were l e s s v i a b l e than n o n - a g g r e s s i v e cohorts, r a t h e r the r e v e r s e . . In .the. w i l as w e l l , the 1969 cohort, high i n aggression (measured i n the a v i a r y ) s u r v i v e d much b e t t e r than the 1967 cohort which was low i n aggression. However, perhaps winter r a t h e r than summer i s the p e r i o d when v i a b i l i t y was most severely t e s t e d at Eagle Creek. I f winter l o s s of j u v e n i l e s r e f l e c t e d t h e i r v i a b i l i t y , then the more aggressive cohort (1968) was l e s v i a b l e than the l e s s aggressive cohort (1967), as C h i t t y suggests. To summarize the ways i n which increased aggression may increase winter l o s s , i t may do so by c r e a t i n g and e x p e l l i n g surplus b i r d s , or by -1.01-being l i n k e d w i t h lower v i a b i l i t y . I have presented no evidence.for e i t h e r of these, but have shown t h a t both are compatible w i t h the changes i n ag-gr e s s i o n and winter l o s s reported here• The second question t h a t must be answered i s : how might changes i n aggression account f o r the p a r a l l e l . c h a n g e s i n c l u t c h s i z e and nest f a i l u r e ? Davis (1964) s t a t e d t h a t domestic hens t h a t are aggressive l a y smaller c l u t c h e s than non-aggressive hens. On a p o p u l a t i o n l e v e l the pre-v i o u s l y mentioned hypothesis of C h i t t y ' s suggests that r e p r o d u c t i o n i s lower when aggression increases mutual i n t e r f e r e n c e . Few w i l d s t u d i e s have s p e c i f i c a l l y compared the aggressive l e v e l of the p o p u l a t i o n w i t h reproduction parameters. Watson (1965) noted t h a t c l u t c h sizes'.'paralleled the phase of the p o p u l a t i o n i n S c o t t i s h rock p t a r -migan, as they d i d here. He a l s o found that aggression i n s p r i n g males was highest when numbers were low, so i n e f f e c t described a c o r r e l a t i o n between aggression and c l u t c h s i z e (he d i d not suggest a caus a l r e l a t i o n -ship) . . Mercer (1969) s t a t e d t h a t on a small o f f s h o r e Newfoundland i s l a n d , c l u t c h s i z e s d e c l i n e d i n .a p o p u l a t i o n of w i l l o w ptarmigan as the p o p u l a t i o n d e c l i n e d , but h i s sample s i z e s are not conv i n c i n g (three nests, i n one y e a r ) . On b e t t e r data -, Bergerud showed no c o r r e l a t i o n between c l u t c h s i z e and pop u l a t i o n phase .in w i l l o w ptarmigan.on'the adjacent mainland. In red :-grouse, b i r d s on n u t r i t i o u s moors l a y l a r g e r c l u t c h e s (Jenkins, e t a l . , 1967). They, are a l s o l e s s aggressive (Watson and Moss, i n press, a ) , so, here again i s a p a r a l l e l between aggression and c l u t c h s i z e . In t h i s case, n u t r i t i o n was suggested as an u n d e r l y i n g cause f o r both. N u t r i t i o n as a cause of change i n c l u t c h s i z e has been w e l l documented. Reviewing the l i t e r a t u r e , Lack (1966) found evidence f o r i t i n p a r t r i d g e (Perdix p e r d i x ) , c a p e r c a i l l i e (Tetrao u r o g a l l u s ) , and blackgame (Lyrurus t e t r i x ) . Moss (1968) noted t h a t I c e l a n d i c rock ptarmigan, whose d i e t s were r e l a t i v e l y high i n n i t r o g e n , phosphorus, and s o l u b l e carbohydrates l a i d l a r g e r c l u t c h e s than S c o t t i s h rock ptarmigan. At Eagle Greek, t h a t c l u t c h s i z e s were the same each year i n y e a r l i n g and a d u l t hens (Parp II) suggests a common base, such as n u t r i t i o n might provide. - . There i s , t h e r e f o r e , some evidence i n other s t u d i e s to e x p l a i n why aggression and c l u t c h s i z e s might p a r a l l e l one another. Causes of changes i n c l u t c h s i z e are p r e s e n t l y r e c e i v i n g d i r e c t stucjy (Modafferi, i n prep.). A l i n k between aggression and nest f a i l u r e i s d i f f i c u l t • t o under-stand. As mentioned, pest f a i l u r e was p r i m a r i l y due to weasel p r e d a t i o n on eggs. Perhaps changes i n aggression of hens at nests a l t e r e d suscept-i b i l i t y to p r e d a t i o n . However, ra t h e r than being l i n k e d to aggression, changes i n p r e d a t i o n may have been a r e s u l t of changing ptarmigan numbers, as p r e v i o u s l y discussed. If so, as numbers of ptarmigan went.down, weasel predation.on nests would a u t o m a t i c a l l y i n c r e a s e . T h i s , however, i s spec-u l a t i o n . At present, the reasons f o r the p a r a l l e l changes i n nest preda-t i o n w i t h c l u t c h s i z e and aggression are i l l - d e f i n e d . The t h i r d question r e l e v a n t to understanding the p o s s i b l e r o l e of aggression i n p o p u l a t i o n r e g u l a t i o n i s : How are changes i n aggression . caused? If aggression provides the mechanism that d i c t a t e s p o p u l a t i o n densities', causes, of changes i n aggression are fundamental to p o p u l a t i o n r e g u l a t i o n . Watson (1967), Watson and Moss ( i n press a; i n p r e s s b j , b e l i e v e that a g g r e s s i o n . i n red grouse may be i n h e r i t e d from the p h y s i o l o g i c a l c o n d i t i o n of the hen.. Their data i n d i c a t e that, the q u a l i t y of food eaten by hens a f f e c t s the l a t e r aggression and t e r r i t o r i a l behaviour of o f f s p r i n g poor n u t r i t i o n a f f e c t s egg q u a l i t y which r e s u l t s i n low c h i c k s u r v i v a l and subsequently leads to aggressive t e r r i t o r i a l males. They d i d not propose any s p e c i f i c component of d i e t s whose lack, or excess might lead to aggres-s i o n . I f aggression i s thus l i n k e d to n u t r i t i o n , changes i n aggression between years i m p l i e s changes i n n u t r i t i o n . P o s s i b l e v a r i a t i o n s i n s p r i n g d i e t s of rock ptarmigan a t Eagle Creek are c u r r e n t l y under study (Modaf-. f e r i , i n prep,).. No one has yet i d e n t i f i e d any component of feed t h a t may cause aggression, and f l u c t u a t e i n synchrony w i t h animal c y c l e s -C h i t t y (1967) proposes genetic change as the cause of changes i n , aggression, w i t h s e l e c t i o n pressure on the previous g e n e r a t i o n ( s ) . Such a cause of changes i n aggression has not been supported on a p o p u l a t i o n l e v e l by d i r e c t evidence. However, evidence t h a t aggressive tendencies can be passed on g e n e t i c a l l y has been provided by s e l e c t i v e breeding exper-iments w i t h chickens (Craig et a l . , 1965). Bergerud ( i n press) documented in-breeding w i t h i n w i l d cohorts of Newfoundland w i l l o w ptarmigan which, i f of frequent enough occurrence, would f a c i l i t a t e i n h e r i t a n c e of s p e c i f i c c h a r a c t e r i s t i c s i n i n d i v i d u a l c ohorts. Wynne-Edwards (1962) suggested t h a t changes i n aggression were caused by immediate d e n s i t i e s of animals, r a t h e r than being i n h e r i t e d . My r e s u l t s , however, i n d i c a t e changes i n l e v e l s of aggression can be i n h e r i t e d . In c o n c l u s i o n , data presented i n t h i s study are not s u f f i c i e n t to i n d i c a t e the cause of changes i n aggression beyond being determined by p a r e n t a l i n f l u e n c e s . Whether the p h y s i o l o g i c a l c o n d i t i o n of hens or par-e n t a l genomes were the cause, i s not known. In summing up t h i s t h e s i s , the major conclusions are: 1) Changes i n breeding numbers of rock'ptarmigan were p r i m a r i l y due to o r d e r l y and synchronous change i n w i n t e r l o s s and p r o d u c t i o n , both a c t i n g together i n most years.to e i t h e r increase or decrease numbers. Each c o n t r i b u t e d approximately e q u a l l y to v a r i a t i o n s i n t o t a l l o s s . 2) V a r i a t i o n s i n w i n t e r l o s s were p r i m a r i l y caused by j u v e n i l e b i r d s . V a r i a t i o n s i n production l o s s were p r i m a r i l y caused by p a r a l l e l changes i n c l u t c h s i z e and nest f a i l u r e . 3) P opulation r e g u l a t i o n by d i r e c t e x t r i n s i c c o n t r o l appears u n l i k e l y . Other than p r e d a t i o n by weasels.on n e s t s , no environmental f a c t o r e x t e r n a l to the p o p u l a t i o n i t s e l f appeared s u f f i c i e n t to e x p l a i n changes i n key f a c t o r s - w i n t e r l o s s of j u v e n i l e s and p r oduction l o s s , and t h e i r synchrony. 4) Cohorts of rock ptarmigan c h i c k s d i f f e r e d between years p r i n c i p a l l y i n v i a b i l i t y and i n the p r o p o r t i o n of a g o n i s t i c / a g g r e s s i v e b i r d s . Co-h orts a l s o d i f f e r e d i n growth r a t e s and adrenal and t e s t e s weights. . 5) Changes i n v i a b i l i t y of cohorts of c h i c k s and l e v e l s of a g o n i s t i c / aggressive behaviour appeared to be pre-determined by unknown p a r e n t a l i n f l u o n c e s . . . . The f o u r t h c o n c l u s i o n r e f u t e s the f i r s t p a r t of the o r i g i n a l . h y p o -t h e s i s - that there are no changes i n the q u a l i t y of rock ptarmigan c h i c k s between years. The second p a r t Of the hypothesis was th a t these changes i n q u a l i t y i n f l u e n c e s p r i n g d e n s i t y . Evidence here i s i n d i r e c t but s t r o n g l y suggestive.that such was. true i n the case of aggression. Changes i n aggres-s i o n appear fundamental i n f l u c t u a t i n g Lagopus po p u l a t i o n s , as discussed. From other s t u d i e s , a r o l e appears f e a s i b l e f o r changes i n aggression to i n f l u e n c e both of the important parameters to p o p u l a t i o n change simultan-eously - winter l o s s of j u v e n i l e s and production loss.. I f aggressive b i r d s e i t h e r c l a i m l a r g e r t e r r i t o r i e s or are l e s s v i a b l e i n w i n t e r , w i n t e r l o s s w i l l i ncrease as. more aggressive cohorts enter the p o p u l a t i o n . At the same time, aggression may be l i n k e d w i t h lowered p r o d u c t i o n , through n u t r i t i o n . Although a long way from understanding e x a c t l y how p o p u l a t i o n r e g u l a t i o n i s accomplished a t Eagle Creek, i f indeed there i s a never-va r y i n g mechanism, t h i s study has narrowed the p o s s i b l e e x p l a n a t i o n of changes i n numbers to some b a s i c q u a l i t a t i v e change i n the stock. Fur-thermore, i t has suggested t h a t aggression may be the key. The p r i n c i p l e c o n t r i b u t i o n of th i s , t h e s i s , besides d e s c r i b i n g demographic changes i n a p a r t i c u l a r p o p u l a t i o n , i s a demonstration that successive cohorts from a w i l d p o p u l a t i o n may d i f f e r i n inherent l e v e l s of aggression. Although suggested i n general theory, t h i s has not been p r e v i o u s l y demonstrated before under c o n t r o l l e d c o n d i t i o n s . SUMMARY This study attempts to e x p l a i n changes i n abundance of rock p t a r -migan (Lagopus mutus) at Eagle Creek, A l a s k a , from 1960 to 1969. This was done by f i r s t d e s c r i b i n g demographic changes between 1960 and 1969, and secondly, by t e s t i n g the hypothesis t h a t there are no d i f f e r e n c e s i n the q u a l i t y ( s u r v i v a l , growth, behaviour) of rock ptarmigan c h i c k s between, years t h a t i n f l u e n c e s p r i n g d e n s i t i e s . • The hypothesis was te s t e d through a v i a r y and f i e l d comparisons-.between years, i n 1967, 1968 and 1.969. Spring breeding numbers f l u c t u a t e d , r i s i n g to 325 b i r d s on the 15 square.mile study a r e ^ i n 1962, f a l l i n g f o r three years to 126 b i r d s , , r i s i n g f o r three years to 235 b i r d s , and f a l l i n g again i n 1969. This, f l u c t u a t i o n was the r e s u l t of an o r d e r l y and g e n e r a l l y synchronous change i n l o s s of b i r d s i n winter and production l o s s , both a c t i n g i n most years to e i t h e r increase or decrease numbers. Each of these c o n t r i b u t e d approx-imately e q u a l l y to changes i n annual t o t a l l o s s . Changes i n winter loss, were p r i m a r i l y caused by j u v e n i l e b i r d s . Changes i n production l o s s were p r i m a r i l y caused by c l u t c h s i z e l o s s e s and nest l o s s e s , which v a r i e d i n p a r a l l e l most years .to e i t h e r increase or decrease numbers. Mean l o s s of ptarmigan over the 10 years was p r i m a r i l y e s t a b l i s h e d by winter l o s s . Mean winter l o s s , i n t u r n , was p r i m a r i l y determined by l o s s of j u v e n i l e s . . V a r i a t i o n s i n the s u r v i v a l of c h i c k s i n summer were unr e l a t e d to changes i n subsequent s p r i n g numbers. An assessment was made of d i r e c t e x t r i n s i c c o n t r o l of ptarmigan riumbers, by environmental v a r i a b l e s . Evidence was found t h a t weasel pred-a t i o n qn nests played a small r o l e i n i n f l u e n c i n g changes i n s p r i n g numbers Changes i n winter l o s s of j u v e n i l e s were not due t o fopd shortage or hunting. S u p e r f i c i a l evidence suggested t h a t weather and p a r a s i t i s m were a l s o unimportant. Pr e d a t i o n and food q u a l i t y were not assessed. Changes i n c l u t c h s i z e were apparently not i n f l u e n c e d by s p r i n g weather. Although not complete, the assessment of e x t r i n s i c c o n t r o l f a i l e d to i d e n t i f y a d i r e c t environmental source of the v a r i a t i o n s i n winter IQSS of j u v e n i l e s and c l u t c h s i z e , or t h e i r synchrony. This suggested a more ba s i c u n d e r l y i n g cause of f l u c t u a t i o n s , i n the q u a l i t y of the stock. A v a r i e t y of d i f f e r e n c e s was found i n chi c k s between years. Sur-v i v a l of w i l d c h i c k s i n summer changed between years and appeared u n r e l a t e d to environmental v a r i a b l e s . S u r v i v a l of a v i a r y - r e a r e d c h i c k s i n summer,, i n a standard environment, changed i n p a r a l l e l to changes observed i n the w i l d . I thus concluded t h a t changes i n e a r l y s u r v i v a l of c h i c k s i n the • w i l d were determined by changes i n inherent v i a b i l i t y . However, changes i n summer ch i c k s u r v i v a l were r e l a t i v e l y unimportant to changes i n subse-quent s p r i n g numbers. In 1968, weight gains of w i l d c h i c k s lagged behind those i n other years, r e s u l t i n g i n s i g n i f i c a n t l y l i g h t e r j u v e n i l e s i n September. These j u v e n i l e s a l s o had the s h o r t e s t wings and l e a s t stored body f a t . No com-parable d i f f e r e n c e s in'growth were found i n a v i a r y b i r d s . The d i f f e r e n c e s i n p h y s i c a l c o n d i t i o n of w i l d j u v e n i l e s i n 1968 apparently played no r o l e i n i n f l u e n c i n g winter l o s s or subsequent s p r i n g numbers. The weights of adrenal glands of w i l d female j u v e n i l e s i n Sept-ember 1967 were s i g n i f i c a n t l y l i g h t e r than i n 1968 or 1969. Testes were s i g n i f i c a n t l y heavier i n 1969 than 1967 or 1968. However, these d i f f e r -ences appeared u n r e l a t e d to d e n s i t y or aggression, and were considered unimportant. The p r o p o r t i o n of a g o n i s t i c and aggressive c h i c k s i n the a v i a r y increased from 1967 to 1968 to 1969. In the w i l d , c h i c k aggression was not d i r e c t l y measured. Brood hens, however, became p r o g r e s s i v e l y l e s s w i l l i n g to f l e e from the observer and t h i s was l i n k e d i n p a r t w i t h i n c r e a s i n g aggression. Both a v i a r y and w i l d c h i c k s v a r i e d i n other aspects of beha-v i o u r between years such as maintenance and e x p l o r a t o r y behaviour i n the,-a v i a r y , brood movements and f l o c k i n g i n the w i l d , but these could not be r e l a t e d in. any meaningful way to p o p u l a t i o n processes. Changes i n aggres-s i o n , however, p o t e n t i a l l y might e x p l a i n . v a r i a t i o n s i n winter l o s s of j u v e n i l e s , i f aggressive b i r d s c l a i m l a r g e r t e r r i t o r i e s or are l e s s v i a b l e , as suggested i n other s t u d i e s . Changes i n aggression might a l s o e x p l a i n p a r a l l e l changes i n c l u t c h s i z e , i f founded on n u t r i t i o n as suggested i n other s t u d i e s . To conclude, t h i s study has suggested t h a t changes i n aggression may be fundamental to p o p u l a t i o n r e g u l a t i o n of rock ptarmigan a t Eagle Creek. Further s t u d i e s should attempt to e x p l a i n the causes and r o l e of aggression. The p r i n c i p l e c o n t r i b u t i o n of t h i s t h e s i s , besides d e s c r i b i n g demographic changes i n a p a r t i c u l a r p o p u l a t i o n , has been to demonstrate that successive cohorts from a w i l d p o p u l a t i o n may d i f f e r i n inherent l e v e l s of aggression. APPENDICES APPENDIX I . TECHNIQUES OF INCUBATION, HOUSING, AND REARING ROCK PTARMIGAN CHICKS I r a i s e d rock ptarmigan c h i c k s i n the summers of 1967, 1968, and 1969, w i t h the o b j e c t i v e of comparing t h e i r s u r v i v a l , growth, and beha-v i o u r under constant environmental c o n d i t i o n s . Eggs f o r the a v i a r y were c o l l e c t e d i n the w i l d a t Eagle Creek, Alaska. Nests were l o c a t e d by r a d i o - t r a c k i n g p r e v i o u s l y instrumented hens, or searching w i t h t r a i n e d bird-dogs. Nest l o c a t i o n s were marked and r e v i s i t e d p e r i o d i c a l l y u n t i l c l u t c h e s were complete. Eggs were placed i n t o warm g r a i n (100°F) i n g a l l o n thermos jugs f o r t r a n s p o r t a t i o n to a temporary h o l d i n g f a c i l i t y , a propane-operated incubator a t my f i e l d head-q u a r t e r s , and subsequently to my a v i a r y a t the U n i v e r s i t y of Alaska. This technique of handling eggs has been s u c c e s s f u l l y used by Bump et al.. ,, (1947), and Zwickel (1965) . The a v i a r y was i n a c o n t r o l l e d environment room, 15 f e e t by 10 f e e t i n s i z e , where temperature was maintained between 70° and 80°F., and, except f o r a dark p e r i o d between 22:30 and 01:30 hours, l i g h t was c o n t i n u -ous . At the a v i a r y eggs were i n d i v i d u a l l y marked and placed i n a s t i l l -a i r i ncubator. Temperature was maintained a t 100°F. at the top of the eggs, although a f l u c t u a t i o n of + 1°F. was common. Humidity was held as high as p o s s i b l e w i t h water pans. Eggs were r o l l e d twice each day i n opposite d i r e c t i o n s a l t e r n a t e l y to prevent t w i s t i n g of the chalaza (Anon-ymous, 1966). Egg r o l l i n g was suspended f o r any brood when p i p p i n g began. -110-Then , each egg r e c e i v e d a drop of water p e r i o d i c a l l y on the p i p p i n g spot to keep the membranes s o f t and p l i a b l e . Success w i t h these techniques was comparable w i t h t h a t a t t a i n e d by hen ptarmigan i n the w i l d , i n 1968 and 1969. In 1968 I hatched 93% of 84 eggs; i n the w i l d , 86% hatched. In 1969, when 67 eggs were c o l l e c t e d , my techniques and those of w i l d hens both r e s u l t e d i n an 82% hatch. Bump . et a l . (1947) s t a t e d t h a t hatching success around 72%, which they normally a t t a i n e d w i t h r u f f e d grouse "compares favourably.with the h a t c h a b i l i t y of the eggs of other game b i r d s which have, through the years, been f u l l y adapted to a r t i f i c i a l propagation." Success w i t h a r t i f i c i a l i n c u b a t i o n exceeded success a t t a i n e d by w i l d rock ptarmigan hens i f l o s s e s of eggs from hen nest d e s e r t i o n and pr e d a t i o n are considered. In 1967, f a u l t y w i r i n g allowed excessive temperatures on one occa-s i o n , reducing hatching success to 28%. When each chick was dry (eight' to 10 hours a f t e r h a t c h ) , i t was weighed and banded, and placed i n t o a brooder pen, as were wild-hatched c h i c k s brought to the a v i a r y at l e s s than four days of age. The l a t t e r were transported i n l a r g e thermos chests h a l f f i l l e d w i t h warm g r a i n covered w i t h burlap upon which they walked. Each brood was housed i n i t s own pen, measuring f i v e f e e t by three f e e t by two f e e t high. Pens were stacked i n b a t t e r i e s of f o u r . Each pen had a wire f l o o r w i t h a dropping pan beneath, and a wire front.' An i n f r a - r e d heat lamp, t h e r m o s t a t i c a l l y c o n t r o l l e d , was suspended on an angle i n each pen, and provided a choice of temperatures from a maximum of 100°F. d i r e c t l y below i t . Red l i g h t was chosen as i t . reduces c a n n i b a l -ism (Peckham, 1966). In 1968 and 1969 an a d d i t i o n outdoor pen was used i n which broods were mixed. I t c o n s i s t e d of an elevated brooder house, complete w i t h heat lamps and a l a r g e elevated run. T o t a l f l o o r area was approximately 144 square f e e t . In 1969, a f t e r c h i c k s became thermoregulatory at a p p r o x i -mately f i v e days, they were moved to a l a r g e " f l i g h t pen", 2500 square f e e t i n s i z e and over 20 f e e t h i g h , which contained n a t u r a l v e g e t a t i o n and much cover. Chicks were fed Purina's Game B i r d Startena throughout the summer, which contained " i n excess of 30% p r o t e i n " ( a n a l y s i s y i e l d e d . 2 4 % ) . In a d d i t i o n , they r e c e i v e d finely-chopped l e t t u c e and h a r d - b o i l e d eggs, suc-c e s s f u l l y used as a supplement f o r blue grouse c h i c k s (Zwickel, 1965). A l l feed was s u p p l i e d ad_ l i b i t u m . D r i n k i n g water was c o n t i n u o u s l y a v a i l -a b l e , and i n c l u d e d " P o l y o t i c Soluble Powder", a broad spectrum a n t i b i o t i c whose a c t i v e i n g r e d i e n t was t e t r a c y c l i n e h y d r o c h l o r i d e a t 25 grams per pound. I t was d i l u t e d to 100 mgs. powder per l i t r e of water. This had been p r e v i o u s l y used s u c c e s s f u l l y i n r e a r i n g r u f f e d grouse (Fay, 1963) . S t e r i l i z e d g r i t , obtained i n a nearby g r a v e l area, was a l s o c o n t i n u o u s l y a v a i l a b l e . These techniques r e s u l t e d i n e x c e p t i o n a l l y high s u r v i v a l r a t e s i n two years, e s p e c i a l l y i n the indoor a v i a r y (Part I I I ) . Growth r a t e s exceeded those i n the w i l d i n a l l three years. In the a v i a r y , a t the end of seven weeks, mean Weights were 350 grams i n both 1968 and 1969. Wild c h i c k s i n t h e i r e i g h t h week a f t e r mean hatch date weighed 221 and 249 grams i n 1968 and 1969 r e s p e c t i v e l y . In 1967, a v i a r y c h i c k s a t the end of the s i x t h week, the l a s t measure, weighed 311 grams; w i l d c h i c k s weighed only 174 grams. Two explanations are p o s s i b l e f o r the comparatively r a p i d growth r a t e s i n the a v i a r y : lower energy requirements f o r thermoregulation and movement, or the' e f f e c t of the a n t i b i o t i c , ' t e t r a c y c l i n e h y d r o c h l o r i d e . C h l o r t e t r a c y c l i n e , a s i m i l a r compound, i s used t o increase weight of beef c a t t l e (Beeson, 1969). Lewin (1963) found t h a t a r i c h complement of micro-organisms i n the caeca of C a l i f o r n i a q u a i l retarded growth; conversely, t h e r e f o r e , a s i m p l i f i e d b i o t a r e s u l t i n g from feeding a broad spectrum a n t i b i o t i c may have increased ptarmigan growth r a t e s - Chicks i n most ca p t i v e s t u d i e s grow e i t h e r at comparable r a t e s w i t h w i l d c h i c k s (Zwickel, 1965), or slower (Genelly, 1955) . No evidence was found t h a t the high p r o t e i n i n the r a t i o n , pro-vided by the egg i n a d d i t i o n to i t s high l e v e l i n the Startena, was d e t r i -mental. Reportedly (N.A.S.-N.R.C- N u t r i e n t Requirements of P o u l t r y , 1966) i t can r e s u l t i n reduced f a t d e p o s i t i o n . I found comparable amounts of f a t i n a v i a r y and w i l d c h i c k s , i n s p i t e of the d i f f e r e n c e s i n t o t a l body weight mentioned, A r i g i d c l e a n i n g and s t e r i l i z i n g program was followed throughout. APPENDIX I I . MEASURING AGONISTIC AND AGGRESSIVE BEHAVIOUR IN CAPTIVE ROCK PTARMIGAN CHICKS Technique Each brood was presented w i t h a m i r r o r placed i n i t s pen d a i l y f o r f i v e minutes. The m i r r o r measured e i g h t inches by 10 inches. I t was propped a g a i n s t a w a l l of the pen, i n the same p o s i t i o n each day, and the c h i c k s l e f t undisturbed u n t i l i t was time to remove the m i r r o r . No b l i n d was necessary f o r the observer, as the c h i c k s , being imprinted on humans, were not d i s t u r b e d by our presence. Tests were c a r r i e d out from one day to e i g h t weeks of age. Three a c t s , normally o c c u r r i n g i n sequence, were considered ; together as a g o n i s t i c : run up to the image, v i o l e n t peck a t the image, and run away. Gently pecks were a l s o d i r e c t e d to the m i r r o r . These were considered merely e x p l o r a t o r y . One a c t , which o f t e n occurred alone, was considered aggressive: "shadow-boxing", being a r a p i d l a t e r a l head mover ment, accompanied by pecks and sometimes f o o t s c r a t c h i n g a t the m i r r o r . Head feathers were e r e c t . A g o n i s t i c and aggressive behaviour were viewed as e s s e n t i a l l y measuring the same i n t e r n a l l y aroused s t a t e of the c h i c k . Two of the a c t s c a t e g o r i z e d under .agonistic behaviour, namely run up and v i o l e n t peck., can be considered aggressive. Run away was i n c l u d e d w i t h them to increase sample s i z e s , and w i t h t h i s a c t , the b e h a v i o u r a l sequence became a g o n i s t i c , having components of both " f i g h t and f l i g h t " . A g o n i s t i c scores f o r c h i c k s , summed over the e i g h t weeks, c o r r e l a t e d w i t h aggressive scores (r=0.65). Scores f o r both a g o n i s t i c and aggressive behaviour were expressed as acts per minute of o b s e r v a t i o n . Since shadow-boxing was o f t e n a con-tinuous a c t , i t was scored no more f r e q u e n t l y than once every 30 seconds. My o b j e c t i v e was to i d e n t i f y changes i n the t o t a l l e v e l of agon-i s t i c and aggressive habiour i n c h i c k s between years. In f i n a l analyses, t h e r e f o r e , a c t s per minute were r e l e g a t e d i n t o three c a t e g o r i e s , low, medium, and high, and per cent of c h i c k s i n each category compared between years. In t h a t way, a few h i g h l y aggressive c h i c k s could not over i n f l a t e the, t o t a l scores. Over the three summers of study, d i f f e r e n t people were i n v o l v e d i n r a t i n g behaviour. In 1967 and 1968, I r a t e d approximately h a l f , and i n 1969, I r a t e d a l l behaviour. The three a g o n i s t i c a c t s , being d i s c r e t e and evident, were considered f r e e from any o b s e r v a t i o n a l b i a s . P e r i o d i c sim-ultaneous observations by the personnel i n v o l v e d confirmed t h i s . Shadow-boxing, o f t e n being a continuous a c t , was more s u b j e c t i v e . My method of a n a l y s i s took t h i s i n t o account as f o l l o w s : since no c h i c k could be,scored f o r shadow-boxing more f r e q u e n t l y than once every 30 seconds, a maximum score f o r any f i v e m i n u t e ' p e r i o d was 10. However, I assigned a f i n a l value of one to d a i l y scores from one to f o u r , and a value of two to d a i l y , scores from seven to 10. By ommitting observations where scores f e l l a t f i v e or s i x , a computed d i f f e r e n c e between observers of up to 15% was not r e f l e c t e d i n the f i n a l data. No d i f f e r e n c e i n frequency of a g o n i s t i c or aggressive behaviour was observed between aviary-hatched c h i c k s and f i e l d - h a t c h e d c h i c k s . Data were t h e r e f o r e lumped. Test of Technique Tests were designed to v a l i d a t e using a m i r r o r to measure agon-i s t i c and aggressive behaviour. I n t r o d u c t i o n Tests By p l a c i n g strange b i r d s together, I v e r i f i e d t h a t a l l three com-ponents of a g o n i s t i c behaviour shown i n f r o n t of the m i r r o r , could a l s o be d i r e c t e d to a c t u a l c h i c k s . Table 23 d e t a i l s the r e s u l t s of e i g h t t e s t s , each between s i x and 20 minutes long, i n w h i c h . e i t h e r a stranger was i n t r o -duced i n t o a brood, or two c h i c k s were p a i r e d . In three of these, agon-i s t i c behaviour was observed, being extreme i n t e s t 2 where the aggressive b i r d e v e n t u a l l y opened a wound at the base of i t s oponent's beak. However, i n f i v e t e s t s , no a g o n i s t i c behaviour occurred even though a l l but one t e s t ( t e s t 3) i n v o l v e d a t l e a s t one c h i c k who was c o n s i s t e n t l y aggressive i n f r o n t of the m i r r o r . I conclude, t h e r e f o r e , that a g o n i s t i c a c t s d i r - , ected towards a c t u a l c h i c k s are the same as those shown towards the m i r r o r . Actual' c h i c k s , however, are l e s s of a stimulus f o r a g o n i s t i c behaviour than the m i r r o r image. Shadow-boxing d i d not occur, l i k e l y because the subordinate c h i c k always withdrew from encounters. Tests With The M i r r o r Placed Backwards To show that the. a g o n i s t i c response was e l i c i t e d by the image and not the m i r r o r as a strange o b j e c t , I placed the m i r r o r backwards, i t s brown p l a s t i c backing only being v i s i b l e to the c h i c k s . In 25 minutes of TABLE 23. Agonistic behaviour shown by rock ptarmigan chicks towards strange chicks. Test number Conditions Results 1 Two ag o n i s t i c chicks No ag o n i s t i c behaviour 2 Agonistic and npn-agonistic chick Continuous run up and v i o l e n t peck by, a g o n i s t i c chick 3 Two.non-agon-i s t i c chicks No agonistic behaviour 4,5,6 Agonistic chick into another brood Test 4 - no agonistic behaviour Test .5 - introduced chick run up, v i o l e n t peck, run away 10 times Test 6 - introduced chick chased and pecked at 7 times 7,8 Non-agonistic chick into another brood No agonistic behaviour Chicks rated as being a g o n i s t i c by response to mirror presented to the brood. t e s t i n g , made up of three minutes per t e s t at v a r i o u s times during the summer, no a g o n i s t i c acts were d i r e c t e d to the back of the m i r r o r . E x p l o r -atory behaviour only was shown. Test on Chicks Housed In a Large Outdoor Enclosure The m i r r o r was presented to a group of about 25 c h i c k s housed i n a 2,500 square f o o t outdoor enclosure, to be sure the a g o n i s t i c and aggres-s i v e response was not merely an a r t i f a c t of confined housing. A b l i n d was necessary, as these c h i c k s were not used to seeing humans. A l l three components of a g o n i s t i c behaviour, and aggressive behaviour were d i s p l a y e d towards the image i n three twenty minute t e s t s . The behaviour p a t t e r n s were shown i n l e s s e r amount than when indoors, i n d i c a t i n g that c l o s e con-finement might have been p a r t i a l l y r e s p o n s i b l e f o r the high scores indoors, but. not e n t i r e l y . I s o l a t i o n Tests S t a t i s t i c a l t e s t s t r e a t e d c h i c k s as e n t i t i e s , r a t h e r than broods as e n t i t i e s . This was j u s t i f i e d by a set of t e s t s which determined that any. c h i c k ' s r e a c t i o n to the m i r r o r was unaffected by the presence of i t s broodmates. In these t e s t s , a l l but one c h i c k was removed, and the m i r r o r placed i n the pen. A g o n i s t i c c h i c k s again showed a g o n i s t i c and aggressive behaviour i n these c o n d i t i o n s , w h i l e non-agonistic c h i c k s d i d not (Table 24) . D i s c u s s i o n . A m i r r o r was used s u c c e s s f u l l y to measure aggression i n s p r i n g i n w i l d male blue grouse (Dendragapus obscurus) (Mossop, i n prep), and TABLE 24. A g o n i s t i c and aggressive behaviour shown towards t h e i r m i r r o r image by i n d i v i d u a l rock ptarmigan c h i c k s i n i s o l a t i o n Number of minutes of Number of ch i c k s Type of chi c k A g o n i s t i c behaviour Aggressive behaviour t e s t i n g t e s t e d Run up V i o l e n t peck Run away Shadow-box 20 4 Agon.-aggres. 11 19 27 9 30 6 Non-agon . -aggres. 0 0 0. 0 spruce grouse (Canachites canadensis) (MacDonald, 1968). S t i r l i n g (1967) used a m i r r o r w i t h c a p t i v e female blue grouse, as d i d Stout e t a l . , (1969), w i t h w i l d a d u l t glaucous-winged g u l l s (Larus glaucescens). A l t e r n a t i v e methods of measuring a g o n i s t i c . o r aggressive behavi-our were l e s s s u c c e s s f u l than using a m i r r o r . Salzen (1966) measured aggression i n domestic c h i c k s by p r e s e n t i n g them w i t h e i t h e r a dead c h i c k or an e r e c t or prone h^nd. These s t i m u l i d i d not e l i c i t . a g g r e s s i o n or a g o n i s t i c behaviour i n ptarmigan c h i c k s , but i n s t e a d l e d only to e x p l o r a -t o r y behaviour. Salzen (1966) found that p a i r i n g strange c h i c k s was a l s o s u c c e s s f u l . This method, when used on ptarmigan c h i c k s , drew a much lower response than d i d the m i r r o r , as d i s c u s s e d , even though strangers e l i c i t e d more a g o n i s t i c and aggressive behaviour than c h i c k s housed toge-t h e r . Evans (1968) moved a green wooden t r i a n g l e i n f r o n t of domestic c h i c k s . However, he found t h i s e f f e c t i v e f o r only the f i r s t few days a f t e r hatch. L i m i t i n g access to food, a method used w i t h a d u l t domestic fowl (Guhl, 1953) was unsuccessful w i t h ptarmigan c h i c k s , although i t worked , when c h i c k s reached one year of age. Kolb (1969) . ra t e d aggression by observing s o c i a l rank d i s p l a y e d among red grouse c h i c k s a t 3 1/2 to four months of age. However, as c l e a r l y d efined s o c i a l h i e r a r c h i e s occurred only r a r e l y w i t h i n rock ptarmigan broods before e i g h t weeks of age (Appen-di x X) (or i n domestic c h i c k s - Guhl, 1953), t h i s method cannot be used fo r young c h i c k s . Kolb,'s approach of w a i t i n g u n t i l l a t e summer aggression appears on i t s own, however, provides an a l t e r n a t i v e way to o b t a i n an index of aggression before the f i r s t breeding season. In summary, p r e s e n t a t i o n of a m i r r o r to ptarmigan c h i c k s i s a .useful method of drawing out a g o n i s t i c and aggressive behaviour at an e a r l y age. APPENDIX I I I . MAINTENANCE, EXPLORATORY, ANP GENERAL ACTIVITY AND THEIR POSSIBLE RELEVANCE TO CHICK VIGOUR On the hypothesis t h a t the vigorous and healthy s t a t e of c a p t i v e rock ptarmigan c h i c k s might be r e f l e c t e d i n t h e i r behaviour, I r a t e d maintenace, e x p l o r a t o r y , and. general a c t i v i t y each year and.compared.them w i t h each other, and growth and s u r v i v a l . Maintenance a c t i v i t y c o n s i s t e d of preening, e a t i n g , head s c r a t c h , l e g s t r e t c h , feather f l u f , and fan wings. E x p l o r a t o r y a c t i v i t y was d i r -ected towards the m i r r o r and c o n s i s t e d of slow h e s i t a n t approach, g e n t l e peck, l o o k , . d i p head, and cock head. General a c t i v i t y was the number of b i r d s on t h e i r f e e t a t four random times during each day. Maintenance and general a c t i v i t y data were c o l l e c t e d during a d a i l y 10 minute observation p e r i o d f o r each brood. E x p l o r a t o r y behaviour was^ rated during the d a i l y m i r r o r t e s t s used to r a t e a g o n i s t i c and aggres-s i v e behaviour. As w i t h aggressive behaviour (shadow-boxing), continuous a c t s (which included preening, e a t i n g , slow h e s i t a n t approach, look, g e n t l e peck) were scored no more f r e q u e n t l y than every 30 seconds, and d a i l y scores of from one to four were given a value of one, w h i l e d a i l y scores of seven to i 3 were valued a t two, w i t h scores of f i v e and s i x ommitted. This removed d i f f e r e n c e s between observers of up to 15%. Data i n c l u d e only c h i c k s that l i v e d to the end of the summer, and had no v i s i b l e i n j u r i e s . Maintenance A c t i v i t y Each chick r e c e i v e d a t o t a l r a t i n g , expressed as a c t s per minute of o b s e r v a t i o n . This was a l l o c a t e d i n t o t h r e e . c a t e g o r i e s : low = 0 to .149 acts per minute medium - .150 to .299 acts per minute , high = .300.and greater acts per ir\inute. Chicks r a t i n g medium and high i n maintenance a c t i v i t y were much more pr e v a l e n t (97%) i n 1968 than i n 1967 (40%) or 1969 (38%). ( F i g . 23). The high 1968 value was p r i m a r i l y due to excessive preening, which had a pronounced, e f f e c t on plumage c o n d i t i o n i n that year. Most c h i c k s had b a l d spots on the back of t h e i r heads from s c r a t c h i n g , and bare patches at the base of t h e i r t a i l s from p i c k i n g . Chicks showed a l l the a c t s i n c l u d e d as maintenance a c t i v i t y from the f i r s t few days of l i f e onward. Maintenance a c t i v i t y waned s l i g h t l y , a f t e r four weeks of age (Table 25). p i s t i n c t d i f f e r e n c e s , were observ.ed between t o t a l summer scores of i n d i v i d u a l c h i c k s (extremes of .059 a c t s per minute to .374), and as w e l l , between broods. Brood d i f f e r e n c e s were not r e l a t e d to the number of c h i c k s , or whether they were a v i a r y or. f i e l d hatched. Cannabalism, or feather p i c k i n g , i s r e l a t e d to preening, and has i n t u rn been r e l a t e d to a lack of v i t a m i n D, among other t h i n g s , an essen-t i a l amino a c i d . P u l l i a i n e n (1965) found t h a t feeding pat h u l k s , which ; are high i n a r g i n i n e , prevented feather p i c k i n g i n pheasants,.as i t a l s o had i n previous s t u d i e s on domestic f o w l . I fed oat hulks f o r a two week pe r i o d to three broods i n 1968 which d i s p l a y e d a l o t of f e a t h e r p i c k i n g , w i t h no observable e f f e c t s . Anyhow, th a t d i f f e r e n c e s were observed between broods w i t h i n years reduces the p o s s i b i l i t y of any d i e t a r y d e f i -ciency causing the cannabalism, as a l l broods r e c e i v e d the same feed. HIGH RATING MEDIUM RATING 100 90 80 k 70 60 I 50 cc UJ 40 30 20 10 1967 1968 YEAR 969 FIG. 23. Comparison of per cent of c a p t i v e rock ptarmigan c h i c k s w i t h medium and high maintenance a c t i v i t y r a t i n g s i n 1967, 1968, 1969. TABLE 25. E f f e c t s of age'•on maintenance and exploratory a c t i v i t y i n captive rock ptarmigan chicks (acts per minute of observation) Behaviour Age 1 and 2 weeks . Age 3 and 4 weeks Age 5, 6 7, 8 weeks Maintenance Exploratory .197 .310 .221 .332 .209 .28.6 I conclude, t h e r e f o r e , t h a t d i f f e r e n c e s i n maintenance a c t i v i t y were due to inherent d i f f e r e n c e s i n c h i c k s , both between broods and bet-ween years. E x p l o r a t o r y A c t i v i t y As w i t h maintenance a c t i v i t y , each c h i c k r e c e i v e d a t o t a l r a t i n g a l l o c a t e d i n t o three categories:. low = 0 to ,249 acts per minute medium = .250 'to .499 a c t s per minute high =. .500 and greater act^s per minute. In 1967, more c h i c k s rated i n the extreme c a t e g o r i e s (low and high) than i n the other years ( F i g . 24). 1968 c h i c k s , however, r a t e d almost i d e n t i c a l i n t o t a l e x p l o r a t o r y a c t i v i t y , when expressed as acts per minute (.3,72) as 196.7 c h i c k s (.348). 1969 c h i c k s r a t e d lower, .256. Table 25 shows that e x p l o r a t o r y a c t i v i t y waned s l i g h t l y a f t e r four weeks of age. As i n a l l other c a t e g o r i e s of behaviour, d i s t i n c t d i f f e r e n c e s were observed between c h i c k s (extremes of .05 to .969 acts per minute), as w e l l as between broods. Brood d i f f e r e n c e s were not r e l a t e d to the number of c h i c k s , or whether they were a v i a r y or f i e l d hatched. E x p l o r a t o r y a c t i v i t y was not a l l . d i r e c t e d towards the image i n the mirror,, as a l l a c t s were a l s o d i r e c t e d to other f o r e i g n Objects such as a hand l y i n g prone i n the pen, f r e s h spruce boughs, or the m i r r o r placed backwards w i t h i t s brown p l a s t i c backing exposed i n s t e a d of the. r e f l e c t i v e s u r f ace. As w i t h maintenance a c t i v i t y , i n the constant a v i a r y environment HIGH RATING 1967 1968 1969 YEAR FIG. 24. Comparison of per cent of captive rock ptarmigan chicks with low, medium, and .. high exploratory a c t i v i t y ratings i n 1967, 1968, 1969. between years, d i f f e r e n c e s i n t o t a l scores f o r e x p l o r a t o r y behaviour must r e f l e c t inherent d i f f e r e n c e s i n the stock. 1969 b i r d s , t h e r e f o r e , were i n h e r e n t l y l e s s e x p l o r a t o r y • General A c t i v i t y The per cent of c h i c k s on t h e i r f e e t increased s i g n i f i c a n t l y from 1967 to 1968 to 1969 ( F i g . 25). Bropd s i z e s d i d not a f f e c t scores, and no c o n s i s t e n t d i f f e r e n c e was observed between a v i a r y and f i e l d hatched c h i c k s . . Therefore, d i f f e r e n c e s observed between years r e f l e c t e d inherent d i f f e r e n c e s , Vigour With the hypothesis that vigorous and healthy c h i c k s would i n f l a t e the scores i n the three foregoing, c a t e g o r i e s of. behaviour, I r e l a t e d one to the other, and a l l three to c h i c k growth and s u r v i v a l . 1967 1968 1969 Maintenance a c t i v i t y low high low E x p l o r a t o r y a c t i v i t y high high low General A c t i v i t y low medium high Weight at end of summer same S u r v i v a l low high high L i t t l e s i m i l a r i t y i s obvious. E i t h e r my hypothesis was i n c o r r e c t or i t a p p l i e d to only some and not a l l gategories of behaviour. The hypothesis was erected only because i f a c o r r e l a t i o n had e x i s t e d between a l l c a t e g o r i e s , a b a s i c cause would have been s t r o n g l y suggested, and . vigour seems l o g i q a l . The converse hypothesis, however, was a l s o p o s s i -b l e ; t h a t vigorous and healthy b i r d s are.not a c t i v e , not wasting energy 100 80 60 40 20 0 1967 1968 1969 YEAR FIG. 25. Comparison of per cent of c a p t i v e rock ptarmigan c h i c k s on t h e i r f e e t i n 1967, 1968, 1969. on t r i v i a l i t i e s . The r e s u l t s do not confirm t h i s e i t h e r . I f v igour r e f l e c t s i n only c e r t a i n a c t i v i t i e s , which should I choose? I t i s j u s t as l o g i c a l to expect vigour to r e f l e c t i n general a c t i -v i t y as i n e x p l o r a t o r y a c t i v i t y , y e t these showed opposite trends. I t h e r e f o r e i d e n t i f i e d no obvious.behaviour measure Of vigour i n c h i c k s . APPENDIX IV. FOOD, PREDATION, AND DISEASE IN RELATION.TO SURVIVAL OF CHICKS IN SUMMER Food Rock ptarmigan c h i c k s are'apparently more o p p o r t u n i s t s than spe-c i a l i s t s i n t h e i r d i e t s . Very young c h i c k s eat a v a r i e t y of ve g e t a t i o n and i n v e r t e b r a t e s , as shown by my a n a l y s i s of 33 crops (Table 26) from c h i c k s l e s s - t h a n s i x days o l d . Most common item was yaccinium flowers (36% of oven dry weight) (both Vaccinium uljginosum and Vaccinium y i t i s - idaea, which could not be separated). Six d i f f e r e n t p l a n t species and 15 in v e r t e b r a t e f a m i l i e s were represented i n crops. Roberts (1963) reported on the contents of 16 crops from "pre-, f l i g h t age rock ptarmigan" (up to about 14 days of age) c o l l e c t e d at Eagle Creek. He found b u l b l e t s of Polygonum vivjparum the most important s i n g l e food item, and l i s t e d 13 p l a n t species and 13 i n v e r t e b r a t e f a m i l i e s as food items. Weeden (1969) reported on the contents of 16 chic k s crops c o l l e c t -ed a t Eagle Creek throughout June ^nd J u l y . He too found Polygonum v i v i - parum b u l b l e t s most important (47% of oven dry weight), and i d e n t i f i e d 12 p l a n t species and two orders. of i n v e r t e b r a t e s i n the cr^ops. Chicks eat fl o w e r s , l e a v e s , b u l b l e t s , seeds, capsules, and ber-r i e s of various p l a n t s , almost a l l of which are abundant. Food supply, t h e r e f o r e , d i d not i n f l u e n c e s u r v i v a l o f ch i c k s i n summer. Pred a t i o n Chick remains are very r a r e l y found. However, some avian TABLE 26. A n a l y s i s of crop contents of rock ptarmigan c h i c k s one to s i x days of age Item P l a n t p a r t % Frequency of occurrence % oven dry weight Vaccinium spp. a Flower 63 .6 35.9 Vaccinium V i t i s - i d a e a Berry 6.1 13.5 D i p t e r a Fam. Tupulidae Fam.'Lauxanidae Fam. Syrphidae . Fam. Mycetophilidae Fam. Dolichophidae Fam. Sepsidae Fam. Cecidomyidae U n i d e n t i f i e d T o t a l D i p t e r a 24.2 12.1 12.1 .6.1 3.3 3.3 3.3 18.2 60.6 11.1 Moss Capsule 51.5 7.9 S n a i l 6.1 7.0 . U n i d e n t i f i e d Leaf Fragments 33.3 6.2. Vaccinium uliginosum Berry 9.1 5.9 Lepidoptera Larvae 21.2 4.6 Polygonum viviparum B u l b i l s 18.2 '3.3 Coleoptra Larva 3.3 1.1 Ladybug 3.3 .8 P e d i c u l a r i s sp. Leaf 3.3 .7 U n i d e n t i f i e d Larvae 6.1 .7 Hymonoptera Fam. Ichneumonidae 15.3 .6 Sedge Tips 3.3 .6 Spider 3.3 .06 Homoptera Fam. C i c i d e l l i d a e 3.3 .03 Aphids 6.1 -01 Both Vaccinium V i t i s - i d a e a and Vaccinium uliginosum. predators do k i l l ptarmigan c h i c k s . White and Weeden (1966) reported observations of g y r f a l c o n s (Falco r u s t i c o l u s ) c a t c h i n g two c h i c k s . Bet-ween 1961 and 1965, however, Weeden recorded only 13 instances of g y r f a l -cons pursuing ptarmigan a t Eagle Creek. During the three years o f t h i s study, two immature g y r f a l c o n s frequented Eagle Creek i n August, 1968,; Otherwise I saw g y r f a l c o n s on only three occasions. Marsh hawks (Circus  cyaneus) were more common, however Weeden reported only one.case i n which a marsh hawk k i l l e d a ptarmigan (adult) i n nine years (White and Weeden, 1966). An eagle (believed to be golden, A q u i l a chrysaetos, but never observed i n proper l i g h t ) nested e i g h t m i l e s from Eagle Creek i n 1969. I observed the remains of at l e a s t two a d u l t ptarmigan i n the nest, and in. August, Weeden r e t r i e v e d seven ptarmigan bands from the nest. Avian p r e d a t i o n cannot be considered heavy from a few t r a n s i e n t g y r f a l c o n s and marsh hawks, and one p a i r of eagles. Mammals th a t may k i l l ptarmigan c h i c k s i n c l u d e red foxes (Vulpes.  fu l v a ) and weasels (Mustela erminea and r i x o s a ) . Foxes are r a r e ; I ob-served foxes on only two b r i e f occasions i n the three years of t h i s study. No measure was made of weasel abundance. However, weasel pr e d a t i o n on nests may r e f l e c t d e n s i t i e s of weasels. Changes i n nest p r e d a t i o n over the 10 years d i d not p a r a l l e l changes i n chick l o s s i n summer (Part I I ) , as expected i f weasels predated c h i c k s to any great extent. This evidence i s not c o n c l u s i v e , but suggests t h a t weasel p r e d a t i o n d i d not g r e a t l y i n f l u e n c e s u r v i v a l of c h i c k s i n summer. Disease — . i T .i , — • ... There i s l i t t l e evidence that disease i n f l u e n c e s summer c h i c k s u r v i v a l . A l l e n (1969) examined 25 j u v e n i l e ptarmigan c o l l e c t e d w i t h i n f i v e miles of Eagle Creek i n September 1967 and 1968,for helminths. He reported mean cestode loads of 5.6 and 5.4 per b i r d i n 1967 and 1968 r e s -p e c t i v e l y . I examined the weights and stored body f a t of these b i r d s and found no c o r r e l a t i o n between e i t h e r and cestode load ( F i g . 26 and 27). Stored body f a t was sampled as described i n P a r t I I I . A l l e n a l s o found trematodes, p r i n c i p a l l y Brachylaima f u s c a t a . Mean load i n 1968, 112 per b i r d , was much higher than i n 1967, s i x per b i r d , but d i d not c o r r e l a t e w i t h e i t h e r weight or stored body f a t ( F i g . 28 and 29). Babero (1953), who surveyed helminths of ptarmigan, concluded t h a t although " s e v e r a l worms recovered from Alaskan ptarmigan have been p r e v i o u s l y i n c r i m i n a t e d as causes of ' d i e - o f f s ' among c e r t a i n game b i r d s , no recognized p a t h o l o g i c a l e f f e c t s could be a t t r i b u t e d d i r e c t l y to helminth p a r a s i t i s m " . Blood p a r a s i t e s were examined by S t a b l e r e t a l . , (1967) i n rock ptarmigan from Eagle Creek. They reported Leucocytozoan i n 15 of 16 chic k s ( s i x to seven weeks o l d ) , and Trypanosoma i n four c h i c k s . They d i d not r e p o r t on the h e a l t h of the c h i c k s . Anvik (1969) a l s o examined c h i c k s from Eagle Creek, and i n h i s sample of f i v e , none showed any p a r a s i t e m i a . During the course of t h i s study we found no c h i c k s showing any signs of p a t h o l o g i c a l c o n d i t i o n s . Conclusions. Food, p r e d a t i o n , and disease have been surveyed, w i t h no evidence 500 r o o 450 CO — 400 U J 350 o o o o o o o o o o o it. I 300 J i i _ 6 8 10 NUMBER OF CESTODES 12 14 16 FIG. 26, R e l a t i o n s h i p between number of cestodes arid weight of j u v e n i l e rock ptarmigan^ i n September. 0.8 r-0.7 L 03 S 0.6 \-a. CO exo >-O o 00 0.5 -0.4 0.3 or £ 0.2 0.1 o o o o o _ i _ o o o o o 8 o I 8 10 NUMBER OF CEST0DES 14 16 FIG. 27. R e l a t i o n s h i p between number of cestodes and f a t of j u v e n i l e rock ptarmigan i n September. 500 Or 450 ca IE CD UJ 400 350 L . 0 o 0 0 o o o o °o o o o o 300 o 50 o _] 1 : L_ 100 150 200 NUMBER OF TREMATODES o o 250 300 1 I FIG. 28. R e l a t i o n s h i p between number of trematodes.and weight of j u v e n i l e rock p t a r -migan i n September. EE » OuO CD O. CO >-a o 03 Q L U cc o 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 o o 0 o D O o o o o o o o o o _Q L o _Q L 50 100 150 200 NUMBER OF TREMATODES 250 300 I FIG. 29. R e l a t i o n s h i p between number of trematodes and f a t o f j u v e n i l e rock p t a r -migan i n September. that they were s u f f i c i e n t by themselves to cause changes i n ch i c k l o s s To r u l e p r e d a t i o n and disease out completely, they should be s t u d i e d d i r e c t l y over a s e r i e s of years, as was not done. However, on the e v i dence to date, they appear unimportant to l o s s of c h i c k s i n summer. APPENDIX V. DIFFERENCES IN HABITAT USED BY ROCK PTARMIGAN BROODS IN 1967, 1968, AND 1969 An attempt was made to i d e n t i f y p ossible marginal rock ptarmigan habitat on the study area'by comparing habitats used by broods i n the peak year of 1968 with 1967 and 1969. Keith (1963) summarized substantial evidence to suggest that at high d e n s i t i e s , Tetraonidae occupy sub-marginal habitat normally not used. In such habitats, reproduction and s u r v i v a l may be adversely a f f e c t e d . Broods were located during general random search throughout each summer. Frequency of habitat searched was the same each year. This ana-l y s i s excludes most v a l l e y bottoms and south-facing slopes' where vegetation was p r i n c i p a l l y woody rather than herbaceous, and generally over three feet i n height. This habitat was. very r a r e l y frequented by rock ptarmigan (Weeden, 1959). Habitats were categorized as: 1) Greater than 75% Dryas octopetala and rock 2) Greater than 75% Cassiope tetragona 3) Greater than 75% Graminoids, moss, and Dryas octopetala 4) Greater than 75% Bryoids 5) Mixed vegetation The f i r s t habitat, Dryas octopetala and rock occurred p r i m a r i l y on h i l l tops. The second habitat, Cassiope tetragona, was t y p i c a l of poorly drained depressions or slopes where snow was la t e i n melting. The t h i r d type, Graminoids, was found at a l l heights, and covered most high saddles between h i l l s . The fourth type, made up of Salix spp., Betula nana, Alnus spp., and Vaccinium uliginosum, was found p r i m a r i l y on mid and lower s l o p e s , as was mixed v e g e t a t i o n . A l l types graded i n t o one another. Table 27 compares use of these h a b i t a t s by broods i n 1967, 1968, 2 and 1969. H a b i t a t s were used i n s i g n i f i c a n t l y d i f f e r e n t amounts (x t e s t ) . This was p r i m a r i l y due to d i f f e r e n c e s between 1968 and 1969. In 1968, more broods were found i n mixed h a b i t a t than expected, fewer i n Graminoids. . The reverse was true i n 1969. . In 1968 and 1969, brood l o c a t i o n s were a l s o c l a s s i f i e d as t o height on h i l l s (Table 28). No s i g n i f i c a n t d i f f e r e n c e s were found. A t h i r d measure was made - the a b i l i t y of c h i c k s to conceal them-s e l v e s . This was measured by r e c o r d i n g the height of v e g e t a t i o n and per cent overhead cover around each chick a f t e r i t had d e l i b e r a t e l y crouched. By comparing a c t u a l concealment w i t h p o t e n t i a l concealment i n an area w i t h i n 100 square f e e t of the c h i c k , I determined whether each chick a c t -u a l l y chose concealment or was merely hidden by r e p r e s e n t a t i v e v e g e t a t i o n . Concealment c a t e g o r i e s were: Poor = l e s s than 20% overhead cover, and v e g e t a t i o n averaging l e s s than three inches around c h i c k Moderate = anything between poor and e x c e l l e n t concealment E x c e l l e n t = greater than 70% overhead cover, and v e g e t a t i o n averaging more than three inches around c h i c k In 1967, most c h i c k s (63%) concealed themselves w e l l as compared to only 24% i n 1968 and 36% i n 1969 (Table 29). Good concealment was l a r g e l y a f u n c t i o n of the general h a b i t a t the brood was i n when encount-ered. Less than 20% of e x c e l l e n t l y concealed c h i c k s each year a c t u a l l y TABLE 27. Per cent of broods found from hatch to e a r l y August i n v a r i o u s p l a n t a s s o c i a t i o n s . Sample s i z e s are i n brackets Vegetation type .. 1967 1968 1969 > 75% Dryas o c t o p e t a l a and rock 0 1.7 (1) 5.2 (5) > 75%' Cassiope tetragona 0 1.7 (1) 1.1 (1) > 75%. Graminoids, moss, Dryas o c t o p e t a l a 16.2 (5) 19.3. (1) 25.0 (24) > 75% Bryoids 25.8 (8) 14.1 (8) 25.0 (24) Mixed 58.0 (18) 63.1 (36) 43.7 (42) TABLE 28. Per cent of broods found a t d i f f e r e n t heights on h i l l s . Sample s i z e s are . i n brackets Height on h i l l 1968 1969 Bottom 1/3. 20.2 (14) 12.0 (7) Middle 1/3 11.6 ( 8) 27.6 (16) Top 1/3 68.2 (47) 60.4 (35) TABLE 29. Comparison of concealment of c h i c k s when approached by observer, i n 1967, 1968, 1969 Concealment 1967 1968 . 1969 Poorly concealed Per cent Number-of c h i c k s 21.9 7 31.7 20 34.4 21 Moderately concealed . Per cent Number of c h i c k s 15.6 5 44.5 28 29.5 18 Well concealed Per cent Number of c h i c k s 62.5 20 23.8 15 .36.1 22 sought out concealment b e t t e r than was t y p i c a l of t h e i r surroundings. Brood l o c a t i o n s , t h e r e f o r e , d i f f e r e d i n two ways; more broods were i n mixed v e g e t a t i o n i n 1968 than i n 1969, broods were i n denser cover i n 1967 than i n other years. There i s l i t t l e l i k e l i h o o d t h a t mixed v e g e t a t i o n , used to a gre a t e r extent i n 1968 represents sub-marginal h a b i t a t . Food (Appendix IV) and cover are p l e n t i f u l t h e r e . Mixed v e g e t a t i o n i s t y p i c a l of rock ptarmigan h a b i t a t d escribed by Weeden (1959). As w e l l , s u r v i v a l of c h i c k s was the same (26%) i n 1968 and 1969. . , Sparce brood cover was used, i n both 1968 and 1969, even though ptarmigan numbers were lower i n 1969. There i s no evidence, then, t h a t high ptarmigan d e n s i t i e s caused any d i f f e r e n c e i n the d e n s i t y of brood cover u t i l i z e d . I conclude, t h e r e f o r e , t h a t the changes i n brood l o c a t i o n were of l i t t l e consequence to summer s u r v i v a l of c h i c k s . APPENDIX VI. CAUSES OF AVIARY MORTALITY Chick m o r t a l i t y i n the a v i a r y was due to a number of causes. Immediate f a i l u r e to feed i n c a p t i v i t y was the cause of death i n many chi c k s that were hatched i n the wild.and.entered the a v i a r y before f i v e days of age. I t accounted f o r 79% of outdoor c h i c k m o r t a l i t y and 56% of f i e l d c h i c k m o r t a l i t y . In a l l three years, v i s c e r a l i n f e c t i o n s were noted. In 1967, 42% of c h i c k s t h a t d i e d had lung l e s i o n s and e n t e r i t i s . These c o n d i t i o n s were l e s s common i n 1968, shown i n 17% of c h i c k s that d i e d , and i n 1969, 16%. In a l l years, attempts were made to i s o l a t e p a t h o l o g i c a l organ-isms (courtesy R. A. D i e t e r i c h , V e t e r i n a r i a n , I n s t i t u t e o f A r c t i c B i o l o g y ; K. Neiland, Alaska Department of F i s h and Game; C a l i f o r n i a Department of A g r i c u l t u r e , Petaluma, C a l i f o r n i a ; U.S. Dept. of A g r i c u l t u r e , P o u l t r y Disease Lab, Ames, Iowa; Purina Pathology Lab, St. L o u i s , M i s s o u r i ; Canada Dept. of A g r i c u l t u r e , Animal Pathology Lab, Vancouver). A l l gave negative r e s u l t s . In 1968, f i v e of the 12 egg c h i c k s t h a t d i e d had b i r t h d e f e c t s -p e r o s i s and " c u r l y - t o e s " . P e r o s i s l a t e r c o n t r i b u t e d to the deathof two o t h e r s . I t was a l s o present i n s i x c h i c k s t h a t l i v e d . P e r o s i s i s "an anotomical deformity of the l e g bones of young chickens, turkeys, pheas-ants, grouse and q u a i l " . . ( N o r r i s and Scott,.1965). I t e v e n t u a l l y r e s u l t s i n complete c r i p p l i n g . Manganese d e f i c i e n c y i s most o f t e n i m p l i c a t e d , e i t h e r d i r e c t l y by causing shortened and thickened l e g bones, or by lowering bone phosphate. I t a l s o a f f e c t s calcium uptake (No r r i s and S c o t t , 1965). Three other c h i c k s had bone problems i n 1968 - r they broke e i t h e r a wing or l e g or i n one case, both, w i t h no known cause. In 1969, 13 of the 14 deaths of egg c h i c k s , and three of the f i v e deaths of f i e l d c h i c k s occurred a f t e r wing or l e g f r a c t u r e s . These occur-red n a t u r a l l y i n the pens. P e r o s i s was a s s o c i a t e d w i t h three of these, as w e l l as three others who d i d not d i e . P a t h o l o g i c a l r e p o r t s by the U.S. Department of A g r i c u l t u r e and Puri n a Pathology Laboratory c o n f l i c t e d . The former, who used h i s t o l o g i c a l techniques, documented r i c k e t s ( d e f o r m i t i e s i n the shape of bones and la c k of c a l c i f i c a t i o n of c a r t i l a g e , normally r e s u l t i n g from d e f i c i e n t Vitamin D, calcium and/or phosphorus). The l a t t e r found m i n e r a l content "high normal" i n bones, through ash a n a l y s i s . Both agreed, however, t h a t a mi n e r a l imbalance must have occurred. Analyses of feed showed calcium/phosphorus l e v e l s , and manganese l e y e l s t h a t conformed tp those recommended by the N.A.C.-N.R.C. "N u t r i e n t Requirements of P o u l t r y " (1966). These analyses were conducted by Purina Pathology Lab, and Surrey Cooperative Services of Surrey, B.C. Since symptoms, of mi n e r a l imbalance i n bones occurred both i n 1968 and 1969, I conclude that e i t h e r Purina's Game B i r d Startena. was, sub-optimum f o r rock ptarmigan c h i c k s , or the a d d i t i o n of l e t t u c e and egg to the d i e t a f f e c t e d adequate u t i l i z a t i o n of minerals i n the s t a r t e n a . That the l a t t e r i s p o s s i b l e i s recorded by Cohrs (1967) who s t a t e d t h a t d i e t s too r i c h i n p r o t e i n or f a t may reduce u t i l i z a t i o n of calcium s a l t s . Nevertheless, s u r v i v a l on t h i s r a t i o n i n the indoor a v i a r y i n 1968 and 1969 was exceptionally high compared to any species of game b i r d reared i n c a p t i v i t y that I have found recorded i n the l i t e r a t u r e . Sur-v i v a l also exceeded that of wild chicks at Eagle Creek i n these years. Despite the causes of ayiary mortality, be they sub-optimum feed or an unwillingness to eat, differences i n s u r v i v a l between years must r e f l e c t d ifferences i n the v i a b i l i t y of chicks, a t l e a s t i n terms of an aviary environment. Every possible e f f o r t was made to keep aviary condi-tions constant between years, and I have no evidence that t h i s was not so. APPENDIX V I I . GROWTH RATES MEASURED BY WEIGHT-FOOT LENGTH RATIOS S k e l e t a l growth (foot) has n u t r i t i o n a l p r i o r i t y over increase i n muscle or adipose t i s s u e (weight) (Hammond, 1944; Bandy e t a l - , 1956). Therefore any d i f f e r e n c e i n n u t r i t i o n a l c o n d i t i o n s w i l l r e f l e c t i n t h e i r r a t i o s . Comparison of growth, r a t e s u s i n g t h i s method has the advantage i n being unaffected by i n a b i l i t y to age animals. I a p p l i e d t h i s method to data c o l l e c t e d from w i l d c h i c k s i n the summers of 1967, 1968, and 1969 f o r comparison purposes. I used categor-i e s f o r f o o t length which omitted two mm. between each, to c o r r e c t f o r i n a c c u r a c i e s i n measuring. F i g . 30 shows no. c o n s i s t e n t r e l a t i o n s h i p i n t h i s r a t i o when i t i s compared between years f o r each week, Confidence l i m i t s - are wide f o r l a r g e r b i r d s , p a r t l y due to smaller samples, p a r t l y due to l a r g e v a r i a n c e s . This r a t i o , t h e r e f o r e , adds l i t t l e t o the comparison of.growth of p t a r m i -gan c h i c k s between years. 250 A 200 C3 a 150 100 50 5$ o 1967 © 1968 A 1969 H-J-H -2-H (—3—1 4 — ( FOOT LENGTH CATEGORY FIG. 30. Comparison of weights of w i l d rock ptarmigan chicks w i t h s p e c i f i c f o o t lengths (Category.; 1=3.0 to 3.5 cm; 2=3.8 to 4.3 cm; 3=4.6 to 5.1 cm; 4=5.4 to 5.9 cm; 5=6.2 to 6.7 cm.). APPENDIX V I I I . CHARACTERISTICS OF GROWTH OF ROCK PTARMIGAN CHICKS Weekly weights of rock ptarmigan c h i c k s d e s c r i b e a t y p i c a l l o g -i s t i c curve, symmetrical about i t s i n f l e c t i o n p o i n t , as determined by using conversion f a c t o r s d e r i v e d from the l o g i s t i c equation which t r a n s -formed the weight-age curve i n t o a s t r a i g h t l i n e ( F i g . 31) ( R i c k l e f s , 1967). Therefore, i n rock ptarmigan c h i c k s , the f i r s t h a l f of t h e i r u l t -imate t o t a l weight i s achieved i n the same length of time as the second h a l f . During the f i r s t three days of l i f e the "instantaneous r e l a t i v e growth r a t e " (Brody, 1964) was constant f o r most c h i c k s ( F i g . 32), although d i f f e r e n t c h i c k s had d i f f e r e n t r a t e s . A f t e r three days, much i n d i v i d u a l v a r i a t i o n occurred. Brody '(1964) de s c r i b e d growth i n a s e l f - a c c e l e r a t i n g phase as t y p i c a l l y a s e r i e s of constant r a t e s , w i t h abrupt changes between them. Abrupt changes, have been c o r r e l a t e d w i t h p h y s i o l o g i c a l events (Krebs and Cowan, 1962). With ptarmigan c h i c k s , t h i s change at a p p r o x i -mately three days c o r r e l a t e s w i t h the end of the p e r i o d of i n t e r n a l y.olk u t i l i z a t i o n , as evident from autopsies. Males grew at a f a s t e r r a t e than females. F i g . 33 and 34 show tha t from two weeks of age on, males were heavier and had longer.wings. In a n a l y s i s f o r changes i n growth between years, sexes were lumped toge-ther and considered randomized. Autopsies showed no s i g n i f i c a n t depart-ure from an even sex r a t i o any year. Incubator c h i c k s and f i e l d c h i c k s were t r e a t e d together, as they d i d not d i f f e r from one another. FIG. 31. L o g i s t i c curve of weight-gains of c a p t i v e rock ptarmigan c h i c k s , shown by a c t u a l weight, and by s t r a i g h t - l i n e t ransformation u s i n g l o g -i s t i c conversion f a c t o r s . FIG. 32 . Instantaneous r e l a t i v e growth r a t e f o r f i r s t 3.5 days of l i f e of c a p t i v e rock ptarmigan c h i c k s (n=24). 100 u Q 5 o MALES, ALL YEARS • FEMALES, ALL YEARS hatch I'l i 2i ' >3 i I4I 151 i 61 i 71 AGE (weeks) FIG. 33. Comparison of weights of male and. female c a p t i v e rock ptarmigan chicks 17.0 15.0 13.0 3= K— CD 2 11.0 CD 9.0 7.0 ^ i 0 5.0 L o MALES • FEMALES •1' : Z r 3 • 14 l I 51 AGE (weeks) 16 i 171 FIG. 34. Comparison of wing lengths of male and female c a p t i v e rock ptarmigan c h i c k s . As mentioned i n Appendix I , growth i n the aviary exceeded that i n the wild. Two explanations are p o s s i b l e : lower energy requirements for thermoregulation and movement, or the e f f e c t of the a n t i b i o t i c , t e t r a c y -c l i n e hydrochloride. C h l o r t e t r a c y c l i n e , a s i m i l a r compound, i s used to increase weight of beef c a t t l e (Beeson, 1969). Lewin (1963) found that a r i c h complement of micro-organisms i n the caeca of C a l i f o r n i a q u a i l (Loph- ortyx c a l i f o r n i c u s ) retarded growth; conversely, therefore, a s i m p l i f i e d biota resulting,from feeding a broad spectrum a n t i b i o t i c may have increased ptarmigan growth rates. Chicks i n most captive studies grow either at comparable rates as wild chicks (Zwickel, 1965) or slower (Genelly, 1955) . APPENDIX IX.. MEASURES OF'COHESIVE BEHAVIOUR IN WILD ROCK PTARMIGAN BROODS TABLE 30. Distance from pbserver a t which brood hens f l u s h e d i n 1967, 1968, 1969 Distance 1967 1968 1969. Within 20 f e e t Per cent 45.0 46.1 79.2 Number of hens 9 6 19 21 to 50 f e e t Per cent 45.0 46.1 16.7 Number of .hens 9 6 .4 51 f e e t or more Per cent 10.0 7.8 4.1 Number of hens • 2 1 1 TABLE 31. Distance brood hens fl e w upon encounter w i t h observer i n 1967, 1968, 1969 Distance 1967 1968 1969 50 f e e t or l e s s Per cent 25.0 60.0 78.3 Number of hens 5 9 18 51 to 125 f e e t Per cent 25.0 20.0 13.1 Number of hens 5 3 3 126 f e e t or more Per cent 50.0 20.0 8,6 Number of hens °^ 3 2 T TABLE 32. Distances flown by brood hens upon r e l e a s e , i n 1968 and 1969 Distance 1968 1969 50 f e e t or l e s s Per cent 0 15.4 Number of hens 0 6 51 to 125 f e e t Per cent 29.2 25.6 . Number of hens 7 10 126 f e e t or more Per cent 70.8 59.0 Number of hens 17 23 TABLE 33. Defense of broods by hens i n 1967, 1968, 1969 Nest defense 1st and 2nd week post hatch 3rd and 4th week post hatch 1967 1968 1969 1967 1968 1969 Poor Per cent 25.0 43.0 52.6. 50.0 50.0 56.4 Number of hens 3 3 10 6 15 22 Moderate Per cent 33.4 14.0 5.4 33.3 36.7 28.2 Number of hens 4 .1 1 . 2 11 11 E x c e l l e n t Per cent 41.6 43.0 42.0 16.7 13.3 15.4 Number qf hens 5 3 8 1 4 • 6 TABLE 34. Distances.from hens th a t rock ptarmigan h i d when encountered by observer i n 1 9 6 7 , 1 9 6 8 , 1 9 6 9 Distance . 1 9 6 7 1 9 6 8 1 9 6 9 Within 1 0 f e e t Per cent 3 8 . 0 4 9 , 3 6 1 . 7 Number of c h i c k s 1 1 34 4 5 1 1 to 2 0 f e e t Per cent 3 1 . 0 1 8 . 8 . 3 4 . 3 Number of ch i c k s 9 • . • 25 2 1 to 3 0 f e e t ..' Per cent 2 4 . 2 1 7 . 4 4 . 0 . Number of chi c k s . 7 12 . 3 . 3 1 f e e t or more Per. cent . 6 . 8 1 4 . 5 0 Number of ch i c k s 2 — — r — — — : ' ' H ' 1  1 0 o TABLE 35-. Distances from observer a t which c h i c k s f l u s h e d i n 1967.and 1969 Distance 1967 1969 Within 20 f e e t t Per cent 38.6 43.2 Number of c h i c k s 22 19 21 to 50 f e e t Per cent 56.1 40.9 Number of ch i c k s 32 18 51 f e e t or more P e r cent 5.3 15.9 . Number o f c h i c k s 3 7 Data were i n s u f f i c i e n t i n 1968. TABLE 36. Distances c h i c k s flew upon encountering observer i n 1967 and 1969 a Distance 1967 1969 50 f e e t or l e s s Per cent 6.1 17.3 Number of c h i c k s 6 13 51 to 125 f e e t Per cent 14.3 22.7 Number of c h i c k s 14 17 126 f e e t or more Per cent 79.7 60.0 Number of c h i c k s 78 45 Data were i n s u f f i c i e n t i n 1968. APPENDIX X. BROODMATE PECKING AND SOCIAL HIERARCHY IN CAPTIVE ROCK PTARM-IGAN CHICKS Broodmate pecking was witnessed i n c a p t i v e rock ptarmigan c h i c k s from age one day onward. I attempted to e s t a b l i s h i f i t played a r o l e i n s e t t i n g up and maintaining a s o c i a l s t r a t a . Chicks were housed i n brood l o t s . Every pecking encounter was noted during both d a i l y 10 minute per brood o b s e r v a t i o n periods and mi r r o r t e s t s . Each chick was scored by adding a l l pecks i t d e l i v e r e d , and s u b t r a c t i n g a l l pecks he r e c e i v e d . Most of t h i s pecking was no n - v i o l e n t , appearing no more obvious than pecks d i r e c t e d to w a l l s , feeders or other o b j e c t s . Pecking waned co n s i d e r a b l y a f t e r the f i r s t few days o f l i f e , i n c r e a s i n g again a t about seven weeks ( F i g . 35). A n a l y s i s revealed t h a t pecking was not u n i - d i r e c t i o n a l . In only one of the 29 broods was the chick having the highest pecking score never pecked by other c h i c k s . S i m i l a r l y , i n only three broods d i d the chick having the lowest pecking score never d e l i v e r peqks to other c h i c k s . These f a c t s e l i m i n a t e the; p o s s i b i l i t y t h a t broodmate pecking maintained a s t r a i g h t - l i n e h i e r a r c h y . Data were examined to see i f broodmate pecking r e f l e c t e d a t r i -angular type of h i e r a r c h y . In such a h i e r a r c h y , A pecks B, B pecks C, but C pecks A ( A l l e e , 1951, E t k i n , 1964). Again the answer was negative: of 61 c h i c k s t h a t d e l i v e r e d pecks to the top s c o r i n g c h i c k , t h i s top chi c k pecked a l l but one of them. In four broods, the top c h i c k pecked and r e c e i v e d pecks from a l l broodmates. S i m i l a r l y , of the 50 c h i c k s to AGE (Weeks) FIG. 3 5 . Broodmate pecking by c a p t i v e rock ptarmigan c h i c k s , compared between years. whom the lowest s c o r i n g c h i c k d e l i v e r e d pecks, 44 had pecked i t , and i n four broods, the lowest chick both r e c e i v e d and d e l i v e r e d pecks to a l l broodmates. Had a t r i a n g u l a r h i e r a r c h y e x i s t e d , two-way pecking between chic k s as d e s c r i b e d , would not have occurred. I conclude, t h e r e f o r e , t h a t broodmate pecking d i d not r e f l e c t the establishment or maintenance of a s o c i a l h i e r a r c h y . Broodmate pecking d i d not c o r r e l a t e w i t h aggressive behaviour as measured by shadow-boxing, f u r t h e r demonstrating i t s l a c k of s i g n i f i -cance to s o c i a l s t a t u s . Rank w i t h i n broods f o r these behaviours d i f f e r e d by two or more f o r 58% of c h i c k s . As w e l l , F i g . 35 shows that broodmate pecking was most common i n 1968; t h i s was not the year of the highest shadow-boxing scores. However, when strangers were introduced i n t o broods, they were recognized as such and o f t e n attacked (Appendix I I ) . From t h i s , I con-clude t h a t i f a s o c i a l h i e r a r c h y , set up by more s u b t l e behaviourisms than I recognized, d i d not e x i s t , s t r i f e between broodmates was reduced by some mechanism. Perhaps t h i s was r e c o g n i t i o n coupled by p a s s i v e acceptance. Guhl (1958) concluded t h a t no h i e r a r c h y e x i s t s i n domestic fowl u n t i l nine weeks of age. In ptarmigan c h i c k s there was some evidence t h a t , a t the end of the summer (seven to e i g h t weeks), a t r a d i t i o n a l s o c i a l h i e r a r c h y e s t a b l i s h e d by aggression, was beginning to evolve. A g o n i s t i c and aggressive behaviour was i n c r e a s i n g i n s p e c i f i c i n d i v i d u a l s although not on a t o t a l b i r d b a s i s . Some of the broodmate pecking was becoming / c l e a r l y aggressive, accompanied by chases. This accounted f o r the increase i n a l l three years i n broodmate pecking a t seven to e i g h t weeks of age ( F i g . 35). In summary, broodmate pecking played no r o l e i n forming or main-t a i n i n g a s o c i a l h i e r a r c h y , and indeed there was no c l e a r evidence of a h i e r a r c h y up to a t l e a s t seven weeks of age, even though aggressive a c t s commonly used i n h i e r a r c h y formation occurred from day one. Aggressive . a c t s were e l i c i t e d by the m i r r o r or strange c h i c k s , not broodmates. E i t h e r c h i c k s recognized and p a s s i v e l y accepted broodmates, or s u b t l e expressions of dominance-subordination, of which I was not aware, were o c c u r r i n g that e l i m i n a t e d o v e r t aggression. APPENDIX X I . TEMPERATURE AND SNOWFALL DATA COLLECTED.AT FAIRBANKS, ALASKA BETWEEN 1960 AND 1969. F a l l to sp r i n g p e r i o d Mean amount of s n o w f a l l on ground (inches) Mean d a i l y temperature ( 9F.) E a r l y w i n t e r 3 Late winter''3 c Autumn d Mid Winter ^ ' • e Spring 1960-61 0.4 2.7 41 . 0 49 1961-62 1.8 7.2 44 -10 45 1962-63 0.2 11.9 42 - 2 49 1963-64 1.0 4.0 48 - 6 38 1964-65 0.4 0.1 45 -15 43 1965-66 1.6 5.6 48 -11 45 1966-67 0.3 , 12.1 50 -10 46 1967-68 0.4 7.6 46 - 2 48 1968-69 0.5 4.1 42 -12 49 E a r l y winter = September and October Late winter = A p r i l and May °Autumn = September d Mid winter = November, December, January, February d Spring = May Weather data c o l l e c t e d a t Fairbanks were r e p r e s e n t a t i v e of the i n t e r i o r r e g i o n of Alaska (Streten, 1969). APPENDIX X I I . PATTERNS OF PIGMENT ON NINTH WING PRIMARY OF ROCK PTARMIGAN - A NATURAL TAG. The p a t t e r n of pigment on the n i n t h wing primary o f j u v e n i l e rock ptarmigan was used as a n a t u r a l tag to look f o r d i f f e r e n t i a l m o r t a l -i t y i n w i n t e r . In mid summer, rock ptarmigan c h i c k s grow a n i n t h primary feather (measuring outward from the body), which they r e t a i n as j u v e n i l e s through the w i n t e r , and as y e a r l i n g s i n s p r i n g , u n t i l mid summer. This f e a t h e r i s predominately white, but has some black pigment adjacent to the vane near i t s t i p . The pigment may form a v a r i e t y of p a t t e r n s , i l l u s t r a t e d below. I c l a s s i f i e d pigment p a t t e r n s as f o l l o w s : Type 1 = pigment along vane l e s s than 1mm at i t s widest p o i n t -Type 2 = pigment along vane gre a t e r than 1mm but l e s s than 2mm at i t s widest p o i n t . Type 3 = pigment along vane gre a t e r than 2 mm a t i t s widest p o i n t but not ma i n t a i n i n g t h i s width f o r more than 1.5 cm. along the vane. Type 4 = s p e c k l i n g present. Type 5 = pigment predominantly on forward edg^eof'Mfe^e.#ga(tjh^r8^ •.• Type 6 = pigment along vane gre a t e r than 2 mm. a t i t s . w i d e s t . p o i n t , and ma i n t a i n i n g t h i s width f o r more than 1.5 cm. Types 4, 5, and 6 were combined as type 4 f o r a n a l y s i s , to in c r e a s e sample s i z e s . This technique proved u s e f u l i n showing t h a t s t a t i s t i c a l l y s i g n i -f i c a n t d i f f e r e n c e s i n the weights of j u v e n i l e rock ptarmigan i n ' f a l l d i d not a f f e c t winter m o r t a l i t y . . APPENDIX XIII. ADDITIONAL DATA ON AGONISTIC AND AGGRESSIVE BEHAVIOUR IN CAPTIVE ROCK PTARMIGAN CHICKS. TABLE 37. Number of captive rock ptarmigan chicks with low, medium, and' high agonistic ratings i n 1967, 1968, 1969 Age 1 and 2 weeks Age 3 and 4 weeks Age 5,6,7,8 weeks Behaviour 1967 1968 1969 1967 1968 1969 1967 1968 1969 Low agonistic 21 47 36 18 38 31 •17 43 32 Medium agonistic 2 .13 17 1 10 7 1 9 7 High ag o n i s t i c 1 5 17 4 12 15 1 4 11 TABLE 38. Number of captive rock ptarmigan chicks with low, and medium plus high agonistic scores, from hens of d i f f e r e n t ages Agonistic score Age 1 and 2 weeks Age 3 and 4 weeks Age 5, 6, 7, 8, weeks 1968 1969 1968 1969 1968 1969 Adult hens Yearling hens Adult hens Yearling hens Adult hens Yearling hens Adult liens Yearling hens Adult hens Yearling hens Adult hens Yearling hens Low I 7 30 12 20 12 26 5 17 16 27 6 16 • Medium plus high 5 13 11 10 8 13 10 10 4 9 7 9 TABLE 39. Weights of c a p t i v e rock ptarmigan c h i c k s r a t i n g low, medium, and high i n a g o n i s t i c behaviour. Data are combined f o r 1967, 1968, 1969 Age i n weeks Behaviour 1 2 3 4 5 6 7 Low a g o n i s t i c Mean weight Number of c h i c k s 95 Per cent Confidence l i m i t s (+) 36. 64 1. 4 5 80 64 ' 3 •P .5 142 64 5 .7 ,3 210 64 6 .0 .4 268 64 7 ,7 .0 314 53 9 .8 .1 347 36 12 .1 .3 Medium a g o n i s t i c Mean weight Number of c h i c k s 95 Per cent Confidence l i m i t s (+) 36. 29 2. 8 2 81 29 4 .9 -9 144 29 6 .9 .9 209 29 7 .2 .8 271 29 9 .5 .3 317 27 8 .8 .4 351 23 9 .9 .6 High a g o n i s t i c Mean weight Number of c h i c k s 95 Per cent Confidence l i m i t s (+) 39. 13 2. 3 9 84 13 6 .7 .9 146 13 12 .7 .0 212 13 13 .9 .5 276 12 11 .4 .9 325 10 11 .7 .2 360 9 14 .5 TABLE 40. dumber of c a p t i v e rock ptarmigan c h i c k s w i t h low, medium, and high aggressive r a t i n g s i n 1967, 1968, 1969 Year Behaviour 1967 1968 1969 Low aggression 21 41 33 Medium aggression 2 13 21 High aggression 0 10 12 APPENDIX XIV. PHOTOGRAPHS FIG. 37. Female rock ptarmigan brooding c h i c k s . FIG. 39. Locating hens on nests, and t r a c i n g brood movements was f a c i l i t a t e d by telemetry. FIG. 40. B i r d s were captured w i t h a long-handled net. FIG. 41. T y p i c a l rock ptarmigan h a b i t a t at Eagle Creek, Alaska. FIG. 42. South-facing slopes (on l e f t ) on the study area were tr e e d , and r a r e l y used by rock ptarmigan. FIG. 43. Graminoid v e g e t a t i o n on a high saddl a h a b i t a t o f t e n used by rock ptarmigan broods. FIG. 4 5 . Lower slope, with higher vegetation (Betela nana). FIG. 46. Indoor a v i a r y , w i t h 4 - t i e r e d brood-unit pens v i s i b l e . FIG. 47. Outdoor pen, i n which c h i c k s were housed i n 1969. FIG. 4 9 . A g o n i s t i c and aggressive behaviour was measured by presenting c h i c k s w i t h t h e i r own image. FIG. 50. Growth of rock ptarmigan c h i c k s . LITERATURE CITED A l l e e , W. C. 1951. The s o c i a l l i f e of animals. 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Dates of f i r s t flowers of a l p i n e p l a n t s a t Eagle Creek, c e n t r a l A l a s k a . Can. F i e l d - N a t . 82:24-31. Weeden, R. B. 1969. Foods of rock and w i l l o w ptarmigan i n c e n t r a l A l a s k a w i t h comments on i n t e r s p e c i f i c competition. The Auk 86:271-281. Weeden, R. B., and A. Watson. 1967. Determining the age of rock ptarmigan i n Alaska and Scotland. J . W i l d l . Mgmt. 31:825-826. White, C. M., and R. B. Weeden. 1966. Hunting methods of g y r f a l c o n s and behaviour of t h e i r prey (ptarmigan). The Condor 38:517-519. Wynne-Edwards, V. C. 1962. Animal d i s p e r s i o n i n r e l a t i o n to s o c i a l behaviour. O l i v e r and Boyd, Edinburgh. 653 p. Zwicke l , F. C. 1965. E a r l y m o r t a l i t y and the numbers of blue grouse. Unpubl. PhD. Thesis, Univ. of B r i t i s h Columbia, Vancouver. 153 p. Zwicke l , F. C., and A. N. Lance. 1966. Determining the age of young blue grouse.. J . Wild . Mgmt. 30:712-717. Zwick e l , F. C., and J . F. B e n d e l l . 1967. E a r l y m o r t a l i t y and the r e g u l a -t i o n of numbers i n blue grouse. Can. J . Zool. 45:817-851. BIOGRAPHICAL INFORMATION - John B. Theberge Citizenship - Canadian Age - 30 Education - Senior Matriculation, 1959, Oshawa Collegiate and Vocational Institute B.Sc.A., 1964, Department of Biology, University of Guelph M.Sc, 1966, Department of Zoology, University of Toronto Employment - Summers of 1959, '60, '61, '62, Ontario Department of Lands and Forests Wolf Research Project, Algonquin Park. Summer 1963, Metro Toronto Conservation Authority, Stream-bank Erosion and trout habitat study. Summer 1965 (1 month), Contract employee of Canadian Wild-l i f e Service, Wolf research on Baffin Island, Previous Thesis Research - Bachelor's Thesis: "Some Aspects of Timber Wolf Hunting", 1964. - Master's Thesis: "Howling as a Means of Commun-ication in Timber Wolves", 1966. Teaching Experience - Teaching assistant, University of Toronto, compara-tive vertebrate anatomy and general zoology, 1964 and 1965. - Teaching assistant, University of British Columbia, vertebrate anatomy, 1966, 1967, 1968. - Assistant Professor, University of Waterloo, 1970 to present. Teaching courses in ecology, and resource management. Consulting - Contract consultant to Metro Goldwyn-Mayer for their T.V. documentary "The Wolf Men", 1969. Contract consultant to the American Museum of Natural History for their commercial record "The Language and Music of Wolves", 1971. Awards and Scholarships - Ontario P r o v i n c i a l Government Fellowship, 1964 and 1965. - Canadian W i l d l i f e Service Scholarship, 1966, 1967, 1968. - W i l d l i f e Management I n s t i t u t e Fellowship, 1968, 1969. - University of B r i t i s h Columbia Summer Scholarship, 1969. Member of So c i e t i e s - Canadian Society of W i l d l i f e and F i s h e r i e s B i o l o g i s t s (Secretary of S. W. Ontario chapter), National and P r o v i n c i a l Parks Association of Canada (on conserva-t i o n committee), Canadian Audubon Society, U.S. Audubon Society, National W i l d l i f e Federation, Algonquin Wildlands League, Federation of Ontario N a t u r a l i s t s , Alaska Conservation Society. Publications S c i e n t i f i c - "Howling as a Means of Communication i n Timber Wolves" American Zoologist 7:331-338, 1967 (J. B. F a l l s , j unior author) - "Observations of Wolves at a Rendezvous S i t e i n Algonquin Park", Canadian F i e l d N a t u r a l i s t , 83:122-128, 1969 (D. H. Pimlott, junior author) . - "Dynamics of a Fluctuating Rock Ptarmigan Population i n Alaska", Proc. XV O r n i t h o l o g i c a l Congress, 1970, i n press (R. B. Weeden, senior author, gathered data, and I analyzed data and wrote paper). Popular - "Howl of the Wolf". Algonquin Park Raven, 1965. Reprinted i n Onward, United Church P u b l i c a t i o n , 1966. - "The A r c t i c Haunts of the Whitest Wolf", U.S. Audubon 70:59-61, January, 1968. - "Logging i n National Parks", Park News, A p r i l , 1969. - "A New Image for the Wolf", Alaska magazine, October, 1970. Reprinted i n Alaska Hunting Annual, October, 1970. - "Wolf Music", Natural History Magazine, A p r i l , 1971. 

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