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The population dynamics of Newfoundland caribou Bergerud, Arthur Thompson 1969

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THE POPULATION DYNAMICS OF NEWFOUNDLAND CARIBOU by . ARTHUR T. BERGERUD B.Sc. Oregon State U n i v e r s i t y , 1953 M.Sc. U n i v e r s i t y of Wisconsin, 1961 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR 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 t o the r e q u i r e d standard THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , 1969 In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f the r e q u i r e m e n t s f o r an advanced degree at the U n i v e r s i t y o f B r i t i s h C o lumbia, I agree t h a t 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 r e f e r e n c e and s t u d y . I f u r t h e r agree t h a p e r m i s s i o n f o r e x t e n s i v e c o p y i n g 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 g r a n t e d by the Head o f my Department o r by h i s r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g 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 g a i n s h a l l not be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . Department o f Z o o l o g y The U n i v e r s i t y o f B r i t i s h Columbia Vancouver 8, Canada Date S e p t e m b e r 2 3 , 1 9 6 9 i ABSTRACT The p o p u l a t i o n dynamics o f caribou (Rangifer tarandus) on the I s l a n d of Newfoundland were s t u d i e d 1957 to 1967. Four herds were recognized and censused: the Northern P e n i n s u l a — 450 animals i n 1958 and 400 i n 1966, the Avalon P e n i n s u l a — 125 i n 1957 and 720 In 1967., the'. Humber Ri v e r — 130 i n 1956 and 115 i n 1964, and the I n t e r i o r -- 4600 i n 1957 and 6200 animals i n 1966. The I s l a n d p o p u l a t i o n 1900-1910 was estimated at 40,000 animals. A f t e r 1915 these herds r a p i d l y d e c l i n e d and reached a low of perhaps only 2000 animals by 1930. The annual r a t e of increase Cr) of a l l the herds was low. The' Humber and Northern Peninsula herds showed no increase while the I n t e r i o r Herd grew at only 0.044. The Avalon Peninsula Herd showed the great e s t r a t e -o f - i n c r e a s e 1961 t o 1967, r= 0.120. The p o t e n t i a l r of Newfoundland carib o u i s probably greater than 0.30. A herd of carib o u introduced t o Brunette I s l a n d increased at r=0.352, from 17 t o 100 animals i n 5 years. In the I n t e r i o r Herd, b i r t h r a t e s were high and constant and averaged 0.85 c a l f per doe 2-years-of-age and o l d e r and 0.94 c a l f per doe 3 years and o l d e r . N a t u r a l m o r t a l i t y r a t e s were low beyond 6-months-of-age. They were 4 per cent f o r does, y e a r l i n g s , and calves and 9 per cent f o r stags 2-years-of-age and o l d e r . The k i l l of stags by hunters was 11 per cent and reduced the p r o p o r t i o n of stags i n the po p u l a t i o n . The s u r v i v a l of calves t o 6-months-of-age was s t r o n g l y c o r r e l a t e d w i t h growth of populations and appeared the main i n f l u e n c e on numbers ( c o r r e l a t i o n c o e f f i c i e n t r=0.922, P<0.01). The m o r t a l i t y of calves i n the f i r s t summer was h i g h ; an average of 69 per cent died i n the I n t e r i o r Herd and i n the Avalon Pe n i n s u l a Herd 30 per cent of the calves d i e d . i i The major cause of m o r t a l i t y o f calves was apparently predation by l y n x (Lynx canadensis). As e a r l y as 2 weeks a f t e r c a l v i n g , 27 per cent of the calves were missing. They were apparently dragged i n t o f o r e s t cover by lynx. Of 114 dead or morbid calves l o c a t e d 74 per cent were b i t t e n by l y n x , escaped and had developed c e r v i c a l abscesses"; from- i n -f e c t i o n s o f P a s t e u r e l l a multocida. The two major f a c t o r s l i m i t i n g populations o f caribou i n Newfoundland 1900 t o 1967 appeared t o be lyn« pred a t i o n of calves and shooting m o r t a l i t y of a d u l t s . Poor recruitment and high l o s s t o hunting probably caused the d e c l i n e of the herds 1915 t o 1930. The primary f a c t o r l i m i t i n g numbers i n the I n t e r i o r and Avalon Herds, 1957 t o 1967 was l y n x predation of calves i n t h e i r f i r s t summer. I l l e g a l hunting was probably important i n the Northern P e n i n s u l a and Humber R i v e r herds 1957 t o 1967. i i i TABLE OF CONTENTS Page ABSTRACT i TABLE OF CONTENTS . i i i ' ACKNOWLEDGEMENTS ' v i LIST OF FIGURES , v i i INTRODUCTION 1 METHODS • 4 The Exchange of Animals Between Herds and Po p u l a t i o n s . . . . . . . . . . 4 H i s t o r i c a l Research 5 Census 6 Measurement of B i r t h Rates 8 Measurement of Adult M o r t a l i t y . 9 M o r t a l i t y of Calves Overwinter. 9 Time and Amount of E a r l y M o r t a l i t y of Calves. 10 Determination of Cause of M o r t a l i t y of Calves from C e r v i c a l Abscesses 13 DISTRIBUTION OF HERDS AND POPULATIONS. 14 SIZE OF CARIBOU HERDS 18 Numbers 1900-1910 . 18 Numbers and Trends 1900-1956. 21 Numbers and Trends 1957-1967 23 BIRTH RATES. 26 Age of Breeding.. 26 Fecundity. 27 ADULT MORTALITY. . 32 M o r t a l i t y Rates 32 i v N a t u r a l Cause o f Death... 34 Di f f e r e n c e s i n Death Rates of Males and Females................ 38 Hunting M o r t a l i t y o f A d u l t s . . . . . . . . . . . . . 39 Role of Adult M o r t a l i t y i n Popu l a t i o n Growth................... 40 DEATH OF CALVES IN WINTER. 43 EARLY MORTALITY OF CALVES. 48 Time and Amount ..................................... 48 Weather i n M o r t a l i t y of Calves. 54 Disease and P r e d a t i o n . . . . .. 55 Rejected Hypotheses of P a s t e u r e l l a E t i o l o g y . 55 Experiments w i t h Lynx t o I s o l a t e P a s t e u r e l l a . . . . . . . . . . . . . . 58 Pred a t i o n by Lynx on Calves............................... 62 Experimental Removal of Lynx 64 Sex V u l n e r a b i l i t y o f Males Calves t o Lynx P r e d a t i o n . . . . . . . 67 V a r i a t i o n i n Lynx Pr e d a t i o n Between Areas................. 67 V a r i a t i o n i n Lynx Pr e d a t i o n Between Years................. 71 FACTORS LIMITING POPULATION GROWTH 1900 t o 1967. ................ 76 Rate of P o p u l a t i o n Growth 76 Reproduction i n Po p u l a t i o n Growth.............................. 78 N a t u r a l M o r t a l i t y of Calves • 79 Pre d a t i o n by Lynx on Male Calves 82 The Decline of Caribou 1915-1930. 83 Lynx P r e d a t i o n and the D e c l i n e . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84 Hunting and the Decline 86 EVOLUTIONARY IMPORTANCE OF PREDATION. 88 Pop u l a t i o n L i m i t a t i o n by Predation by Wolf..................... 88 V Lynx Pr e d a t i o n i n N a t u r a l S e l e c t i o n . .. — 91 SUMMARY. . .... 94 LITERATURE CITED. , 96 APPENDIX I TABLES 105 APPENDIX I I ANALYSIS OF REPRODUCTIVE TRACTS. 133 BIOGRAPHICAL INFORMATION \ ACKNOWLEDGMENTS Through the years a group o f dedicated w i l d l i f e management o f f i c e r s walked at my si d e as we fol l o w e d the c a r i b o u ; I w i l l always stand i n the debt of Stephen T. H a l l , Michael J . Nolan, Bruce R. P o r t e r , H. Lloyd R u s s e l l , Samuel K e l l y and Hainan . Whalen. I wish t o a l s o thank w i l d l i f e o f f i c e r s David Lomond, Michael C. Nurse, Raymond McGrath, Arthur B u t t , Robert McNeily, and Michael Walsh f o r t h e i r a s s i s t a n c e . My experiences w i t h p i l o t s A u s t i n G a r r e t t and Robert G. Winsor w i l l long be remembered. The Canadian W i l d l i f e S ervice provided funds i n three years and the s e r v i c e s o f f o u r able summer a s s i s t a n t s , Ernest Stenton, Donald W. Simkin, Donald A. Blood, and K e i t h Sandilands. Dr. John M. King journeyed to Newfoundland i n 1958 and 1964- t o conduct p a t h o l o g i c a l i n v e s t i g a t i o n s of young c a l v e s . Drs. H.T. G i e r and G.B. Marion examined the reproductive t r a c t s o f female caribou. Administrative' a s s i s t a n c e was provided by Douglas H. P i m l o t t , who o r i g i n a t e d the study, Harry H. Walters, and Stuart S. Peters. A s s i s t a n c e i n preparing the manuscript was provided by Dr. James F. B e n d e l l , Dr. Peter A. L a r k i n , and Dr. I. McT. Cowan. Danie l T. Bergerud d r a f t e d the p l a t e s f o r t h i s r e p o r t . I wish t o acknowledge the as s i s t a n c e of my w i f e , Wy. She t r a v e l l e d w i t h me i n t o many o f the w i l d e r s e c t i o n s of the i s l a n d and was a constant source of i n s p i r a t i o n during the ten years. This paper i s dedicated t o the memory of Stephen T. H a l l . Steve i s gone but he w i l l always be remembered by those of us t h a t had the p r i v i l e g e t o trudge the barrens i n h i s f o o t s t e p s and share a pot of coffee i n h i s comradeship. v i i LIST OF FIGURES Figure Page 1. The l o c a t i o n of ca r i b o u 1957-1967. . ..T 3 2. Percentage of a d u l t females with v i s i b l e a n t l e r s 15 3. Observations of animals subsequent t o two migrations a f t e r tagging. 16 4. Number of carib o u about 1900.. 19 5. Caribou numbers from a e r i a l census 24 6. The snow p r o f i l e at Gander 1957-58 and 1958-59. 28 7. Regression o f counts of parous does on recruitment. 30 8. S u r v i v a l curve of male caribou i n the i n t e r i o r . 33 9. Caribou observation by hunters compared t o recruitment 35 10. The r e g r e s s i o n of nose bots per doe i n June on age and the r e g r e s s i o n of nose bots per doe on warble p a r a s i t e s per doe i n June 37 .11. A weak c a l f observed i n March 1959 44 12. The r e g r e s s i o n of recruitment of y e a r l i n g s on recruitment of calves 46 13. C a l f s u r v i v a l t o 11-months-of-age i n the I n t e r i o r Herd i n 1957 49 14. The s u r v i v a l of calves u n t i l October i n r e l a t i o n t o m o r t a l i t y In June 51 15. C a l f s u r v i v a l i n the I n t e r i o r and Avalon Pe n i n s u l a herds u n t i l 6-months-of-age 52 16. The percentage of ca l v e s i n f a l l i n the I n t e r i o r , Avalon, and Humber R i v e r herds, 1956 t o 1967 53 17. The mean weight o f calves at b i r t h '56 18. Calves b i t t e n by ly n x t h a t developed abscesses 57 v i i i F igure Page 19. The Pot H i l l c a l v i n g ground..... 59 20. The canine t e e t h of a lyn x s k u l l i n s e r t e d i n t o four l e s i o n s 60 21. L o c a t i o n of lynx trapped at Middle Ridge.......... 65 22. Male calves strayed f a r t h e r than female calves from t h e i r dams 68 23. The r e g r e s s i o n of the percentage of calves i n the I n t e r i o r Herd i n October on the sex r a t i o of calves 1-4 weeks of age 69 24. The r e g r e s s i o n of the per cent male y e a r l i n g s on the recruitment i n June f o r the I n t e r i o r Herd.................. 70 25. The s u r v i v a l of calves i n eastern and c e n t r a l Newfoundland on the t o t a l l y n x harvested.. 73 26. S u r v i v a l of calves i n the Humber R i v e r Herd and production o f snowshoe hares 74 27. The r e g r e s s i o n of the r a t e - o f - i n c r e a s e on s u r v i v a l of c a l v e s u n t i l 6-months-of-age .80 INTRODUCTION A major e c o l o g i c a l problem i s what determines the growth r a t e of animal numbers. One explanation i s t h a t populations are r e g u l a t e d ; as numbers i n -crease density-dependent competition i n t e n s i f i e s , reduces and f i n a l l y h a l t s continued growth. A second school h o l d s , t h a t although some populations may be i n f l u e n c e d by density-dependent c o m p e t i t i o n , most are l i m i t e d by a s h o r t -age of time when the environment permits a p o s i t i v e r a t e - o f - i n c r e a s e ( r ) . This view emphasizes the r o l e of a randomly f l u c t u a t i n g e x t e r n a l environment on p o p u l a t i o n growth, r a t h e r than adjustments a c t i n g w i t h i n populations t o l i m i t numbers. The second theory argues a l s o t h a t the balance of nature con-cept i s f a l s e ; t h a t l o c a l populations f r e q u e n t l y become e x t i n c t and d i s p e r s a l from b e t t e r h a b i t a t s i s important i n r e e s t a b l i s h i n g populations ( f o r recent arguments i n t h i s controversy see Lack 1966, E h r l i c h and B i r c h 1967, and Slobodkin et a l . 1967). In t h i s t h e s i s I r e p o r t on a study of the f a c t o r s t h a t l i m i t e d the r a t e -o f - i n c r e a s e of c a r i b o u (Rangifer tarandus terraenovae) i n Newfoundland from 1900 t o 1967, and d i s c u s s the relevance of the r e s u l t s t o general t h e o r i e s of the growth of animal numbers. Caribou were abundant i n Newfoundland i n the e a r l y 1900's ( M i l l a i s 1907 and Dugmore 1913). Then from 1915 t o 1930 the herds r a p i d l y d e c l i n e d and n e a r l y became e x t i n c t (Dugmore 1930). Since 1930 there has been a s m a l l increase i n numbers; however, the p o p u l a t i o n has never approached i t s former abundance even though the n a t u r a l predator of c a r i b o u , the Newfoundland wolf (Canis lupus beothucus), went e x t i n c t i n 1911 (L. Tuck pers. comm.). Further l e g a l hunting was p r o h i b i t e d 1924- t o 1934 and only a s m a l l k i l l p e rmitted 1935 t o 1965. A l s o there has been a general de-c l i n e i n the i l l e g a l harvest of c a r i b o u s i n c e moose (Alces a l c e s ) became com-2 mon about 1945. S t i l l the numbers of c a r i b o u , i n e x p l i c a b l y , remained low. The ca r i b o u i n Newfoundland appears a s u i t a b l e animal upon which t o i n v e s t i g a t e the important question of what l i m i t s p o p u l a t i o n growth i n nature. The animals can be censused a c c u r a t e l y (Bergerud 1963 and S i n i f f and Skoog 1965) and sex, age, and behaviour can be e a s i l y s t u d i e d i n the f i e l d . The caribo u of Newfoundland i s p a r t i c u l a r l y s u i t a b l e because i t s i s l a n d h a b i t a t minimizes problems o f movement and yet the study area was s u f f i c i e n t l y l a r g e at 42,000 square mile s t h a t d i s p e r s a l should be t y p i c a l . F i n a l l y , much of the p r e s e n t l y occupied range o f the species i n Newfoundland permitted a study i n a n a t u r a l s e t t i n g . The work spanned the p e r i o d 1957 t o 1967. In the e a r l y years I compared b i r t h r a t e s and death r a t e s o f calves and a d u l t s t o determine what numerical changes were r e s p o n s i b l e f o r r a t e s of growth of p o p u l a t i o n . L a t e r , the empha-s i s was on the cause of a high e a r l y m o r t a l i t y of c a l v e s . I a l s o gathered h i s t o r i c a l i n f o r m a t i o n on the s i z e of the herds from 1900 t o 1956. The objec-t i v e was t o c l a r i f y e a r l i e r events and evaluate these r e l a t i v e t o the recent study. Four cari b o u herds were s t u d i e d ; the Avalon P e n i n s u l a , the Humber R i v e r , the I n t e r i o r , and the Northern Peninsula ( F i g . 1). A d d i t i o n a l l y , populations of the I n t e r i o r Herd c a l v i n g a t d i f f e r e n t c a l v i n g grounds were examined sepa-r a t e l y ( F i g . 1 ). In order t o f a c i l i t a t e the o r d e r l y p r e s e n t a t i o n of ideas i n the t e x t t a b u l o r m a t e r i a l has been assembled i n an appendix (APPENDIX I , p. 105). 3 PEN. F i g . 1. The l o c a t i o n of c a r i b o u 1957-1967. 4 METHODS The primary method was t o observe, count, and c l a s s i f y c a r i b o u as to sex and age from the a i r and ground (Appendix I , Table 1 ) . Emphasis was placed on c l a s s i f y i n g the animals during and a f t e r c a l v i n g and during the r u t t i n g season. Caribou were observed from the ground i n March 1959 and March-April 1961. Snow c o n d i t i o n s i n these three months were maximum which provided an opportunity t o observe the animals under extreme s t r e s s . Caribou were seen i n f r e q u e n t l y i n summer since most were under t r e e s by day to escape harassment by f l i e s . The Exchange of Animals Between Herds and Populations Movement of animals between herds could confound measurements of r a t e s of b i r t h and death. The degree of separation of c a r i b o u herds was assessed by a e r i a l surveys i n which i n d i v i d u a l animals were p l o t t e d on maps. Normally, the e n t i r e i n t e r i o r r e g i o n , from the r a i l r o a d on the east coast to the Trans-Canada highway on the west side of the i s l a n d was searched on f l i g h t l i n e s 5 to 10 m i l e s apart. A d d i t i o n a l l y , the I n t e r i o r Herd was tracked from the a i r during i t s m i g r a t i o n i n f a l l and s p r i n g . The Northern Peninsula was checked i n two w inters w i t h f l i g h t l i n e s spaced at 5 m i l e s . Several attempts were made to t r a c k the Humber Ri v e r Herd from the a i r to determine i f . i t j o i n e d the Northern Peninsula Herd ( F i g . 1 ) . The Avalon Peninsula was searched f o r c a r i b o u i n 11 years w i t h f l i g h t l i n e s u s u a l l y spaced at 2 m i l e i n t e r v a l s . A second method used to study movement was to tag c a r i b o u w i t h p l a s t i c streamers. Ninety-two animals were captured and tagged while swimming Lake V i c t o r i a i n November 1962. An a d d i t i o n a l 84 animals were immobilized f o r t a g -ging w i t h s u c c i n y c h o l i n e c h l o r i d e f i r e d i n d a r t s from Cap-Chur equipment . 5' (Bergerud et a l . 1964). The b r i g h t l y c o l o r e d streamers could be d i s t i n g u i s h e d from the a i r . A t h i r d method used t o evaluate the mixing of populations was to d e t e r -mine the percentage of a d u l t does possessing hard a n t l e r s in.October and Novem-ber. This was determined f o r the f o u r main carib o u herds and f o r f i v e r e g i o n a l populations of the I n t e r i o r Herd so that d i f f e r e n t c a l v i n g groups could be d i s -t i n g u i s h e d . The c a r i b o u i n the i n t e r i o r c a l v i n g at Pot H i l l , Mt. Peyton, and Middle Ridge were combined ( F i g . 1 ) . An assumption of t h i s method was t h a t s i g n i f i c a n t d i f f e r e n c e s between herds and populations i n percentage does ant-l e r e d provided evidence of reduced gene flow. To evaluate the method t h a t the percentage of a n t l e r e d does could be used t o d i s t i n g u i s h herds and p o p u l a t i o n s , I compared the v a r i a t i o n i n the percent-age of a n t l e r e d does between years i n which feeding c o n d i t i o n s i n the winter had v a r i e d . For example does w i t h hard a n t l e r s at Sandy Lake i n 7 Octobers was (±95 per cent confidence l i m i t s ) : • 47±7, 47+7, 40±6, 46±9, 49±12, -44±7, and 44±6. Again, two populations t h a t had separate c a l v i n g grounds but the same winter range were d i f f e r e n t i n the percentage of females w i t h a n t l e r s . The g e n e t i c b a s i s of a n t l e r c h a r a c t e r i s t i c s was a l s o s t u d i e d by keeping two a n t l e r e d does i n c a p t i v i t y f o r 5 years. The a n t l e r s of each female were d i s t i n c t i v e ( c f . L i n s d a l e and Tomich 1953). Another c a p t i v e female was always a n t l e r l e s s and without a n t l e r p e d i c e l s . Most of the s k u l l s of a n t l e r l e s s a n i -mals c o l l e c t e d i n the autumn were a l s o without protuberances. H i s t o r i c a l Research The year 1-900 was chosen as the beginning because l i t t l e e a r l i e r informa-t i o n could be found. In the p e r i o d 1902 t o 1911 a wealth of i n f o r m a t i o n was provided by J.G. M i l l a i s (1907) and.A.A.R. Dugmore (1913). M i l l a i s t r a v e l l e d 6' e x t e n s i v e l y i n f o u r autumns i n eastern Newfoundland, and Dugmore spent s e v e r a l autumns photographing c a r i b o u during the f a l l m i g r a t i o n near Grand Lake. W i l d l i f e o f f i c e r s spent e i g h t weeks questioning o l d e r r e s i d e n t s about past c a r i b o u abundance and annual movements i n l o c a l areas. D i a r i e s of w i l d l i f e wardens and annual game r e p o r t s were a v a i l a b l e f o r some years be-tween 1930 and 1950. K i l l s t a t i s t i c s were a v a i l a b l e f o r some years and were used to estimate p o p u l a t i o n t rends. F u r t h e r , the number of cari b o u observed per hunting day was determined from hunter l i c e n s e r e t u r n s f o r 1951 to 1961. Census : The general procedure was to s y s t e m a t i c a l l y search the i s l a n d by a i r and l o c a t e herds of c a r i b o u . Then each herd was counted by f l y i n g t r a n s e c t s across i t . The p r e l i m i n a r y f l i g h t l i n e s t o l o c a t e herds were u s u a l l y spaced at 5 m i l e i n t e r v a l s . Dense concentrations were subsequently counted w i t h a e r i a l t r a n s e c t s u s u a l l y 0.5 to 1.0 m i l e apart (Bergerud 1963a). To i n v e s t i g a t e sampling e r r o r , an e f f o r t was made to secure maximum cover-age of approximately 2000 animals occupying 24-5 square m i l e s . Forty t r a n s e c t s averaging 10 m i l e s i n l e n g t h were flown which provided an a e r i a l scan o f 88 per cent of the occupied area. This.study suggests t h a t 30.per cent of an area should be searched f o r an accuracy w i t h i n 10 per cent (Bergerud 1963a). Transects were u s u a l l y flown i n De H a v i l l a n d Beaver a i r c r a f t at -80-100 mph. at a constant height of 500 f e e t across the i n h a b i t e d range. U s u a l l y two re a r - s e a t observers scanned a \ m i l e s t r i p on each side of the a i r c r a f t . The outer boundaries of a t r a n s e c t were determined by marks on the wing s t r u t s through which the observer could p r o j e c t an imaginary l i n e forward. 7", The p l a c i n g o f these marks was determined b y , f l y i n g over markers s e t . a t known dis t a n c e s on the ground. A s k i of the a i r c r a f t provided the i n s i d e boundary of a . s t r i p . Without g l a n c i n g away from the window, both r e a r - s e a t observers reported t h e i r s i g h t i n g s to the c o - p i l o t . He p l o t t e d a l l c a r i b o u on topographic maps. A p a r t i a l c o r r e c t i o n f o r caribou missed by the r e a r - s e a t observers was made by having three men simultaneously t a l l y the caribou on the r i g h t side of the plane on r e v i s i t f l i g h t s t o four herds. The forward observer delayed r e p o r t i n g h i s s i g h t i n g s u n t i l the cari b o u had been passed, so as not t o a l e r t the other observers. The minimum number of caribou.overlooked by the r e a r -seat observer was determined by comparing h i s t a l l i e s w i t h the counts o f the other two observers. The highest t a l l y of animals i n an aggregation was con-si d e r e d the most accurate. On the b a s i s of t h i s t r i a l t o t a l s were normally increased -20 per cent to compensate f o r animals overlooked by the r e a r - s e a t observers. Herds were s t r a t i f i e d f o r census i n t o areas of l e s s than 0.5 cari b o u per square m i l e or gre a t e r than 0.5 animals per square m i l e . This was necessary because the low and high d e n s i t i e s f r e q u e n t l y d i d not r e c e i v e equal observa-t i o n . The low d e n s i t y stratum was u s u a l l y counted during the herd l o c a t i o n t r a n s e c t s , w h i le dense concentrations were surveyed w i t h repeated census s t r i p s . The c a r i b o u i n the I n t e r i o r Herd t h a t summered on the Buchans Plateau were counted from t h e i r t r a c k s i n the snow where they crossed two logging roads i n f a l l m i g r a t i o n . Tracks were counted s e v e r a l times each day and o b l i t e r a t e d a f t e r t a b u l a t i o n . The accuracy of the count was checked by censusing the a n i -mals by plane and comparing t h i s t o t a l w i t h the t r a c k t a l l y . A t h i r d method of census of the I n t e r i o r Herd i n v o l v e d a complete a e r i a l count of p o s t p a r t u r i e n t does on the c a l v i n g grounds. These f i g u r e s were v a l i d •8v only as trends s i n c e other c a r i b o u were not present on many c a l v i n g grounds. The Avalon Peninsula Herd was counted each October, except 1963, by f l i g h t l i n e s spaced at 1 or 2 m i l e i n t e r v a l s . The census was an attempt at a complete count. The Humber Ri v e r Herd was censused i n most years by a November t r a c k count and complete a e r i a l census on the winter range. The Northern Peninsula Herd was censused i n 1958 and 1966 by the t r a n s e c t method described f o r the I n t e r i o r Herd. Measurement of B i r t h Rates; The b i r t h r a t e was c a l c u l a t e d from t a l l i e s of does w i t h enlarged udders i n p o s t c a l v i n g herds. Does.were c l a s s i f i e d through a 20X spotting.scope as parous, i f w i t h a l a r g e udder for nonparous i f w i t h no v i s i b l e udder (Bergerud 1964a). S h o r t l y before c a l v i n g a pregnant doe develops a l a r g e distended udder which s h r i n k s at d i f f e r e n t r a t e s depending upon i t s use (Bergerud 1964a). U n f o r t u n a t e l y , s t a t i s t i c a l e v a l u a t i o n of the percentage of parous does could not be made since the number of d i f f e r e n t animals observed was unknown. D u p l i c a t i o n undoubtedly occurred when s e v e r a l men c l a s s i f i e d animals over a p e r i o d o f s e v e r a l days. However, I b e l i e v e the c l a s s i f i c a t i o n s were probably random samples. The areas used by the c a l v i n g herds were r e l a t i v e l y small and the fieldmen were able t o v i s i t the p e r i p h e r i e s of the c a l v i n g herds i n t h e i r d a i l y walks. The populations were not moving during the counts. Observations of tagged animals - showed t h a t there was a c o n t i n u a l mixing of animals between groups. In a d d i t i o n t o udder counts, the b i r t h r a t e was measured from a count of fet u s e s i n the u t e r i of 21 does k i l l e d by hunters i n November and December. An a d d i t i o n a l 58 does were c o l l e c t e d i n June to determine the number of es t r u s c y c l e s each doe experienced the p r i o r autumn. Ovaries from the l a t t e r sample 9 were examined by P r o f . H.T. G i e r , Kansas State U n i v e r s i t y (Appendix I T ) . Measurement of Adult M o r t a l i t y A s p e c i a l search was made to l o c a t e a d u l t s dying from n a t u r a l causes. The approximate age.at death of 46 a d u l t s was determined from a tooth-wear key developed f o r Alaskan c a r i b o u by Skoog (1956). Caribou remains were sexed on the b a s i s of a n t l e r c h a r a c t e r i s t i c s , p e l v i c bones, or length of the dentary bones (Bergerud 1964b). Fourteen a d u l t s were autopsied f o r p a r a s i t e s and disease by Dr. John W. K i n g , a p a t h o l o g i s t . W i l d l i f e o f f i c e r s examined an a d d i t i o n a l 46 animals, i n the f i e l d f o r macroparasites. The i n t e s t i n a l t r a c t s of 36 a d u l t s were examined i n the l a b o r a t o r y f o r p a r a s i t e s . P a r a s i t e s were i d e n t i f i e d by P r o f . J.W. E m s l i e , U n i v e r s i t y of Glasgow, Scotland. The age s t r u c t u r e of the l i v i n g s tag p o p u l a t i o n was estimated from 693 mandibles (Table 2) provided by hunters from 1951 t o 1965. Age was estimated from tooth wear (Skoog 1956) and a n n u l i (Table 3) i n the cementum (McEwan 1963). A d d i t i o n a l l y 126 captured does and.stags were aged by counting the a n n u l i i n an e x t r a c t e d i n c i s o r (Bergerud and R u s s e l l 1966). L e g a l hunting s t a t i s t i c s were secured from r e t u r n s of hunter l i c e n s e s . Over 90 per cent of the l i c e n s e holders provided r e t u r n s each year. Data on the i l l e g a l k i l l were based on i n t e r v i e w s w i t h conscientious l o c a l r e s i d e n t s and the r e p o r t s of w i l d l i f e wardens. Al s o the remains of i l l e g a l l y k i l l e d c a r i b o u and t r a c k s of poachers were f r e q u e n t l y observed from the a i r . M o r t a l i t y of Calves Overwinter The percentage of 6-month-old calves i n the I n t e r i o r Herd was compared t o the percentage of the same cohort i n the p o p u l a t i o n . at 24-months-of-age t o determine i f young animals died at greater r a t e s than a d u l t s . The comparison was based on the number of 2-year-old does c l a s s i f i e d on the c a l v i n g grounds i n June. C o r r e c t i o n s had t o be added f o r the missing stag component of the herd. Also not a l l 2-year-old does' were p r o p e r l y d i s t i n g u i s h e d from ad u l t does. The percentage of 2-year-old does mistakenly c l a s s i f i e d a s . a d u l t s was estimated by comparing the percentage of male : female 6- t o 12-month-old animals (40. 17:59.83 n=1282), w i t h the sex r a t i o of 17- to 22-month-old animals (84 males and '77 females). The sex r a t i o determined f o r 6- t o 12-month-old animals i s l i k e l y r e p r e s e n t a t i v e of the p o p u l a t i o n ; whereas at 17- to 22-months-of-age, a l l males are probably a c c u r a t e l y d i s t i n g u i s h e d by t h e i r small a n t l e r s but many of the l a r g e y e a r l i n g females are c l a s s i f i e d as a d u l t does. Since c a r i b o u do not grow from f a l l u n t i l s p r i n g , the percentage of females overlooked at 17-to 22-months-of-age should be s i m i l a r t o the percentage missed at 24-months-of-age, assuming no d i f f e r e n t i a l winter mortality.between males and.females. The c a l c u l a t i o n s t o determine the percentage of unrecognized 2-year-old does were: 059.83)(84)/(4O.17X) - 77 : = 38.45 per cent (•59.83)(84) / (40.17X) Time and Amount of E a r l y M o r t a l i t y of Calves: E a r l y c a l f m o r t a l i t y was assessed by counting does w i t h c a l v e s and does with distended udders but without c a l v e s . (Bergerud 1964b). This was done on the c a l v i n g grounds over a p e r i o d of years: Buchans Plate a u (6 y e a r s ) , Grey R i v e r (5 y e a r s ) , Middle Ridge (3 y e a r s ) , and Pot H i l l (10 y e a r s ) . This technique was f e a s i b l e because c a r i b o u g i v e b i r t h to only one c a l f and c a l v e s always accompany t h e i r mothers i n f l i g h t . A doe t h a t i s separated from her c a l f w i l l c i r c l e - b a c k t o l o c a t e her c a l f . These animals are readily-recognized. F i d u c i a l l i m i t s could not be c a l c u l a t e d f o r the m o r t a l i t y r a t e s of calves si n c e some females were l i k e l y c l a s s i f i e d more than once. F u r t h e r , such s t a -t i s t i c s would have l i t t l e value i n d i s t i n g u i s h i n g d i f f e r e n c e s between areas because the data were gathered at d i f f e r e n t times f o r each c a l v i n g area. Since some calves were-dying during these counts, the m o r t a l i t y from the f i r s t c a l v i n g ground v i s i t e d could be l e s s than t h a t - o f a second area v i s i t e d p a r t i a l -l y because of t h i s t i m e - l a g . A second assessment^) of c a l f m o r t a l i t y was made by l o c a t i n g and aging the remains of c a r i b o u t h a t d i e d from n a t u r a l causes. The age ^of 'calyes ;at^de;ath -was') based on a comparison of t h e i r t o o t h i r r u p t i o n w i t h known age jawbones. Obvious biases i n the search f o r remains were: (1) more time was spent on c a l v i n g grounds than elsewhere, (2) no time was spent searching f o r e s t cover where many calves probably" d i e d , (3) c a l f remains were more d i f f i c u l t t o f i n d than those of a d u l t s , and (4) c a l f remains were more f r a g i l e , l i a b l e to s c a t -t e r i n g and disappearance than a d u l t carcasses. The net r e s u l t of these biases i s not known. Another method of d e t e c t i n g the chronology and s i z e of c a l f m o r t a l i t y was to a s c e r t a i n the percentage of calves i n the herd by c l a s s i f i c a t i o n counts t i l l the young were 12-months-old. A s p e c i a l e f f o r t was d i r e c t e d at determining when m o r t a l i t y occurred i n the 1957, 1958, and 1959 cohorts. Herd composition counts of these cohorts were secured at 1-2 month i n t e r v a l s . Calves were r e -corded e i t h e r as a percentage of the t o t a l animals or as calves seen per 100 does seen. In t h i s paper the calves as a percentage of the herd (C/C+Y+A) w i l l be used i n most d i s c u s s i o n s . C a l f percentages are used r a t h e r than calves per 100 does i n most c a l c u l a t i o n s because l a r g e r samples were a v a i l a b l e on a c a l f 12 percentage b a s i s . Again c a l f t o herd percentages have cu s t o m a r i l y been used by other c a r i b o u workers'and a change i n the t r a d i t i o n would complex compari-sons between i n v e s t i g a t i o n s . The' percentage of c a l v e s i n autumn was a l s o estimated from animals l i s t e d on r e t u r n s of b i g game l i c e n s e s . Space was provided on the l i c e n s e f o r the hunter to l i s t the number of does, stags, c a l v e s , and animals of unknown sex and age observed while hunting. Some r e t u r n s were o b v i o u s l y i n e r r o r and could not be used. These observations were val u a b l e because they spanned 16 years and were from a l l s e c t i o n s of the i n t e r i o r . A few determinations of percentage of cal v e s i n the I n t e r i o r Herd were made by b i o l o g i s t s p r i o r to my s t u d i e s . Percentage of cal v e s i n f a l l were a v a i l a b l e f o r 1950, 1951, 1952, 1953, and 1956. A comparison of m o r t a l i t y between male and female c a l v e s 'was' made by sex-ing them by t h e i r e x t e r n a l g e n i t a l i a (Bergerud 1961b). Age c l a s s e s recognized were: b i r t h ( a c t u a l l y 0- t o 1-day-old as judged on the b a s i s t h a t a man could rundown the c a l f ) , 1-4- weeks, 5-6 months, 10 months, 12 months, and as a d u l t s . C o r r e l a t i o n c o e f f i c i e n t s were c a l c u l a t e d to evaluate the r e l a t i o n s h i p be-tween the sex r a t i o of cal v e s and recruitment. The r e g r e s s i o n used was the sex r a t i o of cal v e s at 1-4 weeks-of-age on y e a r l i n g s per 100 does i n June. Sex r a t i o s at 12-months-of-age were used i n l i e u of f i g u r e s a t 6-months-of-age sin c e the former were a v a i l a b l e f o r 9 years. Again the percentage o f y e a r l i n g s permitted a comparison of the sex r a t i o on recruitment by c a l v i n g grounds, as w e l l as between years. The c a l c u l a t i o n s based on y e a r l i n g s are v a l i d f o r these comparisons' i f : (1) there i s no d i f f e r e n t i a l sex m o r t a l i t y overwinter, (2) both male•and female y e a r l i n g s r e t u r n to the c a l v i n g grounds i n pr o p o r t i o n to t h e i r abundance, and (3) overwinter c a l f l o s s e s are minimal or p o s i t i v e l y cor-r e l a t e d w i t h m o r t a l i t y 0-6 months-of-age. I b e l i e v e t h a t these assumptions 13 are v a l i d . Determination of Cause of C a l f M o r t a l i t y from C e r v i c a l Abscesses In 1957 I l o c a t e d s e v e r a l morbid or dead calves a l l i n f e c t e d w i t h l a r g e c e r v i c a l abscesses. Others were found i n every subsequent s p r i n g . A major e f f o r t i n the research was t o determine the cause of t h i s m o r t a l i t y . Ab-scessed calves were sent t o various Canadian l a b o r a t o r i e s f o r autopsies. The Newfoundland Department of He a l t h , The Department of A g r i c u l t u r e Animal D i s -eases Research I n s t i t u t e , and Drs. H.C. Gibbs and J.G. Cousineau (Canadian W i l d l i f e S e r v i c e ) c u l t u r e d pus from abscesses. Thirty-two i n f e c t e d calves were autopsied by p a t h o l o g i s t Dr. J.M. King and a s s i s t e d . a t times by epide-m i o l o g i s t Dr. Lars Karstad and b a c t e r i o l o g i s t Dr. J.G. Cousineau. To t e s t whether the i n f e c t i o n was c o n g e n i t a l or not, 117 newborn calves were h e l d i n c a p t i v i t y f o r a minimum of 3 weeks while f r e e - r a n g i n g calves were developing abscesses. Seven pregnant does were h e l d u n t i l p a r t u r i t i o n . Caribou were introduced t o Brunette I s l a n d ( F i g . 1) using stock from the Middle Ridge p o p u l a t i o n where many abscessed calves occurred. One explanation of the c o n d i t i o n was t h a t nose bots (Cephenomyia trompe) from the dam burrowed through the neck s k i n of the c a l f (Peters and King 1959). This was t e s t e d by c o l l e c t i n g bots from does and p l a c i n g them on the neck of c a l v e s . A l l s i z e s of bots were t e s t e d . Another theory was t h a t the b i t e of some other arthropod i n i t i a t e d the i n f e c t i o n . A r a i s e d p l a t f o r m was constructed i n the Pot H i l l c a l v i n g ground. Arthropods were prevented from c r a w l i n g up the supports of the p l a t f o r m . S i x calves were h e l d on the stage i n June f o r two weeks. An adjacent exclosure on the ground h e l d seven calves exposed to t e r r e s t r i a l and a e r i a l arthropods. 14 DISTRIBUTION OF HERDS AND POPULATIONS The^ c a r i b o u herds that I recognized i n Newfoundland: the Northern Peninsula Herd, the Humber R i v e r Herd, the I n t e r i o r Herd, and the Avalon Pen i n s u l a Herd, appeared t o be d i s c r e t e u n i t s ( F i g . 1 ) . I was unable to secure any o b s e r v a t i o n s • i n 11 years or informat i o n from l o c a l r e s i d e n t s l i v i n g or t r a v e l l i n g i n the area between the herds that i n d i c a t e d t h a t any animals moved between the Avalon, Humber, and the I n t e r i o r Herds. The Humber R i v e r Herd was fo l l o w e d from the a i r f o r -40 m i l e s . I t d i d not appear to be moving i n t o the range of the Northern Peninsula Herd. F i n a l l y the percentage of does possessing v i s i b l e a n t l e r s v a r i e d between a l l f o u r herds ( F i g . 2). I conclude t h a t a l l four herds were d i s c r e t e . The I n t e r i o r Herd was d i v i d e d i n t o f i v e l o c a l populations on the b a s i s of t h e i r c a l v i n g grounds: La P o i l e R i v e r , Buchans P l a t e a u , Grey R i v e r , Sandy Lake, and the animals u t i l i z i n g the Pot H i l l , Middle Ridge, and Mt- Peyton c a l v i n g grounds ( F i g . 1 ) . The l o c a t i o n o f the c a l v i n g grounds appeared t o be the most r e g u l a r l y v i s i t e d area i n t h e i r movements. There was a need to d i s t i n g u i s h l o c a l , populations s i n c e more cal v e s died at some c a l v i n g grounds than others. L i m i t e d evidence suggested t h a t the carib o u i n the f i v e populations of the I n t e r i o r Herd were not panmictic. The percentage of does w i t h a n t l e r s was great e r i n the La P o i l e P o p u l a t i o n and lower i n the Grey R i v e r P o p u l a t i o n than elsewhere ( F i g . 2 ). Observations of tagged animals i n d i c a t e d t h a t only 3 of 76 animals may have switched c a l v i n g grounds ( F i g . 3 ). A e r i a l censuses i n 1961, 1964, and 1966 showed three d i s t i n c t winter ranges occupied by: (1) the La P o i l e R i v e r P o p u l a t i o n , (2) carib o u m i g r a t i n g from the Buchans P l a t e a u , Grey R i v e r , and Sandy Lake c a l v i n g grounds, and ('3) carib o u from the Pot H i l l , 15 •»**»• RAILROAD TRACK . NORTHERf PEN. HERD 88 + 9(1) HUMBER' RIVER HERD 71 + 8 (3)< NO MOVEMENT ACROSS TRACK / 46±5 46 PER CENT DOES HAVE ANTLERS ± 95°/o C,L, (3) CLASSIFIED IN THREE YEARS BUCHANS PLATEAU 46±5(4) SANDY LAKE 45+3(8) POPULATIONS IN INTERIOR MIDDLE R. 4-POT HILL: 47+3(5) LA POILE 59±6(2) GREY R. 36+4(5) 25 0 zdz ALL INTERIOR HERD 45+2 (9) 25 50 75 100 NO MOVE-MENT ACROSS F i g . 2. Percentage of adul t females with v i s i b l e a n t l e r s i n the autumn. 16 F i g . 3. Observations of animals subsequent to two migrations a f t e r tagging. 17 Mount Peyton, and Middle Ridge c a l v i n g p o p u l a t i o n s . F i n a l l y , the percentage of y e a r l i n g s and 2-year-old caribou on various c a l v i n g grounds i n the s p r i n g was c o r r e l a t e d w i t h c a l f s u r v i v a l t o 6-months-of-age from the same areas, as noted l a t e r . Since the s u r v i v a l of calves f r e q u e n t l y v a r i e d g r e a t l y between c a l v i n g grounds t h i s c o r r e l a t i o n would not be expected i f s i g n i f i c a n t exchange had occurred between pop u l a t i o n s . 18 SIZE OF CARIBOU HERDS Numbers 1900-1910 The annual r e p o r t of the Game and I s l a n d F i s h e r i e s D i v i s i o n 1950-51 st a t e d : "...by a l l accounts the carib o u p o p u l a t i o n reached a peak i n the e a r l y 1900's". The i s l a n d p o p u l a t i o n i n t h a t p e r i o d was estimated by Dugmore (1913)' t o co n t a i n 150,000 animals and by M i l l a i s (1907) t o number 200,000. In c o n t r a s t t o these l a r g e estimates of M i l l a i s and Dugmore, I b e l i e v e t h a t there was probably no more than 40,000 caribou on the i s l a n d i n the i n t e r v a l 1900-1910. This f i g u r e was derived from estimates provided by r e s i d e n t s i n in t e r v i e w s ( F i g . -4). This number seems more reasonable than 150,000-200,000 when we consider the extent of winter range about 1900 and even then there were l a r g e areas of few animals ( F i g . 4 ). Dugmore's observations of ca r i b o u were l i m i t e d t o s i g h t i n g s of animals m i g r a t i n g across the r a i l r o a d between Sandy Lake and M i l l e r t o w n J u n c t i o n . This m i g r a t i o n was the most renowned and probably contained the l a r g e s t con-c e n t r a t i o n of animals i n a l l Newfoundland. Dugmore may have e x t r a p o l a t e d h i s estimate f o r the i s l a n d from these l i m i t e d observations. The 1900 herd i n t e r c e p t e d the r a i l r o a d t r a c k s as three groups. The f i r s t group moved by B i g F a l l s on the Humber R i v e r and crossed the r a i l w a y t r a c k s at Sandy Lake. A second group from the Northern Peninsula crossed B i r c h y Lake at Slaughter P o i n t and went across the r a i l r o a d near the h i l l named the Gaff Top-s a i l . Another component of the herd moved south from the B u r l i n g t o n Peninsula and a l s o swam B i r c h y Lake and then i n t e r c e p t e d the r a i l r o a d near the Gaff Top-s a i l . A f o u r t h body of animals crossed the r a i l r o a d at P a t r i c k s Marsh, M i l l e r -town J u n c t i o n . The most complete h i s t o r i c a l i n f o r m a t i o n f o r these herds was secured f o r F i g . 4. Number of cari b o u about 1900 based on i n t e r v i e w s and the extent of winter range. 20 the a n i m a l s . c r o s s i n g at Sandy Lake; probably more animals moved south at Sandy than at the other two c r o s s i n g s s i n c e more animals were k i l l e d there (unpublished f i l e s ) . In one autumn Dugmore (1908) counted 1200 animals at Sandy i n 9 days. In 1911 Dugmore (1912) s t a t e d t h a t 2000 animals passed w i t h -i n s i g h t i n a 2-week p e r i o d . The l a r g e s t c r o s s i n g i n t h a t year was on October 24 when 8 companies t o t a l l i n g 500 animals passed south. Three o l d e r r e s i d e n t s int e r v i e w e d i n t h i s study each s e p a r a t e l y estimated the B i g Falls-Sandy Lake popu l a t i o n at 2000 animals about 1915. Two newspaper accounts of c a r i b o u ob-served during hunting t r i p s l i s t e d t o t a l s of 1800 animals seen i n 1907 and 1000 i n 1908. I t i s u n l i k e l y t h a t more than 3000-4000 animals could have been i n v o l v e d i n t h i s m i g r a t i o n . At the Gaff T o p s a i l and P a t r i c k s Marsh cros s i n g s the maximum d a i l y counts of m i g r a t i n g animals were s i m i l a r t o those at Sandy and v a r i e d from 250 t o 500 animals. Most of the herd crossed the t r a c k s i n a 2- t o 3-week p e r i o d . The t o t a l s f o r these two c r o s s i n g s would not have exceeded perhaps 3000 t o 4000 animals i f two assumptions are v a l i d : (1) t h a t the d a i l y frequency of c a r i b o u moving south f o l l o w e d a normal d i s t r i b u t i o n curve and (2) t h a t the maximum d a i l y counts (the center of the normal curve) represented 20 t o 30 per cent of the t o t a l animals i n each of the three concentrations. These assumptions are v a l i d f o r the c a r i b o u t h a t p r e s e n t l y s t i l l migrate south from the Buchans P l a -teau and pass by Lake V i c t o r i a (personal f i l e s ) . The t o t a l p o p u l a t i o n t h a t migrated between Sandy and M i l l e r t o w n J u n c t i o n can a l s o be judged from m o r t a l i t y and recruitment s t a t i s t i c s and p o p u l a t i o n trends. The annual harvest from the herd 1900 t o 1915 was between 2000 and 3000 animals. Approximately h a l f the animals were harvested along the r a i l r o a d and such k i l l f i g u r e s compiled by wardens (1911, ,1912, 1914, and 1915) ranged from 1000 t o 1500. In a d d i t i o n , approximately 100 hunters annually k i l l e d 21 animals at Slaughter P o i n t , B i r c h y Lake. A l s o , nonmigratory animals were shot by l o c a l r e s i d e n t s t r a v e l l i n g by dog team t o the White and South H i l l i n March. I estimated the c a l f increment to the herd during the years o f heavy harvest at 20 per cent based on a count o f calves c l a s s i f i e d from the e x c e l l e n t photo-graphs i n Dugmore's book (1913). The above k i l l and recruitment f i g u r e s were apparently f a i r l y balanced s i n c e the po p u l a t i o n maintained i t s numbers or only g r a d u a l l y d e c l i n e d i n the i n t e r v a l 1900 t o 1915. These comparisons as w e l l as those of the t o t a l animals estimated a t each of the three r a i l r o a d i n t e r c e p t s suggest t h a t the l a r g e s t herd i n Newfoundland i n the e a r l y 1900's probably numbered l e s s than 15,000 animals. M i l l a i s ' (1907) d e t a i l e d observations of carib o u do not support h i s e s t i -mate of 200,000 cari b o u f o r the I s l a n d 1900-1910. In 1902 M i l l a i s t r a v e l l e d up the Terra Nova R i v e r ; he observed 306 does i n 36 days. The next year he canoed up the Gander R i v e r ; the f i r s t caribou were not seen u n t i l the p a r t y was w e l l i n l a n d and then only a few animals were observed each day. In 1905 he crossed the i s l a n d from Bay D'Espoir to Glenwood and saw many " l i t t l e p a r t -i e s " o f animals i n the v i c i n i t y of Pipestone Lake. F i n a l l y , i n October 1906, he journeyed up Long Harbour R i v e r and reached Mt. S y l v e s t e r . On t h i s t r i p he observed more c a r i b o u than p r e v i o u s l y and remarked t h a t 4 or 5 companies were seen each day a f t e r he had t r a v e l l e d i n l a n d 5 days. The gr e a t e s t number of caribo u were seen October 30— :124 animals and October 31—159 car i b o u . These observations do not give the impression of thousands of ca r i b o u . In f a c t i t was p o s s i b l e during t h i s survey f o r me t o observe as many carib o u per day near Pipestone Lake as M i l l a i s d i d even though an a e r i a l census showed t h a t there were only approximately 300 animals i n the r e g i o n . Numbers and Trends 1900-1956 22 The number of ca r i b o u on the i s l a n d r a p i d l y d e c l i n e d from 1915 t o 1925. The decrease was f i r s t noted at the r a i l r o a d c rossings but soon spread t o a l l segments of the p o p u l a t i o n . The l a s t l a r g e migration.at Sandy Lake was r e -ported as 1200 animals i n 1925. The l a s t important c r o s s i n g at Slaughter P o i n t , B i r c h y Lake was i n 1925 or 1926. Less than 100 animals swam B i r c h y Lake i n 1930. The d e c l i n e was apparent i n the Southern Long Range Mountains i n 1920. Caribou disappeared from the "Anguille Mountains about 1923 and were almost gone from the Hodges H i l l s by 1920. Caribou became scarce i n a l l the southeastern i n t e r i o r i n the i n t e r v a l 1920-25; hunters had t o t r a v e l as f a r as Middle Ridge t o f i n d animals. By 1925 a l l the l a r g e herds had disappeared and the hunting season was c l o s e d f o r the i s l a n d . The c a r i b o u reached t h e i r n a d i r of numbers between 1925 and 1930. Dugmore (1930:127) s t a t e d : "How l i t t l e d i d I r e a l i z e . . t h a t the vast herds, seemingly u n l i m i t e d and enduring would p r a c t i c a l l y vanish during my own l i f e time; t h a t ten short years from the day when I enjoyed watching the long l i n e s of . . . a n i -mals.. I should be t o l d t o a l l i n t e n t s and purposes they had vanished; vanished with an a s t o n i s h i n g abruptness, u n b e l i e v a b l e and incomprehensible. I am t o l d t h a t there are not two hundred caribou i n the whole i s l a n d today, and those are s c a t t e r e d i n ones and twos i n the w i l d uninhabited r e g i o n s " . I t seems l i k e l y t h a t considerably more than 200 animals remained i n 1930. However, a l l the r e s i d e n t s i n t e r v i e w e d i n t h i s i n v e s t i g a t i o n agreed t h a t c a r i -bou were much sc a r c e r i n 1930 than i n 1957-58 when the f i r s t censuses revealed l e s s than 6500 animals f o r the i s l a n d . Two r e s i d e n t s s t a t e d t h a t - t h e low i n numbers f o r the Avalon Herd was 80 animals. There were probably l e s s than 100 animals remaining i n each of the Northern P e n i n s u l a and Humber R i v e r herds i n 1930. P o s s i b l y 1000 or 2000 animals p e r s i s t e d on the i s l a n d during the years of s c a r c i t y . 23 The herds began t o increase by 1932-35. A l e t t e r from the c l e r k of the Game and F i s h e r i e s Commission (November 10, 1936) reported: " . . . c a r i b o u have been reported as i n c r e a s i n g s l o w l y but s u r e l y , and during the l a s t 4 or 5 years s m a l l southward and northward migrations along the o l d routes have been r e p o r t -ed". A warden r e p o r t s t a t e d t h a t 60 t o 70 animals crossed by the Gaff T o p s a i l i n 1 9 3 3 — t h i s was the l a r g e s t herd r e p o r t e d i n many years. Hunters noted 200 animals at Middle Ridge i n 1933. By 1940 herds were again c r o s s i n g Sandy and B i r c h y Lakes and c a r i b o u had returned t o the Hodges H i l l s and A n g u i l l e Moun-t a i n s . A peak p o p u l a t i o n may have been reached about 1941 si n c e hunting suc-cess d e c l i n e d i n 1942, 1943, and 1944 (Table '4). Commencing about 1946-47 the p o p u l a t i o n again expanded and o l d ranges were reoccupied (personal f i l e s ) - ; l i c e n s e quotas were r e l a x e d and k i l l . s t a t i s t i c s i n creased (Table 4 ) . Another peak of abundance may have been reached about 1951 (Table 4 ) ; the p o p u l a t i o n then d e c l i n e d and was s t i l l decreasing when the current study began. Numbers and Trends 1957-1967 The w i n t e r censuses of the I n t e r i o r Herd i n d i c a t e d t h a t the pop u l a t i o n increased from 1957 t o 1961, p o s s i b l y d e c l i n e d 1962 t o 1964, and again i n -creased 1965 and 1966 ( F i g . 5 and Table 5). U n f o r t u n a t e l y , the La P o i l e popu-l a t i o n was not a c c u r a t e l y counted i n the f i r s t three censuses, thus the f i g -ures f o r i t were excluded from Table 5 t o permit a more v a l i d comparison of the f i v e counts. The counts of the p o s t p a r t u r i e n t doe concentrations showed a g r a d u a l l y i n -cr e a s i n g p o p u l a t i o n (Table '6). The t o t a l s o f does on some c a l v i n g grounds v a r i e d widely between years (Table 6). These d i s c r e p a n c i e s l i k e l y r e s u l t e d from changes i n the l o c a l d i s t r i b u t i o n of animals and sampling e r r o r s r a t h e r 24 1 —i 1 1 1 1 1 1 1 1 1 r 57 58 59 60 61 62 63 64 65 66 67 Y E A R S COUNTED F i g . 5. Caribou numbers from a e r i a l census or t r a c k counts. Figures f o r the I n t e r i o r Herd do not i n c l u d e the La P o i l e p o p u l a t i o n . . 25 than movement between p o p u l a t i o n s . In some June counts the animals were much more concentrated and e a s i e r t o l o c a t e than i n other years. For example, the counts of the Buchans P l a t e a u p o p u l a t i o n i n 1963, 1964-, and 1965 y i e l d e d 643, 1341, and 892 animals (Table 6). The tagged animals counted i n each year were 9, 32, and 1 4 — y e t these animals were tagged i n November 1962 and not l i k e l y dead. Moreover, they were not observed on other c a l v i n g grounds. The inference i s t h a t a group of the Buchans P l a t e a u popula-t i o n was overlooked i n 1963 ,' and 1965 and p o s s i b l y 1964. The autumn t r a c k count of the Buchans p o p u l a t i o n , s i m i l a r t o the winter and June t a l l i e s , suggested t h a t i t had g r a d u a l l y increased. Track t o t a l s were: 1957—592, 1958—585, 1959--730, 1961—1042, and 1963—1028. A e r i a l census gave a p o p u l a t i o n estimate of 1200 i n 1963 (Manuel 1964). The October a e r i a l census of the Avalon Herd showed a p o p u l a t i o n increase from 71 animals i n 1956 t o 720 animals i n 1966 ( F i g . 5 and Table 5). The t o t a l s f o r the years 1956 t o 1960 probably underestimated the p o p u l a t i o n . I t was not u n t i l October 1960 t h a t I discovered a s m a l l group of animals (41 th a t year) i n a r e g i o n not surveyed i n e a r l i e r years. F u r t h e r , i n 1961, the New-foundland government secured i t s own a i r c r a f t ; t h i s permitted more i n t e n s i v e searches than p o s s i b l e w i t h chartered f l i g h t s . The Avalon Herd i n 1956 l i k e l y contained about 125 animals. The Humber R i v e r Herd showed no change between 1956 and 1964 and averaged 111 animals ( F i g . 5 and Table 5). Likewise no t r e n d i n numbers was evident f o r the Northern P e n i n s u l a herd i n the only two a e r i a l censuses made, 1958— 450 animals and 1966—400 ca r i b o u . 26 BIRTH RATES "An animal's innate c a p a c i t y f o r increase depends upon i t s f e c u n d i t y , l o n g e v i t y , and speed o f development" (Andrewartha and B i r c h 1954:33). I t was e s s e n t i a l t o determine i f the slow r a t e - o f - i n c r e a s e of the Newfoundland herds was a r e s u l t of low b i r t h r a t e s . In t h i s s e c t i o n I w i l l d i s c u s s speed of development (age of sexual m a t u r i t y ) and f e c u n d i t y . The next s e c t i o n s on a d u l t and c a l f m o r t a l i t y r e l a t e j t o s u r v i v a l and hence l o n g e v i t y . Age of Breeding In animals t h a t have one young per year the age of sexual m a t u r i t y has a marked i n f l u e n c e on t h e i r p o t e n t i a l r a t e o f i n c r e a s e . S t a r t i n g w i t h one male and one female, a species having one young and breeding at 1 year of age could i n c r e a s e t o 63 animals i n 10 years ( r = 0.361), assuming no m o r t a l i t y and a balanced sex r a t i o ; a species breeding f i r s t at 2 years would increase t o 30 animals ( r = 0.301) and one a t t a i n i n g puberty at 3 years could reach 22 animals i n 10 y e a r s , r = 0.266 (numbers at 10 years based on breeding poten-t i a l t a b l e s of Leopold 1933). The age of puberty i n carib o u i s u s u a l l y considered t o be 29 t o 30 months, Skoog (1968) report e d 4 of 31 (13 per cent) does \\ years of age pregnant and 28 of 46 (61 per cent) 2\ years of age c a r r y i n g young. K e l s a l l (1968) l i s t e d 1 of 3 does l^g years o l d pregnant and 6 of 15 (40 per cent) 2\ years o l d . In t h i s study only 1 of 9 2-year-old does c o l l e c t e d was parous (Table 7). We c l a s s i f i e d only 4 of 327 2-year-old does parous i n 10 years. This f i g u r e should underestimate parous 2-year-olds since only an estimated 62 per cent of the young does were separate from a d u l t s . In c a p t i v i t y , 2 of 3 females reach-ed puberty as y e a r l i n g s . Thus the species has the genetic p o t e n t i a l t o produce . -27 young at 24—months-of-age. The w i n t e r of 1957-58 provided an opportunity t o assess the r o l e of ex-tremely f a v o r a b l e weather and forage c o n d i t i o n s on the age of puberty. L i t t l e snow f e l l ( F i g . 6) and temperatures were above normal so t h a t lakes remained unfrozen f o r much of the w i n t e r . Calves weighed more at b i r t h f o l l o w i n g the m i l d winter than i n any other year (see page 56). This was c o n s i s t e n t with the idea t h a t females had f a r e d e x c e p t i o n a l l y w e l l during the w i n t e r . A s p e c i a l e f f o r t was made i n 1959 t o observe 2-year-old does t o determine i f many had conceived as y e a r l i n g s f o l l o w i n g the favorable w i n t e r . No parous 2-year-old does were recorded. Apparently, favorable w i n t e r forage i s i n s u f -f i c i e n t alone t o advance sexual m a t u r i t y . Twenty-two calves were counted on Brunette I s l a n d i n October 1966. The maximum number of females on the i s l a n d 3-years and o l d e r was 19. Thus at l e a s t 3 calves must have been born t o the 5 or 6 2-year-old females i n the herd. Moreover, a number of male calves had forked a n t l e r s ; t h i s s u p e r i o r a n t l e r development was never observed elsewhere' i n Newfoundland. The p l a n t communities on the i s l a n d were s i m i l a r t o those on the mainland. A s u p e r i o r n u t r i t i o n a l s t a t e of the animals could have r e s u l t e d from the maritime cl i m a t e of the i s l a n d t h a t reduces i n s e c t abundance and permits f o r a g i n g throughout the day. Fecundity The r e p r o d u c t i v e r a t e of a species breeding once each year i s a product of the percentage of females t h a t carry.young t o p a r t u r i t i o n and the mean number of young born per parous female. In Newfoundland cari b o u the reproductive r a t e depended only on the annual percentage of pregnant (parous) does si n c e there was no evidence of m u l t i p l e b i r t h s . Only 6 does were seen i n 11 years t h a t 28 DECEMBER JANUARY FEBRUARY MARCH APRIL F i g . 6. The snow p r o f i l e (depth of snow on ground) at Gander, Newfoundland, f o r the e x c e p t i o n a l l y m i l d winter o f 1957-58 and the very severe winter 1958-59 . allowed two calves t o nurse simultaneously. On four occassions a second doe appeared t o c l a i m the second c a l f . Two calves f r e q u e n t l y f o l l o w e d one doe when alarmed, but most observations showed th a t the dam o f the second c a l f was nearby. The o v a r i e s or u t e r i of 73 parous females showed no signs of m u l t i p l e b i r t h s . The 11-year frequency of parous does f o r the I n t e r i o r Herd based on udder c l a s s i f i c a t i o n was 84.5 per cent (Table 8). This f i g u r e agreed c l o s e l y w i t h a pregnancy percentage of 86 per cent from the examination of 21 reproductive t r a c t s provided by hunters. I attempted t o r e l a t e the parous d o e . s t a t i s t i c s secured each year i n Table 8 t o various f a c t o r s of the environment.. The annual pregnancy r a t e s showed no trends when p l o t t e d against s n o w f a l l i n the previous 1 and 2 years. The pregnancy f i g u r e s were not r e l a t e d to a d e c l i n e of stags (Table 9). Hunter disturbance during the r u t t i n g season d i d not appear t o be a f a c t o r . Hunting pressure was heaviest on the Buchans P l a t e a u and l e a s t at Grey R i v e r ; yet the percentages of parous does were s i m i l a r i n the two areas (Table 8). The numbers of parous does however were s i g n i f i c a n t l y and n e g a t i v e l y c o r r e -l a t e d w i t h the number of calves born 2 years before ( F i g . -7). Changes i n r e -2 cruitment of calves provided 72 per cent ( r ) of the v a r i a t i o n i n per cent parous doe s t a t i s t i c s . I conclude t h a t most of the annual v a r i a t i o n i n frequency r a t e between years and areas r e f l e c t e d changes i n the number of n u l l i -parous 2-year-old does e n t e r i n g the a d u l t p o p u l a t i o n and i n c l u d e d i n the June udder counts. When few 2-year-old does were present on some c a l v i n g grounds, 94- t o 96 per cent of the females 3-years and o l d e r ( a d u l t ) were pregnant. F u r t h e r , the June c l a s s i f i c a t i o n s from a l l years when adjusted f o r 2-year-old does c l a s s i -f i e d as nonparous a d u l t s (see METHODS), i n d i c a t e d t h a t 94 per cent of the 30 1 0 0 -I 9 0 -BY C A L V I N G P O P U L A T I O N S r = - 0 . 6 8 5 P<0.001 n = 2 3 -Y = 9 4 . 6 7 - 0 . 9 8 6 x A UJ z 8 0 UJ O Q 7 0 -A POT HILL • B U C H A N S P L A T E A U • G R E Y R I V E R O M I D D L E R I D G E • S A N D Y L A K E A L A P O I L E R IVER * 1 0 0 a. z UJ o a: UJ 9 0 CL BY Y E A R S r = - 0 . 8 5 0 P < 0 - 0 2 n =9 • Y= 100.12 - 1 . 4 0 x 8 0 -7 0 1 1 1 1 5 10 15 2 0 P E R - C E N T C A L V E S IN P O P U L A T I O N OR H E R D 2 0 M O N T H S PRIOR T O P A R O U S D O E C O U N T S 2 5 F i g . 7. Regression of counts of parous does on recruitment 20 months previous. P r e f e r s t o the p r o b a b i l i t y of the n u l l hypothesis o f no d i f f e r e n c e . 31 • ad u l t does were pregnant. The causes of barrenness i n 6 per cent o f the does are probably v a r i e d . A few females may have been s e n i l e . In a sample of 19 nonparous does, f o u r were at l e a s t 10 years o l d ; whereas, only one 10 year or o l d e r doe would have been expected i n t h i s sample on the b a s i s of the female age d i s t r i b u t i o n i n the p o p u l a t i o n 1963-64, (Table 10). Some females probably d i d not reach puberty u n t i l 40-months-of-age (Table 7). One barren doe was c o l l e c t e d t h a t had a uterus a b n o r m a l i t y — w h i t e h e i f e r disease (King pers. comm.). Seven barren females were c r i p p l e d ; l i k e l y they could not support a stag's weight during c o i t u s . The h i s t o l o g i c a l examination of the ovaries of 9 mature non-parous does (4 years or o l d e r ) showed only one female whose o v a r i e s had never been a c t i v e (Table 7 ) . 32 ADULT MORTALITY Excessive m o r t a l i t y of a d u l t s could l i m i t p o p u l a t i o n growth. Both n a t u r a l and hunting m o r t a l i t y must be considered. M o r t a l i t y Rates' The n a t u r a l annual m o r t a l i t y was low on the Avalon P e n i n s u l a , 1961-66, and averaged 6 per cent (Table 11). There was no known i l l e g a l hunting dur-i n g t h i s i n t e r v a l and the f i r s t l e g a l harvest was i n 1966. The I n t e r i o r Herd l i k e l y had a s i m i l a r low n a t u r a l assumed m o r t a l i t y r a t e . The herd increased 3-4 per cent per annum 1957 t o 1966 ( l a t e r s e c t i o n ) when f a l l increments av-eraged 14 per cent (Table 12, 1958-66). Legal hunting and poaching took an estimated t o t a l o f 6 per cent ( l a t e r s e c t i o n ) . The n a t u r a l m o r t a l i t y l e f t amounted t o perhaps 5 per cent. The I n t e r i o r Herd showed l i t t l e p o p u l a t i o n change 1961 t o 1966 ( F i g . 5). The age a r r a y of stags k i l l e d i n t h i s p e r i o d showed a 22 per cent t o t a l mort-a l i t y ( F i g . 8). The annual l e g a l and i l l e g a l hunting m o r t a l i t y i n the same i n t e r v a l was probably 14 per cent. S u b s t i t u t i n g annual and hunting s u r v i v a l s t a t i s t i c s i n the formula: q = 100 - (s/s, ) (see Bergerud 1967a), i n d i c a t e d n h • a n a t u r a l m o r t a l i t y of stags of 9 per cent. I f n a t u r a l m o r t a l i t y o f both stags and does combined i s c l o s e t o 5 per cent and stags c o n s t i t u t e 21 per cent of the p o p u l a t i o n (Table 13), then the n a t u r a l m o r t a l i t y of does and y e a r l i n g s should be near 4 per cent. Poaching of does was estimated at an a d d i t i o n a l 3 per cent. Annual m o r t a l i t y of 22 per cent f o r stags and 7 per cent f o r does i s s u f f i c i e n t t o a l t e r the male : female r a t i o o f a d u l t s i n 1957 of 32:68 t o a r a t i o of 23:77 i n 1966 (Table 9). The combined m o r t a l i t y s t a t i s t i c s f o r both sexes give a t o t a l annual m o r t a l i t y 11 per cent f o r 1961-1966,: 33 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 AGE IN YEARS F i g . 8. S u r v i v a l of male caribou i n the i n t e r i o r . The c a l f s u r v i v o r -ship curve i s based on the data i n Tables 16 and 19. The 1 curves f o r the a d u l t s are based on the ages of caribou shot by hunters (Tables 2 and 3). 34 Age and Annual M o r t a l i t y i n Percent Sex Legal Hunting Poaching N a t u r a l T o t a l Does, y e a r l i n g s and 6-month calves 0 3 4 7 Adult Stags (2 yr.+) 11 3 9 22 T o t a l P o p u l a t i o n 3 3 5 11 A t o t a l m o r t a l i t y of.11 per cent may be v a l i d a l s o f o r the years 1951 t o 1961. In th a t i n t e r v a l hunter observations o f caribou showed a decreasing t r e n d when c a l f recruitment f i g u r e s f e l l below 11 per cent f o r s e v e r a l con-s e c u t i v e years ( F i g . 9). There was an i n c r e a s i n g trend i n the number of car i b o u observed per hunter when c a l f recruitment exceeded 11 per cent as from 1959 t o 1961 ( F i g . 9). The po p u l a t i o n d i d increase i n these years (Table 5). N a t u r a l Cause of Death-Death from f i g h t i n g during the r u t was the s i n g l e g r e a t e s t cause of mort-a l i t y i n a d u l t stags (Table 14). Most of these stags were 4 t o 6 years o l d . Stags were seen covered w i t h mud, b l e e d i n g , w i t h broken a n t l e r s , and c r i p p l e d l e g s . S e v e r a l were found w i t h broken necks. A stag wishing t o q u i t a se r i o u s f i g h t had t o f r e e h i s a n t l e r s and jump c l e a r . I f he f a i l e d he could be pushed backwards and sideways snapping h i s neck. On the b a s i s of t o t a l animals cen-sused and the dead l o c a t e d , I estimate annual r u t t i n g m o r t a l i t y at 2 per cent i n 1957 and 1958. More females died from aberrant b i r t h s than from any other cause (Table 14), One doe with a breached b i r t h was s t i l l able t o walk when I l e f t her i n the evening, but was dead when l o c a t e d the next morning. 35 20 - i < 1 U o h-z < u ^ 10 H CE • VSS^-11<'/o 7 '• — A —m\" 4 -I/> cc U I cc r-3d Z I Z > U J CO U I l/> > < Q 0 CO ct z z i n i 1 1 1 1 r — i i r r 51 52 53 54 55 56 57 58 59 60 61 YEARS F i g . 9. Caribou observations by hunters d e c l i n e d during successive years when c a l f increment was l e s s than 11 per cent. 36 Heavy p a r a s i t e loads could be f a t a l along with s t a r v a t i o n . Newfound-lan d c a r i b o u were host t o r e l a t i v e l y few kinds of p a r a s i t e s (Table 15). There was no c o r r e l a t i o n between numbers of warbles (Oedamagena t a r a n d i ) and age i n 38 does c o l l e c t e d i n June; however the number of nose bots (Cepheriomyia trompe) increased w i t h age ( F i g . 10). There was a weak c o r r e -l a t i o n between t o t a l bots and warbles per i n d i v i d u a l doe, suggestive of s l i g h t i n d i v i d u a l s u s c e p t i b i l i t y t o f l y attack ( F i g . 10). The only c a r i b o u death a t t r i b u t e d t o p a r a s i t e s i n 11 years was a stag t h a t was observed walk-in g i n c i r c l e s ; autopsy showed th a t nose bots had invaded the c r a n i a l c a v i t y . Adult c a r i b o u o b v i o u s l y i n c a p a c i t a t e d by disease were not noted i n the i n v e s t i g a t i o n . A minimum of 60,000 a d u l t animals were seen i n 11 years. Since there was never more than 8000 ad u l t s on the i s l a n d at one time and the t o t a l 11-year recruitment was about 14,000, many animals were seen s e v e r a l times. A widespread disease could not have passed unnoticed. Approximately 3 i n 1000 carib o u were ob v i o u s l y c r i p p l e d i n 11,239; maxi-mum f i g u r e was 8 of 884 lame i n May and June. A c l o s e i n s p e c t i o n of s t r a g g -l e r s i n a mi g r a t i n g Alaskan herd, subject t o wolf p r e d a t i o n , showed 1.8 per cent s i c k or c r i p p l e d ( C r i s l e r 1956). Skoog (1968) l i s t e d 22 of 31,479 c r i p p l e d i n the Nel c h i n a Herd i n Alaska. The wolf d e n s i t y i n the range of t h i s herd was low i n most years (Rausch 1967). There i s no obvious c o r r e -l a t i o n between wolf p r e d a t i o n and the frequency of c r i p p l e d animals. In many w i l d s p e c i e s , e s p e c i a l l y those subject t o pr e d a t i o n as a d u l t s , few l i v e long enough t o show signs of age. But i n carib o u ( a l s o many other ungulates) there i s increased m o r t a l i t y i n the o l d e r age c l a s s e s ( B a n f i e l d 1955) i n d i c a t i n g a r e l a t i o n s h i p between s e n i l i t y and death. Three animals i n t h i s study were l i s t e d as dying from o l d age (Table 14). One.stag found on June 23 could not stand. His t e e t h were worn t o the gums and he weighed 37-1 5 0 -H o co UJ O 1 0 0 -z u. O DC UJ CD 2 5 0 ' ZD r = 0 . 4 9 7 P < 0 O 1 n = 3 0 Y=. 2 5 . 6 3 + 6.44X < i-O -r-2 —T" I I I 1 I 5 6 7 8 9 A G E IN Y E A R S 10 11 —T 12 1 5 0 - i < z < oc UJ Q -100' 1/5 h-o CO u. O ce UJ CD 1 Z 5 0 -Y= 3 9 . 6 0 + 0 . 3 3 x V • • • • I I JUL I 1 1 1 1 1 1 r 1 1 1 1 1 5 0 100 150 2 0 0 N U M B E R O F W A R B L E S P E R A N I M A L F i g . 10. (above) The r e g r e s s i o n of nose b'dts per doe i n June on age. (below) The r e g r e s s i o n of nose bots per does on warble p a r a s i t e s per doe i n June. 38 only 208 pounds against normal weights of over 300 pounds. Many o l d e r animals wit h regressed a n t l e r s were noted. D i f f e r e n c e s i n Death Rates of Males and Females Adult males d i e d at greater r a t e s than females. The mean age of stags captured during the f a l l m i g r a t i o n was 3.0 years and does 4.7 years (Table 10). L e g a l hunting of stags only should not reduce the mean age of males un-l e s s h e a v i l y b i a s e d t o c e r t a i n age groups. Even when the age cl a s s e s under-represented i n the k i l l were excluded ( c a l v e s , y e a r l i n g s , and 2-year-old s t a g s , Table 2) the age of females was grea t e r than t h a t o f males (Table 10). B e t t e r evidence of a d i f f e r e n t i a l m o r t a l i t y by sex was t h a t 21 dead stags and only 12 dead does were found during the i n v e s t i g a t i o n . The sex r a t i o o f l i v i n g a d u l t s v a r i e d from 32 t o 23 per cent stags (Table 9). With equal sus-c e p t i b i l i t y t o death, a minimum of 40+ dead females might have been expected. A d d i t i o n a l evidence of grea t e r m o r t a l i t y of males than females was the d e c l i n e i n the p r o p o r t i o n of males between r e c r u i t s at 6-months-of-age and a d u l t s (Tables 16 and-9). The sex r a t i o of calves 6- t o 12-months-of-age was 40±3 (95 per cent C L . ) per cent males. The percentage of a d u l t males i n 1957 and 1958 ( p r i o r t o r e s t r i c t i o n s l i m i t i n g hunting t o only stags) was 32±2 (Table 9). On the Avalon, where there was no l e g a l hunting p r i o r t o 1966, the p r o p o r t i o n o f males i n the c a l f increment was 47±10 per cent and i n the ad u l t s 40±4. The sex r a t i o of calves at 6-months-of-age i n the Humber R i v e r Herd was 53±15 per cent males and f o r a d u l t s 26±6 per cent. Figures f o r barren-ground ca r i b o u i n the Northwest T e r r i t o r i e s , where both sexes are harvested, showed tha t males comprised 34 per cent of the a d u l t s ( K e l s a l l 1968). Pre d a t i o n by lynx (Lynx canadensis) might take a higher p r o p o r t i o n of stags than does. Stags i n general are l e s s wary than females. Furthermore 39 more stags than does frequent timbered r i v e r v a l l e y s i n the w i n t e r where ly n x probably take a few animals. Four of 23 lynx scats c o l l e c t e d i n such areas contained c a r i b o u h a i r and -3 of 16 l y n x c o l l e c t e d i n l a t e w i nter had eaten ca r i b o u . An unknown p a r t of t h i s consumption could be from c a r r i o n . I saw a wounded stag i n a r i v e r v a l l e y i n March 1959. I t appeared t h a t a l y n x had jumped on the caribou's back. Again w i n t e r t r a c k s showed where two lynx had s t a l k e d a c a r i b o u l y i n g on the i c e adjacent t o a p o i n t of timber. Caribou t r a c k s were f o l l o w e d t i l l a badly wounded doe was l o c a t e d . Swedish l y n x (Lynx lynx) k i l l many re i n d e e r i n the w i n t e r predominately young but are not s e l e c t i v e i n regard t o sex (Haglund 1966). Losses of a d u l t s to p r e d a t i o n even i f b i a s e d towards males, were so minor (Table 14), t h a t they could not account f o r the d i s p a r i t y i n numbers between sexes. In summary, many f a c t o r s probably c o n t r i b u t e t o the greater m o r t a l i t y of male than female. However, the most important f a c t o r appears t o be a high m o r t a l i t y of males during the r u t . Hunting M o r t a l i t y of Adults The l e g a l harvest from the I n t e r i o r Herd.averaged 184 animals (extremes 56 t o 366) i n the p e r i o d 1956 t o 1966 (Table 4). This k i l l was l a r g e l y stags. The season was opened on the Avalon P e n i n s u l a i n 1966 a f t e r being closed f o r 42 years; 27 animals were secured i n 1966 and 26 i n 1967. There were open seasons f o r the Humber and Northern P e n i n s u l a herds during t h i s survey. I l l e g a l hunting showed a gradual d e c l i n e during the study as enforcement procedures improved and the o l d e r generation gave up t r a d i t i o n a l hunts. Moose became abundant about 1945 and s i g n i f i c a n t poaching pressure switched t o that species t h e r e a f t e r . The i l l e g a l k i l l was not constant between years and depended upon carib o u 4-0 a c c e s s i b i l i t y ( d i s t a n c e from s a l t water and r o a d s ) , and winter t r a v e l l i n g con-d i t i o n s f o r dog teams. I estimated t h a t between 150 t o 300 animals were taken annually. The La P o i l e p o p u l a t i o n sustained heavier l o s s e s than the others. The maximum k i l l was a l l o c a t e d as f o l l o w s : La P o i l e R i v e r Population—-150, Buchans P l a t e a u p l u s Grey R i v e r Populations--50 ( i n c l u d e s Sandy Lake Popula-t i o n ) , and the Middle Ridge-Pot H i l l - - 1 0 0 . Quite d e t a i l e d i n f o r m a t i o n was secured on poaching l o s s e s f o r the Avalon Peninsula herd f o r the years 1955, 1956, and 1957. In each year about 15 t o 25 animals were taken from the herd. I l l e g a l hunting had n e a r l y ceased by 1959 because of improved law enforcement. The Northern P e n i n s u l a Herd was p r i m a r i l y hunted by r e s i d e n t s l i v i n g along the west coast o f the Pe n i n s u l a . The only r e l i a b l e f i g u r e s were secured i n 1959 when an extremely l a r g e k i l l was made of about 150 animals. A road was extended up the Peni n s u l a a f t e r 1959 r e s u l t i n g i n more e f f e c t i v e law enforce-ment and a reduced take. No k i l l comparable to the i l l e g a l harvest i n 1959 occurred 1960 t o 1966. The Humber R i v e r Herd was poached by r e s i d e n t s of Howley when the animals wintered 4 m i l e s n o r t h of the town ( F i g . 5). Others were taken at B i g F a l l s during m i g r a t i o n . Caribou were a l s o taken i n the v i c i n i t y of Adies Lake and Tayl o r s Brook when they were a c c e s s i b l e t o logging roads. Role of Adult M o r t a l i t y i n Popu l a t i o n Growth The n a t u r a l m o r t a l i t y of a d u l t s was a minor f a c t o r i n reducing the growth of the herds. The n a t u r a l m o r t a l i t y r a t e of the Avalon Herd was 6 per cent, 1957 t o 1966, when the herd increased by about 476 per cent. Adults i n the I n t e r i o r Herd had a s i m i l a r l o s s , 5 per cent, yet t h i s herd i n c r e a s e d , 1957 t o 1967, by only 35 per cent. Skoog (1968) reported t h a t a carib o u herd i n Alaska 41 increased annually at 9 per cent w i t h a n a t u r a l m o r t a l i t y r a t e of perhaps 6 per cent and a hunting m o r t a l i t y of 8 per cent. A c a r i b o u herd i n Southern Labrador had a c a l c u l a t e d n a t u r a l m o r t a l i t y r a t e of only 6 per cent (Bergerud 1967a). The above m o r t a l i t y r a t e s are s i m i l a r and are i n l i n e w i t h what might be expected f o r a species w i t h a convex s u r v i v o r s h i p curve and a maximum ecolo-g i c a l l o n g e v i t y of about 17 years. I l l e g a l hunting could not account f o r the slow growth of the I n t e r i o r Herd s i n c e o n l y an estimated 3 per cent of the herd was i l l e g a l l y harvested annu a l l y . Again i l l e g a l hunting of the Avalon Herd was minimal a f t e r 1958. However, poaching was heavy on the Avalon Herd 1956 to 1958 and probably ac-counted f o r the r e l a t i v e s t a b i l i t y i n numbers i n the herd during t h i s p e r i o d . The p o p u l a t i o n i n 1956 was perhaps 125 animals. The approximate recruitment and known minimum poaching l o s s was f a i r l y w e l l balanced: i n 1956 and 1957: 1956—18 r e c r u i t s vs. a poaching l o s s of 15 and 1957, 22 vs. 17. Poaching ceased i n 1959 and the herd immediately began t o increase (Table- 5.) The poaching of a d u l t s i n the Humber and Northern P e n i n s u l a herds during t h i s study probably prevented these herds from i n c r e a s i n g ( F i g . 5). The mean percentage of calves i n the Humber Herd i n 7 winters was 15 per cent (Table 18), c o n s i d e r a b l y above the 5-6 per cent a d u l t n a t u r a l m o r t a l i t y r a t e s determined f o r the I n t e r i o r and Avalon herds. The percentage of c a l v e s on the Northern Peninsula i n October 1961, the only year c l a s s i f i e d , was 19 per cent. The i l l e g a l harvest of about 150 animals from the Peninsula i n 1959 was probably s u f f i c i e n t alone t o account f o r the l a c k of p o p u l a t i o n change between the cen-suses i n 1958 and 1966. The annual l e g a l harvest of 11 per cent of the stags i n the i n t e r i o r ac-t u a l l y improved the r a t e of increase of the herd. The c a l c u l a t i o n s are as f o l l o w s (Kelker 1947 and Buechner 1960): antilogy r = 1 + (does / a d u l t s ) y, 42 where y = number of young per female ( i n c l u d i n g y e a r l i n g s and 2-year-old does). I f we assume th a t a l l c a l v e s l i v e and c o n t r i b u t e to the nonbreeding y e a r l i n g s and 2-year-old female c o h o r t s , then y would probably.be near 0.50. The a d u l t sex r a t i o i n 1957 was probably.47 males per 100 does (based on the r e g r e s s i o n Y = 83.90 - 0.910X, Table 9) and was a l t e r e d by the harvest o f stags 1958 to 1966 to 31:1-00. These s t a t i s t i c s provide r =0.292 i n 1957 and r = 0.322 i n 1966, or an increase i n the r a t e of increase of 4 per cent. 43 DEATH OF CALVES IN WINTER A number of s t u d i e s of other c e r v i d s show th a t the young may starve when snows are deep. Caribou i n Newfoundland must a l s o contend w i t h great snow-f a l l s (see F i g . 6) and frequent i c e c r u s t s . The winters of 1958-59 and 1960-61 were two of the severest winters ever recorded i n Newfoundland and provided an o p p o r t u n i t y t o assess the impact of maximum snow depths and i c e c r u s t s on the s u r v i v a l of c a l v e s . During the winter of 1958-59 the I n t e r i o r Herd was observed from 3 t o 22 March. The animals were g e t t i n g forage w i t h extreme d i f f i c u l t y . I found two dead ca l v e s and noted four weak ones ( F i g . 11). T h i r t y - s i x others appeared equal to a d u l t s i n p h y s i c a l c o n d i t i o n and v i g o r . In 1961 W i l d l i f e O f f i c e r Stephen H a l l v i s i t e d the winter range from March .22 to A p r i l 13. The c a r i b o u were emaciated and spent long hours feeding and stand-ing... However, none of the 69 c a l v e s he observed appeared weak and none were found dead. I n d i r e c t evidence i n d i c a t e d t h a t i n most winters few c a l v e s d i e d . For example, the ages of 85 calves found dead from n a t u r a l causes showed th a t only 6 <(7 per cent) had died overwinter (Table 19). F u r t h e r , m o r t a l i t y i n the f i r s t year of l i f e , based on the ages of 132 dead cari b o u was 68 per cent (Table 19), however, another m o r t a l i t y index, October composition counts, suggested t h a t 69 per cent of the c a l v e s were already dead by only 6-months-of-age (Table 20). The s i m i l a r i t y of these two estimates i s c o n s i s t e n t w i t h the view of l i t t l e w i nter l o s s . Another approach was t o compare the percentage of c a l v e s i n the I n t e r i o r Herd i n f a l l and s p r i n g . Several of the s p r i n g counts were made a f t e r the south slopes were f r e e of snow and the worst of winter had passed. This com-pa r i s o n of the percentage of c a l v e s i n the herd i n October and i n March-April 44 F i g . 11. A weak c a l f observed i n March 1959. 45 f a i l e d to demonstrate t h a t c a l v e s were dying at a r a t e d i f f e r e n t than a d u l t s : Winter Calves as Percentage o f Herd ± .95 C L . Season October March-April 1956-57 4.4±2.9 7.612.5 1957-58 5.511.0 ' 5.312.3 1958-59 15.Oil.5 14.413.1 1959-60 19.013,1 27.416.7 1960-61 15,113.4 18. -614.0 1962-63 9.412.7 8.812.0 1963-64 8.411.3 .9.-411.6 10.810.7 11. O i l . 0 This comparison i s probably l e a s t v a l i d f o r the winter o f 1958-59 cohort since t h a t s p r i n g count was made mostly i n the f i r s t two weeks of March. M o r t a l i t y could have r e s u l t e d i n l a t e March and A p r i l . A l l the other comparisons l i s t e d above were based on sampling done i n the l a s t of March or i n e a r l y A p r i l . As another e v a l u a t i o n o f winter l o s s I p l o t t e d y e a r l i n g per 100 doe s t a -t i s t i c s secured i n June (Table 21) against the percentage of cal v e s i n the herd the previous autumn ( F i g . 12). The y e a r l i n g - c a l f r e g r e s s i o n was h i g h l y s i g n i f i c a n t ( F i g . -12) and suggested t h a t annual v a r i a t i o n s i n s u r v i v a l occurred p r i o r t o winter or th a t the magnitude o f winter m o r t a l i t y v a r i e d d i r e c t l y w i t h summer l o s s . The r e g r e s s i o n showed t h a t the value f o r the winter of 1958-59 d i d depart f u r t h e r from the r e g r e s s i o n l i n e than any of the.other 9 winters i n the comparison. This departure i s c o n s i s t e n t w i t h my f i e l d observations of a few dead and weak cal v e s i n e a r l y March 1959. 46 5 0 H cr 4 0 -u CQ o H 30 • O O O z 5 O _ j _i o L l UJ I 1-10 LU o Q O O 2 0 -10 -30-1 cr LU °- 2 0 -o _J CE < UJ >-1 0 -BY C A L V I N G G R O U N D S r = 0 . 7 2 7 P< 0.001 n = 24 Y= - 0 -82+1^8x BY Y E A R S r = 0 . 8 6 7 P<0.01 n = 10 5 9 - 6 0 6 3 - 6 4 6 0 - 6 1 ' 6 4 - 6 5 5 7 - 5 8 ' 6 2 - 6 3 10 i 15 I— 2 0 — r 2 5 F i g . 12. P E R C E N T C A L V E S IN HERD IN O C T O B E R A POT HILL O MIDDLE RIDGE • B U C H A N S P L A T E A U • SANDY L A K E O G R E Y RIVER * LA POILE RIVER The r e g r e s s i o n of recruitment of y e a r l i n g (12-month-old) on recruitment o f calves (6-months-old). The re g r e s s i o n l i n e by years excluded 1964-65 and 1958-59. June samples 1965 d i d not i n c l u d e caribou from the western c a l v i n g grounds. Winter m o r t a l i t y i s b e l i e v e d t o have occurred i n 1958-59. • 47 A f i n a l index i n v o l v e d comparing the percentage of c a l v e s i n the I n t e r i o r Herd at 6-months-of-age and the percentage of the same cohort at 24-months-of-age ( c o r r e c t e d f o r new r e c r u i t m e n t ) . This t e s t should detect d i f f e r e n t i a l m o r t a l i t y of a cohort r e l a t i v e t o a d u l t s any time between 6 and 24-months-of-age. The assumption was t h a t any d i f f e r e n c e s noted would apply t o the s u r v i v a l during the f i r s t winter of l i f e . This comparison f a i l e d t o demonstrate d i f f e r -e n t i a l m o r t a l i t y of young vs. a d u l t s i n e i g h t winters (Table 22). But again i t appeared a g r e a t e r p r o p o r t i o n of c a l v e s than a d u l t s died i n the winter or 1958-59 (Table 22). Both the i n d i c e s t h a t suggested an increase l o s s of c a l v e s i n the winter of 1958-59 are not independent and presume th a t the c a l f count i n October-November 1958 d i d not overestimate the percentage of c a l v e s i n the herd. The percentage of c a l v e s i n f a l l 1958 was based on the l a r g e s t autumn sample se-cured i n 12 years (n=2253) and included animals from a l l the populations (Table 12). In b r i e f , the evidence suggests t h a t more ca l v e s died than a d u l t s i n the winter of 1958-59, but t h a t calves survived e q u a l l y as w e l l as a d u l t s i n -9 other w i n t e r s . In t h i s paper recruitment i s based on the percentage of 6-month-old animals i n t h e . t o t a l p o p u l a t i o n . 48 EARLY MORTALITY OF CALVES Since the b i r t h r a t e was high and the m o r t a l i t y of a d u l t s and 6-month-o l d c a l v e s was low, we are l e f t w i t h the m o r t a l i t y of ca l v e s i n t h e i r f i r s t summer of l i f e as the main cause f o r the slow growth o f the herds. D e t a i l e d i n v e s t i g a t i o n s of the carib o u herds i n Alaska and Northwest Territories•showed that many cal v e s died during the f i r s t summer (Skoog 1968 and K e l s a l l 1968). To i n v e s t i g a t e the e a r l y m o r t a l i t y of ca l v e s they were observed and c l a s s i f i e d i n each s p r i n g 1957 t o 1967. In t h i s s e c t i o n on c a l f m o r t a l i t y I d i s c u s s the time and amount of c a l f l o s s e s and then consider three p o s s i b l e causes of m o r t a l i t y , d i s e a s e , p r e d a t i o n , and adverse weather. Time and Amount In the years 1957 t o 1967 l a r g e numbers of new born c a l v e s of the I n t e r i o r Herd were dead by the middle o f June (Table 23). The m o r t a l i t y v a r i e d from 6 per.cent a t the Middle Ridge c a l v i n g ground i n 1959 t o 65 per cent at the Pot H i l l c a l v i n g ground i n 1964 (Table 23). M o r t a l i t y was s u f f i c i e n t i n a l l y e a r s , except 1959, t o reduce the number of ca l v e s f a r below t h a t expected on the b a s i s of counts of parous does. C a l f m o r t a l i t y i n the i n t e r i o r continued high i n J u l y and August but de-c l i n e d by September-October ( F i g . 13 and Table 24). The 10-year (1958-67) mean m o r t a l i t y of i n t e r i o r c a l v e s between b i r t h and 6-months was 69 per cent (Table 20). The extreme values were 35 per cent i n 1967 and 85 per cent i n 1963. Calves born on the two western c a l v i n g grounds, the La P o i l e R i v e r and Buchans Plateau-, g e n e r a l l y had b e t t e r s u r v i v a l r a t e s than those reared i n c e n t r a l and eastern Newfoundland (Table 1 2 ) . The number of calves i n f a l l was c o r r e l a t e d w i t h c a l f m o r t a l i t y by June 49 0 1 2 3 4 5 6 7 8 9101112 AGE IN MONTHS F i g . 13. C a l f s u r v i v a l t o ll-months-of-age i n three cohorts i n the I n t e r i o r Herd. The two low counts i n 1957 were from the Grey R i v e r and Sandy Lake populations t h a t l o s t a greater number of calves than populations at Buchans Platea u and Middle Ridge. 50 ( F i g . 14). These c o r r e l a t i o n s might have been more p r e c i s e i f the determina-t i o n of e a r l y m o r t a l i t y could have been made on the same dates on each c a l v i n g ground (see METHODS). However c a l f m o r t a l i t y had t o be measured immediately p o s t - c a l v i n g before the udders of parous does i n v o l u t e d (Bergerud 1964a). The c o r r e l a t i o n of numbers i n f a l l w i t h m o r t a l i t y by "mid-June suggests t h a t v a r i a -t i o n s i n annual m o r t a l i t y of calves were e s t a b l i s h e d i n June, and t h a t the heavy continued l o s s e s i n J u l y and August ( F i g . 13) v a r i e d d i r e c t l y w i t h deaths i n June. I t appeared t h a t more male ca l v e s died i n the s p r i n g than females. At 1-4 weeks-of-age the male:female r a t i o was 48:52, whereas the r a t i o at b i r t h was the r e v e r s e , 52:48 (Table 16). By October the sex r a t i o was s i g n i f i c a n t l y unbalanced f a v o r i n g females (Table 16). C l e a r l y , male ca l v e s died at higher r a t e s than female during the p e r i o d of high e a r l y m o r t a l i t y . Annual s u r v i v a l of c a l v e s t o 6-months-of-age i n the i n t e r i o r showed trends from 1951 t o 1967 ( F i g . 15 and Tables .12 and 25). S u r v i v a l decreased each year from 1951 t o 1956 (5 y e a r s ) , increased 1957 t o 1959 (3 y e a r s ) , d e c l i n e d 1961 to 1963 (3 y e a r s ) , and showed improvement with each annual cohort 1963 to 1967 (5 y e a r s ) . This s e r i e s of runs i s a s i g n i f i c a n t departure from random ( S i e g e l 1956). On the Avalon Pe n i n s u l a more cal v e s survived than i n . t h e i n t e r i o r . The 10-year mean m o r t a l i t y t o 6 months-of-age was 30 per cent w i t h extreme values of 2 per cent i n 1959 and 73 i n 1965 (Table 17). A l s o , s u r v i v a l on the Avalon showed some s y n c h r o n i z a t i o n w i t h the p a t t e r n described f o r the I n t e r i o r Herd ( F i g s . 15 and 16). Both herds reached a peak i n s u r v i v a l i n 1959 (as d i d the Humber R i v e r Herd) followed by s e v e r a l years of d e c l i n e ( F i g . 16). These data suggest a common cause of m o r t a l i t y i n both herds but a d i f f e r e n c e i n degree 51 O 1 1 - i 1 1 1 1 1 r 0 10 2 0 3 0 4 0 5 0 6 0 7 0 8 0 C A L F M O R T A L I T Y A S O F M E A N D A T E J U N E 16 A P O T H ILL • O M I D D L E R IDGE • B U C H A N S P L A T E A U • G R E Y RIVER A L A ROIL E RIVER F i g . 14. The s u r v i v a l o f calves u n t i l October i n r e l a t i o n t o m o r t a l i t y i n June. 52 FOLLOWING LYNX REMOVAL 58 59 60 61 62 63 64 65 66 67 NTERIOR HERD • AVALON PEN. HERD F i g . 15. C a l f s u r v i v a l i n the I n t e r i o r and Avalon P e n i n s u l a herds u n t i l 6-months-of-age. 53 cn Q cr LU IE cr LU Z I— LU 3 cr < o o . LU O i cr LU Q_ 5 0 4 0 3 0 -2 0 -1 0 H HUMBER RIVER HERD AVALON PENINSULA HERD Ps 0 / X / / / D V A A / c o n t A - \ \ / / • D \ b / ^ N TERIOR A' HERD R O L 5 6 5 7 5 8 5 & 6 0 61 62 6 3 6 4 6 5 6 6 6 7 YEARS CLASSIFIED F i g . 16. The percentage of calves i n f a l l i n the I n t e r i o r , Avalon, and Humber R i v e r herds, 1956 t o 1967. 54 on the Avalon. Weather M o r t a l i t y of Calves In barren-ground c a r i b o u , c a l f s u r v i v a l v a r i e d between years i n the North-west T e r r i t o r i e s ( K e l s a l l 1960 and 1968). M o r t a l i t y from adverse c h i l l i n g of neonatal young was c i t e d at a major decimating f a c t o r . In t h i s study, c a l f s u r v i v a l to the f a l l showed three progressive trends over 3 to 5 years (Table 25). I f c a l f s u r v i v a l was p r i m a r i l y a f u n c t i o n o f weather I would expect e a r l y m o r t a l i t y to vary w i t h weather and more or l e s s at random. As noted, these were runs i n the m o r t a l i t y r a t e of calves and these were not at random. This does not suggest e a r l y m o r t a l i t y was caused by f a c t o r s v a r y i n g at random such as weather. The Buchans Plateau c a l v i n g ground had the c o l d e s t spring.weather of any y e t . s u r v i v a l was higher here than elsewhere, except at La P o i l e R i v e r (Table 12). In 1958 on the P l a t e a u . i t r a i n e d h e a v i l y a l l day and night on the peak day of c a l v i n g . Winds were 40 mph. No dead calves were found. The maximum d a i l y w i n d c h i l l f i g u r e s , t a b u l a t e d from w e a t h e r . s t a t i s t i c s at Buchans a i r p o r t , were l e s s than those l i s t e d by K e l s a l l (1960) and Hart e t . a l . ' (1961) as caus-ing m o r t a l i t y i n the T e r r i t o r i e s . F u r t h e r , Newfoundland c a l v e s were heavier at b i r t h than barren-ground animals and might t h e r e f o r e withstand g r e a t e r ex-posure t o inclement weather. During the 11 years t h a t f i e l d p a r t i e s were w i t h the caribou i n June, only two c a l v e s were found w i t h congested lungs. These young could have developed pneumonia independently of weather. Thus there was no evidence t h a t calves died from exposure over the p e r i o d 1957 t o 1967. The depth and hardness of snow cover could modify the abundance of forage i n f l u e n c e through the doe the i n t r i n s i c v i a b i l i t y of c a l v e s at b i r t h ( c f . .55 Dobrotvorsky et a l . 1938). In t h i s study there were s i g n i f i c a n t d i f f e r e n c e s between years i n the mean weight of calves at b i r t h ( F i g . 17). However, these annual d i f f e r e n c e s were only weakly c o r r e l a t e d w i t h winter s n o w f a l l (r= -0.673). Regardless of t h e i r cause these annual v a r i a t i o n s do i n d i c a t e d i f f e r -ences between years i n phenotypic v i a b i l i t y at b i r t h . However there was no s i g n i f i c a n t c o r r e l a t i o n between neonatal weights of calv e s from d i f f e r e n t c a l v i n g grounds and m o r t a l i t y by June (r= 0.120, n = 8 ) . Nor were the mean annual b i r t h weights i n 8 years c o r r e l a t e d w i t h the extent of e a r l y c a l f m o r t a l i t y ; i n 1961 calves at b i r t h averaged only 14.9 pounds, 2 pounds below the weight of young i n 7 other seasons ( F i g . 17). But 'the sur-v i v a l of these c a l v e s exceeded t h a t o f the 1957, 1962, and 1963 (Tables 12 and 20). I conclude t h a t the a v a i l a b i l i t y of winter forage d i d not i n f l u e n c e c a l f s u r v i v a l i n s p r i n g . I t may have i n f l u e n c e d weight of ca l v e s at b i r t h . Disease and Predation Each year dead and moribund neonatal calves were found w i t h c e r v i c a l ab-scesses ( F i g . 18). The dates when the f i r s t diseased calves were found, 1957-64 were: June 1, May 31, June 4,4,6,10,1, and May 29. A healthy newborn c a l f was tagged on May 31 and recovered dead w i t h abscesses on June 4. The abscessed c a l v e s died from septicemia r e s u l t i n g from the pathogenic organism P a s t e u r e l l a multocida mucoid type A. P a s t e u r e l l a i d e n t i f i c a t i o n was provided by three d i f f e r e n t Canadian l a b o r a t o r i e s . . A t o t a l of-84 abscessed calves were found on c a l v i n g grounds i n 11 years (Table 26). Rejected Hypotheses of P a s t e u r e l l a E t i o l o g y Several working hypotheses of the e t i o l o g y of the P a s t e u r e l l a i n f e c t i o n s were t e s t e d and r e j e c t e d . This negative i n f o r m a t i o n i s b r i e f l y mentioned s i n c e 56 1 9 5 8 (7) 1959 (30) 1 9 6 0 ( 8 2 ) 1961 (51) 1962 (52) 1963 (54) 1964 (44) 1966 (12) F i g . 17. The mean weight of calves (+ 1 S.E.) at b i r t h . Sample s i z e s given below years. F i g . 18. Calves b i t t e n by l y n x t h a t developed abscesses. 58 some of the t h e o r i e s are s t i l l c u rrent i n Newfoundland and may occur to.the reader. The theory t h a t the i n f e c t i o n was c o n g e n i t a l was r e j e c t e d since none of 117 newborn ca l v e s s u c c e s s f u l l y held i n c a p t i v i t y f o r a minimum of 3 weeks developed the i n f e c t i o n . Again, the disease was not found i n 59 calves born on Brunette I s l a n d from parent stock introduced from ranges where abscessed ca l v e s were frequent. The theory t h a t the i n f e c t i o n was caused by nose bots or by arthropods was r e j e c t e d . None of the bots held i n c o n t a i n e r s strapped t o the necks of calves penetrated the f l e s h of the animals. None of the s i x c a l v e s held on a wooden p l a t f o r m on the Pot H i l l c a l v i n g ground ( F i g . 19), f r e e of c r a w l i n g i n s e c t s or s p i d e r s , developed the i n f e c t i o n nor d i d the seven calves housed i n the adjacent ground exclosure. But 65 per cent of the f r e e - r a n g i n g calves i n the herd frequenting the bog where the p l a t f o r m was constructed d i e d by June 19 (Table 23) and many abscessed c a l v e s were found. Experiments w i t h Lynx t o I s o l a t e P a s t e u r e l l a Dr. John M. King ( p a t h o l o g i s t ) and Dr. Las Karstad ( e p i d e m i o l o g i s t ) came to Newfoundland i n June 196^ to study the e t i o l o g y of the c e r v i c a l ab-scesses of the P a s t e u r e l l a syndrome. They concluded a f t e r autopsying a number of c a l v e s t h a t the i n f e c t i o n r e s u l t e d from trauma. Subsequent t o t h i s hypothesis, a dead c a l f was l o c a t e d w i t h neck l e s i o n s but no abscesses. The c a l f had died from a broken neck. Four l e s i o n s were present on the neck. The spacing of the f o u r holes and the deep p e n e t r a t i o n suggested the b i t e o f a l y n x . The jaws of a l y n x s k u l l were placed over the neck and the canine t e e t h matched the four l e s i o n s ( F i g . 20). In many calves examined p r e v i o u s l y , the l o c a t i o n of the l e s i o n s had been d i s t o r t e d by pockets 5 9 F i g . 19. The Pot H i l l C a l v i n g Ground. 60 F i g . 20. The canine t e e t h of a s k u l l of a l y n x i n s e r t e d i n t o f o u r l e s i o n s on the neck of a c a l f . 61 of pus. L a t e r , a more c a r e f u l examination of other c a l v e s revealed a c a l f w i t h a long s c r a t c h on the hindquarter, a c a l f w i t h a s c r a t c h on the r i b - c a s e , and a neonate w i t h a t o r n ear. Next the s a l i v a was secured from three w i l d l y n x . C u l t u r e of the. s a l i v a showed P a s t e u r e l l a multocida type A.". Next, three c a l v e s were presented i n d i v i d u a l l y to a lyn x i n a 9x5 foot pen. The lyn x s t a l k e d . t h e c a l v e s w i t h a slow p u r s u i t i n which i t remained to the side and r e a r of the c a l v e s . The s t a l k s l a s t e d 15, 25, and 55 minutes. When the lyn x sprang i t spread i t s f o r e f e e t and struck the cal v e s i n the shoulder.region,.knocking them o f f balance. In two instances the lyn x grasped the c a l f by the neck; once the l y n x and c a l f jumped simultaneously, and the lynx missed and b i t the c a l f on the shoulder. A l l c a l v e s got up w i t h i n 30 seconds a f t e r being b i t t e n . One c a l f developed neck p a r a l y s i s and could not t i l t i t s head upward; i t would have been unable t o nurse i n the w i l d . A l l developed abscesses near the wounds from which P a s t e u r e l l a multocida type A was c u l t u r e d . The c a l v e s died as f o l l o w s : Sex Age When B i t t e n Days Survived A f t e r Attack Male 17 days 15 Male 12 days Female 14 days • 4% Autopsies of the ca l v e s showed b i t e l e s i o n s t h a t resembled those seen on w i l d animals. The evidence was c o n c l u s i v e ; the abscess syndrome was caused by b i t e s of l y n x i n which the c a l f escaped the predator. 62 Predation o f Lynx on Calves C e r v i c a l l e s i o n s occurred on a l l the 84 abscessed c a l v e s t h a t were l o c a t e d . W i l d l i f e o f f i c e r s reported t h a t when lynx k i l l domestic lambs they b i t e them on the neck. This k i n d o f attack:; i s c h a r a c t e r i s t i c o f ly n x predation on c e r v i d s i n Sweden.(Boag 1956 and Haglund 1966). The neck grasp i s a common technique of s e v e r a l other members of the F e l i d a e ( G r i n n e l l et a l . 1937, Marston 1942, Young 1958, Rosenblatt and S c h n e i r l a 1962, Van Wormer 1964,. Pe r r y 1964, and S c h a l l e r 1967). Some of the calves t h a t developed abscesses may have escaped from the ly n x through the defensive t a c t i c s of the doe. On two occasions, I was charged by a doe t h a t had a young c a l f . One o f the does sprang and landed, a l l f o u r f e e t , on the p r e c i s e spot where I had been. Other does were seen chasing a s e t t e r dog and a fo x . One female'ran s t r a i g h t at a bear and shied to one si d e at 10 f e e t to r e t r i e v e her c a l f . Does were q u i t e f e a r l e s s when w i l d l i f e o f f i c e r s captured t h e i r young. Two dams approached so t h a t they could be touched and most females came w i t h i n 25-50 f e e t . The l i t e r a t u r e i s r e p l e t e w i t h references t o female ungulates defending t h e i r young against predators ( D a r l i n g 1937, Einarsen 1948, Muire 1951, Roe 1951, L i n s d a l e and Tomich 1953, Peterson 1955, and Cowan 1956). The c a l v e s known to have d i e d from P a s t e u r e l l a i n f e c t i o n accounted f o r only a minor p o r t i o n of those that died i n June. For example, at the Pot H i l l c a l v i n g ground i n 1958, approximately 478 calves were born; 75 does had l o s t t h e i r young by June 11-17, but only 10 abscessed c a l v e s were l o c a t e d . Again, at Pot H i l l i n 1964, about 256 does gave b i r t h ; 14 i n f e c t e d c a l v e s were found and 12 were removed from t h e i r dams f o r r e a r i n g . Yet by the middle o f June 140 calves were missing. 63 A search f o r the missing calves was made i n June 1958 and 1964 by d a i l y h e l i c o p t e r f l i g h t s over the Middle Ridge and Pot H i l l c a l v i n g grounds ( F i g . 19). The search was made at low a l t i t u d e s and reduced speeds. Both c a l v i n g grounds could be e f f e c t i v e l y t r a v e r s e d i n 1-hour's f l y i n g time. For in s t a n c e , the area where p o s t p a r t u r i e n t does aggregated at Pot H i l l measured 8x10 square m i l e s . Frequently a l l the major doe-calf groups were together i n a 4-square m i l e s e c t i o n o f l a r g e sedge bogs. Search was concentrated i n the v i c i n i t y of does t h a t f a i l e d to show normal f l i g h t behaviour when buzzed by the h e l i c o p t e r . Many of these does ran i n c i r c l e s , g r unting and n e a r l y always we l o c a t e d a dead or s i c k c a l f near them. These f a i t h f u l , conspicuous does helped us to l o c a t e n e a r l y a l l the dead ca l v e s t h a t were v i s i b l e . Where were the miss i n g calves? The ground was s u f f i c i e n t l y f i r m t h a t c a l f remains could not have sunk o u t - o f - s i g h t . A l s o there was no p o s s i b i l i t y t h a t many cal v e s wandered i n t o surrounding timber. Calves always accompanied t h e i r dams i n t r a v e l l i n g and the does d i d not use f o r e s t cover u n t i l l a t e i n June. At times c a l v e s l e f t t h e i r dams on short spurts of e x p l o r a t o r y a c t i v i t y or running dashes, but they stayed mostly i n the open. The missing c a l v e s were apparently dragged from the open h a b i t a t s i n t o the t a n g l e d , stunted v e g e t a t i o n on bog p e r i p h e r i e s t h a t was impossible to search. In the course of the study, four badly decayed c a l v e s were stumbled upon i n f o r e s t cover at Pot H i l l . Bears could drag c a l v e s i n t o the dense cover. A few bears were observed lumbering a f t e r c a l v e s each June, yet no s u c c e s s f u l chase was seen. Presum-a b l y a few young calves were captured. Bears appeared on the grounds a f t e r some cal v e s had died from the pasteurellosis,. They scavenged dead ca l v e s and females t h a t had died i n p a r t u r i t i o n . No bears were seen dragging carcasses; however, they ate them where found. The only other predator i n Newfoundland t h a t could drag a dead c a l f i s 64 the l y n x . A 16-pound c a l f could be hauled by a 19-pound female or 24-pound male l y n x . I have found no records i n the l i t e r a t u r e of ly n x dragging prey. This i s not s u r p r i s i n g since the foods reported f o r l y n x are snowshoe hare (Lepus americanus) and f o r e s t grouse, t h a t would be taken i n concealing f o r e s t h a b i t a t s or l i g h t enough t o c a r r y , and roe deer (Capreolus capreolus) and re i n d e e r (Rangifer t a r a ndus), which are too l a r g e to be p u l l e d (Iurgenson 1955, Saunders 1963a, Van Z y l l de Jong 1966, and Haglund 1966). Presumably i t would be advantageous f o r a ly n x to drag the c a l f o u t - o f - s i g h t of the dam. Several members of the F e l i d a e are reported t o s h i f t t h e i r prey to overhead c o v e r t s , even when the prey exceeds t h e i r own weight (Young and Goldman 1946, Young 1958, Rosenblatt and S c h n e i r l a 1962, Perry 1964, and S c h a l l e r 1967). Experimental Removal of Lynx Lynx t r a p p i n g was undertaken i n the winter of 1964^65 t o o b t a i n estimates of l y n x d e n s i t i e s on c a l v i n g grounds and t o a s c e r t a i n whether removal of lynx could improve c a l f s u r v i v a l . Four trappers worked the Middle Ridge c a l v i n g r e g i o n . As a c o n t r o l , l y n x on the Pot H i l l c a l v i n g ground, 26 m i l e s d i s t a n t , were l e f t undisturbed. Trappers remained at Middle Ridge u n t i l June.attempt-. ing t o get a l l the l y n x ; 44 animals were secured (Table -27) or about 1 lynx per 5 square m i l e s ( F i g . 21). Following the removal program the c a l f i n c r e -ment was grea t e r at Middle Ridge than at Pot H i l l : P o p u l a t i o n Pot H i l l Middle Ridge S t a t i s t i c s l y n x not removed (l y n x removed) C a l f s u r v i v a l i n June 1965 49% (89)* 85% (98) Per cent c a l v e s i n pop. i n Oct. . 2.7% .(299) 16.3% (-92) Y e a r l i n g s per 100 does, June 1966 4.7 (190) -27.5 (109) 2-yr. does/100 a d u l t does, June 1967 2.9 (172) 10.2 (167) " a d u l t does i n sample 65 F i g . 21. Lynx trapped.at Middle Ridge i n the w i n t e r of 1964-65 and 1965-66. Note the concentration near L i t t l e Gander Pond. 66 S u r v i v a l of calves on the Avalon Peninsula exceeded t h a t of the I n t e r i o r Herd-in 8 of 10 years ( F i g . 15). To i n v e s t i g a t e lynx d e n s i t y , l y n x were snared i n 1965-66. Nineteen lynx.were harvested which provided a d e n s i t y of about 1 lyn x per 10 s q u a r e - m i l e s — h a l f the d e n s i t y recorded at Middle Ridge i n 1964-65. The year p r i o r to the l y n x removal program only 27 per cent o f the young on the Avalon Peninsula l i v e d t i l l October^ ( F i g . 15). The year a f t e r the snaring 85 per.cent o f the cal v e s survived t i l l October. I t seems l i k e l y t h a t the removal of lyn x was r e s p o n s i b l e f o r the increased s u r v i v a l . The t r a p p i n g program showed th a t l y n x were common i n the winter on the c a l v i n g grounds but d i d not demonstrate c o n c l u s i v e l y t h a t they were common at p o s t - c a l v i n g time. Saunders' (1963b) s t u d i e s o f movement of Newfoundland l y n x suggested t h a t the animals were q u i t e sedentary. His t r a c k i n g s t u d i e s gave home ranges of three a d u l t s as 6, 7, and 8 square m i l e s . The mean recapture d i s t a n c e f o r 14 tagged animals was 3.3. m i l e s . His data were c o l l e c t e d during a p e r i o d when snowshoe hares were i n c r e a s i n g (Dodds 1965). Lynx range f a r t h e r when hares are scarce (Iurgenson 1955). S t i l l , no d i e - o f f o f hares was noted during the winter t r a p p i n g nor are r e g u l a r extensive w i n t e r - s p r i n g movements of l y n x known f o r Newfoundland. I conclude'that l y n x d e n s i t i e s on c a l v i n g grounds i n the sp r i n g were a t l e a s t equal to that i n win t e r . Our t r a p p i n g showed th a t the home ranges of lyn x were not mutually e x c l u -s i v e ( c f . Haglund 1966). F i v e a d u l t animals were taken w i t h i n a few weeks at one snaring s i t e , f o u r at another. The lyn x at Middle Ridge were concentrated around L i t t l e Gander Pond ( F i g . 21), probably because of the abundance of hares. S i m i l a r l y , i t i s q u i t e p o s s i b l e t h a t lynx could aggregate i n the spring adjacent to c a l v i n g areas. 67 Sex V u l n e r a b i l i t y of Male Calves to Lynx Predation More male than female c a l v e s died between b i r t h and 6-months-of-age but there was no s i g n i f i c a n t change i n the sex r a t i o from 5- to 12-months-of-age (Table 16). 'When I combined a l l samples 5- to 12-moriths-of-age,^ the male: female percentages were 40.2 and 59.8, n =1285 (Table 16). Hence i n . t h e f i r s t 6 months of l i f e 1.3 males were l o s t f o r each female t h a t d i e d , based on the assumption t h a t the sex r a t i o a t b i r t h was 52:48 ( c f . K e l s a l l 1968). Male c a l v e s may have been more vu l n e r a b l e to l y n x because some wandered f a r t h e r from t h e i r dams than females. There was a h i g h l y s i g n i f i c a n t d i f f e r -ence between the sexes i n t h i s behaviour ( F i g . 22). A lynx might be bolder i n s t a l k i n g s o l i t a r y c a l v e s . F u r t h e r , l y n x move u n o b t r u s i v e l y about a home range r e y l i n g on s i g h t and sound to detect prey (Saunders 1963b and Haglund 1966). An a c t i v e , c u r i o u s c a l f , t r a v e l l i n g a wide r a d i u s might a t t r a c t more a t t e n t i o n than a more sedentary i n d i v i d u a l . Then too, a s t r a y i n g c a l f would l i k e l y be l e s s able t o observe warning s i g n a l s from a d u l t s . The p r o p o r t i o n of male ca l v e s a l i v e a t 1- to 4-weeks-of-age was gr e a t e r i n years of good c a l f s u r v i v a l ( F i g . 23), which i s to.be expected i f males are more prone t o pr e d a t i o n than females, but the percentage of males i n the r e -cruitment at 12-months-of-age was l e s s w i t h improved c a l f s u r v i v a l ( F i g . 24). This l a t t e r r e s u l t would not be expected i f male s u s c e p t i b i l i t y t o death i n -creased p r o p o r t i o n a l l y w i t h t o t a l c a l f m o r t a l i t y . Perhaps i n years w i t h l a r g e l o s s e s , i n d i v i d u a l s u s c e p t i b i l i t y matters l e s s ; p r e d a t i o n i s so severe t h a t few animals are u l t i m a t e l y excluded. V a r i a t i o n i n Lynx Pr e d a t i o n Between Areas The s u p e r i o r s u r v i v a l of c a l v e s born on the La P o i l e R i v e r and Buchans D I S T A N C E N U M B E R O F dd O B S E R V A T I O N S CHI O B S E R V E D O B S E R V E D E X P E C E D O N BASIS 99 SO, < 5 Y D S . 41 5 9.7 5.9 > 5 £ 10 Y D S . 24 2 7.7 0-5 >10< 2 0 Y D S . 3 8 33 .5 0.6 >20< 5 0 Y D S . 32 24.7 0.3 > 5 0 Y D S . 18 7.3 15.7 4 0 1 < 5 > 5 < 1 0 >10< 20 >20< 5 0 > 5 0 D I S T A N C E O F C A L F F R O M D A M (YDS. ) F i g . 22. Male calves s t r a y e d f a r t h e r than female.calves from t h e i r dams. 69 F i g . 23. The r e g r e s s i o n of the percentage of calves i n the I n t e r i o r Herd i n October on the sex r a t i o of calves 1-4- weeks-of-age. 70 7 0 LU 3 6 0 -r = - 0 . 5 4 6 P< 0 .02 n=21 CALV ING P O P U L A T I O N S • POT H I L L • B U C H A N S P L A T E A U A G R E Y RIVER O M I D D L E R I D G E • SANDY L A K E cr  5° < LU > LU _ l < 4 0 -LU O cr LU CL 3 0 ' Y= 5 2 . 2 9 - 0 . 8 7 x 2 0 - 1—r — r -10 - I — 15 —T— 2 0 2 5 3 0 YEARLINGS PER 100 DOES IN JUNE F i g . 24-. The r e g r e s s i o n o f the per cent male y e a r l i n g s on the recruitment i n June f o r the I n t e r i o r Herd. 71 P l a t e a u c a l v i n g grounds r e l a t i v e to the other c a l v i n g s i t e s (Table .12) may-be due to lower d e n s i t i e s of l y n x . Only four b i t t e n c a l v e s were found on the Buchans i n e i g h t s p r i n g s . Both the La P o i l e and Buchans Plate a u c a l v i n g grounds are i n the subalpine and a l p i n e v e g e t a t i v e zones (below) where c o n i f e r s are stunted and f r e q u e n t l y p r o s t r a t e . Such stands catch snow and are l e s s s u i t a b l e t o snowshoe hares (Lepus americanus) and thus l y n x . The remaining c a l v i n g grounds have more f o r e s t cover. C a l v i n g Mean Per Cent Calves i n Ground E l e v a t i o n ( f t . ) P o p u l a t i o n i n the Fall±95 C l . La P o i l e R i v e r 1400-1600 f t . 19.8+2.1 •C6)* Buchans P l a t e a u 1500 f t . 15.211.4 (10) Grey R i v e r 1000-1100 f t . ll.-3±1.2 (9) Sandy Lake 900-1000 f t . .9.'911.0 (10) Middle Ridge 700-800 f t . 10.311.5 (6) Pot H i l l 700 f t . 11.111.3 (6) * herd c l a s s i f i e d i n 6 years V a r i a t i o n i n Lynx Pr e d a t i o n Between Years The s u r v i v a l o f calves u n t i l October i n the I n t e r i o r Herd showed nonrandom trends f o r at l e a s t 16 years (Table 25). S u r v i v a l on the Avalon Peninsula showed a s i m i l a r p a t t e r n f o r 10 years and i n the Humber R i v e r Herd f o r 7 years of data (Table 18). These s u r v i v a l trends of 3 to 5 years could r e f l e c t c y c l i c changes i n the amount of l y n x p r e d a t i o n . The magnitude of l y n x p r e d a t i o n could depend on the number of l y n x and t h e i r search f o r c a r i b o u . C a l f s u r v i v a l i n the i n t e r i o r was c o r r e l a t e d w i t h numbers of l y n x trapped ( F i g . 25). But i t i s a moot poi n t whether the number of l y n x trapped r e f l e c t e d population changes. Iurgenson (1955) showed t h a t lynx n e a r l y doubled t h e i r c r u i s i n g r a d i u s when hares d e c l i n e d ; increased move-ment would increase t r a p p i n g v u l n e r a b i l i t y and d i s t o r t f u r r e t u r n s as i n d i c e s of abundance. Lynx depend on snowshoe hares f o r food i n Newfoundland (Saunders 1963a). Th e i r "searching image" (sensu of Tinbergen 1960) may be f o r hares when hares can be e a s i l y found. Dodds (I960 and 1965) reported a high i n hare numbers i n Newfoundland i n 1960-61. A high i n c a l f s u r v i v a l i n the Avalon, I n t e r i o r , and Humber Ri v e r herds occurred i n 1959 ( F i g . 1 6 ) . C a l f s u r v i v a l i n the Humber herd may have been c o r r e l a t e d w i t h the abundance of snowshoe hares i n t h a t r e g i o n ( F i g . 26). During a d e c l i n e of hares l y n x p r e d a t i o n on caribou might i n c r e a s e . In theory, there i s a l a g . i n numbers between predators'and prey; predators do not respond immediately t o the prey d e c l i n e and continue t o increase while the prey i s decreasing (reviews by H o l l i n g 1961 and S a l t 1967). Iurgenson's (1955) data from the U.S.S.R. show th a t l y n x d i d increase a f t e r hares d e c l i n e d : Winter Number of Varying Number of Lynx A l i v e i n Average Length Season Hares Per 10 km. N a t i o n a l Forest D a i l y T r a v e l of Lynx km. 1931- 32 -44.2 6-9 8.6 1932- 33 11.3 13-16 7.7 1933- 31+ 6.3 16-18 14.3 1934- 35 10.4 12-14 11.4 K e i t h ' s (1963) review of North American hare and l y n x c y c l e s i n d i c a t e s t h a t l y n x at times remain high f o r a few years a f t e r hares d e c l i n e . However, h i s data are based on t r a p p i n g . A p r i o r i one could reason t h a t the numbers of a 73 F i g . 25. The s u r v i v a l of calves i n eastern and c e n t r a l Newfoundland on the t o t a l lynx harvested f o r the i s l a n d . 74 cr > 4 0 1 o LU 0-| — , 1 1 1 ^ 50 60 70 80 90 PER-CENT JUVENILE SNOWSHOE HARES IN HUMERI SAMPLES, HUMBER RIVER F i g . 26. S u r v i v a l o f calves i n the Humber R i v e r Herd and production o f snowshoe hares (snowshoe hare data from Dodds 1965). mobile, l o n g - l i v e d predator as the ly n x would not respond immediately to the decrease o f i t s prey. A judgement on the r e l a t i v e r o l e s of predator and the abundance of a l t e r n a t i v e prey on c a l f l o s s e s r e q u i r e s f u r t h e r study. 76 FACTORS LIMITING POPULATION GROWTH 1900 t o 1967 Rate of P o p u l a t i o n Growth The t h e o r e t i c a l growth i n numbers of a p o p u l a t i o n i n the absence of mor-t . rm t a l i t y i s p r e d i c t e d from the formula N^ = N^ , where r ^ equals the i n t r i n s i c r a t e of i n c r e a s e . The i n t r i n s i c r a t e of increase i s a measure of the innate c a p a c i t y of the species t o increase under optimum conditions.(Andrewartha and B i r c h 1954). I f r can be c a l c u l a t e d , i t provides a means by.which the a c t u a l r a t e of increase ( r ) of populations can be compared i n assessing t h e i r growth and the s e v e r i t y of f a c t o r s a f f e c t i n g growth. The growth of the c a r i b o u herd on Brunette I s l a n d may provide an a p p r o x i -mate estimate of r f o r Newfoundland c a r i b o u . The animals were introduced m i n t o t h i s new environment and increased e x p o n e n t i a l l y from 17 to 100 animals i n 5 years. No animals are known to have died and some females reached p u b e r i t y as y e a r l i n g s , suggestive of good c o n d i t i o n s . The r a t e - o f - i n c r e a s e f o r the Brunette I s l a n d animals over 5 years was 0.352 young per i n d i v i d u a l per year. This r a t e r e s u l t e d from the a t y p i c a l sex r a t i o of 3 males and 14- females and should be adjusted t o the a c t u a l sex r a t i o expected i n undisturbed Newfoundland po p u l a t i o n s . I t h i n k the best estimate of the sex r a t i o of a d u l t s i n a p o p u l a t i o n not subject t o s e l e c t i v e hunting of stags i s 36 males t o 64 females. This value i s midway between the percentage of stags i n the I n t e r i o r Herd i n 1957, 32 per cent (Table 9), and the f igure secured f o r the Avalon Herd of 40:60 (n = 518). This f i g u r e i s s i m i l a r to the p r o p o r t i o n of males and females (36:44) i n a complete c l a s s i f i c a t i o n I made of a small protected herd at Mt. A l b e r t , Quebec i n 1959 (unpublished). 77 I f we a d j u s t the number of animals introduced to Brunette I s l a n d on the b a s i s of a malerfemale r a t i o of 8:14 then the increase i n 5 years i s from 22 to 105 animals. These f i g u r e s g ive a r ^ value of 0.312 young per i n d i v i d u a l per year. The a e r i a l census r e s u l t s provided t o t a l s of 4600 animals f o r the I n t e r i o r Herd (excl u d i n g the La P o i l e population) i n 1957 and 6200 i n 1966 (Table 5). These f i g u r e s g ive an r value of 0.044. The Avalon Herd probably d i d not i n -crease 1956 to 1958 (Table 5). Census f i g u r e s i n 1959 and 1960 are u n r e l i a b l e . From 1961 to 1967 the Avalon Herd increased from 350 to 720 animals or r 0.120. The t a l l i e s of the Humber Herd suggested no increase from 1956 to 1964 (Table 5). The two winter counts of the Northern P e n i n s u l a Herd i n 1958 and 1961 showed no p o p u l a t i o n t r e n d . These data i n d i c a t e t h a t a l l the herds were se v e r e l y l i m i t e d i n growth compared to t h a t of animals introduced to Brunette I s l a n d . The accuracy of the census r e s u l t s i n p r e d i c t i n g r a t e s - o f - i n c r e a s e can be p a r t i a l l y checked f o r the I n t e r i o r and Avalon Herds by c a l c u l a t i n g the r a t e s - o f - i n c r e a s e from herd composition data t h a t are independent of census t a l l i e s . In the I n t e r i o r Herd there were 55.3 does f o r every 100 animals (Table 13). These does gave b i r t h to 46.6 c a l v e s (55.3 x 0.843, Table 20) and 14.5 of these c a l v e s l i v e d t i l l f a l l (46.6 x 0.310, Table -20). The a d u l t m o r t a l i t y r a t e was 11 per c e n t — t h e d i f f e r e n c e ; the r a t e - o f - i n c r e a s e was 3.5 per cent. For the Avalon Herd, 39.2 does i n 100 animals (Table 13) produced 29.2 c a l v e s (39.2 x 0.745, Table 1 7 ) , and 20.4 c a l v e s l i v e d t i l l the f a l l (29.2 x 0.699, Table 1 7 ) ; a gain of 12.0 per cent, 20.4 per cent - 8.4 per cent . t t o t a l • m o r t a l i t y (Table 11). A c t u a l l y the I n t e r i o r Herd d i d not increase each ..year"at "the -calcu- - . . l a t e d r a t e of 4 per cent. Counts of c a l v e s i n the f a l l suggest t h a t r e c r u i t -78 ment was i n s u f f i c i e n t t o balance m o r t a l i t y l o s s e s i n 1957, 196-2, and 1963. P r i o r to t h i s study the annual increments may have f a i l e d to compensate f o r m o r t a l i t y i n 1952 to 1956 (Table 25). Thus the herd could have d e c l i n e d i n 8 of 17 years. Reproduction i n P o p u l a t i o n Growth Annual v a r i a t i o n s i n the reproductive r a t e of females appeared due t o change i n the percentage of n u l l i p a r o u s 2-year-olds i n the p o p u l a t i o n . The f e c u n d i t y of mature does seemed constant even though there were great extremes between years i n the r e l a t i v e abundance of winter forage. In a sample of 18 nonparous does 6 were 3-years-old t h a t had never ovulated. I t seems l i k e l y t h a t the p r o p o r t i o n of females reaching puberty at 2\ years could vary w i t h n u t r i t i o n . The number of females pregnant, 84-.5 per cent, was s i m i l a r to that r e -ported f o r the Northwest T e r r i t o r i e s ( K e l s a l l 1968), Alaska (Skoog 1968), and Ontario (Simkin 1965). The l i c h e n range of the Ontario herd was l a r g e l y un-d i s t u r b e d , while many of the ranges a v a i l a b l e to the animals i n the Northwest T e r r i t o r i e s had been destroyed by f i r e s (Simkin 1965 and S c o t t e r 1964). Two of the herds were i n c r e a s i n g when sampled, and one was p o s s i b l y s t a b l e or de-c l i n i n g yet the r e p r o d u c t i v e r a t e s of a l l the populations were s i m i l a r . In Sweden, the numbers of mature pregnant r e i n d e e r i n a small herd averaged 84 per cent over 7 years (Skunke pers. comm.). In some winters the animals fed on very overgrazed pastures and i n others on ranges w i t h more abundant s u p p l i e s of l i c h e n (Skunke pers. comm.). Snow depths i n the 7 years ranged widely and the animals r e c e i v e d supplementary r a t i o n s of 1 kg. per day i n 5 seasons. I could see no apparent c o r r e l a t i o n between frequencies each year and the extremes i n the a v a i l a b i l i t y of winter forage. 79 K l e i n (1968) c o l l e c t e d female r e i n d e e r from.St. Matthew I s l a n d , Alaska j u s t p r i o r to a crash from winter s t a r v a t i o n on an over-grazed range. He a l s o c o l l e c t e d from the s u r v i v i n g herd a f t e r the mass m o r t a l i t y . Females i n both samples had continued t o ovulate. I t seems t h a t c a r i b o u , u n l i k e North American deer and moose, have l i t t l e phenotypic p l a s t i c i t y i n t h e i r r e p r o d u c t i v e a d a p t i v e . s t r a t e g y that might vary and a f f e c t p o p u l a t i o n growth. This f i n d i n g i s c o n s i s t e n t w i t h the view of David Lack (1966) t h a t species have evolved the r e p r o d u c t i v e r a t e t h a t provides the maximum number of s u r v i v i n g young but i s at odds with the theory of Wynne-Edwards (1962) t h a t animals can r e g u l a t e t h e i r numbers by c o n t r o l l i n g b i r t h r a t e s through s o c i a l behaviour. In c a r i b o u the v a r i a b l e parameter l i m i t i n g p o p u l a t i o n growth i s m o r t a l i t y . N a t u r a l M o r t a l i t y of Calves The major n a t u r a l l o s s from the populations was a high m o r t a l i t y of calves i n t h e i r f i r s t summer of l i f e . The r a t e s - o f - g a i n of the.Avalon and I n t e r i o r herds were c o r r e l a t e d w i t h the s u r v i v a l of calves u n t i l 6-months-of-age ( F i g . 27). Therefore e a r l y m o r t a l i t y determined p o p u l a t i o n growth. Over 10 years, an average of -69 per cent of the c a l v e s born i n the i n t e r i o r were dead by October, and 30 per cent of the c a l v e s on the Avalon Peninsula had d i e d by autumn. Calves began to disappear immediately a f t e r c a l v i n g . In the I n t e r i o r Herd, '27 per cent of the c a l v e s born were missing from the open c a l v -ing grounds before J u l y (Table 23). Yet behaviour s t u d i e s showed t h a t does and c a l v e s d i d not leave the open c a l v i n g areas f o r the woods u n t i l J u l y , when f l i e s became bothersome. My i n t e r p r e t a t i o n i s t h a t c a l v e s were k i l l e d and dragged from the c a l v i n g areas. Since 84 of 114 dead or morbid c a l v e s found were b i t t e n 80 -.10 I I 1 1 1 1 1 : 1 1 1 0 10 20 30 4 0 50 60 70 80 90 PER CENT CALF SURVIVAL UNTIL 6 MO. F i g . 27. The r e g r e s s i o n of the r a t e - o f - i n c r e a s e on s u r v i v a l of calves u n t i l 6-months-of-age. 81 by l y n x t h i s predator was most l i k e l y r e s p o n s i b l e f o r the high l o s s e s of c a l v e s . C a l f m o r t a l i t y remained high i n J u l y and August but had l a r g e l y ceased by l a t e September. This p a t t e r n can be explained by ly n x p r e d a t i o n . Young ca l v e s are more v u l n e r a b l e t o ly n x because of t h e i r small s i z e , unwariness, and t h e i r a l t e r n a t i n g periods of e x p l o r a t o r y a c t i v i t y and sleep. Calves become more s e l f - s u f f i c i e n t and a l e r t i n J u l y and August, but during these two months some doe- c a l f herds disband and dis p e r s e i n t o f o r e s t cover to escape f l i e s . Thus the s t a l k i n g o p p o r t u n i t i e s f o r ly n x would be enhanced. Also the small s i z e of bands of carib o u i n the f o r e s t would reduce the alarm d i s t a n c e (Bergerud 1961a). Heavy pre d a t i o n ceased i n l a t e September probably because the caribou leave the f o r e s t , a f t e r the f l y - s e a s o n and congregate on open h a b i t a t s p r i o r to the r u t . The hypothesis of predation by ly n x was t e s t e d by removal o f ly n x on the Avalon Pe n i n s u l a and the Middle Ridge c a l v i n g ground of the I n t e r i o r Herd. C a l f s u r v i v a l showed a marked improvement i n both areas f o l l o w i n g the red u c t i o n s of l y n x . The p a t t e r n of pr e d a t i o n by ly n x i s c o n s i s t e n t w i t h the f i n d i n g t h a t c a l f s u r v i v a l f o l l o w s 3- to 5-year i n c r e a s i n g or decreasing trends t h a t could r e -l a t e to approximate 10-years c y c l e s of abundance of l y n x . The hypothesis i s a l s o c o n s i s t e n t w i t h the f a c t t h a t the I n t e r i o r , Avalon, and Humber Ri v e r herds showed some s y n c h r o n i z a t i o n i n s u r v i v a l of c a l v e s . Moreover, i t provides an e x p l a i n a t i o n f o r a g r e a t e r l o s s of male than female c a l v e s . Male calves may wander f a r t h e r from t h e i r dams than females and be more s u s c e p t i b l e t o preda-t i o n by l y n x . L a s t l y the r a t e s - o f - g a i n of three herds were a l s o c o r r e l a t e d w i t h the abundance of l y n x : Brunette I s l a n d r =0.352 and no l y n x , Avalon Peninsula 82 r = 0.120 and 1 lyn x per 10 square m i l e s i n 1965-66, and the I n t e r i o r Herd r = 0.044 and 1 l y n x per 5 square m i l e s i n 1964^65. I conclude t h a t l y n x predation was the f a c t o r l i m i t i n g growth o f the Avalon and I n t e r i o r . herds. The importance of ly n x can be t e s t e d f u r t h e r by i n t r o d u c i n g them t o Brunette I s l a n d . I p r e d i c t that c a l f s u r v i v a l w i l l de-crease and po p u l a t i o n growth w i l l d e c l i n e f o l l o w i n g the i n t r o d u c t i o n . For a v a l i d t e s t snowshoe hares would a l s o have to be introduced. The g r e a t e r s u r v i v a l of ca l v e s on Brunette I s l a n d and the Avalon Penin-s u l a i n d i c a t e s t h a t many of the i n t e r i o r c a l v e s would not have died from other causes i n the absence o f pr e d a t i o n . The l o s t c a l v e s were not a surplus and doomed t o d i e and lyn x reduced the amount of increment. The numbers of ca l v e s recorded i n the f a l l or winter i n other caribou herds i n North America l i v i n g w i t h i n the range of ly n x are s i m i l a r to those found i n t h i s i n v e s t i g a t i o n . The mean increment of ca l v e s i n the Mealy Moun-t a i n Herd i n southern Labrador i n 6 years was 11 per cent (Bergerud 1967a), on the Gaspe Pen i n s u l a i n 6 autumns 16 per cent (Moisan 1958 and.pers. comm.), and Ontario 17 per cent i n 7 winters (Simkin 1965 and pers. comm.). These f i g u r e s imply a heavy l o s s between b i r t h and f a l l and pred a t i o n by ly n x i s a p o s s i b i l i t y . P r e d a t i o n by Lynx on Male Calves The l o s s of more male than female calves to predation by l y n x would a c c e l e r a t e the r a t e - o f - i n c r e a s e of the herd i f i t r e s u l t e d i n a lower percent-age of stags. This would r e s u l t because caribou are f u n c t i o n a l l y polygynous ( c f . Buechner 1960). However, the greater predation of male ca l v e s by l y n x appears i n s u f f i c i e n t to e x p l a i n i n g the sex r a t i o s of a d u l t s favouring females. The sex r a t i o of 83 the a d u l t p o p u l a t i o n i n 1957, p r i o r to hunting of males o n l y , was 32:68 (Table 9). In the Avalon and Humber herd, the a d u l t p r o p o r t i o n of males and females was 33:67 (n = 680), n e a r l y the same as the i n t e r i o r , yet the sex r a t i o of the r e c r u i t s i n autumn f o r both of these herds was -50:-50 (n = 147). In barren-ground cari b o u not subjected to s i g n i f i c a n t l y n x p r e d a t i o n , the sex r a t i o of a d u l t s was-34:66 ( K e l s a l l 1968). The changes i n sex r a t i o between r e c r u i t s and a d u l t s . suggest t h a t male cal v e s died at g r e a t e r r a t e s than females r e g a r d l e s s of p r e d a t i o n . The d i f f i -c u l t y i n these comparisons i s that the sex r a t i o of a d u l t s i n c l u d e s males of a l l ages and r e f l e c t s a d u l t m o r t a l i t y as w e l l as d i f f e r e n t numbers of r e c r u i t s of each sex. The m o r t a l i t y of a d u l t s appears to be the dominant f a c t o r i n the imbalance of the sex r a t i o of a d u l t s since there was no evidence of winter m o r t a l i t y i n e i t h e r the Avalon or Humber herds t h a t might a l t e r t h e i r 50:50 r a t i o of r e c r u i t s and b r i n g i t c l o s e to the 40:60 f i g u r e i n the i n t e r i o r . My c o n c l u s i o n i s t h a t sex r a t i o of a d u l t s i n a l l herds which had d i f f e r e n t l e v e l s of c a l f m o r t a l i t y would have been s i m i l a r i n the absence of hunting of males. The Decline of Caribou 1915-1930 I b e l i e v e t h a t the great d e c l i n e of Newfoundland caribou.between 1915 and •1930 r e s u l t e d from increased p r e d a t i o n by l y n x and a heavy annual harvest of 6000 t o 8000 a d u l t s by hunters. There was no h i s t o r i c a l evidence that c a r i b o u died during the d e c l i n e from winter s t a r v a t i o n or an e p i z o o t i c . The winters i n t h a t p e r i o d were not severe. In s i x winters i n the current study there were gre a t e r s n o w f a l l s at St. John's than the year of maximum•snowfall recorded during the p e r i o d of d e c l i n e , 1915 to 1930. During these years the i n t e r i o r of Newfoundland was t r a v e l l e d by trappers who r e l i e d on c a r i b o u f o r food and fox b a i t ; a mass m o r t a l i t y would have been n o t i c e d and mentioned i n the news-84 papers of t h a t p e r i o d . Lynx Predation and the Decline In the e a r l y 1800's l y n x were exceedingly r a r e i n Newfoundland. Author-i t i e s have even disagreed on whether the lynx i s indigeneous or not (Cameron 1958, Dodds 1960, and Saunders 1961). A f t e r snowshoe hares were introduced to Newfoundland l y n x began to increase (Dodds I960). They became exceedingly abundant when hares reached high d e n s i t i e s about 1896. Many newspaper accounts mentioned the abundance of l y n x and a b i l l to exterminate l y n x was introduced i n the Newfoundland Assembly i n 1900 (Dodds 1960). The f i r s t high i n numbers of hare l a s t e d from 1896 to 1915 (Dodds 4960). Dodds f e l t t h a t t h i s i n i t i a l peak was the g r e a t e s t d e n s i t y of hares ever a t -t a i n e d on the I s l a n d . The p o p u l a t i o n d e c l i n e d a f t e r 1915 and l i k e l y l e f t an abundant l y n x p o p u l a t i o n p a r t l y without food. There are only 14 n a t i v e mammals i n Newfoundland (Bergerud 1963b) and no n a t i v e f o r e s t grouse species. Lynx probably took some a r c t i c hares, Lepus a r c t i c u s (Bergerud 1967b), beaver (Castor canadensis), mice (Microtus pennsylvanicus), and ptarmigan (Lagopus spp.). In a d d i t i o n , they l i k e l y preyed h e a v i l y on c a r i b o u c a l v e s . I t might be argued t h a t l y n x would not g r e a t l y reduce caribou numbers dur-in g a hare d e c l i n e s i n c e l y n x should a l s o d e c l i n e , The a v a i l a b l e evidence suggests t h a t l y n x d i d d e c l i n e f o l l o w i n g the high i n hare abundance. This supports the view t h a t a l t e r n a t e foods i n c l u d i n g c a r i b o u were u n s a t i s f a c t o r y to maintain l y n x . However, an abundant pop u l a t i o n of l y n x , even i f d e c l i n i n g , could k i l l many cal v e s when hares were scarce. They need prey h e a v i l y on c a l v e s f o r only 3 to 5 years and w i t h a heavy human harvest numbers of caribou would be d r a s t i c a l l y reduced. Recently the percentage of c a l v e s d e c l i n e d each year 1951 t o 1957 (Table 25) and 1959 t o 1962 (Table 12). Hence ly n x apparently 85 d i d continue t o take l a r g e numbers of calves f o r s e v e r a l consecutive years when hares d e c l i n e d ( c f . Dodds 1965 r e l a t i v e to hare f l u c t u a t i o n s ) . I can only speculate as to the p l a s t i c i t y l y n x have to su r v i v e low numbers of hares and the l a c k of an adequate winter d i e t . Lynx may have considerable p l a s t i c i t y i n f e c u n d i t y r e l a t i v e t o hare numbers. Saunders (1961) examined l y n x r e p r o d u c t i v e t r a c t s . secured during a hare low i n 1956 and 1957. He • suggested t h a t -24 per cent of the ad u l t females might not have bred i n the year c o l l e c t e d . In 14 female t r a c t s t h a t had v i a b l e young he counted 41 v i a b l e embryos, 6 p l a c e n t a l s c a r s , and -77 corpora l u t e a . Another t r a c t had 5 embryos tha t were c l e a r l y being reabsorbed. These data suggest t h a t the reproductive r a t e may be reduced i f food i s scarce. I t i s p o s s i b l e t h a t the d e c l i n e s of ly n x repo r t e d i n the l i t e r a t u r e are mostly due to a r e d u c t i o n i n b i r t h r a t e s ( p o s s i b l y p o s t p a r t u r i e n t m o r t a l i t y of k i t t e n s a l s o ) . Seton (1929) i s the only a u t h o r i t y I have l o c a t e d t h a t a c t u a l l y reported he found dead a d u l t l y n x t h a t may have starved to death. Again l y n x could show p l a s t i c i t y i n t h e i r hunting h a b i t s f o r hares i n the course of hare f l u c t u a t i o n s . When hares were low lyn x would t r a v e l g r e a t e r d i s t a n c e s searching. Lynx don't appear to have mutually e x c l u s i v e home ranges; t h i s behaviourism would permit hunting l y n x to l o c a t e and u t i l i z e . l o c a l popu-l a t i o n s of hares t h a t remained common during a p e r i o d of general s c a r c i t y . Again N e l l i s and K e i t h (1968) provided evidence t h a t there were between year d i f f e r e n c e s i n the e f f o r t expended by lynx i n chasing hares, i n catching food, and i n v i s i t s to c a r r i o n . During a low i n hares i n 1957 on the Avalon P e n i n s u l a , I noted t h a t hares were s t i l l common i n small discontinuous pockets ( c f . K e i t h 1966). Dodds (1965) was able to secure a small sample of 911 humeri bones of hares from r e s i d e n t s on the West Coast when the pop u l a t i o n was low i n 1957. Newfoundland 86 r e s i d e n t s continue t o have some success snaring hares,.even when numbers are down, e s p e c i a l l y at the beginning o f the open season f o r sn a r i n g . Dodds (1960 and 1965) i n d i c a t e d high populations o f hares i n Newfound-land i n 1940, 1952, and 1960-61. These are periods t h a t appear t o be high p o i n t s f o r carib o u numbers. These c o r r e l a t i o n s are c o n s i s t e n t w i t h the t h e s i s t h a t l y n x switched t o caribou a f t e r hares had d e c l i n e d . Such a switch seems p l a u s i b l e f o r a l o n g - l i v e d and v e r s a t i l e animal such as the ly n x . Hunting and the Decline The l o s s of calves from 1915 t o 1930 would not have been great enough t o reduce the i s l a n d ' s caribou herds from perhaps 40,000 t o 2,000 animals i n 15 years. A d u l t s a l s o must have died at high r a t e s t o e x p l a i n a d e c l i n e of t h i s magnitude. Presented below i s a t h e o r e t i c a l d e c l i n e of 40,000 caribou based on the f o l l o w i n g assumptions: (1) an annual harvest of 7,000 animals, (2) a n a t u r a l m o r t a l i t y r a t e of a d u l t s o f 5 per cent, and (3) c a l f recruitment s i m i l a r t o th a t which occurred from 1951 to 1957 (Table 25) when the I n t e r i o r Herd d e c l i n e d ( F i g . '9). Year i n T o t a l P o p u l a t i o n A f t e r N a t u r a l Per cent T o t a l Decline P o p u l a t i o n Hunting Loss M o r t a l i t y Calves i n Oct. Recruitment 1 40,000 33,000 1,650 .11.2 3,973 2 35,473 28,473 1,424 8.2 2,416 3 29,465 ' 20,465 1,023 7.3 1,531 4 20,973 13,973 697 5.6 788 5 14,064 7,064 . 353 5.5 . 391 6 7,102 102 5 5.4 6 7 .' 103 -87 These c a l c u l a t i o n s i n d i c a t e t h a t the c a r i b o u herd could have been destroyed i n a few years i f hunting m o r t a l i t y remained high and there were s e v e r a l years of low c a l f s u r v i v a l . Such a t h e o r e t i c a l d e c l i n e could only have r e s u l t e d i f the law-of-d i m i n i s h i n g r e t u r n s was an i n e f f e c t i v e check on e x p l o i t a t i o n . Caribou are h i g h l y v u l n e r a b l e to hunting because of a gregarious herd s t r u c t u r e , l a c k of wariness, use of open h a b i t a t s , and migratory h a b i t s . The c o n t i n u a l wander-i n g of the bands g r e a t l y increases the p o s s i b i l i t y of people from some s e t t l e -ment making contact with the animals. Again the caribou were a primary source of f r e s h meat f o r the Newfoundland people i n the e a r l y 1900's; i t i s c l e a r from the i n t e r v i e w s w i t h former hunters that these men t r a v e l l e d f a r t h e r and stayed i n the country longer searching f o r animals as the herds d e c l i n e d . Even as l a t e as 1959 hunters t r a v e l l e d i n t o some of the roughest t e r r a i n i n Newfoundland on the Northern P e n i n s u l a and harvested a reported 150 of the estimated 500 animals remaining i n the herd. These animals could have been anywhere i n an area of 3,000 square m i l e s , 1 c a r i b o u per 6 square m i l e s . The d e n s i t y of caribou i n Newfoundland i n year 6 of the h y p o t h e t i c a l popula-t i o n d e c l i n e would have been 1 ca r i b o u per 6 square m i l e s . For these reasons i t seems p o s s i b l e f o r the hunters of Newfoundland t o destroy the herds i n a matter of 10 t o 15 years i n the absence of s a t i s f a c t o r y annual increments. 88 EVOLUTIONARY IMPORTANCE OF PREDATION In my view, species u s u a l l y f l u c t u a t e w i t h i n narrower l i m i t s than poten-t i a l l y p o s s i b l e because they are the product of past Darwinian s e l e c t i o n and have only s u r v i v e d because they have evolved e f f e c t i v e s t r a t e g i e s t o cope with past contingencies. There i s value i n assessing the r o l e of f a c t o r s such as p r e d a t i o n i n the n a t u r a l s e l e c t i o n of i n d i v i d u a l s . Such.study provides i n s i g h t i n t o the'adaptations t h a t permit i n d i v i d u a l s , and thus c o l l e c t i v e l y p o p u l a t i o n s , t o prosper. The f u t u r e of a species depends on how e f f e c t i v e the present adaptations, forged i n the p a s t , are i n coping w i t h a dynamic present and f u t u r e environment. P o p u l a t i o n L i m i t a t i o n from Wolf Pr e d a t i o n The Newfoundland c a r i b o u apparently evolved i n a r e l a t i v e l y simple i n s u l a r environment i n the presence of p r e d a t i o n by the Newfoundland wolf and i n more recent c e n t u r i e s the predation of the Beothic Indians. The Beothics became e x t i n c t i n the e a r l y 1800's and the l a s t wolf was k i l l e d i n 1911. I b e l i e v e t h a t the s t r u g g l e between caribou and wolf f o r s u r v i v a l i n the simple Newfoundland ecosystem r u l e d out the e v o l u t i o n of a system of s e l f -r e g u l a t i o n i n caribou. P i m l o t t (1967:275) i n d i s c u s s i n g why deer, moose and ca r i b o u apparently have not evolved i n t r i n s i c p o p u l a t i o n c o n t r o l s s t a t e d : " I t seems reasonable t o p o s t u l a t e t h a t . i t may be because they have had very e f f i c i e n t p r e d a t o r s , and the forces of s e l e c t i o n have kept them busy e v o l v i n g ways and means not of l i m i t i n g t h e i r own numbers but of keeping abreast of m o r t a l i t y f a c t o r s " . The wolf appears t o have the t r a i t s necessary t o l i m i t the numbers of ca r i b o u . The p o t e n t i a l r e productive r a t e of wolves i s g r e a t e r than c a r i b o u 89 ( c f . Rausch 1967). Wolves are v e r s a t i l e , mobile predators t h a t should be a b l e . " t o ^ s e a - r c f i ^ u t c a r i b o u i n most h a b i t a t s . The f o o t - l o a d i n g s of wolves and caribou i n snow are reasonably s i m i l a r (Nasimovich 1955). Both species avoid deep, s o f t snows (Nasimovich 1955). Wolves should be able t o f o l l o w c a r i b o u at a l l seasons except i n the s p r i n g when they pup. E r r i n g t o n (1946, 1956, 1967) f e l t t h a t canid p r e d a t i o n on ungulates was an-:.exception t o h i s g e n e r a l i z a t i o n t h a t predators took mostly surplus animals and d i d not l i m i t numbers. Evidence t h a t wolves may be able to l i m i t a c a r i b o u p o p u l a t i o n i s pro-vided by the growth of a c a r i b o u herd and a wolf p o p u l a t i o n i n c e n t r a l Alaska. From 1956 to 1963 the Nelchina Herd increased from 40,000 to 71,000 animals at a r a t e of 9 per cent per year (Skoog 1968). The wolves preying on t h i s herd increased from an estimated 12 animals i n 1953 t o perhaps 400 animals i n 1965 (Rausch 1967) or at a r a t e of 27 per cent per year. Burkholder (1959) reported t h a t a pack of 10 wolves i n t h i s p o p u l a t i o n d i v i d e d t h e i r hunting time about e q u a l l y between moose and c a r i b o u and i n a p e r i o d of 6 weeks k i l l e d 14 c a r i b o u . Skoog (1968) estimated t h a t t h i s pack would k i l l 12 c a r i b o u per wolf per year. At t h i s m o r t a l i t y r a t e the wolf p o p u l a t i o n i n 1955 (estimated at 35 animals, Rausch 1967) would have taken 1.5.per cent of the herd. In 1965 the wolf p o p u l a t i o n would have taken approximately 5 per cent of the c a r i b o u , and increase of 200 per cent i n 10 years. The wolf p o p u l a t i o n i n 1965 was about 1 animal per 50 square m i l e s . P i m l o t t (1967) i n d i c a t e d t h a t a maximum d e n s i t y of wolves i n North America might be 1 wolf per 10 square m i l e s . At t h i s d e n s i t y the wolves could have k i l l e d 24,000 caribou annually. These c a l c u l a t i o n s are based on a constant r a t e of p r e d a t i o n ; however as populations of both prey and predator expanded, wolves might take more caribou per wolf. Rausch (1967) reported an increase i n pack s i z e w i t h increased den-s i t i e s of wolves. Larger packs might increase k i l l i n g efficiency.;-. As caribou 90 i n c r e a s e d , the searching time of wolves would be .reduced. A d d i t i o n a l l y , there i s evidence t h a t c a r i b o u become more vu l n e r a b l e to predation i n very l a r g e herds during stampedes ( C r i s l e r 1956 and K e l s a l l I960). Elsewhere i n North America Murie (194'4) and Mech (1966) r e p o r t t h a t wolf p r e d a t i o n appeared to have s t a b i l i z e d the numbers of a mountain sheep (Ovis  d a l l i ) and a moose po p u l a t i o n during.short i n t e r v a l s of study. Both species produce twin c a l v e s and l i k e l y have b i r t h r a t e s higher than caribou ( c f . Buechner 1960 and P i m l o t t 1959). I f wolf p r e d a t i o n l i m i t e d the numbers of Newfoundland cari b o u i n the p a s t , what determined the upper l i m i t i n numbers of ca r i b o u before t h e i r growth was halted? For t h i s d i s c u s s i o n one assumes th a t the w o l f - c a r i b o u populations were not s t a b i l i z e d and c a r i b o u were i n c r e a s i n g . Such an unbalance could r e s u l t because the predator-prey r e l a t i o n s h i p was i m p e r f e c t l y density-depend-ent (Milne 1957) w i t h both species subject t o c a t a s t r o p h i c m o r t a l i t y f a c t o r s such as disease i n wolves or mass s t a r v a t i o n i n c a r i b o u . The p o p u l a t i o n l e v e l t h a t c a r i b o u would reach before p r e d a t i o n h a l t e d growth would depend on, (1) the i n i t i a l numbers of ca r i b o u when r became pos i t i v e , ' .(2) the value of r (wolf d e n s i t i e s i n v o l v e d ) , and (3) the l e n g t h of time that r remained p o s i t i v e . This model i s t h a t of the Andrewartha and B i r c h school of p o p u l a t i o n l i m i t a -t i o n (see Andrewartha and B i r c h 1954:656). Thus I b e l i e v e t h a t populations i n the past reached v a r i o u s u n p r e d i c t a b l e l e v e l s . The numbers of ca r i b o u about 1890-1900 may have been a major peak f o r the Newfoundland herds. For example, Cormack.(1822), the f i r s t white man to cross Newfoundland, t r a v e l l e d vast s e c t i o n s of the i n t e r i o r without seeing l a r g e numbers of animals. The abundant pop u l a t i o n of 1900 occurred between the d i s -appearance of the Indians and n e a r l y a l l the wolves, and at the s t a r t of the increase of l y n x . A l s o i n t h i s time the main herds were l i g h t l y hunted because 91 the Newfoundland r a i l w a y was not completed u n t i l about 1898 (Davis 1895). The herds probably had a high p o s i t i v e r a t e - o f - i n c r e a s e f o r many years be-tween the disappearance of wolves and the increase of l y n x p r i o r to heavy hunting. Lynx Pr e d a t i o n i n N a t u r a l S e l e c t i o n The adaptations of c a r i b o u e f f e c t i v e against wolves may place caribou at a disadvantage when they encounter l y n x . This would help e x p l a i n the high c a l f l o s s e s caused by l y n x i n t h i s i n v e s t i g a t i o n . L i n d r o t h (1963) concluded t h a t there was no p o s t - g l a c i a l land bridge between Newfoundland and Labrador. Thus carib o u may have been w i t h wolves but w i t h few or no l y n x f o r many thou-sands of years. Elsewhere I have suggested (Bergerud 1961a) t h a t the combination of a synchronized c a l v i n g season i n Newfoundland and the p o s t p a r t u r i e n t aggrega-t i o n s of does w i t h c a l v e s was an e f f e c t i v e defense against the open approach of wolves. This behaviour i s of l i t t l e defense against l y n x . The l y n x am-bushes prey and t r a v e l s most at n i g h t . In general a dispersed d i s t r i b u t i o n i s more e f f e c t i v e against predators than clumping, unless the cooperation be-tween members i s s u f f i c i e n t l y e f f e c t i v e t o overcome the disadvantages of con-c e n t r a t i o n ( H o l l i n g 1961 and S a l t 1967). Again, c a r i b o u apparently are adapted t o perceive motion; a f e a t u r e important i n d e t e c t i n g the approach' of a t e s t i n g wolf. Caribou u s u a l l y do not show alarm r e a c t i o n s to a man standing s t i l l and a crouched l y n x may not be avoided. The s e l e c t i o n by wolves takes place most o f t e n during a chase where.the s i c k , young, s e n i l e , and c r i p p l e d , become conspicuous (Murie 1944, C r i s l e r 1956, and Mech 1966). With l y n x , t h i s k i n d of c u l l i n g i s l a r g e l y absent. 92 Lynx pr e d a t i o n i s focused almost e x c l u s i v e l y on the young. The conspicuous prey f o r l y n x i s the a c t i v e c u r i o u s c a l f t h a t frequents t e r r a i n n e a r . s t a l k i n g • cover. Lynx p r e d a t i o n , i n the absence of wolves, has l i k e l y s t a r t e d the n a t u r a l s e l e c t i o n of Newfoundland car i b o u i n a new d i r e c t i o n . S e l e c t i o n may now fav o r the h i d i n g o f c a l v e s and w i l l l i k e l y strengthen the maternal bond. The d i s t a n c e between the dam and c a l f and the defense of the c a l f w i l l now l i k e l y take on more importance than running away. Again i t may be advantageous to have a longer c a l v i n g season w i t h widely dispersed animals r a t h e r than con-gregations at c a l v i n g . Caribou t h a t c a l f i n bleak t r e e l e s s h a b i t a t s l i k e l y now have an advantage. To c a l v e i n the open on the edge between bog and f o r e s t , i s t o court d i s a s t e r . However, the s t r u g g l e between lynx and caribou i s not l i k e l y as equal as t h a t between wolf and c a r i b o u . The l y n x s t i l l depends on the hare and i t s adaptations cannot depart too f a r from those which are e f f e c t i v e i n c atching them. Thus the c o n s t r a i n t s to adaption seem l e s s f o r c a r i b o u than l y n x . Caribou on the Avalon Peninsula show three behaviourisms l a c k i n g • i n the i n t e r i o r animals t h a t seem adaptions t o lynx and support the idea of such s e l e c t i o n pressure. The Avalon Herd has no s p e c i f i c c a l v i n g ground - the animals are w e l l d i s p e r s e d , the females do not form l a r g e p o s t - c a l v i n g aggre-g a t i o n s , and c a l v i n g i s spread over.three weeks r a t h e r than two weeks as i n the i n t e r i o r (Bergerud 1961a). P h y s i o g r a p h i c a l l y the Avalon Peninsula r e -sembles the i n t e r i o r barrens. There i s a h i s t o r y of wolves on the Avalon Pe n i n s u l a s i m i l a r to the i n t e r i o r . One d i f f e r e n c e i s t h a t the c l i m a t e on the Avalon i s more oceanic than i n the i n t e r i o r (Hare 1952). Gene flow.between the Avalon and I n t e r i o r herds has l i k e l y been s l i g h t s ince the connecting isthmus became w e l l t r a v e l l e d by people—perhaps 100 to 150 years ago. In t h i s I n t e r v a l the herd was reduced t o l e s s than 100 animals f o r many-years. The number of e f f e c t i v e breeding:stags was l i k e l y only 5 t o 10. N a t u r a l s e l e c t i o n i n small populations can pro.ceed very r a p i d l y (Ford 1965), and i t i s conceivable t h a t t h i s has i n f l u e n c e d the r a t e of adaption of the herd t o l y n x . The d i f f e r e n c e s i n behaviour between the two herds might p a r t i a l l y e x p l a i n the 1:2 per cent r a t e - o f - i n c r e a s e of the Avalon p o p u l a t i o n vs. the 4 per cent annual gain f o r the I n t e r i o r Herd. L a s t l y , I b e l i e v e t h a t t h i s study i s another reminder of the f r a g i l e balance between predator and prey i n i n s u l a r faunas. I t i l l u s t r a t e s the l o n g -delayed but f a r - r e a c h i n g e f f e c t of the i n t r o d u c t i o n of snowshoe hares, a new prey s p e c i e s , i n t o a r e l a t i v e l y simple ecosystem. 94 SUMMARY 1. The popu l a t i o n dynamics of the ca r i b o u on the i s l a n d of Newfoundland were i n v e s t i g a t e d 1957 t o 1967. H i s t o r i c a l i n f o r m a t i o n on po p u l a t i o n s t a t u s was secured 1900 t o 1956. 2. Four c a r i b o u herds were recognized and censused: the Northern Peninsula -450 animals i n 1958 and 400 animals i n 1966, the Avalon Peninsula Herd -125 animals i n 1957 and 720 animals i n 1967, the Humber R i v e r Herd -130 animals i n 1956 and 115 animals i n 1964, and the I n t e r i o r Herd -4600 i n 1957 and 6200 animals i n 1966. 3. The po p u l a t i o n of carib o u was estimated at 40,000 i n 19§0 and d e c l i n e d t o perhaps 1000 t o 2000 animals by 1930. 4. The percentage o f does, 2 - years and o l d e r , t h a t gave b i r t h t o s i n g l e calves was 84.5 per cent (n = 6657). E x c l u d i n g 2 - year o l d does, 94 per cent of the females were pregnant. 5. N a t u r a l m o r t a l i t y of a d u l t s , i n c l u d i n g a l l animals o l d e r than 6 months, was estimated a t 6 per cent f o r the Avalon P e n i n s u l a Herd. 6. N a t u r a l m o r t a l i t y of a d u l t s f o r the I n t e r i o r Herd was estimated at 4 per cent f o r does, y e a r l i n g s , and 6 month - o l d c a l v e s , and 9 per cent f o r stags. The m o r t a l i t y o f the t o t a l p o p u l a t i o n was 5 per cent. 7. Hunting m o r t a l i t y of a d u l t s i n the I n t e r i o r Herd was estimated.at 11 per cent f o r . s t a g s and 3 per cent f o r does. 8. The I n t e r i o r Herd increased when the percentage of calves i n the herd i n October exceeded.11 per cent f o r s e v e r a l consecutive years. 95 9. During 9 years there was no evidence t h a t calves died during the winter at greater r a t e s than a d u l t s i n the wi n t e r of 1958-59 calves may have died a t a grea t e r r a t e than a d u l t s . 10. Many calves d i e d i n the f i r s t summer of l i f e , 30 per cent i n the Avalon P e n i n s u l a Herd and 69 per cent i n the I n t e r i o r Herd. The a v a i l a b l e evidence suggested t h a t l y n x k i l l e d most of these c a l v e s . 11. The two major m o r t a l i t y f a c t o r s t h a t appear to have l i m i t e d p o p u l a t i o n growth of caribou i n Newfoundland 1900 t o 1967 are lyn x p r e d a t i o n o f calves and hunting m o r t a l i t y of a d u l t s . A combination of poor recruitment and high hunting m o r t a l i t y probably caused the d e c l i n e of the herds 1915 t o 1930. 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Stackpole Co., H a r r i s b u r g , Pennsylvania and the W i l d l . Mgmt. I n s t i t u t e , Washington,-D.G. 376 p. Nasimovich, A.A. 1955. The r o l e of the regime of snow cover i n the l i f e 102 of ungulates i n the U.S.S.R. Moskva. Akademiya Nauk SSSR. Can. W i l d l . Serv. T r a n s l . i n press. N e l l i s , C.H. £ L.B. K e i t h . 1968. Hunting a c t i v i t i e s and.success o f l y n x i n A l b e r t a . J . W i l d l . Mgmt. 32: 718-722. P e r r y , R. 1964-.. The world of the t i g e r . C a s s e l l and Co. L t d . , London. 236 p. P e t e r s , S.S.: £ J.M. King. 1959. Newfoundland cari b o u disease i n v e s t i g a -t i o n , 1958. Dept. Mines and Resources, W i l d l i f e D i v i s i o n Progress r e p o r t . 55 p. Peterson, R.L. 1955. North American moose. Univ. o f Toronto Press. 280 pp. P i m l o t t , D.H. 1959. Reproduction and p r o d u c t i v i t y . o f Newfoundland moose. J . W i l d l . Mgmt. 23: 381-401. . 1967. 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L i p p i n c o t t Co., P h i l a d e l p h i a , New York. 125 pp. Van Z y l l de Jong, C.G. 1966. Food h a b i t s of the lyn x i n A l b e r t a and the Mackenzie D i s t r i c t , N.W.T. Can. F i e l d - N a t u r a l i s t , 80: 18-23. 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 t o s o c i a l behaviour. Hafner P u b l i s h i n g Co., N.Y. 653 p. Young, S.P. 1958. The bobcat of North America. The Stackpole Co., H a r r i s b u r g , Pa. and W i l d l . Mgmt. I n s t i t u t e , Washington, D.C. 193 p. and E.A. Goldman. 1946.- The puma mysterious American cat. W i l d l . Mgmt. I n s t i t u t e , Washington, D.C. 358 p. APPENDIX I TABLES Table 1. Sex and age categories used during the study 105 Sex and Age Categories Spring Summer F a l l Winter C l a s s i f i c a t i o n s from Ground Stags Adult Large Medium Small S e n i l e 2-year o l d Does Adult Non-parous Pregnant With udder and c a l f With udder no c a l f Y e a r l i n g s Male Female Sex unknown Calves Male Female Sex unknown x x X X X X X X X X X X X C l a s s i f i c a t i o n s from h e l i c o p t e r Adult Stag Y e a r l i n g Doe C a l f C l a s s i f i c a t i o n s from fixed-wing a i r c r a f t Adult Stag Y e a r l i n g Doe C a l f Spring Summer F a l l Winter x X X X X X X X X X X 107 Table 2. Age composition of the I n t e r i o r Herd based on the lower mandibles of stags • Age i n Number of mandibles years 2 3 4-6 7-9 10+ T o t a l 1951-53* 6 15 17 7 1 46 1956-58 7 21 37 19 6 90 1961 . 13 23 29 34 12 111 1962 8 52 56 37 16 169 1963 6 10 65 19 17 117 1964 4 29 40 • 5 9 87 1965 8 11 44 6 4 73 T o t a l s 52 161 288 127 65 693 * inc l u d e s some females, remainder of c o l l e c t i o n stags Table 3. The age composition of caribou k i l l e d by hunters 1961-63,' from counts of a n n u l i i n i n c i s o r s . Age Number of.stags k i l l e d (years) 1961 1962 1963 T o t a l 13 8 6 27 3k 15 41 13 69 7 24 23 54 ' 5h 11 .11 28 50 6 11 7 24 Ik 6 5 10 21 8k 14 6 9 29 • 4 11 6 21 10^ 4 4 3 .11 nk 2 4 - 6 2 4 - 6 13k - - - -142g - - 1 1 15% - - - -16k - - 1 1 T o t a l s 84 . 129 107 320 109 Table 4. Caribou k i l l e d from the I n t e r i o r Herd during l e g a l hunting seasons 1935 t o 1966. Hunting Licenses Caribou Hunting Licenses Caribou Season Sold K i l l e d Season Sold K i l l e d 1935 33 6 1951 8669 369 1936 65 14 1952 6523 270 1937 82 14 1953 5196 266 1938 80 11 1954 5754 158 1939 100 20 1955 6696 183 1940 100 20 1956 8654 193 1941 234 45 1957 8797 205 1942 220 24 1958 102* 56 1943 294 35 1959 164 82 1944 296 24 1960 200 128 1945 2475 113 1961 300 185 1946 3846 159 1962 '354 243 1947 5048 177 1963 358 203 1948 5159 232 1964 336 161 1949 5930 221 1965 384 196 1950 7200 234 1966 763 366+ * 1935' t o 1957 one b i g game hunting l i c e n s e s v a l i d f o r e i t h e r one moose or one c a r i b o u , 1959 t o 1966 hunting allowed f o r stags only Table 5. Numbers of caribou from a e r i a l and t r a c k census T o t a l caribou Year Avalon Humber Northern I n t e r i o r Brunette Peninsula R i v e r P e n i n s u l a Herd* I s l a n d 1956 . 71** 130 1957 86** 100 4600 1958 86** 105 450 1959 H I * * 100 4800 1960 206** 130 1961 350 6100 1962 409- 114 17 1963 — 99 27 1964 508 115 5700 40 1965 51.8 54 1966 650 400 6200 78 1967 720 100 * La P o i l e p o p u l a t i o n not i n c l u d e d , estimated 1964 at 1300 animals and 1966 at 1500 ** b e l i e v e d t o be undercounted in T o t a l Caribou Year La P o i l e Buchans Grey Sandy Pot Middle Mount R i v e r P l a t e a u R i v e r Lake H i l l Ridge Peyton 1960 500 450+ 1200 75 250 200 ? 1962 650 1000 1300 73 544 502 178 1963 692 643 1800 212 420 265 165 1964 ? 1341 1772 123 275 358 257 1965 800 892 2400 161 333 560 253 112 Table 7. Age of females c o l l e c t e d i n :June and -reproductive c o n d i t i o n T o t a l Sample Nonparous Age i n Pregnant Ovulated Never years p r i o r f a l l ovulated 2 1 8 3 2 1 6 H-6 8 2 1 7-9 1 1 — 10+ 5 5 113 Table 8. Parous does i n the I n t e r i o r Herd i n per cent based on udder counts i n June Parous females (2-years and o l d e r ) Year T o t a l sample Buchans Grey Pot Middle Other T o t a l s i z e P l a t e a u R i v e r H i l l Ridge pop. a l l pop. 1957 245 94.2 93.2 85.5 91.4 1958 464 81.9 84.7 83.2 1959 932 92.1 92.4 88.4 91.1 1960 654 76.6 79.6 76.8 91.4* 78.1 1961 362 76.3 66.2 72.1 1962 742 76.3 70.8 82.6 77.2 1963 878 93.6 89.1 90.4 91.7 1964 286 88.8 94.8 91.3 1965 534 84.2 95.7 79.0 . 85.0 1966 772 79.1 92.6 85.3 .81.3** 83.7 1967 788 80.4 89.5 77.7 88.2*** 83.2 Weighted Means 85.2 83.1 91.0 83.6 83.6 84.5 sample s i z e (2085) (1681) (1750) (768) (378) (6657) * Sandy Lake ** La P o i l e s'cftj't Mt. Peyton 114 Table 9. The sex r a t i o o f adu l t s i n the I n t e r i o r Herd . i n October and November T o t a l Percentag e of.stags Year sample "La P o i l e Buchans Grey- Sandy Pot Middle T o t a l s i z e R i v e r P l a t e a u R i v e r Lake H i l l Ridge ± .95 c. 1. 1957 1265 33 32 31 25 23 30 32.2± 2. 6 1958 1306 — — 31 37 28 — 31.9± 2. 5 1959 437 — — — . 34 15 — 27.9± 4. 2 1960 266 — — 27 30 — — 28.6± 5. 4 1961 101 — — - — ' 30 — — 29.7± 8. 9 1962 425 — — 36 29 — — 30.8± 4. 4 1963 1152 28 26 29 18 21 29 24.3± 2. 5 1964* 597 31 34 35 27 28 40 31.7± 3. 7 1965 748 28 25 27 21 — 36 25.8± 3. 1 1966 780 19 .21 28 23 — — 22.8± 2. 9 * biased towards stags since count made on the peak days of r u t : Regression of stag percentages on years (excludes 1964) was: Y =83.90 - 0.910 X where X equals the l a s t two d i g i t s of the year Table 10. Age composition of caribou i n the Buchans P l a t e a u p o p u l a t i o n captured at Lake V i c t o r i a i n November 1963 and 1964 115 Age T o t a l Animals Percentage of Animals (Years) Stags Does T o t a l Stags Does T o t a l k 12 15 •27 28.8 15.2 19.2 ik 4 • 5 9 9.5 5.1 6.4 2k 2 4 6 4.8 4.0 4.3 3k 9 14 23 21.4 14.2 16.3 ±k 3 16 . 19 7.1 16.2 13.5 5k 4 9 13 9.5 9.1 9.2 6k 3 9 . 12 7.1 9.1 8.5 ik - 4 4 4.0 2.8 8k 1 6 7 2.4 6.1 5.0 9k - 1 1 1.0 0.7 iok - 1 .' 1 ' 1.0 0.7 uk - 3 . 3 3.0 2.1 12k - - -13k - 1 1 1.0 0.7 mk - 1 1 •1.0 0.7 unknown 4 10 14 9.5 10.1 9.9 To t a l s 42 99. 141 . 100.1 100.0 99.9 mean age 3g-14Jg years: stags 3 .0 years and does 4. 7 years mean age 3%-14lg* years : stags 4.8 years and does 6.0 years * c a l c u l a t e d t o reduce hunter '. bias of not shooting k-2k y e a r - o l d stags Table. 11. C a l c u l a t i o n of m o r t a l i t y r a t e s f o r the Avalon Pen i n s u l a Herd 116 T o t a l Per cent T o t a l Population N a t u r a l Year caribou i n calves i n number of minus m o r t a l i t y October October calves calves per cent 1961 350 21.3 75 275 1962 409 19.6 80 329 6.0(21/350) 1963 . 14.5 — 1964 508 17.7 99 409 1965 518 9.8 51 467 8.1(41/508) 1966 '650+27* 26.1 170 507 2.1(11/518) 1967 720+26+25* '* 19.4 140 631 6.8(46/677) N a t u r a l M o r t a l i t y Rate 5.8(119/2053) 1966 650*** 26.1 170 480 7.3(38/518) 1967 720*** 19.4 140 580 10.8(70/650) M o r t a l i t y Rate 8.4(170/2026)**** * plus 27 k i l l e d i n September 1966 ** plu s 26 k i l l e d i n i September 1967 and 25 k i l l e d i n September 1966 (27-C27 x .06) *** These f i g u r e s used i n comparison w i t h r a t e - o f - i n c r e a s e s t a t i s t i c s based on a herd increase from 350 i n 1961 t o 720 i n 1967 and in c l u d e hunting m o r t a l i t y **** in c l u d e s f i g u r e s from 1962 and 1965 (above) 117 Table 12. Percentage of calves at 6-months-of-age i n the I n t e r i o r Herd T o t a l Per Cent Calves Year Caribou Western C e n t r a l Eastern Weighted i n La Buch- Grey Sandy Middle Pot means ± .95 Sample P o i l e ans R i v e r Lake Ridge H i l l conf. l i m i t s 1957 2057 6.3 8.3 4.4 3.8 9.0 7.2 5.5 ± 1.0 1958 2253 A * 16.7 13.0 10.5 16.0 15.0 ± 1.5 1959 621 17.5 20.1 19.0 ± 3.1 1960 1057 15.1 9.9 10.8 A 12.6 ± 2.0 1961 331 * 13.0 4.4 10.6 ± 3.3 1962 1025 10.9 5.7 8.5 3.3 7.8 ± 1.6 1963 1567 13.0 8.2 8.9 13.6 A 4.3 8.4 ± 1.4 1964 725 17.3 17.6 9.2 12.3 51 6.3 11.6 ± 2.3 1965 893 25.7 15.8 8.3 10.8 A 15.1 ± 2.3 1966 1126 :22.6 21.8 10.8 11.6 17.6 ± 2.2 1967 839 27.1 26.4 20.2 ' — - 24.7 ± 2.9 Weighted Means . 19.8 15.2 11.3 9.9 10.3 11.1 13.4 ± 0.6 Sample Sizes (1418) (2457) (2529) (3397) (564) (2129) (12 ,494) * percentages not shown f o r samples l e s s than 100 animals 118 Table 13. Composition o f the I n t e r i o r and Avalon P e n i n s u l a herds i n October - November based on the assumption t h a t c a l f m o r t a l i t y beyond 6-months-of-age i s s i m i l a r t o th a t of a d u l t s Composition of the herd i n per cent Year I n t e r i o r Avalon Peninsula Stags* Does Yrs. Calves Sta£ Does Yrs. Calves 1957 28. ,0 59. .3 7. ,2 5. 5 28, .3 42. .7 11. ,6 17. ,4 1958 25. .0 55. .3 4. ,7 15. 0 26. ,7 40, .5 14. .2 18. ,6 1959, 20. ,8 48. .0 12. .2 19. 0 23. ,6 35, ,7 13. ,6 27. ,1 1960 20. .8 50. .0 16. ,6 12. 6 22, .2 33, .5 20. .7 23. .7 1961 22. .2 55. .9 11. ,3 10. 6 23, ,9 36, .2 18, .6 21, ,3 1962 22. .3 60. ,1 9. ,8 7. 8 25, .4 38, .3 17. .3 19. .6 1963 22. ,5 62, .0 7. ,1 8. 4 27, .3 41, .4 16, .8 14, .5 1964 20. .8 60. .2 7. ,4 11. 6 28, ,2 42, .6 12, .0 17, ,7 1965 18. .6 • 56, .5 9. .8 15. 1 29, .5 44, .7 16. .0 9, .8 1966 16. ,7 53, .3 12. .4 17. 6 26, .5 40, .1 7, .2 26, .1 1967 14. .2 • 47, .8 13, ,3 24. 7 23, .7 35, .8 21, .0 19, .5 Means .21. .1 55. .3 10. .3 13. 4 25, .9 39, .2 15. .4 . 19, .6 * sex r a t i o of the I n t e r i o r Herd based on the r e g r e s s i o n Y =83.90 -0.91 X, Table 9: sex r a t i o of the Avalon Herd based on 39.8 per cent males, counts made i n 1956, 1958, 1959, 1960, 1961, and 1964, n = 518. Table 14. Causes o f n a t u r a l . m o r t a l i t y o f a d u l t s , 1957 t o 1967 M o r t a l i t y Number dying f a c t o r females males I n t e r a c t i o n s Locked A n t l e r s — 4 Gored 1 2 Broken neck — 3 Unknown — 6 Died i n p a r t u r i t i o n 6 S e n i l i t y 1 2 Accidents Drowned 2 C r i p p l e d f r o n t legs 1 2 Nose-bots i n c r a n i a l c a v i t y - 1 Pred a t i o n Lynx 1 Bear - 1 120 Table 15. Common p a r a s i t e s of Newfoundland car i b o u Common name S c i e n t i f i c Number of Caribou Minimum name examined frequency Warble F l y Roundworm Nose Bot Roundworm Rumen Fluke Roundworm Roundworm Lungworm Roundworm Oedemagena t a r a n d i  O s t e r t a g i a mossi  Cephenomyia trompe  O s t e r t a g i a gruhneri  P aramph i s t omum sp. Elaphostrongylus sp. Pneumostrongylus sp. D i c t y o c a u l i s (Micrurocaulus) e c k e r t i  Nematodirus f i l i c o l l i s and or Nematodierella 51 14 60 9 26 9 5 37 100 86 83 78 69 55 40 38 l o n g i s s i m e s p i c u l a t a 35 47 121 Table 16. The p r o p o r t i o n of males from b i r t h t o 12 months of age i n annual cohorts i n the I n t e r i o r Herd Per Cent Male Year At 1-4 5-6 10 12 b i r t h weeks months months months 1957 — — • — — 44(43) 1958 54(35)* 50(121) 35(204) 35(23) 35(69) 1959 50(34) 49(273) 36(58) — 33(91) 1960 52(86) 49(197) **(19) 45(58) 32(122) 1961 56(57) 45(40) **C5) — 39(108) 1962 49(67) 44(251) **(19) — 41(74) 1963 43(35) 46(424) 40(52) — **(13) 1964 51(76) 42(102) 40(30) — 60(43) 1965 — 50(265) — — 46(142) 1966 ft*(12) 55(351) — — 48(109) 1967 — 47(261) — — — T o t a l s ± 95% C L . 52±5(402) 48±2(2285) 38±5(387) 42±12(81) 41±3(814) * sample s i z e s i n parentheses ** percentages not l i s t e d f o r l e s s than 20 animals Table 17. C a l c u l a t i o n of s u r v i v a l o f calves i n the Avalon Peninsula Herd t o 6-months-of-age Year Per Cent Per Cent of Herd Newborn Per cent of % s of x calves parous Adult 2-Year calves/100 calves i n Herd calves born doesCl) doe(2) doe(3) caribou(4) June(5) Nov.(6) 6 mo.(7) 1958 80.3 42.7 6.1 39.2 28.2 18.6 56.4 1959 75.8 40.5 7.5 36.4 26.7 •27.1 98.9 1960 74.1 35.7 7.2 31.8 24.1 23.7 94.9 1961 62.2 33.5 11.0 27.7 21.7 21.3 94.7 1962 67.0 36.2 9.8 30.8 23.5 19.6 77.0 1963 70.3 38.3 9.2 33.4 25.0 14.5 • 49.4 1964 73.5 41.7 8.6 37.0 27.0 17.7 56.4 1965 79.8 42.6 6.3 39.0 28.1 9.8 27.0 1966 76.0 44.8 8.3 40.4 28.8 26.1 84.7 1967 86.4 40.1 3.8 37.9 27.5 . 19.5 '61.9 Means 74.5 39.6 7.8 35.4 26.7 19.8 70.1 C a l c u l a t i o n s : .Cl) c a l c u l a t e d from the r e g r e s s i o n Y = 100.12 - 1.40X (Figs.- -7) assumed t h a t the f e r t i l i t y of does on the Avalon Pen i n s u l a i s s i m i l a r t o t h a t i n the I n t e r i o r Herd. (2) and C6) from Table 13, (6) based on October-November c a l f counts (3) from y e a r l i n g s i n Table 13 c o r r e c t e d f o r females on b a s i s of sex r a t i o of calves i n October (4) ( a d u l t does + 2-year does) x (per cent parous does) (5) (newborn c a l v e s ) / (newborn calves + 100) (7) sample c a l c u l a t i o n s 1958: s^ = (18.6 x 71.8 x 97.0) / (28.2 x 81.4), 81.4 = 100.0 - 18.6,.71.8 = 100.0 - 28.2, 97.0 = a d u l t s u r v i v a l \ year Table 19. The age composition of carib o u dying from n a t u r a l causes Age Number found* Percentage < 1 Month 47 52 1-3 Months 19 21 3-6 Months 13 14 6-12 Months 6 6 C a l f Unknown 6 6 C a l f T o t a l 91 99 1-2 Years 0 — 2-3 Years 6 14 3-4 Years 5 12 4-6 Years 16 38 7-9 Years 9 21 10+ Years 6 14 Adult T o t a l 42 99 * does not in c l u d e calves l i s t e d i n Table 26 124 Table 18. Per cent calves i n the Humber R i v e r Herd i n the F a l l and Winter Year born T o t a l caribou T o t a l Caribou C l a s s i f i e d Per Cent Calves ± 95 % C.L.* 1957 100 80 • 5.0 ±2.1 1958 105 80 - 21.6 ± 4.4 1959 100 70 35.7 + 6.1 1960 130 130 10.0 1961 65 10.8 ±4.8 1962 114 74 6.8 ± 3.4 1963 99 87 12.3 ± 2.4 Means 108 84 14.6 * 95 per cent C L . = (1.96/ p x q / n) (/ N-n / N) ** herd estimated at 108 animals Table 20. C a l c u l a t i o n o f s u r v i v a l o f calves of the I n t e r i o r Herd u n t i l 6-months-of-age 125 Year Per Cent Adul t Does 2 Yr. Does Newborn Per Cent of % s of X calves parous per 100 per 100 calves/100 calves i n herd calves born d o e s ( l ) caribou(2) caribou(3) caribou(4) June(5) Nov.(6) 6 mo.(7) 1958 89.5 59.3 4.3 56.0 36.2 . 15.0 29.4 1959 92.4 55.3 2.6 53.5 34.8 19.0 41.5 1960 79.1 48.0 7.9 44.2 30.7 12.6 30.8 1961 73.5 50.0 10.9 44.8 30.9 10.6 25.1 1962 82.5 55.9 7.0 51.9 34.2 7.8 15.4 1963 85.3 60.1 6.0 56.4 36.1 8.4 15.3 1964 89.2 62.0 4.1 60.0 37.5 11.6 20.7 1965 88.4 60.2 4.3 •57.0 36.3 15.1 29.5 1966 83.9 56.5 4.7 51.3 33.9 16.7 36.9 1967 79.0 53.3 6.6 47.3 32.1 24.7 65.6 Means 84.3 56.1 5.8 52.3 34.3 14.2 31.0 C a l c u l a t i o n s : (1) c a l c u l a t e d from the r e g r e s s i o n Y = 100.12 - 14.40X ( F i g s . 7) (2) from Table 13 (3) from y e a r l i n g s Table 13, sex r a t i o s from Table 16 (4) ( a d u l t does + 2-year does) x (per cent parous does) (5) (newborn c a l v e s ) / (newborn calves + 100) (6) October-November composition counts Table 12 (7) sample c a l c u l a t i o n s f o r 1958: s = (15.0 x 63.8 x 94.5) / (36.2 x 85.0) 63.8 = 100.0 - 36.2, 85.0 = 100.0 - 15.0, 94.5 = a d u l t s u r v i v a l \ year 126 Table 21. Comparison o f observations o f y e a r l i n g c a r i b o u made by the w i l d l i f e s t a f f i n May and June on various c a l v i n g grounds of the I n t e r i o r Herd T o t a l Y e a r l i n g Per 100 Does Year sample Buchans Grey Pot Middle Other Weighted s i z e P l a t e a u R i v e r H i l l Ridge Areas Means* 1957 1322 4.5 — 2.2 0.5 2.9 1958 1917 9.5 — 3.6 2.5 — 5.4 1959 2331 10.9 7.5 14.6 8.9 10.1 1960 2788 22.7 17.1 22.6 28.6 47.5 28.7 1961 1846 • 21.6 — 10.6 — 23.9 21.0 1962 1656 14.0 11.9 4.3 13.4 17.5 12.3 1963 1675 7.3 11.5 1.0 6.6 6.3 7.4 1964 370 7.1 A 2.6 — — 6.6 1965 806 — 6.2 — 7.3 — 6.4 1966 927 — 10.6 4.7 27.5 35.2 19.9 1967 863 — 14.1 14.7 21.2 18.5 Weighted Means 12.2 12.1 8.1 12.9 — 12.7 Sample Sizes (4895) (3113) (3372) (2713) (2409) (16,501) * f i g u r e s not shown f o r samples of l e s s than 100 animals Table 22. The percentage of young carib o u at 6 and 24-months-of-age 127 Animals Does C l a s s i f i e d Winter Exposed Per Cent of Year Counted 2 Years L a t e r to M o r t a l i t y p o p u l a t i o n at 6 Mo.* Adult 2 Years As Calves As Yrs. 6 Mo.** 24 1957 796 908 24 1957-58 1958-59 6.9 ± 1.8** 5.0 1958 1443 584 35 1958-59 1959-60 16.3 ± 1.9 9.5 1959 239 320 41 1959-60 1960-61 21.3 ± 5.2 .' 18.3 1960 677 427 34 1960-61 1961-62 13.1 ±2.5 12.9 1961 216 211 19 1961-62 1962-63 13.0 ±4.5 14.8 1962 526 273 13 1962-63 1963-64 7.8 ± 2.3 8.9 1963 912 512 22 1963-64 1964-65 6.9 ± 1.6 8.1 1964 339 487 18 1964-65 1965-66 6.8 ± 2.7 8.6 1965 255 750 38 1965-66 1966-67 9.4 ± 3.6 10.5 * i n c l u d e s only those populations i n which both June counts of does and October c a l f counts were a v a i l a b l e . ** 95 per cent confidence l i m i t s *** a d u l t stags c a l c u l a t e d on the b a s i s or the r e g r e s s i o n Y =83.90 -0.910 X(Table '9), 2 y e a r - o l d stags c a l c u l a t e d on the b a s i s of the percentage o f males i n cohorts 5-12 months-of-age (Table 16), and 2-year-old-does correc t e d on the assumption t h a t 38.45 per cent of the young does were not recognized Table 23. M o r t a l i t y of calves by 2-4 weeks of age based on counts of does with udders w i t h and without calves Year Females C a l f M o r t a l i t y i n Per Cent calves i n Buchans Grey Pot Middle Weighted born sample Pl a t e a u R i v e r H i l l Ridge Means 1957 165 33 — 35 — 34 1958 183 — — 16 — 16 1959 581 9 — — 6 8 1960 249 — 33 37 — 35 1961 245 14 — 19 — 16 1962 481 18 49 26 — 32 1963 328 27 — 44 — 37 1964 261 17 — 65 — 37 1965 454 — . 38 51 15 . 35 1966 339 — 49 27 37 1967 589 — 30 21 17 24 Weighted Means 17 • 38 32 11 27 Sample Sizes (953) (934) (1502) (486) (3875) 129 Table 24. Loss of calves u n t i l 6-months; -of-age i n 1957 Month Calves observed per 100 does and Buchans Grey Pot H i l l and Middle Week Pla t e a u R i v e r Sandy Lake Ridge B i r t h , May 4 94 93 86 June 1 72 67 53 June 2 73 59 — June 3 — 57 48 June 4 60 — — J u l y 4 41 31 — August 4 7 — — September 3-4 6 6 — October 1 27 7* — October 2 — 6* — October 3 — 9* — October 4 g ft — 16 November 3 13 8* — 13 November 4 .13 — — T o t a l c a r i b o u c l a s s i f i e d 1449 703 2758 769 * The apparent increase i n the number of calves; per 100 does from t h a t shown f o r e a r l i e r counts l i k e l y r e s u l t e d from sampling e r r o r s Table 25. Percentage of calves i n the I n t e r i o r Herd i n f a l l based on hunter l i c e n s e r e t u r n s Hunting Caribou Per Cent Calves Season i n Sample ' ± .95 Conf. L i m i t s 1951 653 11.5 + 2.4 1952 440 8.2 + 2.6 1953 862 7.3 + 1.7 1954 499 5.6 + 2.0 1955 290 5.5 + 2.6 1956 434 5.4 + 2 . 1 \ 1957 681 6.9 + 1.9 1958 217 11.1 + 4.2 1959 567 13.5 + 2.8 1960 1002 13.7 + 2.1.,. 1961 1646 12.2 + 1.6 1962 1699 10.0 + 1963 1399 10.9 + 1.6 1964 1193 13.4 + 1.9 1965 1389 13.4 + 1.8 1966 N 1641 14.9 + 1.7 * there are f o u r runs i n the above s e r i e s which i s a s i g n i f i c a n t departure from a random s e r i e s at the 95 per cent confidence l e v e l ( S i e g e l 1956) Table 26. Causes of n a t u r a l m o r t a l i t y of calves 1957 t o 1967 131 Causes of Number of Calves M o r t a l i t y Females Males Sex Unknown Disease and i n f e c t i o n s P a s t e u r e l l a multocidav. 27 30 27 B r a i n or lung abscesses 2 — 1 I n f e c t e d u m b i l i c a l cord 2 — 1 Pneumonia — 1 1 B i r t h anomalies Breach b i r t h — — 6 S t i l l b i r t h (cause unknown)* 2 2 1 P a r a l y s i s carpus extensor 1 — — B l i n d 1 — — Legs deformed — 1 — Subaortic s e p t a l defect 1 — — C l e f t l i p — — 1 Accidents A n t l e r stab 1 1 — Drowned — — 2 Trampled — 1 — Mired bog hole — 1 — P r e d a t i o n Lynx 3 1 — Bear . — — 1 P o s s i b l e winter s t a r v a t i o n — — 2 Tot a l s 40 38 43 * 26 animals t e s t e d f o r B r u c e l l o s i s , a l l negative (Peters' £• •' King 1959) Table 27. Decline of the lynx p o p u l a t i o n from t r a p p i n g at Middle Ridge, 1965. Date T o t a l lynx trapped Males Females T o t a l February 15-28 10 2 12 March 1-14 3 1 4 March 15-31 8 6 14 A p r i l 1-14 1 2 3 A p r i l 15-30 - - -May 1-14 2 " i 3 May 15-31 1 2 3 June 1-14 1 - 1 T o t a l s 26 .' 14 40* * 4 ly n x trapped date unknown APPENDIX I I REPRODUCTIVE HISTORY OF THE CARIBOU AS REFLECTED IN THE ANATOMY AND HISTOLOGY OF THE OVARIES AND UTERUS by H . T . G i e r and G.B. Marion Kansas State U n i v e r s i t y . A l l o v aries r e c e i v e d have been weighed, measured, and hand s l i c e d i n t o s e c t i o n s of 2 t o 2.5 mm. t h i c k n e s s . Corpora l u t e a , corpora r u b r a , and f o l l i c l e s were measured and t a b u l a t e d . Representative s e c t i o n s from each ovary were embedded i n p a r a f f i n , s e c t i o n e d at 8p, and one s l i d e from each was s t a i n e d i n each of (1) haematoxylin-acid f u c h s i n , (2) Mallory's t r i p l e s t a i n , and (3) p e r i o d i c a c i d S c h i f f (P.A.S.) Sections were s t u d i e d c o n c u r r e n t l y by Dr. G.B. Marion and me, and s i g n i f i c a n t s t r u c t u r e s analyzed and noted. The u t e r i were weighed a f t e r removal of excess mesenteries, and measurements were taken on c e r v i x , body, and both horns. The horns were s p l i t along the d o r s a l w a l l and opened f o r examination and measure-ment of caruncles. Representative t r a c t s were photographed i n t a c t and again a f t e r the d o r s a l w a l l was removed. H i s t o l o g i c a l s e c t i o n s were taken through one u t e r i n e horn, and i n s e v e r a l specimen, from the vagina. RESULTS Ovaries from 58 c a r i b o u were examined. The\normal.ovaries were 16-20 mm l o n g , 10-15 mm broad, 6-12 mm t h i c k , and weighed 0.5 t o 1.2 gm. The ovary c o n t a i n i n g the corpus luteum of pregnancy weighed 1.1 t o 2 gm. Each ovary was attached at both ends i n the ovarian ligament, and along the a n t e r i o r - v e n t r a l border by the mesovarium. The o v i d u c a l f u n n e l attaches t o the l a t e r a l end of the ovary and i s i n loose contact w i t h the a n t e r i o - d o r s a l surface of the ovary. Ovaries contained. f o l l i c l e s at a l l seasons of the ..year, regardless of the s t a t e of reproduction. Even the ovaries from two-year o l d does contained s e v e r a l f o l l i c l e s from 2 t o 5 mm diameter i n June, a l l the . 135 l a r g e r ones being a t r e t i c . In October and November, a l l non-pregnant does had one t o f o u r f o l l i c l e s 3 t o 7 mm diameter which appeared' t o be h e a l t h y , f u n c t i o n a l s t r u c t u r e s . F o l l i c l e s of 6 t o 8 mm may o v u l a t e . A corpus luteum, formed a f t e r o v u l a t i o n , r e g u l a r l y enlarges t o 10-12 mm and i s lemon ye l l o w t o orange i n f o r m a l i n - f i x e d specimens. Such t r e a t -ment does not s e r i o u s l y change the c o l o r of corpora l u t e a i n dogs and cows, so probably does not i n caribou. A corpus luteum reaches maximum s i z e , i n a few days (probably 5-8) and maintains f u l l f u n c t i o n a l c o n d i t i o n u n t i l two or three days before the next o v u l a t i o n - b a r r i n g conception. In the event of pregnancy, the corpus luteum remains f u l l s i z e , and apparently f u l l y f u n c t i o n a l u n t i l a f t e r p a r t u r i t i o n , then regresses over a two month p e r i o d t o a mass of blood v e s s e l s w i t h s m a l l c l u s t e r s of "rubra" c e l l s between. The "rubra" c e l l s are r a t h e r l a r g e , f a t t y c e l l s t h a t contain considerable q u a n t i t i e s of a red-brown pigment t h a t gives the corpora r u b r a t h e i r chara-c t e r i s t i c r e d d i s h c o l o r . Corpora rubra regress t o a reddish-brown mass approximately 2x3x4 mm i n about 6 months, and t o a s t r i n g about 1x2x4 mm i n a year. They may remain g r o s s l y v i s i b l e and h i s t o l o g i c a l l y d etectable f o r s e v e r a l y e a r s , accounting f o r 8 t o 12 corpora i n o l d does. Estrous c y c l e s of the past season were determinable by the s i z e of the corpora rubra (over 2 mm i n the l e s s e r dimension) and the loose mass of blood v e s s e l s w i t h s m a l l lumena and t h i c k w a l l s . The blood v e s s e l s were n e a r l y gone w i t h i n a year. Regressing f o l l i c l e s were never found t o l u t e i n i z e or produce "accessory corpora l u t e a . " Rather, the t y p i c a l process of a t r e s i a , found i n f o l l i c l e s of a l l s i z e s at a l l seasons.consisted of (1) loosening and degeneration of the c e l l s of the stratum granulosum, (2) aedema of the theca i n t e r n a , (3) g r a d u a l , i r r e g u l a r c o l l a p s e of the f o l l i c l e , and (4) h y a l i n i z a t i o n of the remaining theca, l e a v i n g a s m a l l w h i t i s h streak b a r e l y v i s i b l e w i t h the unaided eye, but r e a d i l y d i s t i n g u i s h a b l e i n h i s t o l o g i c a l preparations as u n i f o r m l y . s t a i n e d masses with few n u c l e i . These h y a l i n e remnants p e r s i s t f o r months or even years - there were always l a r g e numbers i n the o v a r i e s of o l d does. These f o l l i c u l a r remnants at times appear y e l l o w i s h t o yellow-orange and may be mistaken f o r o l d corpora rubra. We have been able t o p o s i t i v e l y d i f f e r e n t i a t e between h y a l i n i z e d f o l l i c l e s and o l d corpora r u b r a only by h i s t o l o g i c a l s e c t i o n s . About h a l f o f the pregnant or recent postpartum does had conceived during t h e i r f i r s t e s t r u s - there was no l a r g e corpus rub rum present. Twelve does had passed one heat p e r i o d , and conceived during the second. None of those examined had conceived during a t h i r d e s t r u s , as evidenced by the presence of a s i n g l e r e g r e s s i n g corpus l u t e a during e a r l y pregnancy or a l a r g e corpus r u b r a during l a t e pregnancy. Only h a l f of the does th a t were s p e c i f i c a l l y marked " l a t e c a l v i n g " had f a i l e d t o conceive during the f i r s t e s t r u s . C a l v i n g time i n d i c a t e s e i t h e r an e a r l y l o s s of the conceptus and r e t u r n t o heat about the time f o r the t h i r d estrous p e r i o d , or a slowness i n coming i n t o heat, thus passing the f i r s t p e r i o d , then p o s s i b l y f a i l i n g t o conceive at t h e i r " f i r s t " p e r i o d at the time of normal second p e r i o d s . Many cows (Bovine) (up t o 15% of a l l conceptions) los e t h e i r embryos between 16 and 30 days, then r e t u r n t o estrus i n another 5 t o 10 days. Why not e x p l a i n some of these l a t e calves the same way when a s i n g l e corpus rubrum i s present? No case of two f u n c t i o n a l corpora l u t e a was found; In two o v a r i e s , newly formed corpus luteum of 1 or 2 days age (6x5x5 mm) was.found-with a r e g r e s s i n g corpus luteum of 4x4x3 mm, cases t h a t could be confused by-gross observation as two corpora l u t e a . In two mid pregnancies, the l a r g e "corpus luteum of pregnancy" was accompanied by a s m a l l e r corpus, i n t e r -p r e t e d t o be the corpus luteum of the previous c y c l e , saved from complete r e g r e s s i o n by the f a c t o r s t h a t s t i m u l a t e d formation of the new corpus luteum. A second o v u l a t i o n , a f t e r conception, as reported by Halazon i n the e l k i s not i n d i c a t e d . In f a c t , the occurrence of ten cases i n which there was no corpus rubrum accompanying the f u n c t i o n a l corpus luteum i n pregnant does d e f i n i t e l y c o n t r a - i n d i c a t e s such procedure i n caribou. The s i z e and c o n d i t i o n of the uterus provides co n c l u s i v e evidence as to previous pregnancy. There are f o u r c r i t e r i a , any one of which can be used d e c i s i v e l y . 1. Weight. The non-parous t r a c t , severed from the vagina immediately p o s t e r i o r t o the c e r v i x and f r e e d from excess f a t and mesometria, weighs between 15 and 35 grams; the p r e v i o u s l y parous t r a c t weighs over 60 grams. I t i s probable t h a t a non-parous animal i n or approaching e s t r u s would have a uterus approaching or even surpassing the 60 gram l i m i t . A postpartum uterus regresses t o about 100 grams i n two months a f t e r p a r t u r i t i o n . 2. Diameter of u t e r i n e horn. The never-pregnant u t e r i n e horn i s round i n cross s e c t i o n and was never found t o exceed 10 mm i n diameter at the a n t e r i o r curvature. In June, the'..average non-parous horn was 5 t o 7 mm. Once a uterus has expanded t o . c a r r y a conceptus, i t . n e v e r r e t u r n s t o the o r i g i n a l roundness; r a t h e r i t i s d i s t i n c t l y f l a t t e n e d , appearing as a thickened extension of the mesometrium over 12 mm broad and one-half t o two-thirds as t h i c k . 138 3. S i z e of caruncles. When a u t e r i n e horn i s s p l i t along i t s d o r s a l surface and layed open, a s e r i e s of 2 t o 4 ( u s u a l l y 3) car-uncles can be seen extending i n t o the u t e r i n e lumen from the meso-m e t r i a l border. In the never pregnant u t e r u s , these caruncles are t h i n blades about 1 mm t h i c k , 2 t o 2.5 mm wide and 20 to.60 mm long, f r e q u e n t l y overlapping so t h a t a cross s e c t i o n of the uterus may cut through the main p o r t i o n of one and through a t h i n n e r e l o n g a t i o n of another. In the p r e g n a n t • t r a c t , the caruncles enlarge t o many times t h e i r o r i g i n a l s i z e , forming the cores of the "placentomes" (maybe you c a l l them "cotyledons"). A f t e r p a r t u r i t i o n , the caruncles s h r i n k r a p i d l y but never r e t u r n t o pre-pregnant s i z e , u s u a l l y t o no l e s s than 2 mm t h i c k and 6 or 7 mm broad. 4. Vascular bed. During pregnancy, the. v a s c u l a r i t y o f the car-uncles and the u t e r i n e w a l l i n general i s increased t o p o s s i b l y 500 times what i t was i n the v i r g i n uterus. The blood v e s s e l s , once expanded, never s h r i n k t o pre-pregnant s i z e , and the remaining blood v e s s e l s c o n s t i t u t e the mass t h a t keeps the caruncles from s h r i n k i n g t o pre-pregnant s i z e . The c o n d i t i o n of the v a s c u l a r bed i s i n d i c a t e d by enlarged, sometimes almost " v a r i c o s e v e i n " c o n d i t i o n on the s u r f a c e , but i s best analyzed from h i s t o l o g i c a l s e c t i o n s . Apparently barren does taken during the. summer months a c t u a l l y may be p o s t p a r t u r i e n t animals,with large remnants of corpora l u t e a and t y p i c a l expanded blood v e s s e l s i n the caruncles and u t e r i n e w a l l . These does had c a r r i e d calves t o or n e a r l y t o term, then l o s t t h e m . — i f a c t u a l l y they were not l a c t a t i n g at the time of c o l l e c t i o n . Corpora l u t e a are maintained at 10-12'mm d i a m e t e r . u n t i l p a r t u r i t i o n , then regress t o 5-6 mm i n about two months, then p r o g r e s s i v e l y slower t o about 1.5x2x4 mm at one y e a r , and 1x1x3 mm.at two years. The l a t t e r s i z e . i s maintained, as a y e l l o w i s h t o brownish streak f o r s e v e r a l years. In the s e c t i o n i n g procedure used i n t h i s survey, a t h i r d t o a h a l f o f the s m a l l corpora rubra were missed, but few of the one-year corpora would have been l e f t i n t a c t . The c o l o r i s intense enough t h a t they would be i n f r e q u e n t l y overlooked. At l e a s t f i v e of the "parous but non-pregnant" does had formed at l e a s t one corpus luteum the previous f a l l . They e i t h e r d i d not conceive or aborted before the fetus developed very f a r . U t e r i are much more e l u c i d a t i v e of reproductive performance than are the o v a r i e s . As p o i n t e d out p r e v i o u s l y , the never-pregnant uterus i s s m a l l , round, and r e l a t i v e l y non-vascular, w i t h . a c t u a l weight of the uterus ( l e s s ovaries and mesometrium) of only 10-20 grams, and car-uncles as t h i n blades 15-40 mm l o n g , 1 mm t h i c k and 1-2.5 mm broad. During pregnancy, the uterus increases t o about 2kg, expands l a r g e r than the c a l f , and the caruncles (plus f e t a l cotyledons) enlarge t o as much as 125 mm long and 60 mm t h i c k . A l l the u t e r i n e w a l l and the caruncle are b o u n t i f u l l y s u p p l i e d w i t h l a r g e blood v e s s e l s . A f t e r p a r t u r i t i o n , the u t e r i n e w a l l s h r i n k s r a p i d l y , t o about 350 grams i n 15 days and 100 grams i n 60 days. Without d e f i n i t e l y dated specimens, c l o s e r estimates are not p r a c t i c a l . The placentomes contract a f t e r p a r t u r i t i o n , becoming n e c r o t i c and sloughing a l l of the caruncular m a t e r i a l t h a t had been d i r e c t l y i n v o l v e d w i t h embryonic t i s s u e i n the. p l a c e n t a . As n e a r l y as we can t e l l , the sloughing occurs between 6 and 10 days postpartum, r e p a i r 140 proceeds r a p i d l y , and the caruncles are re-covered by e p i t h e l i u m by about 20 days. There are r e g u l a r l y 3 (sometimes 2 or 4) c a r u n c l e s , hence placentomes during pregnancy, i n each u t e r i n e horn, and at times 1, 2, 3, or 4 s m a l l placentomes i n the body of the uterus. Bergerud, A.T. 1964. R e l a t i o n s h i p of mandible length t o sex i n New-foundland caribou. J . W i l d l . Mgmt. 28(1): 54-56. Bergerud, A.T. 1964. A f i e l d method t o determine annual p a r t u r i t i o n r a t e s f o r Newfoundland caribou. J . W i l d l . Mgmt. 28(3): 477-480. Bergerud, A.T. 1964. Newfoundland w i l d l i f e management r e p o r t . Ann. Rep. of Dept. of Mines, A g r i . and Res. 68-128 pp. Bergerud, A.T. 1967. The d i s t r i b u t i o n and abundance of A r c t i c hares i n Newfoundland. Can. F i e l d Nat. 81(4): 242-248. Bergerud, A.T. 1967. Management o f Labrador caribou. J . W i l d l . Mgmt. 30(4): 621-642. Bergerud, A.T. 1968. Numbers and Density — a chapter i n the I n t e r n a t i o n B i o l o g i c a l Handbook ( i n p r e s s ) . Bergerud, A.T. 1969. Status of Newfoundland pine marten. Can. Fi e l d - N a t . ( i n p r e s s ) . Bergerud, A.T., F. Manuel £ H. Whalen. 1962. Moose management s t u d i e s i n C e n t r a l Newfoundland. N.E. W i l d l . Conf. 49 pp. Bergerud, A.T. £ L. R u s s e l l . 1964. E v a l u a t i o n o f rumen food a n a l y s i s f o r Newfoundland caribou. J . W i l d l . Mgmt. 28(4): 809-814. Bergerud, A.T., S.S. P e t e r s , £ R. McGrath. 1964. Determining sex and age of w i l l o w ptarmigan. J . W i l d l . Mgmt. 27(4): 700-711. Bergerud, A.T. £ F. Manuel. 1964. W i l d l i f e management. Ann. Rep. Dept. of Mines, A g r i . and Res. 73-93 pp. Bergerud, A.T. £ W.E. Mercer. 1965. Census of w i l l o w ptarmigan i n south-eastern Newfoundland. J . W i l d l . Mgmt. 30(1): 101-113. Bergerud, A.T. and H.L. R u s s e l l . 1966. E x t r a c t i o n of i n c i s o r s of New-foundland caribou. J . W i l d l . Mgmt. 30(4): 842-843. Bergerud, A.T., F. Manuel £ H. Whalen. 1968. The harvest r e d u c t i o n of a moose po p u l a t i o n i n Newfoundland. J . W i l d l . Mgmt. 32(4): 722-728. Bergerud, A.T. £ F. Manuel. 1968. Moose damage t o balsam f i r - w h i t e b i r c h f o r e s t s i n c e n t r a l Newfoundland. J . W i l d l . Mgmt. 32(4): 729-746. Bergerud, A.T. 1964. Relationship of mandible length to sex i n New-foundland caribou. J . Wildl. Mgmt. 28(1): 54-56. Bergerud, A.T. 1964. A f i e l d method to determine annual p a r t u r i t i o n rates for Newfoundland caribou. J . Wildl. Mgmt. 28(3): 477-4-80. Bergerud, A.T. 1964. Newfoundland w i l d l i f e management report. Ann. Rep. of Dept. of Mines, Agri. and Res. 68-128 pp. Bergerud, A.T. 1967. The d i s t r i b u t i o n and abundance of Ar c t i c hares i n Newfoundland. Can. F i e l d Nat. 81(4): 242-248. Bergerud, A.T. 1967. Management of Labrador caribou. J . Wi l d l . Mgmt. 30(4): 621-642. Bergerud, A.T. 1968. Numbers and Density — a chapter i n the Internation B i o l o g i c a l Handbook ( i n press). Bergerud, A.T. 1969. Status of Newfoundland pine marten. Can. Field-Nat. ( i n press). Bergerud, A.T., F. Manuel £ H. Whalen. 1962. Moose management studies i n Central Newfoundland. N.E. Wi l d l . Conf. 49 pp. Bergerud, A.T. £ L. Russell. 1964. Evaluation of rumen food analysis f o r Newfoundland caribou. J . Wildl. Mgmt. 28(4): 809-814. Bergerud, A.T., S.S. Peters, £ R. McGrath. 1964. Determining sex and age of willow ptarmigan. J . Wi l d l . Mgmt. 27(4): 700-711. Bergerud, A.T. £ F. Manuel. 1964.. W i l d l i f e management. Ann. Rep. Dept. of Mines, Agri. and Res. 73-93 pp. Bergerud, A.T. £ W.E. Mercer. 1965. Census of willow ptarmigan i n south-eastern Newfoundland. J. Wil d l . Mgmt. 30(1): 101-113. Bergerud, A.T. and H.L. Russell. 1966. Extraction of incisors of New-foundland caribou. J. Wil d l . Mgmt. 30(4): 842-843. 

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