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Ecology, population dynamics, and management of the black bear in the spruce-fir forest of Northwestern… Jonkel, Charles J. 1967

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The U n i v e r s i t y FACULTY OF  of B r i t i s h  Columbia  GRADUATE STUDIES  PROGRAMME OF THE FINAL ORAL EXAMINATION FOR THE DEGREE OF DOCTOR OF PHILOSOPHY of CHARLES JONKEL  B.Sc,  University  of Montana, 1957  M.Sc,  University  o f Montana, 1959  MONDAY, August 28, 1^967 a t ICb-OO A.M. IN ROOM 3332 BIO. SC. BUILDING COMMITTEE IN CHARGE Chairman:  I . McT. Cowan  Do C. C h i t t y H. D. F i s h e r John P h i l l i p s  External  Examiner:  University  Wra, Hoar A. J . Wood H. Nordan  A. S t a r k e r  of C a l i f o r n i a ,  Research S u p e r v i s o r :  Leopold  Berkeley  I . McT. Cowan  THE ECOLOGY, POPULATION DYNAMICS, AND MANAGEMENT OF THE BLACK BEAR IN THE SPRUCE-FIR FOREST OF NORTHWESTERN MONTANA ABSTRACT T h i s r e s e a r c h was designed to study the e c o l o g y and p o p u l a t i o n dynamics of b l a c k bears i n the spruce , and f i r f o r e s t of northwestern Montana, to t e s t the h y p o t h e s i s t h a t e x t r i n s i c f a c t o r s caused f l u c t u a t i o n s i n p o p u l a t i o n numbers, and to develop management p r i n c i p l e s f o r bears. The rough topography and moderate to heavy prec i p i t a t i o n on the B i g Creek study area have c r e a t e d v a r i e d e c o l o g i c a l c o n d i t i o n s which i n many ways are excellent f o r black bears. S e r a i and c l i m a x stands of the P i c e a - A b i e s / P a c h i s t i m a m y r s i n i t e s a s s o c i a t i o n are used most e x t e n s i v e l y by bears, but other veget a t i v e types are important s e a s o n a l l y . The home ranges of a d u l t bears on the area are s m a l l and they remain the same s i z e from year to y e a r . As r e s i d e n t males mature, however, t h e i r ranges i n crease i n a r e a . Bears do congregate, but o n l y where, there i s an o v e r l a p i n t h e i r home ranges. Even then they do not form compact groups, but keep a t l e a s t 50 yards (48 metres) between i n d i v i d u a l s . Many a d u l t females (bears a p p r o x i m a t e l y 4-1/2 years or o l d e r ) do not have young, a p p a r e n t l y because of the f a i l u r e of females to o v u l a t e , p r e n a t a l mort a l i t y , and e a r l y m o r t a l i t y . T e n t a t i v e c o n c l u s i o n s suggest t h a t s e a s o n a l r e s t r i c t i o n s i n n u t r i t i o n d e l a y the p h y s i c a l m a t u r i t y and thereby the s e x u a l m a t u r i t y of some b e a r s . These r e s t r i c t i o n s are caused by the c l i m a t e of B i g Creek and are d e t r i m e n t a l even to a d u l t females on c e r t a i n y e a r s . Inadequate n u t r i t i o n i s a l s c suggested by the o b s e r v a t i o n t h a t some y e a r l i n g s i n h i b i t e s t r u s f o r two y e a r s by s u c k l i n g up to 16 months of age. The n u t r i t i o n of a d u l t males and of many a d u l t females g e n e r a l l y i s e x c e l l e n t , however. Litter s i z e s on B i g Creek and throughout the West are s m a l l e r than i n E a s t e r n North America.  The s u r v i v a l of cubs i s h i g h (95 perccent) from 1/2 t o 1-1/2 years of age w h i l e they are w i t h t h e i r mothers, but a l l s u b - a d u l t s are p h y s i c a l l y weak i n l a t e s p r i n g and n a t u r a l l o s s i s c o n s i d e r able among s u b - a d u l t s 1-1/2 to 3-1/2 years o l d . They appear e s p e c i a l l y v u l n e r a b l e to changes i n c l i m a t e , p a r a s i t i s m , p r e d a t i o n , food q u a n t i t y and q u a l i t y , and the behaviour o f a d u l t b e a r s . Many s u b - a d u l t males d i s p e r s e from the a r e a . Annual changes i n the d e n s i t y of bears on Big Creek are caused i n p a r t by man, by d i s p e r s a l , of s u b - a d u l t s , and through changes i n the r e p r o d u c t i v e success of a d u l t s and the n a t u r a l mortali t y of sub-adults. The numbers of a d u l t s on the a r e a remain r e l a t i v e l y c o n s t a n t from year to y e a r . Even though f o o d i s u n l i m i t e d d u r i n g some seasons, a form o f t e r r i t o r i a l i t y w i t h i n " s o c i a l groups" spaces the bears on B i g Creek and u l t i mately e x e r t s a d e f i n i t e c o n t r o l over d e n s i t y . The cfensity i s r e l a t i v e l y h i g h on B i g Creek and .probably r e s u l t s i n more s o c i a l i n t e r a c t i o n and t e r r i t o r i a l i t y than iri bears elsewhere. Longer care o f young,smaller i i t t e r s i z e s , and i n c r e a s e d s o c i a l o r g a n i z a t i o n a l l seem e v i d e n t as r e a c t i o n s to the B i g Creek environment. E x t r i n s i c and ; i n t r i n s i c forces unite, therefore, i n population r e g u l a t i o n , and the n e t r e s u l t i s the c r e a t i o n of an e x c e l l e n t h a b i t a t f o r a d u l t b l a c k bears, but an harsh environment f o r s u b - a d u l t s a f t e r they have l e f t t h e i r mothers.  GRADUATE STUDIES  Field  of Study:  Zoology  Animal G e n e t i c s  D. Suzuki  Advanced E c o l o g y  D. C h i t t y  I n v e r t e b r a t e Zoology Comparative E t h o l o g y Directed Studies (Reproductive Physiology)  P. - A. D'ehnel M. D. F, Udvardy W, D. K i t t s  PUBLICATIONS  J o n k e l , C. J . 1959. An e c o l o g i c a l and p h y s i o l o g i c a l stu. of pine marten. Unpub. M.S, t h e s i s . Montana S t a t e Univ., M i s s o u l a , v i i + 81 pp. J o n k e l , 0. J . and R. P. Weckwerth, 1963, Sexual m a t u r i and i m p l a n t a t i o n of b l a s t o c y s t s i n the w i l d p i . marten. J . of W i l d l . Mgmt. 27(1):93-98. J o n k e l , C. J . and K. R. Greer, 1963. F a l l food h a b i t s of Spruce Grouse i n n o r t h w e s t e r n Montana. J . W i l d l . Mgmt. 27(4):593-596. J o n k e l , C. J . 1964. E s t i m a t i n g whole weights o f b l a c k bears from hbg-dressed w e i g h t s . J.Wildl. Mgmt. 28(3):581. Stoneberg, R. P. and C. J . J o n k e l , 1966. Age determinat of b l a h k bears hy cementum l a y e r s . J.Wildl. Mgmt. 30.(2) : 411-414. J o n k e l , C. J . 1966. Robin p r e d a t i o n of the western mouse. M u r r e l e t 4 7 ( 1 ) : 9 .  jumpir.  THE ECOLOGY, POPULATION DYNAMICS,  AND  MANAGEMENT:  OP THE BLACK BEAR I N THE SPRUCE-FIR FOREST OF NORTHWESTERN MONTANA  CHARLES J . JONKEL  A  B. S c . , U n i v e r s i t y  o f Montana,  1957  M. S c . , U n i v e r s i t y  o f Montana,  1959  thesis  submitted  i n partial  requirements  fulfillment  f o r the degree  of  DOCTOR OP PHILOSOPHY in  t h e Department of  We  Zoology  accept t h i s t h e s i s as conforming to the r e q u i r e d standard  THE U N I V E R S I T Y OP B R I T I S H August,  1967  COLUMBIA  of the  In presenting 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 of the requirements for an advanced degree a t the U n i v e r s i t y of B r i t i s h Columbia, I agree that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r reference and study,  I f u r t h e r agree that permission.for  extensive  copying of t h i s  t h e s i s f o r s c h o l a r l y purposes may be granted by the Head of my Department or by h i s representatives.  I t i s understood that copying  or p u b l i c a t i o n of" t h i s t h e s i s f o r f i n a n c i a l gain s h a l l not be allowed without my w r i t t e n permission.  Department of  Zoology  The U n i v e r s i t y of B r i t i s h Columbia Vancouver 8, Canada  i i  ABSTRACT  T h i s r e s e a r c h was d e s i g n e d  t o s t u d y t h e e c o l o g y and  p o p u l a t i o n d y n a m i c s o f b l a c k "bears i n t h e s p r u c e forest  o f n o r t h w e s t e r n Montana, t o t e s t  extrinsic and  factors  to develop The  itation  caused  management p r i n c i p l e s  rough  topography  on the B i g Creek  ecological  fluctuations  and f i r  the hypothesis  that  i n p o p u l a t i o n numbers, f o r bears.  and moderate t o heavy  precip-  s t u d y a r e a have c r e a t e d v a r i e d  c o n d i t i o n s w h i c h i n many ways a r e e x c e l l e n t f o r  black bears.  Serai  and c l i m a x stands  of the Picea-Abies/  P a c h i s t i m a m y r s i n i t e s a s s o c i a t i o n a r e u s e d most  extensively  by b e a r s , b u t o t h e r v e g e t a t i v e types a r e i m p o r t a n t s e a s o n a l l y . The and  home r a n g e s  they remain  o f adult bears  t h e same s i z e  males mature, however, t h e i r do  congregate,  on the a r e a a r e s m a l l  from y e a r t o y e a r . ranges  Bears  b u t o n l y where t h e r e i s a n o v e r l a p i n t h e i r E v e n t h e n t h e y do n o t f o r m  keep a t l e a s t  50  yards  Many a d u l t  compact g r o u p s , b u t  (48 m e t r e s ) between  females  individuals.  ( b e a r s a p p r o x i m a t e l y 4-1/2  o r o l d e r ) do n o t h a v e y o u n g , a p p a r e n t l y b e c a u s e to ovulate, prenatal mortality,  Tentative  c o n c l u s i o n s suggest  nutrition  delay the p h y s i c a l  maturity  resident  increase i n area.  home r a n g e s .  of females  As  o f some b e a r s .  that  years  of the f a i l u r e  and e a r l y  mortality.  seasonal r e s t r i c t i o n s i n  m a t u r i t y and t h e r e b y t h e s e x u a l  These r e s t r i c t i o n s  are caused  by the  iii c l i m a t e o f B i g Creek and a r e d e t r i m e n t a l even to a d u l t females on c e r t a i n y e a r s .  Inadequate n u t r i t i o n i s a l s o suggested  by  the o b s e r v a t i o n t h a t some y e a r l i n g s i n h i b i t e s t r u s f o r two y e a r s by s u c k l i n g up t o 16 months o f age.  The n u t r i t i o n o f  a d u l t males and o f many a d u l t females g e n e r a l l y i s e x c e l l e n t , however.  L i t t e r s i z e s on B i g Creek and throughout the West  are s m a l l e r than i n e a s t e r n N o r t h America, b u t a p p a r e n t l y t h e cause i s g e n e t i c a l r a t h e r than The  nutritional.  s u r v i v a l o f cubs i s h i g h (95 p e r c e n t ) from 1/2  to 1-1/2 y e a r s o f age w h i l e they a r e w i t h t h e i r mothers, b u t all  sub-adults  a r e p h y s i c a l l y weak i n l a t e s p r i n g and n a t u r a l  l o s s i s c o n s i d e r a b l e among s u b - a d u l t s old.  1-1/2 t o 3-1/2 y e a r s  They appear e s p e c i a l l y v u l n e r a b l e t o changes i n c l i m a t e ,  p a r a s i t i s m , p r e d a t i o n , f o o d q u a n t i t y and q u a l i t y , and the behaviour the  of adult bears.  Many s u b - a d u l t males d i s p e r s e from  area. Annual changes i n the d e n s i t y o f b e a r s  on B i g Creek  are caused i n p a r t by man, by d i s p e r s a l o f s u b - a d u l t s , and through changes i n the r e p r o d u c t i v e s u c c e s s o f a d u l t s and the natural m o r t a l i t y of sub-adults.  The numbers o f a d u l t s on  the a r e a remain r e l a t i v e l y c o n s t a n t  from y e a r t o y e a r .  Even though f o o d i s u n l i m i t e d d u r i n g some seasons, a form o f t e r r i t o r i a l i t y w i t h i n " s o c i a l groups" spaces the bears  on B i g Creek and u l t i m a t e l y e x e r t s a d e f i n i t e c o n t r o l  over d e n s i t y .  The d e n s i t y i s r e l a t i v e l y h i g h on B i g Creek  and p r o b a b l y r e s u l t s i n more s o c i a l i n t e r a c t i o n and t e r r i t o riality  than i n b e a r s  elsewhere.  Longer c a r e o f young,  i v  smaller seem  l i t t e r  evident  E x t r i n s i c  habitat  as  and  regulation,  sizes,  reactions  i n t r i n s i c  and  the  f o r adult  sub-adults  and  after  net  black they  increased to  the  s o c i a l  B i g  Creek  organization a l l environment.  forces  unite,  therefore,  r e s u l t  i s  c r e a t i o n  bears,  but  have  l e f t  the an  t h e i r  harsh,  of  i n an  population e x c e l l e n t  environment  mothers.  f o r  V  TABLE OF  CONTENTS Page ii  ABSTRACT LIST  OF TABLES  v i i  LIST  OF ILLUSTRATIONS  ix  ACKNOWLEDGMENTS PART I .  x i  GENERAL TOPICS.  Chapter  1.  INTRODUCTION  1  Chapter  2.  THE STUDY AREA  5  Chapter PART I I . Chapter  Chapter  3-  Geology and Topography Climate Vegetation Land-use P r a c t i c e s  5 8 10 14  METHODS  17  RESULTS 4.  5-  ECOLOGICAL STUDIES  25  Home R a n g e s o f B e a r s Den E c o l o g y Dispersal R e l a t i v e D i s t r i b u t i o n o f G r i z z l y and B l a c k Bears on B i g Creek D i s c u s s i o n o f B l a c k Bear E c o l o g y . . . .  26 39 41  REPRODUCTIVE STUDIES  55  B r e e d i n g Season Sex R a t i o s Minimum B r e e d i n g Age L i t t e r Sizes Frequency o f L i t t e r s D i s c u s s i o n o f Black Bear  55 57 57 60 62 65  Reproduction  . .  42 44  v i  Page Chapter  6.  DEATH  RATES  M o r t a l i t y Causes  Rates  7.  CAUSES .  .  .  OF .  .  MORTALITY .  .  .  Family  i n Bears  Behaviour  .  .  .  Changes  .  .  .  .  .  .  .  87 91 93  MECHANISMS  and  .  90  Behaviour V a r i a t i o n  REGULATORY  CONCLUDING  78  85  CHARACTERISTICS  Density  LITERATURE  .  83  i n Behaviour  POPULATION  Population Growth and Discussion  9«  .  .  Discussion  Chapter  72  .  83  Individual  I I I .  .  - 72  75  o f M o r t a l i t y  T e r r i t o r i a l  PART  .  .  Relationships  Seasonal  8.  .  .  BEHAVIOUR Agonistic  Chapter  .  .  o f M o r t a l i t y  Discussion Chapter  AND  Numbers  .  Structure N u t r i t i o n  AND 99 99 103 108 119  REMARKS  Conclusions  and  Summary  133 140  CITED  APPENDIX  1  149  APPENDIX  2  155  APPENDIX  3  ,  163  vii  L I S T OF  TABLES  TABLE 1.  2.  3.  Page Maximum d i s t a n c e b e t w e e n p o i n t s a d u l t b e a r s on B i g C r e e k Approximate dates t h a t bears emerged f r o m t h e i r dens Breeding season based  on v u l v a l  4.  Sex  c o m p o s i t i o n o f the B i g Creek  5.  Minimum b r e e d i n g age  6.  A d u l t t o young r a t i o s  and  population. .  average 61  Numbers o f m a r k e d a d u l t  and m a t u r e f o l l i c l e  counts  females, with  63  cubs, 64  Survival rates  of B i g Creek b e a r s  E s t i m a t e s o f the 1959  total  101  b e a r p o p u l a t i o n on  t o 1961  Creek,  11.  Age  structure  12.  Numbers o f a d u l t b e a r s o n B i g C r e e k , 1959 t o 1965 S u r v i v a l o f t h e d i f f e r e n t age g r o u p s on B i g Creek Weights of a d u l t females a t d i f f e r e n t  14.  . . .  t o 1966  Big  13.  58 59  .  8.  10.  swelling  of females  Corpora l u t e a  9.  40  pairs  7.  1959  and  56  male-female  sizes  32  entered  and  litter  of capture f o r  of the bear p o p u l a t i o n  102 105  106 107  elevations  110  15.  H u c k l e b e r r y a b u n d a n c e on B i g C r e e k  115  16. 17.  Ga ai in n i o rn wl eo is gs h ti no w en ag rs G f e ii gn hd ti v io df u ai ln d bi ev ai rd su a ld u rb i d u r i n g and t h e autumn spring summer . . . . . . .  149 150  viii  TABLE  Page  18.  Colour of females  and t h e i r  19.  Colour  20.  Hormone-like e x t r a c t s bear foods  of a l l bears  156  litters  c a p t u r e d on B i g Creek of  . . .  156  certain 165  <  ix  LIST  OF ILLUSTRATIONS  FIGURE 1.'  , Geographic study  Page  l o c a t i o n o f t h e B i g Creek 6  area  7  2.  D e t a i l of t h e B i g Creek  3.  A n n u a l p r e c i p i t a t i o n a t t h e West G l a c i e r station A v e r a g e d a i l y t e m p e r a t u r e and m o n t h l y p r e c i p i t a t i o n a t t h e West G l a c i e r s t a t i o n  4.  drainage  5.  Burned  6i  Logging  activity  7.  Minimum  home r a n g e s  of adult  females  8.  Minimum home r a n g e s  of adult  males  9.  Movements o f b e a r s area,  areas  on t h e B i g Creek  Movements  11.  Types o f h a b i t a t  . . . .  11  observed  . . . . . .  27  .  28  i n the China  . . . . . . .  Basin  . . . . . .  i n which bears  30 33  o f aberrant females were  35  12.  Dispersal  movements  13.  S u r v i v a l c u r v e f o r b e a r s on t h e B i g Creek study area ' I n d i v i d u a l weights of adult females, 1959 t o 1965 Average weights o f a d u l t females,  of sub-adult bears  1959 t o 1965 . . growth r a t e s  . . . . . .  43  74 I l l I l l  16.  Seasonal  17.  Monthly weights o f adult females, 1959 t o 1965 A v e r a g e . weights o f a d u l t males, 1959 t o 1965  18.  9  16  or observed  15.  . . .  . .  captured  14.  9  on t h e B i g Greek study a r e a  S e p t e m b e r , '1961  10.  study area  .  of adults  112  112 114  X FIGURE 19.  ,  Page  I n d i v i d u a l weights 1959 t o 1965  of adult  males, 114  20.  Average weights  21.  S e a s o n a l changes i n the weights known-age s u b - a d u l t s  117  sub-adults of  117 151  22.  Aldrich  23.  Newhouse  24.,  Cubby t y p e  25.  Closed forest  26.  Open f o r e s t  27.  Snowslide  28.  D r y meadow t y p e  29.  Seeded  30.  D i s t r i b u t i o n o f t h e brown phase i n North America  158  D i s t r i b u t i o n of whitebark p a r s n i p on B i g Creek  167  31.  trap  o f known-age  and snare  150  steel  trapsite  trap,  canvas,  and s t e p p i n g s t i c k s  . . . .  151 152 152  type  155  type  area i n the s p r u c e - f i r  strip  and b e a r  forest  i n the s p r u c e - f i r  a l o n g t h e B i g Creek  forest road  153 154 154  p i n e a n d cow  xi  ACKNOWLEDGMENTS F l e t c h e r Newby of the Montana F i s h and suggested  t h i s study and  Game Department  a s s i s t e d i n making the i n i t i a l  plans.  Vernon Hawley, f o r m e r l y w i t h the Montana F i s h and Game Department, and R i c h a r d Weckwerth, a management b i o l o g i s t w i t h Montana F i s h and Game Department, b o t h a i d e d me w i t h comments and study.  the f i e l d  considerably  c r i t i c i s m i n p r e p a r i n g the d e s i g n of  Edward T i s c h , Gary G i e r , and  the  the  James R i c e a s s i s t e d w i t h  work i n c o n s e c u t i v e y e a r s , and many i n d i v i d u a l s i n  the W h i t e f i s h and Columbia F a l l s , Montana, v i c i n i t y  cooperated  i n many ways.  research  s i n c e 1963  Dean I . McT.  and h e l p e d me  members of my  Cowan has  with suggestions  committee: Dean I . McT.  Dr. H. D. F i s h e r , and  s u p e r v i s e d my  Dr.  and  Cowan, Dr.  J . E. P h i l l i p s ,  my  through the summer o f 1963 t h r o u g h 1965. cial  D. H. C h i t t y ,  I wish to  s i n c e r e a p p r e c i a t i o n to a l l of these  The Montana F i s h and  The  a l l made v a l u a b l e  comments f o r the p r e p a r a t i o n of t h i s t h e s i s . express  advice.  people.  Game Department f i n a n c e d the and d u r i n g summers from  study  1964  The U n i v e r s i t y of B r i t i s h Columbia gave f i n a n -  a s s i s t a n c e from 1963  through 1966.  Personnel  of  the  N a t i o n a l P a r k S e r v i c e , the U n i t e d S t a t e s F o r e s t S e r v i c e , and the American Timber Company a l l a i d e d the study i n v a r i o u s ways.  Without the a s s i s t a n c e of these  c o u l d not have been completed.  agencies  the  study  PART I GENERAL TOPICS  1  CHAPTER  ONE  INTRODUCTION  This the of  Montana black  The  1966.  10  miles  F i s h  bears  study  of  study  area  there  was  was  i n  believed  l i t t l e  numbers.  to  s i n c e  been.  involved  i n  e x t r i n s i c a l . ,  the  1955), and  such  climate  of as  (Bendell,  1955)  same  high,  and  to  of  be  the  species changes  1956), to  which  as  the  food and  p a r a s i t e s  i n t r i n s i c  drainage  I960  and b l a c k  on  were  much  B i g that  annual  observations  p o p u l a t i o n of  numbers  North as  i t  has  mechanisms  have  ranged  (Lack,  1954;  i n  from P i t e l k a  1954),  (Varley,  changes  bear  the  i t seemed  there  Birch,  May  area.  r e g u l a t i n g  i n  through  1959  abundant  numbers  species.  Creek  these  of  by  management  game  p o p u l a t i o n  throughout  (Andrewartha  Craighead,  the  maintenance  appears  t h e o r i e s  c o n t r o l  f a c t o r s  (Craighead diseases  General  of  i n  e s p e c i a l l y  ever  study  The  important,  bear  During  the  way  the  a  B i g  pressure,  and  b l a c k  the  i n  be  i n  as  hunting  r e g u l a t i o n  the  and 1959  to  a i d  Montana  continued  was  h a b i t s  study  p r i o r  and  Montana.  food  t h i s  years  area  selected  the  America  et  with  to  P a l l a s )  1959*  June,  a  northwestern  Department  Whitefish,  conducted  the  f l u c t u a t i o n s  i s  of  i n  americanus,  The  study  to  Game  i n  In  r e l a t e  o r i g i n a t e d  begun  north  although  and  (Ursus  a s s o c i a t i o n  Creek  was  was  (1961)  Tisch i n  study  predators  194?),  and  reproductive  2 r a t e s or e n d o c r i n e a c t i v i t y years  ( C h r i s t i a n , 1950).  In  recent  a t t e n t i o n has been d i r e c t e d to the i n t r i n s i c  or  e v o l u t i o n a r y changes i n b e h a v i o u r as a r e g u l a t i n g mechanism ( C a r r i c k , 1963;  Wynne-Edwards, 1962), and  i n h e r e n t i n the g e n e t i c c o m p o s i t i o n Wellington My  even t o causes  of s p e c i e s  (Chitty,  1965;  of t h i s study was  that  I960; Krebs, 1964). hypothesis  a t the b e g i n n i n g  m o s t l y e x t r i n s i c f a c t o r s ( f o o d and populations  climate) maintained bear  a t e x i s t i n g l e v e l s i n d i f f e r e n t h a b i t a t types  and  accounted f o r some of the y e a r l y f l u c t u a t i o n s i n numbers w i t h i n a h a b i t a t type. hypothesis  and  This study was  and  checking  t h e i r growth,  i n t e r r e l a t i o n s h i p s through r e c a p t u r e s  and  d i f f e r e n t components o f t h e i r h a b i t a t , and  sur-  obser-  v a t i o n s over an extended p e r i o d , e v a l u a t i n g c a r e f u l l y  the  that  a s s o c i a t e d problems by marking known-age  animals i n a n a t u r a l h a b i t a t and vival,  d e s i g n e d to t e s t  the  r e l a t i n g each to  other. Only i n r e c e n t y e a r s has  field  i t been p o s s i b l e to conduct  s t u d i e s on w i l d b e a r s by c a p t u r i n g them  repeatedly.  Advances i n h a n d l i n g l a r g e w i l d animals w i t h drugs p r o j e c t i l e s y r i n g e s have made t h i s f e a s i b l e . b e a r s p r i o r to 1957 morphological  were r a t h e r c a s u a l f i e l d  and  Studies  of  observations  or  s t u d i e s ; a g r e a t d e a l on the b i o l o g y of b e a r s  had been w r i t t e n , however, based on g e n e r a l  impressions  and  assumptions. Most r e c e n t centred  s t u d i e s o f the b l a c k b e a r have been  i n e a s t e r n N o r t h America i n deciduous f o r e s t s .  King  3 et  (I960)  a l .  hematology study New  of  of  long  bears  concerned the  i n  on  1961)  done  has  V i r g i n i a , home  implantation  i n  bears  (1957, 1959) e c o l o g i c a l  have  and  he  spruce  (Picea  (1961)  has  of  and  to  notes  on  m o r t a l i t y  or  numbers. l e f t  either  tion,  such  general these and  on  to as  Wyoming.  of  persons stockmen  i s  of  black  and  lumbermen,  conducted on  other  i n  ecology  on  many  Current  and  of  i n  repro-  a  serious bear  areas i n  i t s  merely work  Wisconsin,  species  Rausch  bears,  regulate  has  the  presented  has  i n t e r e s t or  i n  n a t u r a l  nor  i n  r a t e s  bears  captive  done  i n  f o r e s t s .  and  habits,  bears  management.  works  and  forces  s p e c i a l  (1957,  America.  Alaska  bears,  what  black a  North  been  management  ovarian  deciduous of  were  comparative  bear  b i o l o g y  w i l d  the  S t i c k l e y  i n  on  which  reproductive  denning  i n  with  game  being  Major  on  has  of  of  i n  studies  f o r  i n  (1964)  a l .  and  black  western bears  determine  management  theories  problems  to  on  the  work  behaviour  made  The  of  black  no  et  maturity,  young.  l i v i n g  p a r a s i t e s ,  P r a c t i c a l l y  been  of  d e n t i t i o n data  duction.  attempt  known  on  r a t e s  (1963)  conducted  studies,  sexual  estimates  f o r e s t s  published  growth  at  bears  been  spp.)  Their  research  given  black  has  E r i c k s o n  and  Wimsatt's  also  e x c e l l e n t data  age  recent  has  was  reproductive  provided  and  reproductive  Michigan.  sizes,  some  p a r a s i t o l o g y ,  York,  and  and  s e l f - s u f f i c i e n c y  ranges  a d d i t i o n  New  northern  L i t t l e  good  i n  l i t t e r  and  pathology,  bears  p r i m a r i l y with  function,  and  the  "black  term  species,  purposes  on  E r i c k s o n  undertook  of  the  delayed  York.  black  worked  has  been  destruc-  followed on  some  of  Washington,  bears  throughout  4 the world vations, 1964;  have been l a r g e l y based on o p i n i o n , g e n e r a l or morphological  P e d e r s o n , 1957;  data.  Studies  largely  and o t h e r s )  o f bear behaviour  on c a p t i v e animals  behaviour  studies  ( C o u t u r i e r , 1954-; and o f f e r  obser-  Davis,  few c o m p a r a t i v e  have been g e n e r a l  (Meyer-Holzapfel,  or based  1957)*  o f the b l a c k bear has been p a r t i c u l a r l y  The  neglected.  D i s c o v e r i n g i n f o r m a t i o n u s e f u l i n t h e management o f a game s p e c i e s u s u a l l y i s , o f c o u r s e , of r e s e a r c h met o r n o t .  on t h a t  solution animals.  s p e c i e s , whether other  I hope t h a t t h i s  b e t t e r management  the ultimate  study  o f black bears  of biological  purpose  research goals are  has c o n t r i b u t e d both to  a s a game s p e c i e s a n d t o a  problems b a s i c to bears  and a l l  5  CHAPTER • This 10  miles  the  study  north  of  THE  has  STUDY AREA. been centred  Whitefish,  80  square miles  a northeasterly direction River,  a south-flowing  Range. crop  Almost  land.  the  The  (Figure 2). environment of black  (see  characteristics  G e o l o g y and The  the  basaltic  along  this  logging  study  of  drainage  is  B i g Creek flows  in  The  and  fire  area presents  Chapter 4),  the  drainage  habitat described  the  Flathead  Whitefish  are  forest  accessible  control roads quite a  different  i n other  studies  a d e s c r i p t i o n of  the  physical  essential.  associated with  Continental  uplift the  area  the  i s dominated by  sharp r i d g e s .  of  Pre-Cambrian  Livingstone  D i v i d e , w h i c h i s about  i n t r u s i o n s throughout  d i v i d e d by  slope  i s F e d e r a l l y owned  i n G l a c i e r National Park.  The  eastern  N o r t h Fork of  the  W h i t e f i s h Range i s a n  form the east  i n t o the  and  drainage  Topography  sedimentary rock that  is  the  stream t h a t p a r a l l e l s  t h a n does the  bears  i n area,  main branches of  Since  B i g Creek  ( F i g u r e 1).  e n t i r e drainage  vehicular traffic  i n the  Montana, on  W h i t e f i s h Range o f m o u n t a i n s  approximately  to  TWO  There are drainage  Mountains 30 m i l e s  to  scattered  (Jonkel,  1959)*  numerous s m a l l v a l l e y s  There are  abrupt  changes i n e l e v a t i o n  \  8RITISH  \  BIG  ALBERTA  \  COLUMBIA  \  CREEK  STUDY AREA  White fish  Kalispell  MONTANA  N A  (  I  H  ( I \  Figure  1.  Geographic  l o c a t i o n  o f  the B i g Creek  study  area.  40  MILES  Figure  2.  Detail  of  the B i g Creek  drainages, and  t r a i l s ,  and hut  other  study  pertinent  observations  area  showing  data. were  the  Trapsites  made  i  l o c a t i o n were  throughout  the  of  roads,  r e s t r i c t e d area.  to  t r a p s i t e s , roads  8 from  a b o u t 3,800 f e e t up t o 7 , 5 2 1 f e e t  The  entire  and  narrow stream  a t the highest p o i n t .  area i s c h a r a c t e r i z e d by steep h i l l s i d e s ,  cliffs,  bottoms.  Climate The lower  climatic  c o n d i t i o n s v a r y c o n s i d e r a b l y from the  to the upper reaches  o f the study  a r e a and f r o m  one  slope t o another.  I t s upper p o r t i o n s l i e c l o s e to the c e n t r e  of  t r a c k , which causes  a Pacific  maritime spring, south  storm  aspects during winter and which r e s u l t s  s l o p e s a t lower  the area to take  and sometimes d u r i n g f a l l  i n snow d e p t h up t o 1 0 f e e t ,  levels  o f t e n remain r e l a t i v e l y  free.  P r e c i p i t a t i o n comes m o s t l y  annual  and monthly p r e c i p i t a t i o n averages  14 m i l e s  southeast  of the study  ative  a r e a , and these  range from  the study  the  West G l a c i e r  the  topography o f the B i g Creek drainage  semiarid  areas  local  and r a i n - f o r e s t  Creek as a r e s u l t  station  area.  Mean to the  data f o r  i n F i g u r e 4, b u t  renders  significance. l i e adjacent  The  as represent-  The t e m p e r a t u r e  Station are also presented  values of l i t t l e  Glacier,  around 20°F i n winter  sixties  climatic  snow-  a t t h e West G l a c i e r  low  Big  f o r West  d a t a c a n be taken  i n s p r i n g a n d summer.  while  ( F i g u r e s 3 and 4 ) .  o f average c o n d i t i o n s throughout  monthly temperatures  or  a s snow, a s shown i n t h e  area  same w e a t h e r p a t t e r n s p r e d o m i n a t e as on t h e s t u d y  on  a l l average  Extremes o f  i n many p a r t s o f  of d i f f e r e n c e s i n aspect  and s l o p e .  1959 I 960 1 961 1962 1963 1964 1965 F i g u r e 3« Annual p r e c i p i t a t i o n a t the West G l a c i e r , Montana, station. Compiled from Annual Summaries, U. S. Weather Bureau 1 9 5 9 - 1 9 6 5 .  <L>2JZ V c  J F M A M J J A S O N D Figure 4 . Average d a i l y temperature and monthly p r e c i p i t a t i o n a t the West G l a c i e r , Montana, s t a t i o n . Compiled from Annual Summaries, U. S. Weather Bureau 1 9 5 9 -  1965.  10 Vegetation Since marily  a vegetarian seeking  change w i t h study  the black bear  the seasons,  i t s food  animal  and i s p r i -  from p l a n t sources  that  a b o t a n i c a l c o n s i d e r a t i o n of the  a r e a was n e c e s s a r y .  plants or f l o r a l  i s a forest  I n the f o l l o w i n g d e s c r i p t i o n only  c o n d i t i o n s o f importance t o t h i s  study a r e  described. By Creek study  the c l a s s i f i c a t i o n area l i e s  o f Daubenmire  i n the spruce  ( A b i e s l a s i o c a r p a ) zone, a l t h o u g h menziesii var. glauca) and  western r e d cedar  trees  on  stands  The  ponderosa), ( a group o f  s i m i l a r requirements)  form  local  Alpine conditions exist  peaks.  Closed Forest.  (1961) has g i v e n  (Pinus  (Thuja p l i c a t a ) tree unions  The m a i n f o r e s t  composed o f a d e n s e s p r u c e - f i r Tisch  Douglas f i r (Pseudotsuga  o n some e x p o s u r e s .  some o f t h e h i g h e s t  the B i g  (Picea engelmanni)-fir  and ponderosa p i n e  and o t h e r p l a n t s w i t h  near-climax  (1952),  stand  an e x t e n s i v e  on the area i s  (Figure 25,in  Appendix).  account" o f t h e v e g e t a t i o n a l  conditions  on B i g Creek, i n c l u d i n g a s u c c i n c t d e s c r i p t i o n o f  the  forest.  cent  climax  This forest  of the drainage,  Picea-Abies/Menziesia  covers  approximately  and i s d i v i d e d a l m o s t glabella  80 p e r  e q u a l l y between  and P i c e a - A b i e s / P a c h i s t i m a  myrsinites associations. T i s c h a l s o d e s c r i b e d t h e s e r a i v e g e t a t i o n on t h e a r e a , but  he d i d n o t e m p h a s i z e t h a t a l a r g e p a r t o f t h e s t u d y  was b u r n e d a t some t i m e i n t h e p a s t stands  ( F i g u r e 5)»  comprise a major p o r t i o n o f the bear  area  The s e r a i  h a b i t a t and v a r y  Figure  5.  P o r t i o n s of the B i g Creek study area were f i r s t begun on the a r e a . These t o the a r e a by c r e a t i n g openings and to bears.  that have been turned since records burns provide an a d d i t i o n a l d i v e r s i t y serai stages of vegetation important  H H  12 w i t h age of  and  either  site;  larch  a l l show an  spruce-fir The  is  at  (1)  shrubs  and  ation,  or  The  second  pine  orderly  The  per cent  the h i g h e r  dominated by  whitebark  facing  more o p e n p o r t i o n s o f t h e  of the  total  area.  e l e v a t i o n s where t h e  mixed stands  and  spruce  a t low  e l e v a t i o n s on  ( F i g u r e 26  and  an u n d e r s t o r y  stands  made d e t a i l e d  the  entire  tundra  and  drainage.  The  grassy parks  Douglas f i r .  total  less  and  clear-cut  logged  areas.  and  these  The  (1952,  vegetative  man-made  t h a n 10  per  types.  treeless cent  of  are near-alpine slopes  p e a k s and  e l e v a t i o n s , wet  areas,  the  Daubenmire  the h i g h e s t peaks, t a l u s  s l o p e s at lower  m o u n t a i n meadows, s n o w s l i d e  southerly  both  a l o n g n o r t h f a c e s o f t h e h i g h e s t r i d g e s and southerly facing  topo-  dominated by v e g e t a t i o n from  manor o p e n a r e a s  on  under  the  type  d e s c r i p t i o n s of  they  slopes.  T h i s second  T h e r e a r e n a t u r a l and  on B i g Creek, b u t  associ-  open  a s s o c i a t i o n s formed by  Open A r e a s . areas  spaced  of e i t h e r  i s found  the P i c e a - A b i e s / P a c h i s t i m a m y r s i n i t e s a s s o c i a t i o n  has  zone  among l o w - g r o w i n g  steep, rocky,  i n Appendix).  found  spruce-fir  southerly facing  i s composed o f n e a r - c l i m a x  c o n d i t i o n s c h a r a c t e r i z e d by  o f f o r e s t has  1953)  forest  They a r e  of wind-deformed, w i d e l y  (Pinus a l b i c a u l i s )  type  slopes  various  the  f o r b s of the P i c e a - A b i e s / M e n z i e s i a g l a b e l l a (2)  mainly (Pinus  s u c c e s s i o n towards  Douglas f i r or ponderosa p i n e unions, graphic  a r e composed  forest.  Open F o r e s t .  encompass a b o u t 10 either  a r e v e r y d e n s e and  ( L a r i x o c c i d e n t a l i s ) or lodgepole pine  contorta), but climax  they  and  on dry  creek bottoms, r o a d s i d e s ,  v e g e t a t i o n of  t h e wet  and  13 d r y m o u n t a i n meadows, t h e roadsides the  i s especially  important  f o o d h a b i t s s t u d y by  cribed briefly the  for this  observation of The  a b r u p t l y by a r e a s may  wet  snowslide  areas, creek bottoms,  to b e a r s ,  (1961).  Tisch study,  mature s p r u c e . f o r the  The  poor  drainage  absence o f t r e e s .  drainage courses  i n l o n g , narrow p a t t e r n s .  Bluejoint  grass  total  and  Sedges  are  surrounded  evident i n these Wet  meadows o f t e n  may  be  (Oarex  quite spp.)  (Calamagrostis canadensis) predominate  d r y meadow t y p e makes up  area, but  the  factors  i s q u i t e widespread  s o u t h e r l y exposures  ( F i g u r e s 26  and  28  and  and  in  u s u a l l y dominated by  rocky,  the Agropyron  bordered  by  an  Both  exposure  Balsamorhiza  saggitata,  sun.  spicatum,  Except  the  many  soil as  f o r these  the  as w e l l  as  meadows a r e of  Daubenmire fir.  Festuca idahoensis, and and  Carex  geyeri.  cliffs,  of Douglas f i r a s s o c i a t i o n s ,  Douglas f i r o r Rocky Mountain j u n i p e r  scopulorum) t r e e s .  on  type,  spicatum union  meadow o f t e n i n c o r p o r a t e s r o c k y o u t c r o p s  single  Dry  Achillea millefolium,  typical  and  open s t a n d of Douglas  species are Agropyron  of shrubs  cent of  i n small patches  a l l o w i n g good d r a i n a g e  Common p l a n t  patches  per  involved i n maintaining this  i s s h a l l o w and  ( 1 9 5 3 : 3 0 4 ) and  one  ridges at a l lelevations  i n Appendix).  seem t o be  about  h i g h e v a p o r a t i o n r a t e s under a d i r e c t  The  in  meadows. The  soil  des-  s i n c e t h e y were i m p o r t a n t  extensive  of  T h e y s h o u l d be  meadows a r e g e n e r a l l y s m a l l a n d  account  shown i n  bears.  follow p o o r l y developed  these  a s was  and  and  (Juniperus  i n c o r p o r a t i o n s , some o f  14 the  d r y meadows  slopes,  o r may  f o r e s t e d  extend e x i s t  study  movement  area o f  o r i g i n a t e v a l l e y the  timber  f l o o d i n g  down  on  the  along  broader  the c r e s t s  o r  (Figure  27  wider  o f  o f  dogwood  Heracleum  lanatum,  Open and  areas  c l e a r - c u t s  vegetation  and  exotic  species  turbed  areas.  Land-use  p o r t i o n s  by  the  o f  annual  They  u s u a l l y  extend  to the  abrupt  paths  as  s t o l o n i f e r a )  have  (logged  s c a r i f i e d ) .  through  t h e i r i n t h e  openings  alder  a r e  (Alnus  and by  spp.) and  large  forbs  spp., and Equisetum  been  created  areas Both  n a t i v e  through  openings  These  such  A n g e l i c a  and by  and  maintain  v a l l e y s .  shrubs  that  areas c u t t i n g  action,  (Cornus  courses.  i n the drainage,  t h e main by  the upper  Appendix).  streams  dominated  c l i f f  s t r i p s ,  i n  on  and maintained  t r a d i t i o n a l  i n narrow  canopy  redozier  that  by  man  were  plants  that  spp.  are the  cleared  are subject  t o  such  of a l l  invasion  are lovers  o f  by  d i s -  P r a c t i c e s E a r l y  on  a r e created  and meandering  generally  roads  f i n g e r s  a r e common  i n d r y meadow  The  as  narrow  areas  and  snow  bottom  f o r e s t  as  acres  ridges. Snowslide  the  f o r several  the study  trappers. open  d i v i d e  some  of  i n the nineteenth area  From  were  1932  country  the major  to  trapped 1939  The  bears  extensively  sheep  a t the head  ridges.  century  of  were  and  by  bands were o f  animals  commercial  pastured  the drainage  f u r  along and  about  the  along  2,000  head  15 maximum of  the  both  and  spent  study  black  records  and  i n  For by  but the  the  logged  lower  are  common  (Canachites are  also  shot  actual  during  this  numbers.  Ho  of  period, stock  done  u n t i l  the  i t has  been  under  i n t e n s i v e  Forest A  of  Forest the  put  some  a  and  short  and  bears, but  has  no  been  area  i s  and  1950's.  e a r l y  many  camp  1933  i n  management  areas  have  l o c a t e d  at  been the  area. moose  (Alces  w h i t e t a i l  hunters Blue  the  and  Service  canadensis),  a t t r a c t  into  Service  study  hemionus),  f o r  boundaries  numbers  was  canadensis)  hunted  considerable  the  logging  (Cervus  and  w i t h i n  were  6).  (Odocoileus  time  roads  years  end  the  since.  States  (Figure  Elk deer  15  were  the  area  l i t t l e  United  extreme  of  f i r s t  of  Apparently  kept  past  part  g r i z z l y ,  the  The  1934,  area.  were  pastured  only  to  the  Grouse  period  i n  a l c e s ) ,  deer  (0.  area;  v i r g i n i a n u s ) Spruce  (Dendragapus  the  f a l l .  mule  Grouse  obscurus)  Figure  6.  Logging a c t i v i t y on the B i g Creek study area. The c l e a r - c u t j u s t before or during the study p e r i o d .  black  areas ';  have  be  17  CHAPTER  THREE  METHODS  Studies rounded study area i n  completely  area was  the  could  chosen  be  an  the  graduate of  United  there  with  States  traps and  trapping  Surrounding extent. logging f i t  23  roads  l o c a l  Tisch, the  a  area  Service  was of  B i g  roads open  were  sur-  that  known  o f marked  to  be  and  t r a i l s  areas  promised  p e r s o n a l l y Montana  were  with  were  high  animals.  made  prepared  a e r i a l  the  Creek  U n i v e r s i t y o f  maps,  studies  captured  i n modified  i n Appendix)  Traps  drainages  Traps  of  i n order The  extensive  evaluations  F i e l d  techniques  (1957)•  Erickson  (3)  system  system  photos,  r e s t r i c t e d  or  the a i d  and p r i m a r i l y  September. were  (Figure  density  good  and  and  Forest  through  h a b i t a t  observations  Maps  to  Bears  bear  drainage  i f necessary.  a  Edward  observations.  single  bear  was  drainage;  ground May  (1)  because  student.  a  expanded  c o l l e c t i o n s  cooperation  on  n a t u r a l  a i d i n making  B o t a n i c a l i n  begun  by  be  (2)  area;  throughout to  were  were i n the  conditions  as  followed were  were  a l s o  area, the  but  used  h i s method  placed  o r i g i n a l l y  as  f i r s t  trapped,  this  study  by  Black  and  throughout  placed  150  Newhouse  0.5  but  t o  miles  procedure  progressed.  those  s t e e l  (1958), o f  the  study  a  l e s s e r  apart  was The  area.  along  modified most  to  18 s u c c e s s f u l l o g s i n  and  the  s e t  was  r o c k s  r e a r  S t e p p i n g  a  a g a i n s t  of  the  s t i c k s  were  t h e r e b y  c a r e f u l l y  c a p t u r e d  were the o f  o t h e r s  t h a t  t h r o u g h  above  main  the  t r a p t h i s  b y  k e e p i n g  was  p a d .  t h e  a  j u s t  b e a r  sets  h i g h found  t r a p  t h e  When  t h a t  jaws  t h e s e  o i l e d  a n c h o r e d  the  s e t s  the  and  some  i n j u r i e s  b e a r  o r  the  t r a p  w i t h  t h e  A l d r i c h  t r i p p i n g  the  escape  i n j u r y  of  f u n c t i o n e d the  paw  w i t h  s m a l l  l e g s  were  c o u l d  so  would  b i r d s  i n  to  t r a p  a c r o s s  c o u l d  and  the  e s p e c i a l l y  l e g ,  e n t r a n c e .  mammals  t o  w i t h  p l a c e d  c a p t u r e  t h a t  and  t r a n s v e r s e l y  on  the  and  the  b u i l t  b a i t  c o n t r i b u t e d  c a p t u r e d  c a p t u r e s . h e l d  a t  b e f o r e  d i s r u p t i n g of  t h e  t r a p  S m a l l  O c c a s i o n a l l y ,  t o o  w i t h  i n s u r i n g  manner. i n  A p p e n d i x )  s e t  the  i m p r o p e r l y  I  t r a p  around  d i s t u r b a n c e  b e a r  manner.  c l o s e d  be as  j u s t b e a r s , b r o k e n  r e d u c e d t h e  f o o t  d e s c e n d i n g . I  ( F i g u r e  u s e d i n  22  r o a d s .  more  d i f f i c u l t  a t t a c h e d  t o  a  The  a  c a p t u r i n g  made  on  b e a r s  s e t when  t r a p  d r a g . o f  t r a p p i n g was  Traps  any  e x p e r i m e n t s  S q u i b b  the  s e t .  h e a v y  c a p t i v e  determine  s n a r e  to  I n i t i a l ( S u c o s t r i n ,  s i m i l a r  A p p e n d i x )  f r o m  i n  n u i s a n c e  i n  22  bank,  the  c o n t r o l l e d ,  a t y p i c a l  c l o s e d  i n  of  d e s i r e d  were  the  was  a  T h e i r  p r o p e r l y ,  the  the  sometimes  b e a r s  and  movements  i n  t r a p s .  h o l l o w e d  p l a c e d  The  be  a  ( F i g u r e  cubby,  s e c u r e l y . be  cubby  dosages  b e a r s  were  B o t h  on  t r a i l s  some  i n  w e i g h t ,  b u t  e i t h e r  t y p e s  t r a p  of  anchored t r a p  d i s t a n c e i t  was  f a s t  were  or  e f f i c i e n t  age. w i t h  I n s t i t u t e ,  w i l d  l i g h t  s n a r e  s u e c i n y l c h o l i n e  New  f r o m  n e c e s s a r y  B r u n s w i c k ,  Y e l l o w s t o n e to  New  c h l o r i d e J e r s e y )  N a t i o n a l  i m m o b i l i z e  b e a r s .  P a r k The  were t o  19 methods o f B l a c k e t a l . (1959) were f o l l o w e d ; numerous adaptat i o n s were made i n t h e t e c h n i q u e , however.  Dosages were  c a l c u l a t e d from the e s t i m a t e d weight o f each c a p t u r e d h e a r , and t h e drug was a d m i n i s t e r e d i n t r a m u s c u l a r l y w i t h the a i d of an automatic p r o j e c t i l e s y r i n g e f i r e d by a c a r b o n d i o x i d e powered l o n g range s y r i n g e p r o j e c t o r ("Cap-Chur" gun, Palmer Chemical Company, I n c . , A t l a n t a , G e o r g i a ) .  O c c a s i o n a l l y the  drug was a d m i n i s t e r e d manually by the use of a hand  hypodermic  s y r i n g e o r e l s e a hand s y r i n g e mounted on the end o f an aluminum p i p e .  Supplemental dosages were g i v e n w i t h a hand  syringe. S u c c i n y l c h o l i n e c h l o r i d e a d m i n i s t e r e d on the b a s i s o f 1 mg p e r 2.3 kg o f e s t i m a t e d body weight approximated  an i d e a l  dosage f o r most a n i m a l s , b u t was e x c e s s i v e f o r a few.  Bears  were e a s i l y saved from l e t h a l dosages by a d m i n i s t r a t i o n o f a r t i f i c i a l r e s p i r a t i o n u n t i l t h e excess drug h y d r o l y z e d .  Bears  were k e p t i m m o b i l i z e d t o t h r e e hours w i t h s m a l l supplemental dosages  o f 5 t o 10 mg, b u t n o r m a l l y an animal had f u l l y  r e c o v e r e d from t h e i n i t i a l dosage w i t h i n 30 minutes. d e l e t e r i o u s s i d e e f f e c t s of t h e drug were noted.  No  Bears were  g e n e r a l l y s u f f i c i e n t l y i m m o b i l i z e d from a p p r o x i m a t e l y f i v e minutes  a f t e r a d m i n i s t r a t i o n of t h e drug u n t i l about 20 minutes  later.  Some i n d i v i d u a l and s e a s o n a l v a r i a t i o n i n the response  to  t h e drug was noted; b e a r s i n the autumn remained i m m o b i l i z e d  almost t w i c e as l o n g as the t h i n n e r b e a r s g i v e n dosages  i n the spring.  comparable  T h i s agrees w i t h the f i n d i n g s o f  C r a i g h e a d e t a l . (I960) on g r i z z l y b e a r s , b u t S t i c k l e y  (1961)  20 found no marked d i f f e r e n c e s i n the response of t h i n and f a t hears.  Complete f a m i l i a r i t y w i t h the a c t i o n of the  proved as v a l u a b l e as the d r u g  drug  itself.  D u r i n g F e b r u a r y , I960, t h r e e denned b e a r s were g i v e n dosages of s u c c i n y l c h o l i n e c h l o r i d e .  S i n c e the b e a r s were i n  a semidormant s t a t e w i t h an a p p a r e n t l y reduced m e t a b o l i c it  rate,  seemed l o g i c a l t h a t s u s c e p t i b i l i t y t o the d r u g might be  higher.  S m a l l e r dosages were unnecessary,  however, as the  b e a r s were not i m m o b i l i z e d u n t i l g i v e n normal dosages o f a p p r o x i m a t e l y 1 mg p e r 2.3 All  kg of body  weight.  animals were marked i n s e v e r a l ways.  Metal stock  tags t h a t v a r i e d by number and c o l o u r were p l a c e d i n b o t h e a r s of every b e a r .  A d i s t i n g u i s h i n g number was  the t i p of each ear or beneath animals.  tattooed i n  the r i g h t f o r e l e g of some  V i n y l tape r i b b o n s ( C r a i g h e a d and S t o c k s t a d , I960)  were p l a c e d i n s l i t s and r i v e t e d .  The  the r i b b o n s was  i n the e a r s , s e p a r a t e l y from the t a g s ,  l o c a t i o n i n the ear of b o t h the t a g s  and  v a r i e d f o r d i f f e r e n t animals to g i v e a d d i t i o n a l  i n d i v i d u a l c o l o u r combinations.  The metal t a g s were more  d u r a b l e t h a n the r i b b o n s , and except f o r some i n i t i a l  losses  they were permanent throughout  study.  Ribbon l o s s was ear. to  the seven y e a r s of the  g r e a t e r , e s p e c i a l l y from breaks c l o s e to the  Because o f f a d i n g , a l l r i b b o n c o l o u r s became d i s t i n g u i s h a f t e r two  or t h r e e y e a r s .  difficult  Even so, many b e a r s  were i d e n t i f i e d by the p l a s t i c r i b b o n s f i v e y e a r s a f t e r had been p l a c e d i n the bears*  ears.  The a r t i f i c i a l  caused some i n d i g n a t i o n among p e o p l e who  they  markers  f r e q u e n t e d the a r e a ,  21  and  some  b i o l o g i c a l  hunters  f a i l e d  this  problem  were  used  onto the  canvas  i n the  were  were  and  i n order  treated  onto  manually  were were  that  a  checked  the  strong  one  Only  and  with  begin  tarp  the  to  during  out  trap.  30  x  bad  During or  power the  watched  made  with  Forest  a  Cubs a  were  foot  square  both  canvas;  bear  and  a  pole  t r i p o d  as  much  as  a i d o f  mornings  the  S e r v i c e  day  with  cuts  o r  and  20  At  l e a s t  one  animals  not  other  wounds  were  r e c e i v e d  member  u n t i l  o f  they  bears  the were  were  more  spend  given  ( p e n i c i l l i n  bears  Immobilized  sometimes  would  some  a n t i b i o t i c  every  and  were an  and a  too  strepto-  s e r i o u s  t r a p p i n g able  to  covered  crew stand  with  a  weather.  f i e l d  with  a  i n j u r y  captured  of  away.  Observations 6  o f  r e c o v e r i n g move  twice  a n t i s e p t i c ,  mycin).  remained  markings  hooking  onto  and  the  against  animals  a l l bears  i n j e c t i o n  from  with  guarded  intramuscular  wound  by  counter  methods.  scales.  r o l l e d  scale,  to  Natural  spring  weighed  were  or  t r i e d  a r t i f i c i a l  with  the  I  releases.  were  hooked  trap;  with  o r  r e s e n t f u l  tackle.  Traps  i n t h e  trap  when  though  these  weighed  bears  bears  p o s s i b l e .  with  l o s t  even  press  Larger  l i f t e d  The  long  k i l l s , and  were  scale.  block  often  t a l k s  bears  corners  and  with  while  t h e  r e p o r t  i n combination  A l l weighed  to  i n f o r m a t i o n was  of  bears  glasses and  f i e l d  spotting  and  were a  evenings  glasses, scope.  personnel  were  30  made  power  open  but  with  a i d o f  spotting  h i l l s i d e s  evaluated  made and  scope.  were  i d e n t i f i c a t i o n s  Observations also  the  by  scanned  were  u s u a l l y  loggers  recorded.  and  22 Observations  i n drainages  systematically, were r e c o r d e d United  S t a t e s F o r e s t S e r v i c e and  throughout  and  the v i c i n i t y the r a t i o  f o r use  study and  a r e a were made  untagged  With the  Game  a d u l t t o young  the  study  of tagged  a r e a were a s k e d  to untagged bears  Hunters  about b e a r  killed  i n c a l c u l a t i n g p o p u l a t i o n d e n s i t y and  was  with foods  consumed b y  berry  (Vaccinium  spp.)  5,000 f o o t  level,  with  A n o t h e r t r a n s e c t was exposure,  and  exposure. recorded  the whitebark 100  pine  pace i n t e r v a l s .  at the  6,600 f e e t ,  c o u l d be  c o n e s on  forest with Ten  compared.  a l l t r e e s was  with a  t r e e s sampled  s e l e c t e d whitebark  with  the  exposure.  southern southern was  established i n f o r cones  at  pine  t r e e s were  so t h a t  individual  E a c h September the  counted  the  at a l l l e v e l s  t r a n s e c t was  discs  available  again with a  abundance o f b e r r i e s  A four mile  recorded  huckle-  each t r a n s e c t at a d i f f e r e n t  a l s o p e r m a n e n t l y marked w i t h m e t a l trees  permanent  t r a n s e c t s were e s t a b l i s h e d a t  relative  each year.  Four  p l a c e d a t 5,800 f e e t  another,  The  bears.  kills,  f o r management.  Sample t r a n s e c t s were e s t a b l i s h e d t o compare foods  Depart-  ratios  r a n g e i n M o n t a n a were r e c o r d e d .  of  bears  cooperation of  Montana F i s h and  o b s e r v a t i o n s of the  the bear  the  t h e numbers o f t a g g e d  t o measure d i s p e r s a l .  ment p e r s o n n e l ,  in  and  surrounding  total  a i d of the  number  of  spotting  scope. I noting  the  examined b e a r s s p e c i e s and  were c h e c k e d  f o r p a r a s i t e s whenever time  abundance o f each,  for internal  parasites.  and  permitted,  a l l dead  bears  23 Phenological climatic on  the  differences  by  contacting hunters  during  the w i n t e r  mortality  stored. 10 p e r  d e s c r i b e d by Some f e m a l e  m a t e r i a l was  formalin.  and  cleaned with  2 mm  and  Jonkel  reproductive tracts  hunters  a game a n i m a l .  to  determine  from  periodically  winter  to  effect  mile  strips  of the  a b o u t 4,000 f e e t  (1966) t o determine  I n the  black bears  fall  (Pactylis  were  the  covered  Since  onto  1962,  technique  where  clover  The The  they seeded  (Trifolium  plantings s e e d was  snow o r o n t o  periodic  wet  being  species  glomerata) at every  B i g Creek road. t o 6,000 f e e t .  age.  the  of I960 I  to white  as  studies.  w o u l d come t o r o a d s  directly  snow.  from  a  corpora  sectioned  g o o d management o f  hand r o t a r y s e e d e r s with  t o make  were o b t a i n e d  of roadbed  orchard grass  16 m i l e s  sectioned with  T h e r e f o r e , I t e s t e d a management  whether bears  beetles  e t c . were p l a c e d  and  f o r comparative  h u n t e d more e a s i l y .  r e p e n s ) and along  sites  d e n s were  dermestid  intervals  t e e t h were d e c a l c i f i e d  Stoneberg  as  one-tenth  den  soliciting  to determine  I n d i c a t i o n s were t h a t t o o f e w  c o u l d be  Other by  O v a r i e s were h a n d  W a s h i n g t o n Game D e p a r t m e n t  by  and  Dens were o b s e r v e d  a g a i n i n May  at approximately  counts,  killed  snow.  Tissues, reproductive tracts,  cent  razor blade lutea  obtained,  Information  rates.  Skeletal  in  annual  activity.  l o g g e r s and  the p r e s s .  and  was  i n the  and  to evaluate  to bear  bears  t r a c k i n g bears  information through  and  in relation  movement o f i n d i v i d u a l  were l o c a t e d b y found  d a t a were r e c o r d e d  mile  ranged  spread  with  ground  soon  o b s e r v a t i o n s have  been  made a l o n g strips  this  16 m i l e  area,  and t h e numbers o f b e a r s  a n d t h e numbers o f b e a r s  o f f the strips  have  on the  been  recorded. The by  reproductive  c o n d i t i o n o f f e m a l e s was  examinations o f the v u l v a .  ranked on a s c a l e of zero colour.  Animals ranked  sidered  The d e g r e e o f s w e l l i n g was  t o f o u r b a s e d on measurements and  a t stages  three  a t the peak of the estrous The  important  f o r s e v e r a l reasons.  and f o u r w e r e  wild populations are  Capturing  and h a n d l i n g  c e d u r e s c a n i n c r e a s e m o r t a l i t y o r can i n d u c e may f l e e  using  certain parts of their  rare,  i s valuable  composite value unnecessarily population. upset will  from  range.  esthetically,  the area,  Also,  Obviously,  or cease  i f a species i s  o r i s p r i z e d as a trophy,, t h e  or defacing the less  through  individuals  that research  of the procedures  n a t u r a l conditions the b e t t e r that p a r t i c u l a r be.  I have t r i e d  to f o l l o w these  became a c c u s t o m e d t o b e i n g  captured  e v e n when I a p p r o a c h e d , b u t b e a r s became f r i g h t e n e d . was e v i d e n t trap-shy,  precepts.  research  Many  bears  and would s i t q u i e t l y  t h a t were i n j u r e d u s u a l l y  T h i s f e a r o f t h e t r a p a n d o f man u s u a l l y  i n future captures  and p r o b a b l y  t h o u g h I do n o t b e l i e v e t h i s  significant  pro-  some s p e c i e s t o  o f t h e r e s e a r c h c a n be negated  deforming  con-  cycle.  methods u s e d i n s t u d y i n g  change t h e i r h a b i t s ; t h e y  determined  during this  study.  made some  disturbance  bears  became  PART I I RESULTS:  25  CHAPTER  POUR  ECOLOGICAL  The of  a  study  of  the  must  be  based  populations.  This  species  natural  techniques  and  (1965)  pointed  to  study  and to  nas  that an  a  animals  i n  without  those  understanding  of  i r r e s p e c t i v e  (Andrewartha an  area  what  i n  which  same  i n  time,  the I  adaptations natural  of  the  found  such  an  study of  1954),  i s  becoming  under  the  which  studies  are  i n  The  man,  w i t h i n  which  l i v i n g  f o r e s t s  areas  to  important.  and  short  the  to  bears  to  Big  of  great  distances  I such  and  study  natural Creek,  the  At  or  me  to  of  the  nearly  ranging  f o r e s t  as  evolutionary  transformed  v a r i e t y l e d  the  wanted  what  populations.  completely  disturbance  abundance  considerations  under  of  ecology. and  important  area  evolved,  of  are  an  Lack  i r r e l e v a n t  d i s t r i b u t i o n  bear  special  d i f f i c u l t  they  aspects  equally  a f f e c t  of  area.  forces  increased  area.  already  evolutionary  population  by  of  study  f u n c t i o n a l problems,  undisturbed  drainage  i a t i o n s Creek  a  the  our  from  development  evolutionary  environment  of  i t i s  information  the of  management  the  wanted  annually  s e l e c t i o n  and  study  conditions.  completely  involves  the  the  to  e c o l o g i c a l  conditions  B i r c h ,  environmental  changes  the  and  dynamics  conditions  of  ecology,  on  that  the  Functional animals  population  c a r e f u l out  STUDIES.  i n  from areas,  portions  plant  consider  assocBig  26 Home R a n g e s o f B e a r s Big one  Creek  i s divided  into  two b a s i c  meets a l l t h e needs o f i n d i v i d u a l  year-round cover  by bears;  animals  the basis  I determined  females,  were c o n f i n e d t o a c e r t a i n p a r t  tended  t o be c a p t u r e d or observed  areas, even though  throughout  o f the year-round  home r a n g e s  captured or observed home r a n g e .  p a t t e r n most c l e a r l y . 15 t i m e s  (four  Bears  No. 19 a n d 62  No. 19,  Bear  Creek  Hallowat  that  i n maximum l e n g t h ( s e e F i g u r e s 2 a n d 7 ) .  11 was  8 ) , a n a d u l t m a l e whose r a n g e  B, was c a p t u r e d o r o b s e r v e d  17  o b s e r v a t i o n s ) b e t w e e n J u n e 19, never  seen o r caught  entire  illustrate  times I960,  m e a s u r e s 2.0 m i l e s  Bear  extends  seen o r caught  No. 62 from P o i n t s A  ( s i x captures, a n d May 2 2 , 1 9 6 6 .  o u t s i d e o f an a r e a on H a l l o w a t  t h a t m e a s u r e s 6.0 m i l e s i n g r e a t e s t d i s t a n c e b e t w e e n The  captures  c a p t u r e s , 11 o b s e r v a t i o n s ) b e t w e e n  outside  an a r e a on upper  year  a f e m a l e , was c a p t u r e d  She was n e v e r  and  from  The e x t e n t o f  J u l y 2 5 , 1959, a n d J u n e 2, 1965.  (Figure  The a r e a i n  d i d n o t c h a n g e much w i t h a d d i t i o n a l  observations o r with time.  or observed  repeatedly i n par-  the study area.  t o y e a r was c o n s i d e r e d t h a t b e a r ' s  this  a n d 312 o b s e r -  trapping operations or observations  w h i c h e a c h b e a r was r e g u l a r l y  and  autumn.  t h a t most o f t h e b e a r s , b o t h m a l e s a n d  were e q u a l l y i n t e n s i v e  their  f o o d and  A s shown i n F i g u r e s 7 a n d 8, b o t h m a l e a n d f e m a l e  habitat.  ticular  through  o f 280 c a p t u r e s o f 158 b e a r s  vations,  adults  and i s i n h a b i t e d  the other provides supplemental  and has s e a s o n a l u s e from m i d - J u l y On  types of h a b i t a t :  drainage i s t y p i f i e d  by l o c a l l y  abundant  He  Creek  sites. food,  TO  TO  COAL  CHECK  tWIFT CREEK  BIG  CREEK  FEMALE  STUDY  AREA  RANGES  CANYON CHECK  Figure  ?•  H t c p A J t c o r w o u u.s. renin  KHVICC MAPS a AERIAL  PHOTOS  Minimum home r a n g e s o f a d u l t f e m a l e s o n t h e B i g C r e e k s t u d y a r e a b a s e d o n c a p t u r e and o b s e r v a t i o n p o i n t s . Only the ranges of bears d i s c u s s e d i n t h e text are c i r c l e d . A r e a s A a n d B a r e a t a p p r o x i m a t e l y 6,000 f e e t i n e l e v a t i o n and a r e t y p i c a l o f t h e h a b i t a t u s e d s e a s o n a l l y b y b e a r s .  BIG  CREEK  MALE TO  AREA  RANGES  CANYON CNCtK  F i g u r e 8.  STUDY  W C F A t t D F K C * U.S. FOREST SCKVICC MAPS & AERIAL  PMOTOS  Minimum home ranges o f a d u l t males on the B i g Creek study a r e a based on T J ^ Points. Only the raSges o f b e a r ! discussed i£ one uexo a r e c i r c l e d .  •?SE ?f + t  e  a  n  d  o  b  s  e  r  a  i  ro oo  29 since  the  berry  tions  and  on  r e s i d e n t other a  the  the  where  bears  only  crop  various  the  d i d  small  f a i l s  p a r t  of  Ranger  garbage  dump,  t r a v e l e d to  Bears Lake  (area  A  7  Figures  and of  some  i n 8)  years  huckleberries  or  these  and  tolerant of  one  small  of  part  feeding  of  on  areas  when  Even  area.  tagged  adult  male  males. male area, area  The  (No.  female  129)  though shown  i n  stayed b e r r i e s Figure  i n  such  an  Bears an  to  w i t h i n  seemed  by  female t h e i r  cub  and  near  the  periphery  9«  most  bears  from  her  were  do  area,  Figure  unmarked  the  bears  the  abundant  one of i n  as  and size  the  was  In  Septembers  of  e i t h e r  congregate they  100  quite  200  yards  i n  were  one  observed  There  6  were  cub, to  i n  seem  or  stay  tagged the  i n  f e e t ,  September  9.  Moose  B  food  6,000  abundance  Basin i n  from  at  (area  July.  d i f f e r e n t  shown  more  such  when  about  e a r l y  cones.  China  or  area  i n d i v i d u a l s g e n e r a l l y  which  and  addition,  Basin  at  great  i n  In  Other  f r e e l y  are  approaching  are  bears,  bears  pine  Eleven  huckleberries movements  a  i t , however;  abundant  used  China  by  bears  v i s i t o r s .  areas  snow  was  eleva-  of  mile  source.  or  areas  have  so,  Their  8)  feeding  bears,  the  unmarked  of  one  regular  these  two  c l e a r  1961.  large  to  l i v i n g food  Only  use  area.  food  d i f f e r e n t  year.  made  seasonally  and  whitebark  other  another.  a  7  These  these  places,  to  moved  become  were  at  that  where  this  dump  Figures  there.  u s u a l l y  to  each  i n  bears  S t a t i o n ,  adjacent  and  a v a i l a b l e  the  abundant  abundant  those  Creek  close  was  congregate  Big  l i v i n g  i s  exposures  food  not  or  and  be  to  four f i v e  adult  sub-adult huckleberry  long  15,  c e n t r a l  o Figure  9.  The  movements  of  11  bears  observed  China B a s i n area of the B i g Creek of bears observed most often.  from  September  drainage.  6  Shaded  to  1£>  areas  1961,  i n  i n d i c a t e  the ranges  The maximum d i s t a n c e between c a p t u r e and p o i n t s was  measured f o r a l l a d u l t b e a r s on B i g Creek.  r e s u l t s o f 146  The  l o c a t i o n s f o r 31 a d u l t females and 83  f o r 16 a d u l t males are shown i n Table 1.  A few  made u n u s u a l l y  l o n g movements.  66,  ( F i g u r e 8) and  females No.  examples.  observation  Female No.  156  125 and  Males No. and  a d u l t bears  67,  and  ( F i g u r e 10)  156  male No.  locations  84  are  67 were animals w i t h  garbage dump e x p e r i e n c e t h a t moved r e g u l a r l y between the Ranger S t a t i o n dump and southeast.  I have no  the v i l l a g e of Apgar 10 m i l e s  information  d i s t a n t wandering o f the o t h e r  was  cause of  7 and  8 shows t h a t the  a d u l t females o v e r l a p p e d , but  a d u l t ranges, though, o v e r l a p p e d c o n s i d e r a b l y T r a p s i t e 62B  s i t e of the  ranges  there  during  c a p t u r e of two  the same p e r i o d .  t r a n s i e n t s , but  were a l s o c a p t u r e d  o t h e r s had  the but site  appeared t o  home ranges almost i d e n t i c a l Female No. 59)  61 remained on  a t l e a s t through 1965  years o l d (Figure 7).  of e n t i r e l i t t e r s  I960,  at that  Some of the s u b - a d u l t s  home range of her mother (No. 5-1/2  w i t h a d u l t home  a d u l t females d u r i n g  those o f t h e a d u l t f e m a l e s .  she was  Sub-  on lower B i g Creek ( F i g u r e 2) was  seven d i f f e r e n t s u b - a d u l t s  be  the  a minimal o v e r l a p between a d u l t s o f the same sex.  ranges.  the  adults.  A comparison o f F i g u r e s o f the a d u l t males and  about the  to  I noted s i x other  s t a y i n g on t h e i r mothers* home ranges  the f a m i l y groups had b r o k e n up.  A d d i t i o n a l d a t a on  t o p i c are i n the Chapter on b e h a v i o u r .  to  the when cases after  this  32  Bear No.  No. of Years Involved  No. of Points  2 3 6 7 2 6 6 4 5 2 2 4 5 3 5 6 4 6 3 4 6 5 2 5 5 6 1 3 3 1 2  23  24  32  34  36  47  51 52 59  61  70  71  75 85  87 113 115  121 123  124 150  151  162 177  192  6 6 12 5  3 15  4  .3  5 2 5 3  4 3 3  6  3 10 5 3  6 3  4 7  3  6 2 2 3 2 2  1.  2.1 1.7  3 6 7 21  2.5  1.6  49  2.5  2.0  50 57  2.5 1.5  62  2.2 1.2 2.4 .4 1.2 2.3 2.1  63  64  77 86  116 148 155 167  .5  2.4 1.7 1.4 .9 1.3 1.0 .3 2.2 .3 1.3 1.0 .9 1.2  Distance i n Miles  No. of Points  The  maximum  ture study  or  4  2.1 3.0  7 7 2 5 6 2 17  3 7 1  6 6  1 7 6 3 3  3.4  2.0  7.4  5.7 4.2 6.0 3.3 6.3 3.6 3.0 3.0 2.7 5.6 •5  4  2 6  4  4  4  4  8  6  3 2  3 2  .0  distance during  3.9  Average  observation  area  4  .5  1.6  Average  Table  No.  No. of Years Involved  Males  Females  1 2 10 12 16 19  Bear  Distance i n Miles  i n  miles  between  f o r  adult  bears  1959  through  1966.  on  points the  of  Big  capGreek  34 The the  home r a n g e o f some a n i m a l s  animal  matured.  F o r example, b e a r  s u b - a d u l t m a l e when f i r s t observed  captured  i n c r e a s e d i n s i z e as No. 7 ( F i g u r e 8 ) , a  i n 1959, was c a p t u r e d a n d  o n l y i n a small p a r t o f upper Skookoleel 1961.  through  old) through a lower  F r o m 1962 (when he was a minimum o f 6-1/2 1965 he was c a p t u r e d  area near  o r seen  the confluence  i n 1961;  to bear  area  systematic  evidence  i n these  surrounding  these  areas.  bears  from  Eighty-five of  " o u t s i d e " o b s e r v a t i o n s o f unmarked  i n the B i g Creek  b e t w e e n J u n e 12, adjacent  t h e home  F i g u r e 11  were e i t h e r  ranges  captured or Some  data  area are included.  T h e r e i s some b i a s i n t h e s e  data  observed  t h e d r y meadow t y p e ,  like  bears  shows t h e  1959, a n d May 3 0 , 1 9 6 6 .  to the B i g Creek study  i n open areas  In  drainage.  o f h a b i t a t i n w h i c h 708 b e a r s  areas  o f 89 b e a r s  w h e t h e r t h e y were m a r k e d .  R e q u i r e m e n t s o f Home R a n g e s .  observed  the B i g  f o u r were n o t s e e n  were made o n l y a f e w h o r i z o n t a l m i l e s f r o m tagged  was p r o v i d e d b y  surrounding  and t h e r e m a i n i n g  enough t o d e t e r m i n e  many c a s e s  type  open  r e s i d e n t on the  B e t w e e n 1959 a n d 1965 a t o t a l  t h e s e were u n t a g g e d ,  of  that area  t h a t the a d u l t bears  observations i n drainages  observed  clearly  i n the l a t t e r  left  s e l d o m l e a v e t h e i r home r a n g e s  Creek d r a i n a g e . was  and B i g C r e e k s .  No. 7* Further  study  apparently h i s death  years  i n t h a t l o c a t i o n and  o f Skookoleel  A', l a r g e m a l e , No. 6, was s h o t b y a h u n t e r location  Creek  since bears  c a p t u r e s h a v e some b i a s s i n c e I o f t e n t r a p p e d  were m o s t  easily  and even the  i n the F i c e a -  CO  o U  jd  cd co •  as d  .  o  c d , a cd T3 <D CQ a> cu ca  •H  CO  CO  m  -H  ,ri-p  o to  cd cd-P a> o co  u  d rH  •d  -P  «H  CO -P CO  a  U  3  <l>  ^1  U bO ^  ,a  cd -oco  o  -P  cd tn co ri cc H  K o  JS  CD -P - H CQ Cd -P  to O  !>(d  CD  .ri  ri  CQ  O  •HO  (0  «J  .  ri O +3 . r i cd ri CQ cd cd co iH ri co ft cd*-P-P •P P i ri  •H  •P - d O •H 0  f4  CD  CQO*M  Cd  .ri  t>--H  ri o <u O « H (4 o CQ o - d  CM CD  a>  co CD  >s'H  cd cd  r-t H CO  I P>4  .  36 Abies/Pachistima As the  shown  study  t i o n  area  has  serai  popular  with  burned  by  Recently  logged  avoided  by  area  a  a t  Bears vegetation  the  of  begin  that  surrounding  tions  were  observed were  made  merely  quarter  the  no  climax  f o r e s t  type.  As  of  c u t area  the  p a r t i c u l a r l e f t  areas  was  type  home  None  made  they  Werner used  of  feeding;  near  i n the  and the  much  seven  bears  bears  up  they  observed  timbered  d i d feed  as  observa-  apparently  The the  as  Greek  to  edges, one-  t r e e s . and  range  h a b i t a t  area  The  i s the  i s of  are  so  measurements  types.  d e s c r i p t i o n  drainage  on  was  opening.  quite  vegetative  i n the  the  the  topography  the  type. completely  captures  c l e a r i n g .  the nearest  on  i n that  they  s e r a i  w i t h i n  within  c l e a r - c u t s i n  the  A  i n  e q u a l l y  c l e a r - c u t s as  frequent  or  o f  be  year.  since  density  to  p e r  areas,  the  a r e now  almost  square  o l d i n 1963  from  shown  were  years  g e n e r a l l y  Because  even  10  d r y meadow  seem  of  a s s o c i a -  mile  dense.  c l e a r e d  burns  neglect  burns  one-half  were  mile  two-fifths  more  p o r t i o n  c l e a r - c u t s are being  through  i n the  area,  New  moving  c u t areas  stages  i n a l l types  to  lower  a s s o c i a t i o n i n d i c a t e s that  to use  was  i n other  although  up  becomes  2)  (Figure  areas  the  These  t h e i r  recent  the bears. r a t e  past.  but  use  of  bears.  the Picea-Abies/Pachistima  Picea-Abies/Pachistima not  much  A l l serai  the bears,  would  the  5,  i n the  stages.  probably  i n  i n Figure  occupied  been  various  the  a s s o c i a t i o n f o r s p e c i f i c  o f  this  only  diverse  were  on  made  extensive  Picea-Abies/Menziesia the  area,  type,  but  approximately only  eight  per  cent  In  of  the  e l e v a t i o n  roughly north  the  slopes  i n  summer.  the i n  snow  p l a n t  completely any  of  of  animal.  about  one  the  5,000  and  of  higher  various  shown  that  avoided  pointed  out  g l a b e l l a ,  of  the  and  of  r e s i d e n t s of  Range home  may  numbers  always  o f f e r s  i s  on  type  u n t i l  (1961),  l a t e  i t i s  composed  l i t t l e  type  food  to  comprises 55  f o r  Boundaries. range  group  per  bears  cent  v i c i n i t y  requirements,  the  to  spring.  i n which  they  move  f o r  animals.  congregate  i n  Bears  boundaries  several  habitat  snowslides the  lower  May.  small  on  o f t e n  accounted  and  and  l i e s  f o r e s t  Tisch  but  d e n s i t y  areas  f o r e s t  bears  area,  bear  meadow  by  meadow  t h e i r  this  i n i t .  This  dry  Home  w i t h i n  and  made  extends  the  during  Within  by  understory  comparison,  areas  on  so  Menziesia  cent  but  slopes.  i s  were  climax  south  The  reasons,  sections  as  feet,  species.  observations  c e r t a i n  on and  A l s o ,  Movements to  observations  6,000  and  slowly,  In  per  and  Picea-Abies/Menziesia  between  clears  poor  captures  In  I  the  have  feed  on  dry  They  were  were  feeding,  however. Adult w i t h i n  t h e i r  the  study,  the  mid-summer. the  Abies/Pachistima only an  three  even  sex  have  than  u n t i l  at  to  ranges  year  roads  seem  home  f i r s t  main  of  males  were  Most  of  lower type.  males,  r a t i o  at  Of  the  of  f i v e  seasonal  p r o j e c t  t r a p p i n g was  of 16  a  females.  trapping  which  the  do  the  end  more  the  study  a d u l t s i s  area  captured  s i g n i f i c a n t l y  per  cent  l e v e l  1959,  In d i d  done i n  s h i f t the  not  begin  along  the  the  that  P i c e a season,  d i f f e r e n t of  the  from  Chi-square  38 Test. more was  I n t h e f o l l o w i n g y e a r s , when t h e a r e a h a d b e e n thoroughly  a t a l l e l e v a t i o n s , t h e sex r a t i o  even (46.9 p e r cent females),  almost  males were n o t i n t h e permanent b e a r during  late  confirmed  summer a n d f a l l  by l a t e r  o f 1959.  trapped  of adults  indicating  t h a t the  h a b i t a t w i t h the  females  This hypothesis  was  o b s e r v a t i o n s , as, f o r i n s t a n c e , by the  preponderance o f a d u l t males i n the s u b - a l p i n e China  Basin  a r e a d u r i n g t h e autumn. Bears one-tenth I960. of  a l s o moved w i t h i n t h e i r home r a n g e a r e a s  mile  I seeded along  strips  methods and p o o r s o i l  a t the lower  6,000 f e e t  14 o f t h e b e a r s  outside cent  were o b s e r v e d  i t .  of the t o t a l  increase No  Since  tagged  observed  along  seeded  strips.  growth  at elevations  Starting  i n 1962,  t h e 16 m i l e  strips.  stretch  T h r o u g h 1966, road  were o n t h e s e e d e d p o r t i o n , and 10 were  the seeded road-bed,  moved  1962  feeding along the experimental  strips  this  i n use of the seeded bears  because  but by  B y 1964 e v e n t h e s t r i p s  o f r o a d were f e e d i n g on t h e seeded  area;  quality,  were e a s i l y r e c o g n i z a b l e .  I r e c o r d e d whether bears  24 b e a r s  probably  e l e v a t i o n s were s h o w i n g g o o d  ( F i g u r e 29 i n A p p e n d i x ) . near  the B i g Creek road i n  The p l a n t i n g s were s l o w i n s t a r t i n g ,  the seeding  the  strips  to the  comprise  represents a  areas  outside their  over  o n l y 10 p e r thirteenfold  the non-seeded  home r a n g e a r e a s  areas.  to these  39  Den  Ecology On B i g Creek a few b e a r s emerge from t h e i r dens as  e a r l y as m i d - A p r i l , but, as shown i n Table 2, most do appear u n t i l mid-May. melts e a r l i e r ,  and  I n some y e a r s , such as I960,  by the f i r s t week of May, s t a r t e d on May  the snow  the d r y meadow areas have g r e e n  and g r a s s e s by e a r l y May.  15th.  not  sedges  I n I960 many b e a r s were observed and t r a p p i n g o p e r a t i o n s were  The b e a r s g e n e r a l l y e n t e r e d t h e i r dens  by l a t e October, b u t the f a l l  of I960 was  unusual a l s o i n  t h a t the weather c o n t i n u e d to be warm u n t i l the f i r s t week of November.  There were no heavy f r o s t s o r snow, and f o o d  abundant l a t e r t h a n u s u a l . s c o p u l i n a and S.  Mountain  ash b e r r i e s  was  (Sorbus  s i t c h e n s i s ) , which do not u s u a l l y  ripen  b e f o r e t h e y f r e e z e or b e f o r e the b e a r s go to t h e i r dens, d i d ripen that f a l l I960).  and were eaten i n g r e a t q u a n t i t i e s  Much b e a r a c t i v i t y was  were s u c c e s s f u l u n t i l  n o t e d , and  (Jonkel,  trapping operations  a snow storm came on November 8.  In  o t h e r y e a r s b e a r s were u s u a l l y denned by then; i n 1961, f o r example, w i t h the advent o f heavy snows a l l a c t i v i t y ceased by October  had  20.  A common b e l i e f i s t h a t b e a r s i n poor c o n d i t i o n for  s h o r t e r p e r i o d s t h a n b e a r s i n good c o n d i t i o n  1961;  Spencer,  1955)•  T h e r e f o r e , one might  Creek  (Rausch,  expect b e a r s i n  poor c o n d i t i o n t o emerge e a r l i e r from t h e i r dens. Big  den  On the  s t u d y a r e a 60 p e r c e n t of 12? b e a r s observed or  captured during A p r i l  and May  were a d u l t s .  S i n c e a d u l t s are  g e n e r a l l y i n b e t t e r c o n d i t i o n than s u b - a d u l t s , the o p p o s i t e  Approx. of Year  date  Approx.  f i r s t  of  Emergence  1959  date  Approx.  General  of  Emergence  ?*  1  June  ?  date  Denning  October  31  I960  A p r i l  10  May  5  November  1961  A p r i l  20  May  20  October  20  1962  A p r i l  20  May  15  October  31  1963  A p r i l  20  May  15  •  1964-  ?  May  25  •  1965  •  May  15  1966  •  May  15  *At p o i n t s the study  Table  2.  of question area to get  m a r k I was unable to the necessary data.  be  7  on  The approximate dates that bears entered and emerged from t h e i r dens on the B i g Creek Study area. G e n e r a l e m e r g e n c e was a r b i t r a r i l y taken to o c c u r w h e n b e a r s c o m p r i s i n g r o u g h l y 50 per cent of the p o p u l a t i o n were seen throughout the snow-free p o r t i o n of the drainage.  41 might have been e x p e c t e d , o n l y 31  used.  per  cent  The  base of  hollow  miles  trees.  caves,  dens dug  of  31  of  but  fall  when n e s t  the  per  females;  site  the  cent  of  these  and  materials  into  f e m a l e s add  the  nest  unavailable.  materials of  quantity  into the of  the  den  others  made a l a r g e n e s t  with  this  blocked  the  den  nest  materials  similar  to t h a t  with  few  bears modified  adjusting  the  nest  on  material.  the the  bears  were  One  female  surrounding Two  bears  i n a manner  hibernators.  A  materials.  are  to in  study  cedar bark from trees  and  entrance  later  unknown.  10  Erickson  T h r e e o f 10  in this  was  only  materials  den  denning p e r i o d  underground  den.  are  true  or  were i n  i n which to l i e , but  materials  of  often  were i n  f o u r were  b e c a u s e males den  a great  1966.  area  logs, five  was  sex  most  study  this  the  and  bears.  that only  thought  t h a t moved n e s t  stripped  by  b e a r s moved n e s t  he  55  b e a r s made a h o l l o w  den,  the  t r e e was  under a c a b i n ,  enlarged  (1964) s u g g e s t e d  adult  a hollow  i t , and  was  comprised  b e a r s t a g g e d b e t w e e n 1959  T h r e e were u n d e r f a l l e n  one  or All  out  155  since adults  T w e n t y - n i n e dens were l o c a t e d on  w i t h i n 100  rock  of  especially  discussed  their  dens d u r i n g  Their  activities  i n greater  detail  the  winter  during i n the  by  the section  behaviour.  Dispersal During outside  the  d i s p e r s a l by  this  study  study  area.  a 2-1/2  year  18 The  b e a r s w e r e known t o h a v e g r e a t e s t d i s t a n c e was  o l d male.  T h i s b e a r was  travelled  a 30  mile,  seen  several  42 times  i n m i d - S e p t e m b e r as he  Valley,  and  he  was  Four of  the  18  1- 1/2  o r 2-1/2  t h a t was  finally  moved s o u t h  shot  across  on  the  outskirts  bears  were f e m a l e s ,  and  three  years  old.  The  Flathead  of  Kalispell.  of these  f o u r t h f e m a l e was  an  were  adult  156);  she  i s d i s c u s s e d i n the  s e c t i o n o n home r a n g e s a l o n g w i t h  one  of  (No. of  a dump a d d i c t (Ho.  the  67).  their  Three others  o f the  movements f r o m t h e  (eight miles  sub-adult  2- 1/2  o f age; their  the  Distribution G r i z z l y bears  Creek study Since  they  grizzlies I  area, but  was  i m a t e l y 90 of  was  to be  i n 1961  the b l a c k  bears.  known.  black bears  F i v e out  the  are  tagged  The  Black  black bears  Using  enough  a r e a were 1-1/2  m a l e s and  and  I t has  as  dispersal  three  sub-adult  B e a r s on sympatric  Big on  Creek the  s p e c i e s , some i n f o r m a t i o n capture  not  black bear  ( p a g e 100),  sub-  Big  a r e f a r more n u m e r o u s .  and  visit  o f 15  the  since, the  p o p u l a t i o n was  a ratio  on  observation data,  been as h i g h  t h a t many g r i z z l i e s The  of  or  g r i z z l y population frequenting  six.  each year.  not  of G r i z z l y  entire  approximately  some t i m e  ( T a b l e 1).  f i v e were f i r s t  12.  and  males  m i g h t h a v e b e e n n o r m a l move-  i n Figure  essential.  the  a r e a i n 1961  a r e a were s h o r t  range  are c l o s e l y r e l a t e d  estimated  although  age  sub-adult  are presented  Relative  other  exact 10  movements o f t h e females  own  adult  were a d u l t m a l e s , b u t a l l  m a l e s t h a t moved f r o m t h e  years  adults, but  study  or l e s s ) that they  ments w i t h i n p a r t o f t h e i r 10  18  the  t o one  area  at  approxin  favour  i  i  BRITISH  ALBERTA  COLUMBIA  BIG  CREEK  STUDY AREA N  71  Whltefish  Kolispell  ONTANA  t  i  r  i -  ( s V  Figure  12.  Dispersal  o f  sub-adult  bears  from  the B i g Creek  40  study  area.  MILES  44 All in  typical  grizzlies  captures  black bear h a b i t a t . were m a i n l y  association with and  and o b s e r v a t i o n s During  the black  bears,  the higher  country  i n summer  but observations  by loggers  indicated that g r i z z l y  myrsinites of tracks  and F o r e s t  Service  a c t i v i t y was c o n c e n t r a t e d i n  and f a l l .  Repeated captures  observations  of four  forest  home r a n g e s a r e n o t much l a r g e r t h a n m a l e  their  b e a r home r a n g e s ,  grizzlies  show t h a t  which concurs  were  early spring the  i n the Picea-Abies/Pachistima  s c a t s and b e a r o b s e r v a t i o n s  personnel  o f g r i z z l y bears  with  and  i n the s p r u c e - f i r black  t h e f i n d i n g s o f Mundy  (1963). 30 m i l e s  About  much o f t h e t i m b e r fires  during  much more e x t e n s i v e  c l o s e l y resemble of bears  30 t o 4 0 y e a r s .  there,  bears  have been r e p o r t e d  counted on the roads  i s much h i g h e r . there  during  observations  of g r i z z l y  G r o u p s o f 11 this  study,  grizzly and s c a t s  Bear  Ecology c a n be d e f i n e d  ways, b u t g e n e r a l l y , a s i n t h i s i n which an i n d i v i d u a l  pre-  bears.  "home r a n g e "  ( B u r t , 1943).  Limited  otherwise  i n t h e more o p e n s t r e t c h e s were  dominantly from g r i z z l y  Discussion of Black  features  i n d i c a t e that the r a t i o  to black bears  time  i n many p l a c e s f o r  B i g Creek c o n d i t i o n s .  bears  term  extending  forest  Treeless areas are  C l i m a t i c and t o p o g r a p h i c  i n that area  The  i n t h e W h i t e f i s h Range  has been b u r n e d r e p e a t e d l y by l a r g e  the past  several miles.  farther north  study,  i n a number o f  i trefers  t o an  area  spends t h e g r e a t e s t p o r t i o n o f i t s  M o s t mammals make o c c a s i o n a l  sallies  45 o u t s i d e t h i s a r e a , "but t h i s type of movement i s u s u a l l y e x c l u d e d when one  i s c a l c u l a t i n g home ranges.  t i o n of home ranges was  An  i n c l u d e d i n t h i s study  knowledge of them i s fundamental  investiga-  because  to an u n d e r s t a n d i n g of bear  management and p o p u l a t i o n r e g u l a t i o n . Most o t h e r e s t i m a t e s o f b l a c k bear home ranges have been r a t h e r vague.  T r i p p e n s e e (1948) thought t h a t the a r e a  a bear moved over was  so l a r g e t h a t i t was  not a range  but  a c i r c u i t , and S c o t t (1947) a l s o s a i d they t r a v e l l e d w i d e l y i n search of food.  Other e s t i m a t e s r u n from 10 to 20 m i l e s  i n e x t e n t (Seton, 1929;  Cahalane,  1947;  Spencer,  1955).  r e c e n t s t u d i e s i n W i s c o n s i n , Knudsen (1961) found t h a t  In either  sex would s t a y i n a s m a l l a r e a f o r a s h o r t time, b u t t h a t the a n i m a l s , e s p e c i a l l y the males, a p e r i o d o f time.  moved around c o n s i d e r a b l y over  E r i c k s o n and P e t r i d e s (1964) s a i d  that  M i c h i g a n b e a r s had a minimum summer range of s i x square m i l e s , but an annual range o f 15 1/3  square m i l e s , w i t h female  s m a l l e r and male ranges 1/3  l a r g e r than those  ranges  averages.  Hayne (1950) p o i n t s out t h a t home ranges cannot  be  c a l c u l a t e d f o r animals caught i n t r a p s t h a t are i n a s t r a i g h t l i n e , and  t r a p p i n g o n l y a l o n g roads on the s t u d y a r e a d i d put  some of the t r a p s on B i g Creek i n s t r a i g h t l i n e s . on a g r i d p a t t e r n , however, was  Trapping  s i m p l y i m p r a c t i c a l f o r so l a r g e  an a n i m a l , and f o r t u n a t e l y the roads d i d c o i n c i d e w i t h the b e a r habitat.  Hayne a l s o notes a r e l a t i o n s h i p between the  home range and the d i s t a n c e between t r a p s .  I believe  apparent that  b o t h o f these problems were a d e q u a t e l y compensated f o r on B i g  46 Creek w i t h t h e o b s e r v a t i o n s o f tagged a n i m a l s , a method t o which the bear l e n d s i t s e l f and one which i s s u p e r i o r t o r e c a p t u r e d a t a a c c o r d i n g t o Davis (1953).  O b s e r v a t i o n s were  r e l a t i v e l y e q u a l over t h e e n t i r e a r e a . The boundary  s t r i p method of measuring  ranges  ( S t i c k e l , 1954) and the o b s e r v a t i o n - a r e a curve method (Odum and K u e n z l e r , 1955) were n o t s u i t a b l e f o r t h i s s t u d y because b o t h the b e a r h a b i t a t and the bear home ranges were s t r o n g l y l i n e a r as a r e s u l t because  of t h e l i n e a r i t y of the topography,, and  t r u e home a r e a s i z e s were masked by t h e g r e a t  e l e v a t i o n a l extremes w i t h i n the home range of i n d i v i d u a l s . Stumpf and Mohr (1962) a l s o have shown t h a t many mammals and b i r d s and even some r e p t i l e s n o r m a l l y have home ranges showing  strong l i n e a r i t y .  F o r these r e a s o n s , even  though  the a n a l y s i s o f home ranges based on d i s t a n c e s between c a p t u r e s o r o b s e r v a t i o n s a l s o has b i o l o g i c a l and s t a t i s t i c a l d e f i c i e n c i e s , I b e l i e v e i t t h e most s u i t a b l e method f o r t h i s study.  The c o n s i s t e n c y o f the home range s i z e s l e n d s con-  f i d e n c e t o the method.  The average maximum movements ( T a b l e 1)  of 1.6 m i l e s f o r females (146 l o c a t i o n s on 31 a d u l t s ) and 3.9 m i l e s f o r males (83 l o c a t i o n s on 16 a d u l t s ) were below e s t i m a t e s from deciduous f o r e s t a r e a s .  Further refinements  of t h e e s t i m a t e s would be meaningless, b u t t h e diameters o f the ranges o f b o t h males and f e m a l e s , even i f a r b i t r a r i l y assumed c i r c u l a r , would g i v e home ranges o f 2.0 square m i l e s f o r females and 11.9 square m i l e s f o r males.  These  figures  are s t i l l below the more c o n s e r v a t i v e e s t i m a t e s based on the  47 o f a l l movements f o r 29 b e a r s by E r i c k s o n and P e t r i d e s  average  (1964) and which a l s o assumed c i r c u l a r r a n g e s .  Because many  of the s u b - a d u l t s were t r a n s i e n t s , t h e i r movements were not calculated.  Sub-adult r e s i d e n t s on the a r e a were e i t h e r w i t h  t h e i r mothers o r grew i n t o a d u l t s and were i n c l u d e d i n the study i n t h a t manner. The g r e a t d i v e r s i t y of topography,  c l i m a t e , and  v e g e t a t i o n on the B i g Creek study a r e a makes the s m a l l ranges p o s s i b l e by p r o v i d i n g v a r i e d e c o l o g i c a l c o n d i t i o n s w i t h i n small boundaries.  There was  a d i f f e r e n c e i n the q u a l i t y of  h a b i t a t , but o n l y because the one  type was  too h i g h i n e l e v a -  t i o n and had a c l i m a t e too severe t o be permanent b e a r habitat.  Knudsen (1961) s a i d t h a t i n W i s c o n s i n the b e s t b l a c k  bear h a b i t a t i s an a r e a of d i v e r s e h i g h l a n d s and Trippensee  swamps.  (1948) s t a t e d , from g e n e r a l i m p r e s s i o n s , t h a t  rough  t e r r a i n makes the b e s t bear h a b i t a t because i t p r o v i d e s dens, c o v e r , and water.  Small as home ranges  are on B i g Creek,  they  i n c l u d e a r e a s t h a t are important i n e a r l y s p r i n g s u r v i v a l , t h a t are d e s e r t - l i k e and d e v o i d o f f o o d by l a t e June.  but  Other  areas t h a t a r e under deep snow u n t i l  e a r l y summer are  important  to the s u r v i v a l of b e a r s i n autumn.  There i s an abundance of  f o o d i n the stream bottoms and s n o w s l i d e s i n e a r l y summer, and i n l a t e summer and f a l l  the n o r t h s l o p e s have many b e r r i e s .  High areas o f t e n have abundant f o o d l a t e i n autumn. Harlow (1961:491) suggests t h a t b e a r s i n e a s t e r n Worth America  move i n t o areas when acorns are abundant.  Drahos  (1951) c i t e s r e f e r e n c e s of b e a r s d u r i n g c o l o n i a l times making  48 mass f a l l Schorger  m i g r a t i o n s i n t o New  York when f o o d was  scarce.  (1949) l i s t s numerous r e f e r e n c e s i n the e a r l y 1800's  of  bear i m m i g r a t i o n i n t o a r e a s of abundant f o o d i n W i s c o n s i n ,  of  mass s p r i n g m i g r a t i o n s of b e a r s t o open g r a s s l a n d a r e a s i n  s o u t h e r n W i s c o n s i n and elsewhere, and of immense droves o f b e a r s accompanying b u f f a l o movements i n the f a l l .  He  con-  c l u d e s , however, t h a t these p r o b a b l y were merely l o c a l ments and t h a t y e a r s of h i g h p o p u l a t i o n d e n s i t y may r e s u l t e d i n e m i g r a t i o n because  of i n t r a s p e c i f i c  move-  have  strife  and  i n s u f f i c i e n t f o o d , and t h a t t h i s i n c r e a s e i n e m i g r a t i o n would e x p l a i n the i n f l u x of b e a r s i n t o c e r t a i n a r e a s i n some  falls.  Except f o r the d i s p e r s a l of s u b - a d u l t s , n o t h i n g i n t h i s study i n d i c a t e d t h a t b e a r s under n a t u r a l c o n d i t i o n s make a n y t h i n g o t h e r than l o c a l annual movements.  Sub-adults d i d  move from the a r e a , however, and i n c e r t a i n y e a r s e m i g r a t i o n may  be h i g h e r .  movements by two  this  The l o n g and p r e d i c t a b l e  spring  a d u l t b e a r s t h a t had become accustomed t o  f e e d i n g i n the Apgar and B i g Creek Hanger S t a t i o n garbage dumps i l l u s t r a t e t h a t home range bonds can be under s p e c i a l c o n d i t i o n s .  Together w i t h the r e p o r t s o f  s i m i l a r movements t o spawning streams bears and brown b e a r s ( T r o y e r , 1964; p e r s o n a l communication),  circumvented  i n A l a s k a by b l a c k A. M. Pearson, 1965»  t h e s e d a t a suggest t h a t t h e r e  may  have been some t r u t h i n e a r l y r e p o r t s of s e a s o n a l b e a r migrations. little  E r i c k s o n and P e t r i d e s (1964), however, found  d i f f e r e n c e between movements of dump and w i l d b e a r s  i n Michigan.  N e v e r t h e l e s s , b e a r s t h a t r e g u l a r l y made l o n g  49 movements b e f o r e t h e would and  no  doubt  the t a l e n t  to cubs,  seeded  have had would  either The  and  advent  a selective  or  and  strips  of d i s p e r s a l  t h e 90  the growth  only i n a large c h a r a c t e r i z e d by holding  Stickley  range.  that  The can  little  and  an  adult  female  (1961) r e p o r t e d  miles.  The r e s u l t s  a  of  this  illustrate  locusts,  entire populations move—the the j u v e n i l e s  i n herds or packs Animals  i n a similar  stable populations of adults  habitat,  exploit  adults them.  manner,  s u c h as b e a r s , however,  t h e most s u i t a b l e h a b i t a t ,  f i tinto  that  manner.  With p o p u l a t i o n s s u c h as  r e s o u r c e s , and  range.  serai  of young b l a c k b e a r s from t h e a r e a i n  (1956) says t h a t  Many mammals t r a v e l  to  s i x m i l e s each  miles.  there i s dispersal  Kennedy  were  areas.  m i l e movement r e p o r t e d b y S t i c k l e y  t h e y were b o r n .  mother  showed t h a t b e a r s  (1964) c o u l d f i n d  y e a r o l d male t h a t moved 90  which  from  i n bear populations i n Michigan, although  and h e r c u b moved 19.4  find  clearly  home r a n g e  to hunters i n t h i s  y e a r l i n g s moved a b o u t  that  transmitted  d r y meadows d e m o n s t r a t e d  E r i c k s o n and P e t r i d e s  s t u d y and  i n some a r e a s ,  snowslides, c e r t a i n  move t o f o o d w i t h i n t h e i r  be made more a c c e s s i b l e  2-1/2  America  culturally.  of such a r e a s as  experiment w i t h seeded  two  i n North  i n c r e a s e d use by b e a r s o f r o a d a r e a s t h a t  stands f o l l o w i n g burns,  evidence  advantage  have been e a s i l y  genetically  the use  bears w i l l  o f t h e w h i t e man  leaving  seem  tenaciously  t h e young to t r y  or to search elsewhere  for a  suitable  50 Relationships be  considered  i f  the  i n  species  a  study  are  else,  other's  environment.  species  might  of  bears  the  are  k i l l e d  pine  the  the keep  such  s t u d i e s  black  g r i z z l y  bear.  Why  numerous i n  i n  Big  the  known that  can  the  open  country  remains  i n  d e s t r u c t i o n , o f g r i z z l i e s c o n t r o l  on  as  the  g r i z z l y  dense  greater  30  country  the  miles  by  man,  numbers,  stage  of  proceed  as  described  same  i s  the  black  i n  black  such than  f o r e s t  much  the  animal, north  bear  p r e d a t i o n  i s  and  bears.  f a r t h e r  which  even  food  dominant  the  i s  s e r a i  numbers  The  have  a  that  because  density  they  Their  black  and  bears  range.  f o r e s t s  i s  The  bears  the  on  obscure.  but  increases  open  prey  example,  c l o s e l y  b l a c k of  one  southeast  l e t i t  between  and  which  bears  main  abundant  to  by  f o r  but  climax,  some  f a r  i n  I f  each  pines.  range  than  to  i n  reach  g r i z z l y ,  of  miles  pines,  compatible,  the  other.  environment  winter  m y r s i n i t e s  g r i z z l y  the  the  r a t h e r  l e s s  be  on  f o r  Creek  the  winter  perhaps  the  on  compete  bear  the  lodgepole  trees  are  each  nine  they  bear  even  about  bears  suggest  management,  components  r e l a t i o n s h i p  i s  also  range  g r i z z l y  bear  must  species;  as  g r i z z l y  the  The  area  other  l a y e r  willow,  (1953).  g r i z z l y  h a b i t a t  scarce  to  and  since  the  but  of  to  an  the  g i r d l e  p i i c ata/Pachi stima  c r u c i a l  be  a f f e c t  cambium  numbers tended  mutual  M o d i f i c a t i o n s of  i n d i r e c t l y  species  can  l e a s t  the  Daubenmire  and  at  a f t e r  by  bear  are  i n d i f f e r e n t  area  a  My  and  study  to  because  b i o l o g y  Creek  lodgepole  more  t h e i r  winter  of  r e l a t e d  i n  moose  has  Thuja  species  a  great  a c t i v i t y  they  on  B i g  merely  of  the  seemingly  nothing  black  between  i s by  decreases,  thought  easier  i n  to the  n o r t h e r n , more open a r e a where g r i z z l y numbers a r e h i g h e s t . The  f o o d h a b i t s o f the two  s p e c i e s d i f f e r somewhat i n t h a t  g r i z z l y b e a r s p r e y more on o t h e r animals I f b l a c k b e a r s are important g r i z z l i e s s h o u l d be more  than do b l a c k b e a r s .  to g r i z z l i e s as p r e y , i n B i g Creek.  abundant  then  B i g Creek  i s l e s s remote from human h a b i t a t i o n , however, and the c o n t a c t w i t h man  perhaps  l i m i t s the g r i z z l y t h e r e , w h i l e  b l a c k bear, because of p r e v i o u s heavy p r e d a t i o n by  the  grizzlies,  a v o i d s the more open areas to the n o r t h . Denning d u r i n g the w i n t e r appears black bears  to be u n i v e r s a l i n  i n temperate and n o r t h e r n a r e a s .  I included a  s t u d y of den ecology because I b e l i e v e d t h a t v a r i a t i o n s i n w i n t e r m o r t a l i t y r a t e s might be important r e g u l a t i o n of b l a c k b e a r s .  Gerstell  (1939) s a i d t h a t i n  P e n n s y l v a n i a b e a r s den f o r f o u r months and they den f o r s h o r t e r p e r i o d s .  i n population  Dalquest  that farther  ( i n Rausch,  s t a t e d t h a t i n Washington b e a r s den f o r 5-1/2 a l t i t u d e s and f o r 2-1/2  to t h r e e months a t low  Schoonmaker (1938) found t h a t i n New  south  1961)  months a t h i g h altitudes.  York b e a r s den  i n late  November or the f i r s t week i n December, and E r i c k s o n (1964) found t h a t i n M i c h i g a n some bears s t a r t to den by  early  October, b u t t h a t most b e a r s den from mid-November t o  mid-  April,  (1937)  a p e r i o d of approximately  f i v e months.  Aldous  and Morse (1937) r e p o r t e d t h a t b e a r s l e a v e t h e i r dens by A p r i l i n Minnesota,  and Spencer (1955) s a i d t h a t i n Maine  they l e a v e t h e i r dens the f i r s t two  weeks i n A p r i l .  mid-  52 Bears than  elsewhere. 20)  October are  t h i s  may  says  eating  weeks  more  found  that  poorest  of  G r i n n e l l i s  s t a r v a t i o n  f a c t o r s  also  t r i g g e r i n g inhabit.  f e d  s t i m u l i  c o n d i t i o n  was  the  or  He  "that the  are  hibernation,  review  of  forced  They  the  that and  supercede  on  B i g  Creek,  even  bears  and  should  s t i l l  mechanisms  i n  other  regions  that the  of  concluded i n t e r n a l n u t r i t i v e  dormancy.  storms.  Climatic  n u t r i t i v e ,  or  black  as  B i g  photo-  s t i m u l i  considered that  of  s q u i r r e l s  and  such  theory  food."  of  though be  the  period  while  c l i m a t i c  endocrine,  (1961)  i n  (1965)  that  cease  c o n d i t i o n  with  ground  Kayser  by  may  was  the  den,  Matson  and  s c a r c i t y  induction  den  not  i n d i c a t i n g  or  i n  do  Youatt  of  some-  (1961)  areas.  agreed  that  are  Rausch  that  l e n g t h  study  c o n d i t i o n  p h y s i c a l  female  longest,  the to  p h y s i c a l  " f e d up"  h i b e r n a t i o n  i n  denning  E r i c k s o n and  important,  important  of  b e l i e v e s  a  Creek  causes  c o n d i t i o n  abundance  however,  The  southern  they  bears,  (1937)  u n t i l  poor  important.  eminently  are  i n  active  the  B i g  (approximately  important.  climate.  showed,  apparently  p e r i o d i c  coastal  r e g u l a t e d by  are  "bears  i n  stayed  a l .  excellent  factors  bears  penned  hastens  conditions  Creek  et  that  than  four  t r i g g e r i n g  i s most  the  May).  b e l i e v e  denning.  i n  e a r l i e r  (early  and  because  before  (1930)  Johnson  h i s  den  c o n d i t i o n  dormancy  i n  they  c o n d i t i o n  p h y s i c a l  l a t e r  animal  true  periods  denned  authors  be  of  u s u a l l y  timing  Other  important  longer  out  the  i t p o s s i b l e  (1954)  i s  i n  i n d i v i d u a l  thought and  came  obscure.  the  f o r  They  and  involved  what of  denned  may  possible  bears  53  Krott have  an  and  K r o t t  (1962)  innate  d a i l y  and  hibernators. however. to  as  They  Black  have  bears  hibernators.  semantics,  and  y e a r l y  l i t t l e  have  The  under  i n  very  probably  continue  Erickson  and  Youatt  (1961)  bears  not  have  great  do  winter  l i k e  the  temperature of  3 -  than  i s  The  Greek  oxygen  1965).  constantly the In  even deep  a  have  a  endured  through  of  when  unaware  at  another  t e r r i t o r i a l i t y of  rough  topography  turn  small  provides  black  seems  home  a  of  do  bear  diverse  home  to  and  years  12).  (No.  As  enhance on  creates food  during  during  shown  on  68°F  i n  drop  higher  t h e i r  deep of  however  shivered  almost  something  bears areas  on  Big  which  bears page  97,  attachment.  diverse  a  attachment  four  a  supply  most  f o r  Creek  a  arousal.  t h i s  Big  during  expenditure  range  t h i s  and  black  found  observed,  ecology, to  that  reports  Youatt  observed  being  w i l l  temperature  Hock  energy  of  (I960)  hibernators,  I  only  seven  ranges  which  true  reported,  l e a s t bear  and  r e f e r r e d  they  approximately  bears  attachment  heretofore  quacy  of  denned  strong  than  f o r  that  and  true  statement,  matter  Hock  body  bears  are  commonly a  hibernators  consumption to  of  are  they  however,  i n  Erickson  Some  summary  shown,  brown  t h i s  d e f i n i t i o n  hibernators."'  true  hibernators  smaller  years  the  that  been  l a r g e l y  reduction  temperatures of  and  hibernators.  have  and  European  v e r i f y  past  i s  c a l l e d  7°F  comparable  (Kayser,  which  these  the  to  l i b e r a l  "deep  of  temperatures  dormancy. bears  true  drop  4°F;  a  be  that  rhythm  data  problem  a  to  maintain  seems  small  has  and a The  dependent  climate  and  areas.  are  eight form adeon  which  the i n  Apparently  54 this  need  i n d i v i d u a l  as  well  bears  as are  the  other  met  i n  habitat  other  areas  requirements by  l a r g e r  of  home  ranges.  55  CHAPTER  FIVE  REPRODUCTIVE  Bears  are  reproductive muskox, lower this  and  than low  rate the  unique  i n  of  land  any  stems  p a r t l y  from  the  age  s i x months  survive months  the  are  separated  of  y e a r l i n g s  August  breeding seen  on  was  young.  June  23,  Nine  adult  ing  The  of  the  t h e i r  even  and  by  f i g h t e r s .  Michigan  mothers  of  mothers  young;  i n  even  adequacy  of  foragers  bears  the  appears  competence  young from  now  b i o l o g i c a l  capable  that  p o s s i b l y  lowest  at  can  seven  Season  with  her  bears  the  age.  as  them  of  the  i n having  except  nature  are  i f they  l a t e  of  they  shown  Females  were  precocious  has  Breeding  the  from  (1959)  E r i c k s o n  mammal,  suspected.  p a r t l y  and  of  North. A m e r i c a  r e p r o d u c t i v e rate  p r e v i o u s l y  rate  STUDIES  were 10,  with  u s u a l l y  season. 20,  June then One  i n  and  were  estrus  peak  i n  them  close  example,  but  when  the  were  seen  company was  not  i n  early  as  (Table  3).  by  two  u n t i l  females  again an  i n  adult  to  y e a r l i n g s  examined  found  of  observed  her  as  June  For  while  females  a  i n  kept  female  however,  season  found  be were  d u r i n g estrus,  the but  peak  with  early  peak  as  July,  and  three  each  without estrus  with of  of  y e a r l i n g s  p a r t i a l  s t i l l  and  Females the  male  i n  25  May  her.  the of  on  breed-  these  56  Character  Vulval  Swelling  Male-female  Table  3.  P a i r s  May  June  J u l y  2  25  12  6  0  10  3  0  The b r e e d i n g s e a s o n o f of vulval swelling and  bears based male-female  on the p a i r s .  August  incidence  57 had  c u b s w i t h them.  Five  females  i n W a s h i n g t o n b e t w e e n June 12 8 t o 12  follicles in  another  earliest lutea  mm  female  date  was  June 1 and  and  116  10.  July  on  Erickson  male i n  and  i n males does n o t  and  that  the a c t i v i t y  Sex  Ratios  112  males:  (Table 4 ) . even,  has  the B i g Creek 100  While  the  b u t no  start  aged f e m a l e s .  cent females. cent l e v e l  by  Minimum B r e e d i n g No  was  seen  The corpora  between  w i t h m a l e s No.  females  were e v e r  62  observed  until  The  Chi-square  of the  2-1/2  and  mid-September  sex r a t i o  was  was 1966  and  adults  and  y e a r o l d and  almost  ratio  testicular  October.  study area the  This difference the  were o b s e r v e d  to d e c l i n e  ceased by  m a l e s c a p t u r e d o n t h e a r e a was similarly  (1964) o b s e r v e d  ( 1 9 6 4 ) h a v e shown t h a t  sex r a t i o s  t h e number o f 1-1/2  observed  1965.  J u n e 14,  c a p t u r e d b e t w e e n 1959  females  mature  attendance.  Nellor  activity  On  19  F e m a l e No.  a l l had  killed  20.  pairs  c o n s e c u t i v e days,  w i t h more t h a n one  Nellor  July  T h i r t e e n male-female  and  C o r p o r a l u t e a were  i n W a s h i n g t o n on  E r i c k s o n and  i n Michigan bears  I examined were  J u n e 27  and  i n diameter.  killed  that  that  double  c u b s were  sub-adult  t h e number o f  192:100,  is significant  o r 35  a t the  per one  per  test.  Age  bears younger  Table  5 shows t h a t  5-1/2  y e a r s o f age,  than 4-1/2  on B i g C r e e k two  two  were o b s e r v e d females  were a t l e a s t  6-1/2  i n estrus.  were a t y e a r s of  least age,  Percentage t h a t were Females  Age  M  F  Cubs  8  10  18  55.6*  1-1/2 & 2-1/2 yr. olds  19  12  31  38.6  Sub-adults  29  13  42  31.0  Adults  26  38  64  59.4*  Total  82  73  155  Total  •These do not d e v i a t e s i g n i f i c a n t l y by t h e C h i - s q u a r e t e s t .  Table 4.  47.1*  from an even sex  ratio  The sex c o m p o s i t i o n of b e a r s c a p t u r e d on the B i g Creek s t u d y a r e a d u r i n g the p e r i o d 1959 to 1966.  Bear  No.  4  At F i r s t Estrus  A g e * M i n i m u m A t w h i c h B e a r was A t which Bear l a s t observed had h e r F i r s t w i t h o u t Cubs Cubs  4-1/2  6-1/2  Unknown  10  Unknown  7-1/2  8-1/2  61  Unknown  5-1/2  Unknown  71  Unknown  5-1/2  6-1/2  4-1/2  6-1/2  7-1/2  113  * S e v e r a l o f t h e s e a n i m a l s may h a v e b e e n one o r more y e a r s older than indicated i n t h i s table.  Table  5.  The minimum b r e e d i n g age o f f e m a l e B i g Creek study a r e a .  bears  on the  60 and  7-1/2 y e a r s  one was a t l e a s t  raised  a litter  b e a r s may b r e e d spring  o f cubs.  o f age w i t h o u t  The p o s s i b i l i t y  successfully but lose  was i n d i c a t e d b y f e m a l e  No. 4.  when s h e was a minimum o f 4 - 1 / 2 y e a r s recaptured  the next  year  i n July,  having  ever  t h a t some y o u n g  t h e i r young i n e a r l y She was f i r s t  captured  o l d ; when s h e was  t h e c o n d i t i o n o f h e r mammae  showed some d e v e l o p m e n t , b u t s h e d i d n o t h a v e y o u n g w i t h h e r then  a n d s h e was i n e s t r u s .  Litter  Sizes A  summary o f t h e l i t t e r  other  studies i s presented  sizes  f o r the B i g Creek study  and  s i z e s r e p o r t e d f o r t h i s and  i n T a b l e 6. were b a s e d  observation data, but the r e s t  were r e c o r d e d b y p e r s o n n e l  The a v e r a g e on both  litter  capture  o f t h e Montana  observations  o f t h e M o n t a n a F i s h a n d Game  D e p a r t m e n t , t h e U n i t e d S t a t e s F o r e s t S e r v i c e , and G l a c i e r N a t i o n a l Park. last  T h e i r o b s e r v a t i o n s were r e s t r i c t e d  week o f J u l y  and t h e e n t i r e month o f A u g u s t ,  when v e r y f e w f e m a l e s litter other  still  s i z e s were b a s e d studies cited  capture, accounts.  were c o l l e c t e d kills,  Yearling  The d a t a f o r t h e  i n v a r i o u s ways s u c h a s road k i l l s ,  On B i g C r e e k , 2 9 b l a c k f e m a l e s  yearlings per l i t t e r ,  a period  h a v e y e a r l i n g s w i t h them.  on B i g Creek d a t a .  observation, hunter  to the  and n e w s p a p e r  h a d 1.6 c u b s o r  a n d 16 b r o w n f e m a l e s  had 1 . 7  cubs o r  yearlings per l i t t e r . Corpus luteum made f r o m b l a c k b e a r  and mature f o l l i c l e reproductive tracts  counts  were  collected  also  on the  61  Cubs/ 100 Adults  Total Bears  Area  Family Groups  Montana Cubs B i g Creek State-Wide 1^61 1962 1963 1964 1965  No. of Young  38  66  1.7  33 53 18 28 34  59 80 29 48 54  1.8 1.5 1.6 1.7 1.6  203  334  1.6  23  36  1.6  Survey 189 471 123 248 311 1,342  Av. Litter Size  12 20 34 26 21  Yearlings Maine (Spencer, 1955)  38  2.4  F l o r i d a (Harlow, 1961)  10  2.2  M i c h i g a n ( E r i c k s o n and N e l l o r , 1964)  20 23  A l a s k a ( E r i c k s o n and N e l l o r , 1964) W i s c o n s i n ( S c h o r g e r , 1949) Virginia  284 19*  ( S t i c k l e y , 1961)  C a p t i v e ( a t b i r t h ) Baker  (1912)  •Embryos and cubs a r e i n c l u d e d i n t h i s  Table 6.  2.2 2.0 2.4 2.6 2.4  total.  The number o f cubs p e r 100 a d u l t s i n Montana, and the average l i t t e r s i z e s f o r the B i g Creek study a r e a , f o r a l l of Montana, and f o r o t h e r s t u d y areas.  62 Big  Creek study a r e a and i n western Washington.  They are com-  p a r e d i n T a b l e 7 w i t h s i m i l a r d a t a c o l l e c t e d i n M i c h i g a n by E r i c k s o n and N e l l o r  (1964) and i n V i r g i n i a by S t i c k l e y  The numbers o f mature f o l l i c l e s E r i c k s o n and N e l l o r  (1961).  were a l s o counted because,  as  (1964) p o i n t e d out, the b l a c k bear i s an  i n d u c e d o v u l a t o r , and near the peak of the b r e e d i n g season several f o l l i c l e s  a t t a i n mature s i z e .  A t t h a t time they c a n  be counted as e a s i l y as the c o r p o r a l u t e a a f t e r Two  ovulation.  b e a r s had b o t h c o r p o r a l u t e a and a t r e t i c mature  follicles,  however, i n d i c a t i n g t h a t the number o f u n r u p t u r e d mature follicles  i s l i k e l y to be i n excess of the number o f  follicles  a c t u a l l y i n v o l v e d i n the o v u l a t i o n r a t e . Frequency o f L i t t e r s Two b e a r s on B i g Creek had two a three year period. for  a t l e a s t two  three years. accompanied 1964.  each w i t h i n  Nine o t h e r a d u l t females had no  c o n s e c u t i v e y e a r s , and two  litters  females s k i p p e d  As shown i n T a b l e 8, the p e r c e n t a g e o f females  by cubs was  a l s o low e v e r y y e a r except 1959  and  None o f the 59 marked a d u l t females observed o r cap-  t u r e d on B i g Creek d u r i n g 1961, them.  litters  1962,  and 1965  had cubs w i t h  Some unmarked females observed on the a r e a d u r i n g those  y e a r s had cubs, but the r a t i o f o r the e n t i r e p o p u l a t i o n must have been v e r y  low.  63  No. o f Female Tracts  Area  W a s h i n g t o n and Early June  of Mature Follicles  Av. No. o f Corpora Lutea  Montana  June t o December  Total  Montana  A v . No.  8  2.0  16  1.9  24  1.9*  1.8  only  Michigan  12  2.4  Virginia  22  2.4  •Mature  Table  7.  follicles  and c o r p o r a  lutea.  C o r p o r a l u t e a c o u n t s f r o m Montana, Washington, M i c h i g a n , and V i r g i n i a . Mature f o l l i c l e counts from Washington.  64  F e m a l e s Year  T o t a l No. Captured or Observed  No. w i t h Cubs  Percentage w i t h Cubs  1959  13  .5  38.5  I960  16  3  18.8  1961  18  0  0  1962  9  0  0  1963  12  0  0  1964  10  4  40.0  1965  14  2  14.3  1966  4  1  25.0  96  15  15.6  Total  T a b l e 8.  The numbers and p e r c e n t a g e of marked a d u l t females w i t h o r w i t h o u t cubs on B i g Creek 1959-1966. R e p r o d u c t i o n o r s u r v i v a l of the young was v e r y low from 1961 through 1963-  65 Discussion  of  The be  on  the  the  that  i n  g r e a t e s t i n  small is  the  response  of  and  these  o v u l a t i o n the  a  suggested  m o r t a l i t y among  h i b e r n a t o r s  of The  such  as  young  Big  reproductive l i t t e r s  be  f a i l s .  The  i t i e s , for  and  come  of  normally  species i s  vary  i s  adapted and  into  are  and  with  nor  can  to  the  more  than  i n  size  (1950),  n u t r i t i o n i n  the  breeding  age, has  even  s u r v i v a l  s i m i l a r  f o r c e s  r a t e s  i n  and  seasonal i n  c o n d i t i o n s can occur  i s o l a t e d  There  i s a  i f  from  favourable  once  too,  poor  bears.  remating  most  does  reproductive  the  s i g n i f i c a n c e  no  young.  l i t t e r  (1960:496)  Lord  season  g e n e t i c a l l y  bearing estrus  under  the  minimum  reproductive  l i t t l e  size  mammals,  changes  because  black  produces  Severinghaus  i n  (1957)  a l .  the  In  the  to  g e n e t i c a l l y ,  that  and  Apparently  low  et  " h i b e r n a t o r s " have  mating  has  but  seems  which  d i f f e r e n c e s  young.  the  Creek  the  size  that  l i t t e r s , of  Lack  habitat.  expressed  of  the  since  propagated,  breeding  bears  i n  r a t e s  the  shown  higher.  of  bears  young,  bears  l i m i t e d  brood  non-hibernators i s  i s  the  i n  have  r a t e s  adequacy  length  s i z e  to  Creek  successfully,  mammals  than  B i g  species.  Cheatum  frequency  rate  s u r v i v a l  can  v a r i a t i o n s  that  the  more  others  species  l i t t e r s  explain  c l u t c h  changes  of  the  s u r v i v i n g  to  smaller of  of  and  rates,  e a r l y  f o r  g e n e t i c a l l y .  (1963),  that  the  survive  c o n t r o l l e d  c a p a c i t y  correspond  number  capacity  or  to  f a m i l i e s  Jenkins  Reproduction  p o t e n t i a l birds  average,  change  Bear  reproductive  f a r below  b e l i e v e  Black  no  year,  time  breeders  determining second pregnancy such of  c a p a b i l the  i n d i c a t i o n but  the  year that  time  of  66 e s t r u s does v a r y reproductive  considerably  and  might be  s u c c e s s because o f l o c a l e c o l o g i c a l c o n d i t i o n s .  There i s even some evidence t h a t the be  involved  (see Appendix  I t has  types o f food  E r i c k s o n and  Rausch,  1961;  N e l l o r , 1964).  Knudsen (1961) s t a t e t h a t the b r e e d i n g  extends from June to e a r l y August. the B i g Creek a r e a  The  seems to l a s t l o n g e r  Stickley season  b r e e d i n g season i n than t h a t  reported  elsewhere, a l t h o u g h the June - J u l y peak c o i n c i d e s w i t h season r e p o r t e d  i n other  been c o l l e c t e d i n o t h e r o f the  season, b u t ,  conditions  areas.  Perhaps not  the  enough d a t a have  s t u d i e s to determine the  full  length  a l t e r n a t i v e l y , the wide range of c l i m a t i c  on B i g Creek may  The  may  been g e n e r a l l y b e l i e v e d t h a t b l a c k b e a r s mate  et a l . , 1937;  (1961) and  eaten  3).  i n l a t e June or e a r l y J u l y (Baker, 1904; Grinnel  significant i n  extend the  estrous  cycle.  apparent l o n g b r e e d i n g season on B i g Creek c o u l d  be d e l e t e r i o u s to some b e a r s , s i n c e females coming i n t o  estrus  too l a t e i n the y e a r might be  i n e s t r u s at a time when most  a d u l t males have moved h i g h e r  i n t o the mountains, a c o n d i t i o n  analogous to the  condition i n fur seals (Callorhinus ursinus),  where the females must come i n t o e s t r u s when they are on i s l a n d s w i t h the males (A. M. cation).  Prell  C r a i g , 1966,  (1930) has r e p o r t e d  personal  c y c l e , and  t h i s may  be  communi-  the o c c u r r e n c e o f pseudo-  e s t r u s i n p o l a r b e a r s and brown b e a r s f o l l o w i n g the estrous  the  regular  an a l t e r n a t e e x p l a n a t i o n  the apparent l o n g b r e e d i n g season i n b l a c k  for  bears','but'other  a u t h o r s don't agree t h a t p o l a r b e a r s have a p s e u d o e s t r u s p e r i o d .  67 Knudsen (1961) i n W i s c o n s i n and E r i c k s o n and  Petrides  (1964) i n M i c h i g a n found the sex r a t i o i n b l a c k b e a r s to be even.  Only when b e a r s were t r a p p e d a t dumps d i d the males  outnumber the f e m a l e s , and t h i s they a t t r i b u t e d to a of  females to a v o i d o t h e r b e a r s and man.  The M i c h i g a n study  a l s o showed t h a t 36 p e r c e n t of the cubs were females t h a t 55 p e r c e n t of the y e a r l i n g s were f e m a l e s . i n r e l a t i o n to t h e i r sample s i z e s , however, the from an even sex r a t i o was  tendency  not s t a t i s t i c a l l y  and  Considered difference  significant.  S t i c k l e y (1961) found an even sex r a t i o i n V i r g i n i a , but Spencer  (1955) found t h a t o f 236 b e a r s k i l l e d  42 p e r cent were f e m a l e s . i n the y e a r l i n g , 2-1/2, and  i n Maine, o n l y  The u n u s u a l preponderance s u b - a d u l t group  of males  on B i g Creek c o u l d  r e s u l t from h i g h e r m o r t a l i t y r a t e s f o r female cubs d u r i n g the f i r s t w i n t e r w i t h o u t t h e i r mother, b u t t h i s e x p l a n a t i o n seems u n l i k e l y as the even sex r a t i o s f o r a d u l t s would then have to be e x p l a i n e d i n some o t h e r way.  A l s o , as the s e c t i o n  on  growth (p.108 ) shows, the weights f o r females and males were approximately equal during that p e r i o d .  The  d i s p a r i t y more  p r o b a b l y r e s u l t s from the movement o f young males through the a r e a a t a g r e a t e r r a t e than females of the same age; r e c o r d s o f d i s p e r s a l do show t h a t i t was t h a t moved away from the a r e a .  The  my  p r i m a r i l y young males  f i g u r e s from Maine showing  a r a t i o f a v o u r a b l e to males were based on animals k i l l e d  by  h u n t e r s and p r o b a b l y merely i n d i c a t e a s e l e c t i o n by h u n t e r s for  l a r g e r bears.  Because males have l a r g e r r a n g e s , t h e r e  would a l s o be a s t a t i s t i c a l  tendency  f o r hunters to k i l l  a  68 d i s p r o p o r t i o n a t e number o f m a l e s , the  fox r a t i o  on  in Illinois  high  i s not  therefore, illusory adult  and  as  the  low  a result  of the  males c r o s s i n g the The  sexes of  ratio  age  of  reach  puberty  three  c a p t i v e f e m a l e s t h a t had  age.  E r i c k s o n and  Rausch  age.  On  appeared bears. reach but to  the  years  their  first  B i g Creek study  t o be  higher  than  Wild black bears sexual  they 7-1/2  are  years  animals  (as measured by  first  b e s t known e x a m p l e o f a high protein diet ovulation rate.  their  sub-  the  they  the  latter  (1912)  sexes  listed years  and  6-1/2  minimum b r e e d i n g  a r e 4-1/2 litters be  the  or  forest  of  age  Montana  before  of  age,  6-1/2  involved, since  in  maturity  ovulation rates.  time to  maturation  of  Michigan  years  sexual  in  years  i s t h a t of p l a c i n g sheep  to breeding  slow sexual  2-1/2  c u b s a t 4-1/2  i t does a f f e c t b o t h  o v u l a t i o n ) and  captive  c a p t i v e females h e l d  spruce-fir  time  a  that both  Baker  c u b s a t 4-1/2 area,  i n deter-  successfully at  that f o r captive bears  the  prior  This  only  transient  first  t h a t two  N u t r i t i o n may  mature d o m e s t i c  i s apparently  and  successful i n raising  o f age.  bears,  (1961) r e p o r t e d  bred  o f age,  i n the  m a t u r i t y by not  May.  natural  black  N e l l o r (1964) s a i d  (1961) found  o u t d o o r pens had  and  a l s o i s important  Stickley  years  of  f e m a l e s were  r a t e or  sub-adult  of females  that apparently  a t 3-1/2  birth  found  area.  mining reproductive r a t e s .  age.  (1958)  April  l a r g e number o f  minimum b r e e d i n g  female b l a c k b e a r  Layne  dens d u r i n g  a differential  m o r t a l i t y r a t e between the  as  t o m a l e s when t h e  s m a l l home r a n g e s n e a r t h e i r  There p r o b a b l y  just  increase or l a t e  The on  the  breeding  i n b e a r s no doubt  lowers the r e p r o d u c t i v e r a t e o f the p o p u l a -  tion considerably.  F a i l u r e t o d e v e l o p mature f o l l i c l e s  l i k e l y cause, e s p e c i a l l y among young a d u l t s .  is a  The a c t u a l  mechanisms i n v o l v e d a r e d i s c u s s e d below and i n the s e c t i o n s on b e h a v i o u r and on growth and development. Litter areas.  s i z e s o f b l a c k b e a r s may be v a r i a b l e i n d i f f e r e n t  Rowan (1945) found b l a c k bear l i t t e r s  o f t h r e e t o be  common i n J a s p e r N a t i o n a l Park, A l b e r t a , and says l i t t e r s f o u r , f i v e , and s i x have been observed. r e p o r t e d average l i t t e r litter litters  of  Most s t u d i e s have  s i z e s i n excess o f two.  My d a t a on  s i z e s and c o r p o r a l u t e a counts show c o n c l u s i v e l y  that  on B i g Greek, throughout Montana, and i n western  Washington a r e s m a l l e r than i n e a s t e r n N o r t h America. s m a l l amount o f d a t a a v a i l a b l e on A l a s k a b l a c k b e a r s  The also  c o r r e s p o n d s t o those of Montana and Washington. Brambell  (1948:385) says t h a t t h e r e a r e no  methods o f d e t e r m i n i n g l i t t e r s i z e can s t i l l be u s e f u l .  adequate  s i z e s , but i n d i c e s t o l i t t e r  Estimates of l i t t e r  s i z e based on  o b s e r v a t i o n s d u r i n g t h i s study s h o u l d be more r e l i a b l e  than  those f o r many of the o t h e r s t u d i e s , s i n c e the s t a t e - w i d e survey was made a t a time when cub and y e a r l i n g f a m i l y would not be c o n f u s e d .  Data from o t h e r s t u d i e s p r o b a b l y g i v e  minimal e s t i m a t e s because y e a r l i n g f a m i l y groups.  groups  they i n c l u d e an unknown number of On the o t h e r hand, those  t h a t were based on v o l u n t e e r e d d a t a no doubt p r o p o r t i o n a t e number o f l a r g e r l i t t e r s , i n c l i n e d t o remember and r e p o r t l a r g e  studies  contain a d i s -  s i n c e p e o p l e are more litters.  70 The be  g r o w t h r a t e and  i n v o l v e d i n the  using  smaller  s m a l l body s i z e  and  a small  strain  average l i t t e r  litter  size.  account  as  pared with  generations  The  smaller  b e a r s on B i g  compared w i t h smaller  s t r a i n had  bears  cause  reproductive  The  fluctuations since  restriction  on  litter  o f young w h i c h can  be  effect  rates  frequency  compared t o o t h e r  black bear every  other  Stickley  i n the year  only  on  the  Big  had  restricted could  l u t e a com-  i t was  constant  smaller  litter  sizes  but  i t would  annually.  Whether  the  this  l a r g e s t number (1956)  question.  i n B i g Creek bears  also i s a  female  Z o o l o g i c a l P a r k t h a t had  a  litter  Drahos  stopped breeding  t h a t 48  litters  Creek study  per  cent  annually. area  on  not  (1951) r e p o r t s  areas.  (1961) r e p o r t s  males i n V i r g i n i a litters  of l i t t e r s  smaller  since  corresponds with  further  cent  also  r a i s e d s u c c e s s f u l l y , as L a c k  National and  the  large  i n fecundity  seems s i g n i f i c a n t ,  p r o p o s e s f o r b i r d s , i s open to The  of  i t i s constant  size  (1948)  per  are  a v e r a g e number o f c o r p o r a  may  large  elsewhere, which  cause, however,  West.  a  the  Creek apparently  have a p u r e l y g e n e t i c the  produced  a l m o s t 100  This reduction  overall  low  and  eastern bears.  throughout  MacArthur  musculus) s e l e c t e d f o r  of mice t h a t d i f f e r e d sizes.  for their  of l i t t e r s .  (Mus  f o r 21  Black  nutritionally  may  size  l a b o r a t o r y house mice  and  in  adult weight of western bears  was  a t 24  of The only  38  years  wild  adult  frequency 16  per  of  age. fe-  of  cent  annually. Hausch c a n be  induced  ( 1 9 6 1 ) and  Wimsatt  every  i f the  year  ( 1 9 6 3 ) h a v e shown t h a t cubs of  the  year  are  estrus  taken  71 from  the  mother  p r i o r  bears  normally  keep  1-1/2  years  age  breeding adult In  of  when  females  V i r g i n i a ,  Creek  the  during  from  then  young  further  i n  t h e i r and  since  young  are  any  1964  from  such  approached  the  again at  with  i n  proper  sections  a  1/2  year  such the  them  o l d ,  should a  r a t i o . on  1964  and  u n t i l  50 have  the  B i g  1965* during  behaviour  and  d i d  are  i n h i b i t s cent  cubs and not  of  with on  a l l them.  B i g  vary  1961,  1962,  Creek  area,  This  black  they  per  percentage,  During  i n t e r v a l s  Since  apparently  percentage  zero  on  season.  l a c t a t i o n  p o p u l a t i o n  1959  and  breeding  young  found  increased  produce  the  S t i c k l e y  s t a t i s t i c a l l y reproduction  to  and  however,  f a i l u r e  1961-1963 population  1965  to  i s  discussed  regulation.  72  CHAPTER  DEATH RATES AND  Forty-two killed in  CAUSES OP  from  by  man  between June,  a trap  was  killed  accidentally is  bears  by  SIX.  an  MORTALITY  the B i g Creek 1959,  and  May,  adult bear,  or f o r study.  The  total  s t u d y a r e a were 1966,  and  p o p u l a t i o n are s t i l l not found  s e v e n were  killed  number known t o be  scattered  mortality within  obscure.  The  o b v i o u s l y on  the B i g  remains  dead  open w i n t e r ranges  h e r b i v o r o u s mammals, n o r  scats  a s f o r s m a l l mammals.  or c a s t i n g s ,  consumed c o m p l e t e l y b y  a r e a s where t h e i r Mortality  bears  i n the  the f e c u n d i t y  potential  T h e y must or else  are not  seen.  study I noted o f B i g Creek  r e p o r t e d from  studies  i n e a s t e r n North America  m o r t a l i t y r a t e s were u n d u l y natural mortality, be  are  are they found i n  other animals, easily  as  are  generally  they die i n  Rates  Early either  remains  Creek  o f dead bears  those of the l a r g e  may  yearling  fifty. Causes of n a t u r a l  be  one  prone  I found  from p r e l i m i n a r y data b e a r s was  o f zoo  f a r below  animals  and  high. little  the  of  o r e l s e p r e n a t a l and In searching f o r  wild  early early  conclusive evidence.  to prenatal mortality,  however, because  a l o n g d e l a y b e f o r e i m p l a n t a t i o n , and  during this  that  Bears  they  delay  have  the  73 blastocysts Detection  are  of  difficult.  vulnerable  these losses Throughout  to  a v a r i e t y of m o r t a l i t y f a c t o r s .  i n a n a t u r a l bear population  the  s t u d y 68  per  cent  of  the  is  females  p o t e n t i a l l y pregnant d i d not  have young t h r o u g h f a i l u r e  ovulate,  or  The  prenatal  mortality,  l o s s f r o m the  p o t e n t i a l through f a i l u r e  indistinguishable accounted  from m o r t a l i t y before  f o r i n the  per  cent  107).  page  killed of  dying  J u l y 20  injuries  cluded,  during  b e t w e e n 1/2  This percentage  on  and  one  then only  five  years  age  and  1-1/2  for  cubs p r o b a b l y b e g i n s  difficult  to  Whole f a m i l y  mortality rates As  lation.  B e c a u s e an  dispersed lated  f r o m the  only  sub-adult  f o r the rates  The b a s e d on  capture. cent  of  the  cub  with  also  age  This  observed, but  only (see  whose m o t h e r as  a result are  ex-  low  mortality  5  information 6 months o f  such l o s s could  age  structure  13  the  mortality rates  more s e d e n t a r y  age.  increase  121),  (page  c u b s and  older could  adults,  i n c l u d e b o t h d e a t h and  mortality rate  is  detection.  u n d e t e r m i n e d number o f true  1/2 rate  y e a r s r a p i d l y d i s a p p e a r f r o m the  area,  was  cubs d i e d between  young are  s e c t i o n on  i n Figure  annual  is  thus i s  I f t h e s e two  the  13).  f o r cubs w i t h o u t  y o u n g b e a r s o v e r 1-1/2  one  soon a f t e r b i r t h , but  not  shown i n t h e  years of  that probably died  (Figure  obtain before l o s s was  and  f i r s t year,  1-1/2  and  cub  per  their  includes  suffered during  of  to breed  birth  13).  (Figure  s u r v i v a l curve.  Cubs f a r e d w e l l 13  early mortality  to  o f 14  a n i m a l s marked i n i t i a l l y as  per  adults  cent and  popu-  sub-adults be  calcu-  while  the  dispersal.  for adults on  is  sub-adults  74-  1.5  0.5  Figure  13,  2.5  12.5 ±  5.5  AGE CLASS S u r v i v a l area  rate,s. 50  curve  based  p e r  on  Loss cent  f o r bears estimated  p r i o r  unknown  amount  f i g u r e s  f o r 1-1/2  broken  l i n e  represents period.  to  pregnancy o f  on  the  and  b i r t h rate  i s based f o r adult  d i s p e r s a l to  running  5-1/2  year  true  and  study  m o r t a l i t y on  a  p o t e n t i a l  females.  i s included  to b i r t h  the probable  B i g Creek  measured  o l d animals. t o  curve  0.5 f o r  An  i n the years that  The  75 that  grew  t o be  c a l c u l a t e d older as  a  and then  I960  during r e s u l t  Causes  adults  o f  o f  making  t o t a l l e d  study  f i n a l  y e a r l i n g s , recorded,  f o r 157  were  Death  animals  Bears  rates  5-1/2  were  years  o r  hunters  or  k i l l e d  by  from  this  have  p e r i o d i c a l l y  excluded  c a l c u l a t i o n .  M o r t a l i t y P e r i o d .  check  a n d 21  Through  o f 31  the c o n d i t i o n a  the study.  1965.  through  t h i s  Denning checked  during  denned  o f t h e den  adults  1966  were  I  bears  d u r i n g  i n May.  Two  observed.  nor d i d any o f the bears  No  appear  the  cubs,  winter, eight  m o r t a l i t y  t o have  was  any  d i f f i c u l t y . Parasites the  primary  t i o n 117  and  form  so were  bears  on  and Diseases. of p a r a s i t i s m included  the study  had  the  and shoulders.  of  neck  i n f e s t a t i o n s  the sub-adult  bears  neck  and  shoulders.  area  and  a l l bears  the  summer  the  study  and  two  heavy  or area  bears  f a l l  pinguis  of  often  t i c k s  had 2 - 6 bears  from  surrounding  were  free  c o l l e c t e d of  of  only  on  u r s i ,  of the study  e u a r c t i d o s , Hopkins,  1954),  with  suggest  c e p t i b i l i t y  t o ectoparasites,  a  b u t there  every  few, b u t inch  bear  area  many  study i n  bears  R o t h c h i l d , had  on  on the  l a t e r  Two  on  1902), extremely  (Trichodectes  the l i c e  i n d i v i d u a l  examined  andersoni)  ectoparasites.  and l i c e  data  I  June  examined  f l e a s ,  These  popula-  t h e B i g Creek  t i c k s ,  thousands.  and  p e r square  areas  ( A r c t o p s y l l a outside  May  had  bear  studies.  (Dermacentor  adults  T h i r t y - s i x  are apparently  the B i g Creek  and during  Some  had f l e a s  i n f e s t a t i o n s  on  i n the m o r t a l i t y  area,  examined  Ectoparasites  i n the  v a r i a t i o n  i s also  a  i n  sus-  geographic  76 v a r i a t i o n i n the d i s t r i b u t i o n of the p a r a s i t e s . (I960) examined 306 b l a c k bears i n New  King et a l .  York and found o n l y  two  t i c k s of the genus Ixodes; Rausch (1961) found no e c t o p a r a s i t e s on A l a s k a n b l a c k b e a r s .  The b e a r s on B i g Creek a p p a r e n t l y  a c q u i r e g r e a t numbers of t i c k s w h i l e f e e d i n g on south s l o p e s or  d r y meadow areas i n the e a r l y s p r i n g .  S i n c e the s u b - a d u l t s  are i n p o o r e r c o n d i t i o n than the a d u l t s a t t h i s time of y e a r , they p r o b a b l y have more d i f f i c u l t y parasites.  i n g e t t i n g r i d of ecto-  Kartman (1942) has shown t h a t r a t s  receiving  r a t i o n s h i g h i n V i t a m i n A and B2 r i d themselves c o n t r o l animals do  while  not.  A d u l t s of the nematode D i r o f i l a r i a 1941,  of l i c e ,  ursi,  Yamaguti,  were found i n two of the bears k i l l e d on B i g  T h i s p a r a s i t e i s common i n New m i c r o f i l a r i a e i n 104  Creek.  York; K i n g e t a l . (I960)  of 109 b e a r s examined.  found  Rausch (1961)  found a d u l t s of t h i s s p e c i e s i n o n l y one b l a c k b e a r i n A l a s k a , but i t i s common t h e r e i n the brown bear. s a g i n a t a was Big  Creek.  The tapeworm Taenia  c o l l e c t e d o c c a s i o n a l l y from b l a c k bear s c a t s on The  i n f e c t i o n s p r o b a b l y arose when the b e a r s ate  meat s c r a p s a t the Ranger S t a t i o n and i n the  trapsites.  Numerous hookworms ( p r o b a b l y U n c i n a r i a y u k o n e n s i s ) were found i n the s m a l l i n t e s t i n e of an a d u l t female k i l l e d i n December, 1964. D i s e a s e s are uncommon i n b l a c k b e a r s .  No d i s e a s e d  animals were found i n the B i g Creek p o p u l a t i o n , and Rausch (1961) i n A l a s k a and K i n g e t a l . (I960) i n New  York found  b l a c k bears i n those areas l a r g e l y f r e e of d i s e a s e s . P a r a s i t e s  77 and d i s e a s e s no doubt c o n t r i b u t e t o some deaths,  especially  among s u b - a d u l t s , b u t they were n o t found important i n t h i s r  study. Predation.  G r i z z l y and b l a c k b e a r s a r e o f t e n seen i n  groups when f e e d i n g i n garbage dumps, b u t t h r e e cases o f g r i z z l y p r e d a t i o n on b l a c k b e a r s d u r i n g the summer and f a l l were noted i n the v i c i n i t y of the B i g Creek study a r e a . A y e a r l i n g i n a t r a p was k i l l e d and eaten e i t h e r by a l a r g e male b l a c k bear o r a g r i z z l y . cass appeared  !Fhe a d u l t chased from the c a r -  t o be a l a r g e b l a c k bear, b u t p o s i t i v e  c a t i o n was n o t made.  identifi-  One b l a c k bear s c a t c o l l e c t e d on the B i g  Creek a r e a c o n t a i n e d the remains  o f a cub, but t h i s might have  been merely c a r r i o n e a t i n g ( T i s c h , 1961).  Carcasses of black  b e a r s a c c i d e n t a l l y k i l l e d d u r i n g t h e study were r o u t i n e l y used f o r b a i t and were r e a d i l y consumed b y o t h e r b l a c k b e a r s a t a l l seasons  of the y e a r .  I was a l s o informed o f two cases of b l a c k  bear p r e d a t i o n on s m a l l e r b l a c k b e a r s i n Y e l l o w s t o n e (M. G. Hornocker;  1965, p e r s o n a l  Hunting P r e s s u r e .  Park  communication).  Of 57 b e a r s marked on t h e B i g Creek  study a r e a i n 1959, o n l y one was shot t h a t same y e a r .  I n I960  p u b l i c i t y g i v e n t o the a r e a and p u b l i c e d u c a t i o n on the methods of h u n t i n g b e a r s i n c r e a s e d the hunter k i l l 47 b e a r s marked t h a t y e a r .  t o 15 p e r cent o f  Hunting s u c c e s s i n c r e a s e d r a p i d l y  and over t h e next few y e a r s 24 p e r cent o f the b e a r s marked i n 1959, 42 p e r cent o f the b e a r s marked i n I960, and 24 p e r c e n t o f those marked i n 1961 were e v e n t u a l l y t a k e n by h u n t e r s .  From  1964 through 1966 t h e season on b e a r s was c l o s e d i n the B i g  78 Creek and  study  1965  area,  were  shot  Other makes and  bears  e a r l y  (page  and only  i n surrounding  m o r t a l i t y .  vulnerable  summer  87).  o f 32  two  when  to hunters,  was  f i n a l l y  spotted  and  The  climate  o f the B i g Creek  can  i n m o r t a l i t y .  shortens  feed  t i o n  (see s e c t i o n  could,  bears  by  on  therefore,  compared  m o r t a l i t y  The  the length  with  r a t e s ,  by  a  longer  o f time growth  cause  bears  on  i t constantly  shot  e s p e c i a l l y  1964  behaviour  t h e d r y meadow  areas  contributed  v i s i t e d  area  a  t o  t r a p s i t e  i s probably  denning each  p e r i o d  year  during  and development).  other  spring  and  hunter.  the smaller  of  during  i n t h e  i n behaviour  death  study  when  i n  e s p e c i a l l y  the  involved  bear  v a r i a t i o n  a r e feeding  I n d i v i d u a l v a r i a t i o n  o f one  marked  areas.  Seasonal  they  bears  size  areas,  and  f o r sub-adults,  i n d i r e c t l y  found  i n  which Poor  this  bears n u t r i -  o f B i g  Creek  i n t h i s  way  may  be  i n f l u e n c e d  loss  of  eggs  climate.  Discussion  o f M o r t a l i t y  (1948:387)  Brambell n o n - f e r t i l i z a t i o n corpora ova  were  must  l u t e a  section  on  i s r a r e  r a t i o s  ovulated  r e s u l t  from  i n Bears i n d i c a t e s  i n most  have  been  induced  reproduction,  o f mature page  ovulators.  66  b u t some  f o l l i c l e s  embryo-  whether  n o n - f e r t i l i z a t i o n  t o ovulate  and Appendix  through  No  c a l c u l a t e d to determine  b u t n o t f e r t i l i z e d , f a i l u r e  that  3  (see  f o r p o s s i b l e  causes). Uterine as  being  "high  m o r t a l i t y has been during  l a t e  reported  pregnancy"  by  Hansson  i n t h e mink  (1947)  (Mustela  79 visort), a t approximately  32 p e r c e n t i n the gray f o x (Urcyon  c i n e r e o a r g e n t e u s ) by Layne (1958), and as h i g h as 43 p e r c e n t d u r i n g t h e f i r s t h a l f o f pregnancy i n t h e w i l d ( B r a m b e l l , 1948).  rabbit  Nalbandov (1964) says 30 t o 50 p e r cent o f  the f e r t i l i z e d eggs a r e l o s t d u r i n g g e s t a t i o n i n domestic and l a b o r a t o r y animals.  L o s s e s p r o b a b l y v a r y between s p e c i e s ,  e s p e c i a l l y among p o l y t o c o u s animals, and l o s s e s a r e g e n e r a l l y h i g h e r i n s p e c i e s w i t h h i g h o v u l a t i o n r a t e s (Hammond, 1921). Bears n o t o n l y have s m a l l l i t t e r s n o r m a l l y , r e d u c i n g the poss i b i l i t y o f l i t e r i n e l o s s , b u t the pregnancy p e r i o d c o i n c i d e s w i t h t h e p e r i o d o f abundant n u t r i t i o n f o r t h e bear. o p p o r t u n i s t i c food h a b i t s o f the s p e c i e s seemingly ensure  would  an adequate f o o d s u p p l y o f some s o r t d u r i n g summer and  autumn i n almost  any type o f bear range.  weight from m i d - J u l y u n t i l f a l l supports t h i s view. is  The  The r a p i d g a i n i n  by a l l b e a r s on B i g Creek  K r o t t and K r o t t (1962) s t a t e t h a t hunger  the o n l y n a t u r a l check on European brown bear p o p u l a t i o n s ,  but t h e y have l i t t l e ment.  information to substantiate t h i s  state-  Even i n poor b e r r y y e a r s B i g Creek b e a r s made s i g n i f i c a n t  g a i n s i n weight d u r i n g autumn.  The c o r r e l a t i o n o f h i g h and low  r e p r o d u c t i v e r a t e s o f B i g Creek b e a r s w i t h good and poor b e r r y y e a r s i s c o n t r a r y e v i d e n c e , however (see page 113). Nothing  i s known about p a r t u r i t i o n l o s s e s of the b l a c k  bear, b u t s i n c e the mother bears a r e as competent as o t h e r mammals and t h e new-born a r e s m a l l , t h e s e l o s s e s a r e p r o b a b l y low.  P o s t p a r t u r i t i o n l o s s o f the young b e f o r e the bears  t h e i r dens i s a l s o d i f f i c u l t  to evaluate.  leave  The s i m i l a r i t y o f  80  average c o r p o r a l u t e a counts and average l i t t e r  sizes indicates  t h a t i f many young a r e l o s t , the l o s s must g e n e r a l l y whole l i t t e r s .  Brambell  involve  (1948:396) s a i d t h a t the l o s s o f  s i n g l e embryos o u t o f a l i t t e r w h i l e l o s s o f whole l i t t e r s  i s usually intrinsic  (genetic),  i s p r o b a b l y caused by e x t r i n s i c  events a f f e c t i n g t h e m a t e r n a l environment. M o r t a l i t y r a t e s f o r b e a r s 1/2 t o 1-1/2 y e a r s o f age are low, b u t once the young a r e s e p a r a t e d from t h e i r mothers at  1-1/2 y e a r s ,  losses increase r a p i d l y .  Hornocker (1962) a l s o  showed t h a t s u r v i v a l i n g r i z z l i e s was h i g h were w i t h t h e i r mothers. cubs f o r l o n g e r 1964)  as l o n g  Occasionally black bears r e t a i n t h e i r  t h a n 1-1/2 y e a r s as do p o l a r b e a r s  and g r i z z l y b e a r s , and t h i s may p r o l o n g  death r a t e .  as the young  (Harington,  the p e r i o d  S u b - a d u l t s s e p a r a t e d from t h e i r mothers  o f low  apparently  succumb a t a f a s t e r r a t e t o a l l o f the d e c i m a t i n g f a c t o r s mentioned i n t h i s  section.  Adult bears are stable i n the population, n a t u r a l m o r t a l i t y was observed. a d u l t s m o r t a l i t y might i n c r e a s e are r e q u i r e d  A t some p o i n t  and no  i n the l i f e o f  s i g n i f i c a n t l y , but f u r t h e r data  to determine i f t h i s o c c u r s or i f d e a t h r a t e s  constant f o r a l l a d u l t s .  In general,  adults  seem w e l l  stay  adapted  to the B i g Greek h a b i t a t . K u r t e n (1958) r e p o r t s  a h i g h w i n t e r m o r t a l i t y i n cave  b e a r s , as shown by the s k e l e t a l remains i n caves, and Wright (1910:67)  claims  t o have found the c a r c a s s e s  i n t h e i r w i n t e r dens.  o f many b l a c k  D e s p i t e these c l a i m s , m o r t a l i t y  the denning p e r i o d must be low.  bears  during  Bears s u r v i v e w e l l even i n the  81 s p r u c e - f i r f o r e s t where c l i m a t i c changes f o r c e them to  den  b e f o r e they become s a t i a t e d . Schorger  (194-9) s a i d t h a t i n the p a s t timber  wolves  were the c h i e f n a t u r a l enemy o f b l a c k b e a r s , e s p e c i a l l y i n the w i n t e r .  Boyer (1948) r e p o r t e d t h a t two  C a l i f o r n i a a t t a c k e d and k i l l e d was  denned under a f i r , and  coyotes i n  a s u b - a d u l t b l a c k bear  i n t h i s study two  that  coyotes were  seen c h a s i n g an a d u l t male b l a c k b e a r , a l t h o u g h the chase seemed c a s u a l , too p l a y f u l f o r p r e d a t i o n .  Some s m a l l e r bears  on B i g Creek were k i l l e d by l a r g e r b l a c k b e a r s and bears.  A c c o r d i n g to Rausch (1961),  grizzly  t h e r e i s a widespread  b e l i e f i n A l a s k a t h a t g r i z z l y b e a r s p r e y on b l a c k b e a r s , e v o l u t i o n i s t s h o l d t h a t the b l a c k bear animal  e v o l v e d as a f o r e s t  E r i c k s o n (1957) r e p o r t e d  to a v o i d g r i z z l y p r e d a t i o n .  t h a t a cub i n a t r a p was  and  k i l l e d and  eaten by an a d u l t b l a c k  bear, but he b e l i e v e d t h a t s i n c e b e a r s  i n h i s study d i d not  eat the remains of o t h e r b e a r s i n the f a l l ,  they preyed  on  s m a l l e r b e a r s o n l y d u r i n g the s p r i n g and o n l y because of extreme hunger.  On B i g Creek, bears  ate the remains of  other  bears when the o p p o r t u n i t y a r o s e . A p p a r e n t l y man  has always been a p r e d a t o r of  and o f c o u r s e he s t i l l i s today. 33 p e r c e n t of the bears he shot by h u n t e r s  management of  bears.  S t i c k l e y (1961) found  that  t r a p p e d and marked i n V i r g i n i a were  the same f a l l .  form of " p r e d a t i o n " can be  bears  My  study has  shown t h a t t h i s  e a s i l y i n c r e a s e d or decreased  i n the  82  The pregnancy adults Food  overriding  rate  of  account  quantity  changes  i n  u l t i m a t e l y predators  f o r and  the what also  evidence  adults most food  rates these a l t e r  and of  the  the  q u a l i t y  and  the  l e v e l s or  of  t h i s  high  study  i s  m o r t a l i t y  l o s s  i n  seem  responsible  climate are,  contribute  but to  t o t a l  of  the  that rates  the of  population  area  for  low sub-  numbers.  annual  d i c t a t e s  behaviour,  p a r a s i t e s ,  changes  the  i n  rates.  and  83  CHAPTER  SEVEN  BEHAVIOUR  Several this  study  are  r e g u l a t i o n family  of  Agonistic  bear  b l a c k two  observations bears  and  during  probably  a  p r o t e c t i v e  humans  movement, Other  t h i s and  man  but  h u f f i n g  alternate considered and  because  are  and  d a i l y  during  bears  agonistic  i n d i v i d u a l  these  and  i n  the  behaviour,  changes  v a r i a t i o n  i n i n  actions  bears  bears  forms  of  toward and  Some a an  a  other swat,  bears  loud  behaviour, behaviour.  to  low  s o l i t a r y  growl,  the  with as  this  are  w i t h  s i l e n t "huff"  action;  to  Lorenz  animals,  to  pitched, may of  w i l l  type, warning this  the  jaws,  sometimes  t h e i r stated  s o c i a l  and  prolong  Drahos  i n  (1953)  t h e i r  at  c o n c u r r e n t l y .  f l e e .  demonstrative  but  p r i o r  they  They  f i r s t  l i t t l e  "chopping"  lunge.  are  action  The  v a r i o u s l y  attempts  most  agonistic  comes  trapped  there  bears.  warning  extended,  expressions,  are  f r e e - r a n g i n g and  three  p r i o r  with  on  indicate  f o l l o w i n g  black vocal  made  lunge  give  growl  v o c a l i z a t i o n  body,  They  of  study  and  a l l give  subdued  some  s u r v i v a l  observed  t h i s  recognize.  i n d i v i d u a l s  rather  and  behaviour  the  seasonal  behaviour,  toward  that  i n  numbers.  d i r e c t e d sudden  "bear  Behaviour  The  l e a s t  of  important  r e l a t i o n s h i p s ,  t e r r i t o r i a l  w i l d  aspects  (1951) f a c i a l , that  r e l a t i o n s  84 are  poorly developed,  the  f u r n i s h e d w i t h muscles without warning, snapping evidently  observed  skin of their  o f e x p r e s s i o n , and  rather  with their  thick  face  they s t r i k e  than l a y i n g hack t h e i r  jaws l i k e the f i r s t  other large  i s sparsely  ears  suddenly  and  carnivores.  type of a g o n i s t i c  Lorenz  behaviour  that  I described. The swatting toward  second  and  form of a g o n i s t i c  biting  attack,  the opponent.  The  charge  often  This motion  i s u s u a l l y p r e c e d e d by h u f f i n g ,  of  the e a r s .  slowly  Initially,  towards  position.  T h e y do  given before this the  huffing  the  canids.  previous  deceit ing  The  Failure  f r o m two  (this  closer  or c u r l  and  laying  an  the l i p s .  familiar  More w a r n i n g  growl  both  is  forms  or s n a r l  in  o b s e r v a t i o n s and  from d i f f e r e n c e s  before this  or causes:  back  attacking  i n individual  from d i f f e r e n c e s between w i l d  situations  the  o f t h e b o d y i s moved  type of a t t a c k , but under as t h e  of  paws.  and  a t t a c k seems  (1) the bear  (2) the opponent u n e x p e c t e d l y  practicing approach-  tolerated.  third  been d e s c r i b e d  brown b e a r s  chopping  to maneuver i n t o  to give warning  is rare);  than  part  the  or both front  sometimes by  d i s c r e p a n c i e s b e t w e e n my  among b e a r s  The has  snarl  second  and  the a n t e r i o r  i s as m e a n i n g f u l  zoo b e a r s . arise  not  lip,  reports probably arise  behaviour  to  s t r i k i n g w i t h one  the opponent  sudden  terminates with  and  e x t e n s i o n of the upper  is a  w i t h the bear r u s h i n g s t r a i g h t  body r a i s e d  jaws,  the bear  behaviour  type of encounter resembles i n g r i z z l i e s by Hornocker  ( U . a. y e s o e n s i s ) b y M a s a t o m i  a ritual. (1962),  (1964),  and  It  i n Yezo i t also  85 has  been observed  animal  i n wild black  assumes a s i d e w a y s s t a n c e  Most o f t h e s e  encounters  m o v i n g away b e f o r e Family  (1957) r e p o r t e d female bears  end w i t h  recognizes.  t h e second bear f l e e i n g or i s made.  during  to allow  a similar  are harsh  this  study  t h e i r young  observation  or training  c u b s a r e one y e a r the den.  movement b y t h e b e a r s  Erickson  i n Michigan bears.  together  t h e young.  o l d the female  When t h e y  in a  That  i n the a p p l i c a t i o n of d i s c i p l i n e to  when t h e f a m i l y f e e d s  nursing  females held  to suckle.  y o u n g i s common k n o w l e d g e , b u t t h e y  indulgent  in  threatening  Relationships  t r a p were o b s e r v e d  is  The  which the opponent  an a c t u a l attack  On two o c c a s i o n s  their  bears.  During  c a n a l s o be  quite  a n d when t h e f e m a l e the winter  when t h e  and the young crowd  together  are disturbed,  there  i s a  constant  t o s e e k t h e w a r m e s t a n d most  protected  position. F e m a l e s do n o t a l w a y s p r o t e c t Knudsen with  (1961) and E r i c k s o n  Wisconsin  ranging  female  is,  under  trapped black  (1957) a l s o f o u n d  and M i c h i g a n b l a c k b e a r s . repeatedly  we were c a p t u r i n g "before we c o u l d  t h e i r young a g a i n s t  attacked  and t a g g i n g  continue  male.  while  She h a d t o b e  subdued  T h i s d e f e n s e o f t h e young  and eaten,  a d u l t males.  apparently  A  by a l a r g e  The m o t h e r o f t h e y e a r l i n g a n d a n o t h e r y e a r l i n g  were e i t h e r i n o r n e a r t r e e s a b o u t 60 y a r d s site  true  However, a f r e e -  some c o n d i t i o n s , d i r e c t e d a g a i n s t  y e a r l i n g was k i l l e d  t o be  my a s s i s t a n t a n d me  h e r young.  t h e work.  this  man;  when t h e l a r g e b e a r was c h a s e d  from  away f r o m t h e t r a p -  the c a r c a s s .  The  86 crushed v e g e t a t i o n i n d i c a t e d t h a t the female had spent most o f the n i g h t and morning a t t e m p t i n g to r e s c u e the y e a r l i n g . Wide t r a i l s  i n d i c a t e d she had approached  repeatedly, only to  he chased back to the s a f e t y o f a l a r g e s p r u c e .  The  trans-  f o r m a t i o n o f the a r e a from a l u s h meadow w i t h v e g e t a t i o n about two  f e e t h i g h t o a c o m p l e t e l y trampled a r e a showed a v a s t  amount o f a c t i v i t y i n a p p r o x i m a t e l y 12  hours.  The females are t o l e r a n t of the young u n t i l t h e y are a t l e a s t 1-1/2  y e a r s o f age.  E r i c k s o n and N e l l o r  (1964)  r e p o r t e d t h a t cubs n o r m a l l y are weaned i n September, b u t  one  i n s t a n c e o f a female f e e d i n g a 16 month o l d y e a r l i n g i n May was  observed d u r i n g my  study.  T h i s o b s e r v a t i o n was  made i n  the upper p a r t o f the d r a i n a g e a t about 6,500 f e e t i n e l e v a tion.  None of the females c a p t u r e d when accompanied by  y e a r l i n g s appeared  to be s u c k l i n g young.  U s u a l l y j u s t a t the onset of the b r e e d i n g season i n l a t e June, the young are no l o n g e r seen i n the company of the female, but i n one p o s i t i v e case and two p r o b a b l e c a s e s y e a r l i n g s were observed i n c l o s e company w i t h the mother a f t e r the b r e e d i n g season.  I n a l l t h r e e i n s t a n c e s the f a m i l y  were r e s i d i n g a t the extreme upper ranges a t 6,000 to 6,500 f e e t .  l i m i t s of permanent  S i x o t h e r f a m i l y groups  a r e a broke up i n l a t e June to e a r l y J u l y . seen on June 23, but one of the females was J u l y 7 without her y e a r l i n g s .  groups  Murie  Two  female on the  groups were  seen a g a i n on  ( i n Schorger, 194-9)  r e p o r t e d t h a t t h r e e y e a r l i n g s i n Y e l l o w s t o n e Park  rejoined  t h e i r mother f o r a s h o r t time a f t e r the b r e e d i n g season, but  87 the  s i t u a t i o n  behaviour ponds  a f t e r  t o my  yearlings  the  w i l l  on  mothers'  t h e i r up.  from  Much these  and  h u f f i n g  cubs  v o i c e  blood  purr  resembles  i n t e r n a l  purr  behaviour a  v o i c e d  c o n t i n u a l l y  r a p i d  on  older,  "pump  cub held  from  were  the family home  group  group  ranges  hungry  rather  (1957)  t h e cubs  may  pump  trap.  t o be  part,  b u t  uncomfortable comfort. than  occasion  the  I  ..." c a l l ,  t h i s  v o i c e heard  two y e a r l i n g s .  The c a l l  The  has described  frequently  one  between  pump  o r  or seeking  and on  i n a  seems  the female's  of grunts,  i n communication  to a  o f young  i n bear  Meyer-Holzapfel  When  family  o l dyoung  a f t e r  the family  s e r i e s  subdued  year  the  t o  One  repeated  seemed  d i r e c t e d  the cub and n o t a t the handlers.  Seasonal  Changes  i n  Schoonmaker a  corres-  r e l a t i o n s h i p s .  t o the mother,  a  ranges  comfortable  o f cats.  used  home  within  when  further.  c a l l  female  to  a  p l e a d i n g "bawl  t h i s  which  a f t e r  l i t t e r s  c o n s i d e r a b l y when  "purr"  even  o f 1-1/2  b u t seven  and swatting  squall a  maternal  o r a r e i n d i f f e r e n t  o f the overlap  Communication p r i m a r i l y  however,  range  Dispersal  noted,  o r i g i n a t e  small  home  has been  broken  She d i d show  season,  t o l e r a t e  the mother's  has separated.  area  comparable.  the breeding  females  on  observed had  not he  data.  Some  group  may  group  cate  i n the wild,  that  i n d i v i d u a l  under  w i l d  family  Behaviour  (1938)  r e p o r t s  seeing  b u t observations  s i x black  during  c o n d i t i o n s i n Montana  groups  seldom  approach  t h i s  bears  study  i n d i v i d u a l  one  another  i n i n d i -  bears during  or  88 most p e r i o d s o f t h e y e a r . flee  from  from him  an  approaching  at  season.  a d u l t male and  Eleven bears  50 y a r d s  females  observed. a ridge  Three  o n l y one  after  one  r u s h by  h o w e v e r , a d u l t m a l e s and side  for several A  denning  o v e r a 10  have b e e n e x t r e m e l y approaches  tolerant  Three  two  b e a r s was  pair  and  they had  t o be  travel  sitivity  ( A l d o u s , 1937;  observed  advance individ-  or f e e d  d u r i n g the  exhibiting  1937;  Morse,  o u t o f 40  to b i t e  agonistic the  f e m a l e s , and  young w i t h i n  had  t h a t r e p r o d u c t i v e c o n d i t i o n may  be  during  Both  involved  tagging  ears, be  r e d u c t i o n i n sen-  observed  behaviour.  one  side  winter  any  M a t s o n , 1954).  showed c o n s i d e r a b l e a g o n i s t i c at least  season,  of the o b s e r v e r , a l l o w i n g  f e e t without  bears  on  occurs d u r i n g the  s t u d i e s h a v e shown a s i m i l a r  s t u d y o n l y two  any  subdued w i t h drugs b e f o r e t h e y c o u l d  Other  or  observed  were made t o p l a c e t a g s i n t h e i r  marked.  kept  appears  the b r e e d i n g  b e a r s , however, attempted  when a t t e m p t s  drainage  time.  Most b e a r s  to w i t h i n  behaviour. pliers  females  days a t a  also.  day  l a r g e m a l e s were  During  s e a s o n a l change i n b e h a v i o u r  period  yards  the dominant b e a r , b o t h  distances.  to  month b e f o r e  This distance  away f r o m  A c o n f r o n t a t i o n b e t w e e n two  and  100  cases of sub-adult males  moving c a u t i o u s l y  u a l s withdrew to proper  this  observed  s t a y about  where a i r c u r r e n t s p r o b a b l y p r e v e n t e d  warning,  and  was  observed  apart at a l l times.  t o be m u t u a l l y s o u g h t .  by  female  i n the China B a s i n a r e a of the B i g Creek  least  adult  adult  w h i l e f e e d i n g , a l t h o u g h i t was  the breeding period  An  were  a month, in  During mid-winter adult indicating  mid-winter  agonistic k i l l e d  December  other but  behaviour.  bears  both  bears spring there  i s  observed,  of  had  the  d i d  since  e a s i l y  entrance  two  den  bears  both  marked  bears  were  attack,  i n  rushed  at  however.  when  i n  me,  dens I  Since l a t e  before  these  i n  concluded  change  Two  observed,  mid-May.  observed  behavioural  even  though  f o r  was  i n  subdued and  was  zero,  v i c i n i t y  of  the  that  bears  7-5  there  most  leave  of  heads  bodies  d i d  the  tagged  a  her  d i r e c t i o n  the  the  winter,  den  The  and  bear  competent  drugged.  The  nine  of  feet  s i t e ,  year.  bushes. quite  one  d e f i n i t e  survive  from  l a t e r ,  tracked  while f o r  r a n  i t was  about  I  following  t a l l  i t was  were  but  weeks  when  was  i n  temperature snow  i n  the  den.  cent  the  She  but  three  heading  some  before  behaviour  vations, or  drugs,  temperature. per  of  behaviour  mid-winter.  den  being  unusual  m i l e s ,  den.  branches  and  Winter t h e i r  bear  any  checked  were  o r i g i n a l  f i g h t i n g  the  three  i f she  the  with  were  i t was  another  denned the  exhibit  dens  about as  enter  into  near  not  l e f t  constant  she  awake  d i d the  climbing  be  the  when  not  climbed  awake  to  but  One  ing  rushes  they  a  animals  remained she  to  female  dens. Two  both  attempt  observations  since  pregnant  no  only  again  d e f i n i t e l y  made  these the  and  t h e i r  made  of  were  21  Another  of  the  bears  of  bears  Whereas the  time  time.  were  s l i g h t l y  and  true  1965),  a l l but  enough  look  d i r e c t e d  at  h i b e r n a t o r s  (Kayser,  During  aroused  seems  out.  at  one l e a s t  This  r e g u l a t -  are  only  bears  seem  of  42  to  my  obser-  r a i s e  a c t i v i t y  to  was  t h e i r  90 generally  accompanied  r e t u r n  the  to  curled  dominant  e a r l y  cubs  observed  was  though into  not  the  times  from  There  that eat  f o r  on  During  open  tendency during up  to  more  to  T e r r i t o r i a l  t a i n  to  areas.  the  behaviour eight  f i r on  and  to  becomes  month  o l d 7»  October  r e l u c t a n c e to  d a i l y  emerging 1954;  observed  as  were  i n  move  them  and out  several  d i d  while  observed or  morning  t h e i r  home  feed  do  no  not  such feed-  early  May.  a  greater  much  however,  while  c o n t i n u a l l y  days.  periods  state  observed  feeding,  cool  e a r l y  and  bears  but  were  show  to  f e e d i n g  l i t e r a t u r e  others),  A p r i l  bears  i n  spring  Bears  late  d u l l  the  the  and  frequently  the  changes  i n  study.  Creek  rather  addition  bears.  bears  do  do,  areas  1-1/2  Douglas  movements  A l l bears and  a f t e r  f o r were  6:00  Behaviour  They  "vacant"  with  references  t h i s  B i g  bears  d i r e c t  other  p l e t e l y ,  i n  spring  during  female  great  and  early  l i e down  active  appear  i n  as  on  slow  feet.  noted  s i x hours  by  winter  approached  Matson,  September  In  I  a f t e r  areas  early  showed  Numerous  1937;  A  or  This  large  seasonal  time  was  a  they  are  some  (Aldous,  ing  under  80  also.  behaviour  f a l l .  f o l i a g e .  about  shivering  p o s i t i o n .  the  denned,  wet  behaviour  i n  by  at  and  a  to type  of  Even  though  not  higher 2-1/2  t e r r i t o r i a l  move  however,  range  some  out  of  elevations.  year  o l d  behaviour  home  l a t e r a l l y move  attachments,  group  ranges  into  other  t h e i r The also  own  high  bears  toward  cer-  overlap  com-  occupied range r a t i o  indicates  into of  males  s p e c i f i c  p.m.  91 t e r r i t o r i a l increased  pressure  movement  Fixed accepted  by  agonistic the  on  of  routes  e t h o l o g i s t s  Such  I n d i v i d u a l  V a r i a t i o n  t h i s  to  be  v a r i a t i o n  i s probably  subsequent  through  which  are  the  area.  generally  i n the r i t u a l i z a t i o n were  took  observed  the form  erected  g r e a t l y  with  males  trees,"  often  v a r i e s  and  accustomed sequent one  o f  i f they to  the trap  necessary ceased  animals  by  genetic,  of  of  throughout  defacing  or  man.  w i t h i n  the  the population. b u t much  One  by  to  under  often  be  this  type.  own  i t .  trap The  the trap,  logs  of  animals  with  Some  i t appears  were  type  of  to  from  become  i n j u r i n g was  on  habituated  I t  s i t e  the  u n t i l  u s u a l l y  paws. syringe  e x c i t a b l e themselves  sub-  the discomfort  approached,  also  quite  the b a i t .  types  t h e i r hand  o f  cap-  procedure  endure  that  when  h i g h l y  animal  often  f i r s t  a c t u a l l y became  reward  and  a  they  when  the handling  d o c i l e  o r behind  a g i t a t i o n by This  small  the  administered  Some  to  y e a r l i n g  f o r the  f i g h t i n g  hide  and  d o c i l e  injured,  t r a p s i t e s , w i l l i n g  without  escape.  trap  t o remove  waiting  are completely  are not  captures.  steel  t h e i r  young  1963:8),  markers  age  learned.  tured,  the  and  this  important  Behaviour  Many  to  as  behaviour  signs  of  "bear  (Etkin,  destroying  of  t r a n s i e n t and  behaviour  area.  males  The to  they  small  bear  t r i e d  could bears  o f  contributed  attempting  f a r more  became  s a t q u i e t l y  drug  and  o f  prone  to to  to  92 agonistic been  behaviour.  p r e c i p i t a t e d  numerous t i o n  than  The While  ments Big  the  study  evidently  but  or  could  circumvented  within  Krott  by w i l d avoid  b u t with through  new  so p r o f i c i e n t  elaborate placement  make  recaptures. winter  and were  others  remained  Tracks  showed  a f t e r  several  one m i l e  provoca-  (1962)  t o recognize  bears.  captures.  by  mile  S t a t i o n  said  the o f a  species,  an  traps  was  t h e i r  considerable such  from  as  r a t s  home t o be  Many  animals  being  captured  necessary t a l e n t  i n the following b a i t  was  danger,  object  without  on  European  i n t h e i r  t o t h e b a i t .  l o s t  Since  behaviour  became  the b a i t  o f  t h i s  objects  avoided  move-  t h e mouth  sources  Other  a t s t e a l i n g  bears  10  demonstrated  the trap  captured  r a n g e s , , two  National Park.  t h e dump,  success  behaviour.  o f t h e Ranger  o f the animals  some  regular  o f a d d i t i o n a l  e a s i l y  home  S t a t i o n  approaches  p r o f i c i e n t  that  made  i n Glacier  a t taking  Some  have  b u t  apparent  i n learned  small  u n f a m i l i a r  bears  that  the  on  and Krott  t r a p p i n g  simply  areas,  became  V i l l a g e  o f l e a r n i n g  may  i n the trap,  without  was  a t the Sanger  n o t l e a r n  study  coyotes,  remained  d i d n o t frequent  learned.  i n t h i s  range  dump  behaviour  i n j u r y  type  and one female)  r e s i d e n t  area  bear  measure  a  t h i s  trapped.  bears  and Apgar  bears  brown  being  adult  between  other  i n i t i a l  o f this  were  (one male  Greek  an  cases  g r e a t e s t v a r i a b i l i t y  mosi;  adults  by  animals  other  I n some  the t r a p s i t e s  over  year,  year  t o  t o  b u t  year.  completely  93 Discussion The  behaviour  o f many  animals  with  t h e i r  s u r v i v a l ,  reproduction,  This  study  has  that  Behavioural c e r t a i n  observations  other  e c o l o g i c a l they  have  movement  aspects  data not  and  primary  shown  have  shown  developed  stated  that  i n s u r v i v a l  to  and  d i t i o n s .  This  been  an  of  home  are  close  r e g u l a t i o n .  the black  a i d i n  b i o l o g y .  bear.  understanding  F o r example,  ranges  can be  small.  S o c i a l  neighbors  seem  p o t e n t i a l  the  small,  b u t  i n h i b i t i o n to  be  s o c i a l  since  Family i s r e f e r r e d  inheritance.  a  This  l i f e  s o c i a l general  not form  they  do  l i v e  other  bears.  communication  the  shows that  of  the  f a m i l y  This  by  group  statement  that  necessary  black  t e r r i t o r i a l  many  seems  o f  bears  advan-  applicable  of  the areas  I n  agonistic  under  have  such  many  i n avoiding  r i g h t s ,  fac-  higher  i n small  R i t u a l i z a t i o n  becomes  i n  outside  permanently  (1963:4)  the d e c i d i n g  o f f e r s  groups  more  E t k i n  i s common  are important  and  con-  v o c a l  actual  i n  communi-  groups.  behaviour, to  i s much  i s u s u a l l y  do  study  bears  p r e v i o u s l y recognized.  i n e s t a b l i s h i n g  w i t h i n  i n black  bears  expressions  c o n f l i c t ,  i t  of  that  so,  b u t  with  behaviour  cating  b u t  Black  group,  body  than  even  a s s o c i a t i o n  and  they  p o p u l a t i o n  i s true  that  behaviour  i n d i v i d u a l s .  bears.  family  why  aggressive  vertebrates  to  shown  and  i n v o l v e d  reasons.  h i g h l y  tages  have  of bear  tolerance  Agonistic  tor  this  i s i n t i m a t e l y  S c o t t  or  "care-dependency"  (1958),  behaviour  gives  r i s e  i s well-developed  behaviour, to  a  as  c u l t u r a l  i n the  black  94 bear I  as  have  group  a  r e s u l t  included because  s u r v i v a l . is  i n  is  heat  and  this  notes  female  bears  An  "huddle"  f o r  w i l l  and  they  Two  are  apparent  things  enhanced  when  apparently  the  do  between  p o p u l a t i o n control  of  labour.  His  e l i m i n a t i o n  of  This l i k e  other  1-1/2 and  a f t e r  b e l i e f  study  The  has  the  been  the  has  young  s u r v i v a l  endures  exclude  accounts, female  the  the  bears  male  as  apparently  a  familyand  indulgence of  animal  t h e i r family when  season,  to  from  the  shown  that  b l a c k  a p p l i c a behaviour  the  mother  breaking  up  change  but  of  i s  i t seems  the  from great  some  other  young  and  bears.  i s  other  the  adults,  habitat.  d i f f e r e n c e  p l a c i n g  the  and  not  i n  burden  secondary  competition  bear  d i v i s i o n among to  family  the  beyond  groups,  the  normal  t h e r e f o r e present  that  family  i n  the  on  population.  p e r s i s t  indicates  t h i s  of  however,  young  sometimes  by  man  against  major  i s  and  family,  of  longer,  young  f o r  i n s t i n c t  a  i n  against  t h i s :  maternal  that  and  period  vigorously  breeding  species,  estrus,  causes  disrupts  the  surplus  bear  years.  males  a l l u s i o n  during  b e n e f i t  the  t r a i n i n g  l e v e l s  competent  them  or  and on  t h e i r  group  k i l l  male  of  males  i n  (1962:529)  Wynne-Edwards size  defend  family  males,  many  denning  mother.  warmth.  defend  occasions,  at  a d d i t i o n a l the  i n  d i s c i p l i n e  young are  the  w i t h i n  important  harsh  of  method.  Females  the  of  t r a i n i n g  and  with  communication  appears  combination  the  r e l a t i o n s h i p  on  c o n s e r v a t i o n during  young  body  long  communication  organization, o f  the  some  The  common  t i o n  of  t e r r i t o r i a l i t y  groups.  behaviour  improbable  The  during of  the  common  of  the  females  that  the  female  95 would of  suddenly  constant  The  become  care,  observation  elevations longer  then  of a  where  than  i n t o l e r a n t o f the young accept  y e a r l i n g  the season  normal.  This  secutively,  and because  males  j o i n  would  remain the  i n t a c t  Female s o c i a l young were  found  uals  by  This home  idea  d i p accordingly.  o f neighbouring  groups  that  f a m i l i a r i t y extension  exclude among  Several  t h e i r  mothers'  on  This  tolerance  may  have  this  by  home  o f a  The  establishment be  population  i t may  i n an  i n  very  l i m i t e d  o f such  be  observations  though  area  i n d i v i d -  based  or i t could The  o f  range  stay  and  permanent  hierarchy  bears.  premise,  to  bears  i n d i v i d u a l s could  no  study,  instances  the ranges  second  estrus,  o f r e l a t e d  s o c i a l  t h e way  r e l a t i o n s h i p s .  years  s i g n i f i c a n c e i n  o f a  animals,  con-  leads  with  other  two  t h i s  overlap  unrelated  o f f a m i l y  support  cases.  establishment  that  also  high  therefore,  d i d during  to t h e young  a t  bred.  nurse  would,  would  years  sometimes  skipped  as  i s supported  ranges  estrus  group  some  that  females  again  1-1/2  she had been  suggests  year,  female  number  study  The f a m i l y  study.  through  a f t e r  i n h i b i t  the female  e s t a b l i s h e d  the r e s i d e n t  nursing  could  attachment  i n this  r e g u l a t i o n  small  r a t e  back  i s shorter  r e l a t i o n s h i p s i n some becoming  area.  h e r .  another  reproductive  them  a f t e r  on a  s o c i a l learned  natural o f  this  not be  exclusive. Seasonal important and  i n bear  females  bears  and d a i l y  under  changes  s u r v i v a l .  t r a v e l n a t u r a l  together,  During  i n behaviour the breeding  b u t a t other  conditions  times  a r e s o l i t a r y .  a r e  also  season o f the  The f l i g h t  males year o f  96 sub-adult cates  males  that  dominant  In danger,  this  den  the  aroused,  t i n u a l l y able so  t o  says  and  to  Their family  i n the  the body,  and to  conservation o r  h i b e r n a t o r s study  the denning  another  t o  apparently  c u r l  i n this  i n d i -  s u r v i v a l .  Behaviour  i n heat  that  bears  t o  s e n s i t i v i t y  augmented.  to huddle,  males  r u l e .  i n t h e i r  energy,  During  o r t o move  t h i s  reduced  important  some  observed.  f i g h t  a  adult  shiver  only  shivered  period  den, b u t they  con-  bears  a r e  a r e  seldom  i n c l i n e d . dominance  t h e autumn  fat  stores.  from  and f a l l ,  o f  the  Through young  from  population  a  i t sa c t i o n  of  animals  S o c i a l even  a  allow  over  t h e i r  and  o f the grasses  r a p i d  t o  doubt  and forbs  o f  behaviour  summer  i s no  behaviour  build-up  feeding  early  change  other  b e r r i e s a  r e s u l t  and the  l a t e  b e r r i e s . many  thereby  Another  these  c o n d i t i o n s of high  e f f e c t i n g of  mechanism,  desirable  both  animals  f u n c t i o n  d i s p e r s i o n  i n t h e most  groups  under  b u t this  population,  as  s h i f t  t e r r i t o r i a l i t y ,  numbers.  is  also  i n spring  p a l a t a b i l i t y  development  feeding behaviour  c o n t r i b u t e s t o t h e i r  bears  and f o r b s  summer  reduced  of  probably Black  grasses  during of  have  (1965)  from  enforce  a r e important  whereas  while  The i n  tendency  Kayser  female  conserving  a l l o f which  production. when  bears  i n the den i s also  includes  shiver,  adult  t o o seems  i s reduced,  cooperation  an  i n d i v i d u a l s  t h e autumn  and  a c t i v i t y  and of  a  surplus  r e g u l a t i o n  t e r r i t o r i a l reducing  habitats  the  (Tinbergen,  f u n c t i o n s o f density.  eject  o f  behaviour density  1957)•  t e r r i t o r i a l i t y ,  Recently  O a r r i c k  97 (1963), Mykytowycz (1964), and o t h e r s have shown t h a t of  groups  i n d i v i d u a l s o f a s p e c i e s e x c l u d e , e i t h e r as a group  or on  an i n d i v i d u a l b a s i s , o t h e r members o f the same s p e c i e s . Krott  (1962) s a i d t h a t European  brown b e a r s are  s o c i a l l y n e u t r a l a n i m a l s , t h a t they have no t e r r i t o r i e s , t h a t "bear t r e e s " are not marking p l a c e s .  and  G r i n n e l l e t al_.  (1937) s a i d t h a t b o t h males and females mark t r e e s and  that  t h i s a c t i o n i s n o t to mark t e r r i t o r y , but r e s u l t s from  scratch-  ing  and s t r e t c h i n g , even though  i t t a k e s on a s p e c t s of a  E r i c k s o n (1965) says b l a c k bears are not t e r r i t o r i a l , A l a s k a they congregate on salmon streams congregate on dumps.  ritual.  since i n  and i n M i c h i g a n they  The evidence of t h i s study i s t h a t b e a r s  have a form of t e r r i t o r i a l i t y ,  but t h a t t h i s b e h a v i o u r i s  masked w i t h i n s o c i a l r e l a t i o n s h i p s w i t h o t h e r b e a r s i n a g i v e n area.  On a l o c a l s c a l e , i n d i v i d u a l b e a r s move about  f r e e l y , but they are p r e v e n t e d by t e r r i t o r i a l  quite  p r e s s u r e from  moving o n l y a few m i l e s to an abundant f o o d s o u r c e , e s p e c i a l l y i f the movement i s l a t e r a l i n e l e v a t i o n or downwards.  The  r e s u l t a n t s m a l l home areas keep the b e a r s spread out i n the permanent bear h a b i t a t a t a l l t i m e s .  Movements to h i g h a r e a s  where f o o d i s t e m p o r a r i l y abundant are not r e s t r i c t e d .  These  h i g h areas would p r o b a b l y be comparable to the " n e u t r a l a r e a s " d i s c u s s e d by H e d i g e r (1950:15).  The evidence f o r  territoriality  among b e a r s i s , i n summary, the h i g h development and  ritual-  i z a t i o n of a g o n i s t i c b e h a v i o u r ; the c i r c u m s t a n t i a l evidence of male p a r t i c i p a t i o n i n b r e a k i n g up f a m i l y groups and  forcing  the d i s p e r s a l of young; the minimum o v e r l a p i n the home ranges  98 of  adults  small  of  home  the  same  ranges  mutually  f a m i l i a r  objects;  the  breeding  season;  w i t h i n uals  into  natural  bear  only  to  bonds  i n h i b i t i o n s  or  that  One  but  the  bears  not  attachment, of  c e r t a i n  of  bears  r e s u l t  types  on  no  or  seasons  types  found  no  that  attack  important way  to  i n  the  cower  or  repeatedly to  measure  t h i s  of  i n d i v i d -  area,  i n  "learned"  an  area  f a m i l i a r  the  should  that home i n  they  other  break  source. s o l e l y  nature  also  have  leave.  ranges  p r e v a i l s  to  surroundings,  sedentary  males  i n bears  stems  and  this  Movements congregations  studies  over  of  probably  t e r r i t o r i a l  behaviour  wanes  areas.  t h e i r  behaviour  concealment  when  d i f f e r e n t  that  the  by.bears  to  other  seek  movements  congregations  i n  t e r r i t o r i a l  i n  during  food  a  reported  polytypic  except  other  p a r t i c u l a r  t h e i r  mean  and  to  shown  behaviour  of  have  Young  of  ranges  movement  the  d i s t i n c t  that  e x p l a i n i n g  streams  i t could  and  of  i n  trees  l a t e r a l  remain  have  outside  are  to  the  bears  attachment  v a l i d .  "learned"  some  doubt  f o r  data  salmon  when  that  my  bears  Bears docile  seem  and  behaviour, during  d e s i r e  a l t e r n a t i v e  does  travel  hears  of  r e s i d e n t  bears  the  by  of  areas;  or  of  freedom  bears  and  say  animal's  this  of  area,  could  kept  the  s e a s o n a l l y used  of  marking  i n h i b i t i o n  h a b i t a t ;  h a b i t a t  overlap  the  distance  the  spacing  the  animals;  adjacent  from  the  despite  mutual  good  sex;  captured.  degrees  d i f f e r e n c e .  i n  and  with  completely  very  These  aggressive  t r a i t s  s u r v i v a l ,  but  are I  99  CHAPTER  POPULATION  CHARACTERISTICS  REGULATORY  Long-lived seasonal of  and  i n d i v i d u a l  the  study  years  of  both  of  a  and  to  i n  Density  and I  area  by  1959, the  tured known,  and  between  bears  not  i d e a l  because  was  of  e s s e n t i a l  data.  f o r e s t the  Also,  the  comparisons  or  habitat  a  of  study  however,  I  groups  These  species  of  parameters  between  a  f o r  p o p u l a t i o n  f o r  types. of  behaviour  number  p o p u l a t i o n  i n  performance  or  of  subjects  density,  p o p u l a t i o n regulation, these  study  physiology  i n f o r m a t i o n on of  and  count  1961  the  the  data  status  adjustment  p o p u l a t i o n on  and  p o p u l a t i o n were  an  are  the  show  and  the  i t s  Numbers  d i r e c t  while  the  f o r  conditions.  estimated  I960,  i n  they  important  d i f f e r e n t  environmental  the  growth  are  r e l a t i o n s h i p  i n  Since  o b t a i n  species  l i v i n g  suitable  p o p u l a t i o n phenomena  management  attempted  are  but  AND  MECHANISMS  v a r i a t i o n s  animals,  involved.  structure,  animals  y e a r l y  EIGHT  of  the  Peterson  (Peterson,  added  f o r  p o p u l a t i o n between  by  to  many  the  and  B i g  I960  not  was  as  seen  made.  study  method  Since  estimate  was  Creek  Index  1896).  animals  m o r t a l i t y  1959  the  using  new  they  were  again  The  animals  was  loss  c a l c u l a t e d  from  capun-  from the  100 number o f b e a r s marked i n 1959 death or d i s p e r s a l and by 1965.  t h a t had d i s a p p e a r e d  t h a t had not been observed  through  or r e c a p t u r e d  As T a b l e 9 shows, the e s t i m a t e of the annual  r a t e becomes more a c c u r a t e each y e a r o b s e r v a t i o n s are t h e r e f o r e the c a l c u l a t i o n based age of a l l y e a r s . p l e t e , the 1959  on 1959  death continued;  i s s u p e r i o r to an  aver-  S i n c e d a t a f o r o t h e r y e a r s were not as com-  d a t a were used throughout,  even though death  and d i s p e r s a l r a t e s do change from y e a r to y e a r .  For example,  i n I960 a h i g h number o f s u b - a d u l t s were c a p t u r e d .  The  subse-  quent d e a t h and d i s p e r s a l of the s u b - a d u l t s a p p a r e n t l y i n f l a t e d the e s t i m a t e of the d e a t h r a t e f o r t h a t y e a r . The  first  e s t i m a t e o f d e n s i t y was  the t o t a l number of bears d u r i n g 1959  based  t h a t had "been tagged  on a count on the a r e a  and I960, p l u s the number of untagged b e a r s  e s t i m a t e d to be on the a r e a but never c a p t u r e d .  At the  o f the I960 t r a p p i n g season 84 b e a r s had been tagged, 12 of these were known t o have been k i l l e d . 100  of  end  and  only  In evaluating  o b s e r v a t i o n s of untagged bears d u r i n g I960, I e s t i m a t e d  t h e r e were a t l e a s t 18 untagged b e a r s s t i l l area.  I f the 1959  on the B i g Creek  f i g u r e s are a d j u s t e d f o r annual m o r t a l i t y ,  the t o t a l p o p u l a t i o n i n l a t e I960 was A s i m i l a r e s t i m a t e was  about 84  animals.  o b t a i n e d from c a l c u l a t i o n s  on marked-unmarked r a t i o s of animals observed d u r i n g ( S c h n a b e l , 1938).  T h i s f i g u r e was  1961  also adjusted f o r winter  m o r t a l i t y g i v i n g an e s t i m a t e o f 95 b e a r s as the t o t a l t i o n i n 1961  ( T a b l e 10).  based  A t h i r d c a l c u l a t i o n based  c a p t u r e and r e c a p t u r e d a t a from 1961,  popula-  o n l y on  and assuming t h a t  b e a r s became t r a p shy, gave an e s t i m a t e of 104 b e a r s  few  ( T a b l e 10).  No. Marked  1959  F i r s t Recaptured or seen a g a i n i n Year I n d i c a t e d I960  1961  1962  1963  1964  1965  Minimum No. Surviving One Year or more a f t e r Marking  No. Gone or Dead  Annual Mortality  28  6  17.7  44  21  32.3  43  10  18.9  31  1  3.1  29  8  21.6  34  10  22.7  Av.  22.8  *Data f o r 1962 were o m i t t e d from the average because few new b e a r s were marked t h a t year. The d a t a f o r t h a t year, t h e r e f o r e , r e p r e s e n t s o n l y the m o r t a l i t y r a t e o f p r e v i o u s l y marked o l d e r bears l i v i n g on the a r e a . Table 9.  The numbers of marked bears of a l l ages on B i g Creek a t the end o f eacih y e a r and the number r e c a p t u r e d or observed i n f o l l o w i n g y e a r s . The number known to have been k i l l e d through h u n t i n g or d u r i n g h a n d l i n g was deducted from the t o t a l of o l d and new marked animals.  No. Marked 1959-1960 and a t l a r g e Unadjusted A d j u s t e d (B) (D)  1961 Data - Obs. & Trapped T o t a l No. No". Bears t h a t Bears (A) were Tagged (C)  Type o f Data  AB  AD  Observations  53  29  72  52  3,816  2,756  Captures  47  23  72  52  3,384  2,444  Observations: P -  =  Captures:  = - ^ j ^  p =  2  2  ^  6  » 9 5 bears (adjusted)  = 104 b e a r s ( a d j u s t e d )  Annual M o r t a l i t y :  = ^ x  100 = 17.7 p e r c e n t *  •Adapted from Table 9 « Table 1 0 .  E s t i m a t e s o f the 1959-1961 B i g Creek bear p o p u l a t i o n from c a p t u r e , observat i o n , and r e c a p t u r e d a t a . Adjustments were made f o r the c a l c u l a t e d annual mortality. Bears known t o be dead were n o t i n c l u d e d .  103 The f i r s t 1.0  e s t i m a t e gave a d e n s i t y of one bear p e r  square m i l e s d u r i n g I960; the second and t h i r d e s t i m a t e s  p l a c e d the d e n s i t y i n 1961  a t one bear p e r 0.8  square m i l e s .  None o f t h e t h r e e e s t i m a t e s took i n t o account the p o s s i b i l i t y o f h i g h e r m o r t a l i t y r a t e s o f marked animals, but E r i c k s o n (1959) showed t h a t i n young animals a t l e a s t s u r v i v a l  rates  o f i n j u r e d and i n t a c t bears were almost e q u a l .  the  Also,  annual m o r t a l i t y r a t e no doubt i n c l u d e s some animals t h a t merely  emigrated. An e s t i m a t e o f 48 b e a r s on the a r e a i n 1966  was  o b t a i n e d i n a s i m i l a r manner from marked-unmarked r a t i o s o f b e a r s observed i n 1966  and was based on 47 marked b e a r s known  to be on the a r e a i n 1965. 17.7  a d j u s t e d f o r the  p e r c e n t annual m o r t a l i t y c a l c u l a t e d f o r the b e a r s marked  i n 1959. f o r 1966  T h i s low d e n s i t y of one b e a r p e r 1.7  square m i l e s  i n d i c a t e s t h a t the bear p o p u l a t i o n had d e c l i n e d  s i d e r a b l y from I960 - 1961. was  The e s t i m a t e was  low i n 1966,  con-  Even though the d e n s i t y of b e a r s  the i n c r e a s e d p e r c e n t a g e o f s u b - a d u l t s i n  t h a t y e a r i n d i c a t e s i t was  increasing.  Population Structure I cannot d e s c r i b e the p o p u l a t i o n s t r u c t u r e of the B i g Creek b e a r p o p u l a t i o n a d e q u a t e l y ; f a r more d e t a i l e d r e c o r d s of the p o p u l a t i o n would be n e c e s s a r y .  I do, however, have  d a t a on the marked animals t h a t were k i l l e d  and e x t e n s i v e  d a t a on animals s t i l l  A l s o , I have p a r -  l i v i n g on B i g Creek.  t i a l r e c o r d s o f a c o n s i d e r a b l e number of the marked b e a r s  104 t h a t have d i s a p p e a r e d from the p o p u l a t i o n through d e a t h  or  dispersal. T a b l e 11 shows t h a t cubs ( b e a r s 4 - 9  months o l d ) and  y e a r l i n g s ( b e a r s 16 - 21 months o l d ) formed 29 p e r c e n t of 155  bears c a p t u r e d on B i g Creek, a t o t a l almost  identical  with  the r e s u l t s o f S t i c k l e y (1961) i n V i r g i n i a , but f a r below those of E r i c k s o n and P e t r i d e s (1964) i n M i c h i g a n . (bears 28 months to 4-1/2  Other  sub-adults  y e a r s of age) made up a major p o r t i o n  o f the B i g Creek p o p u l a t i o n , but t h e r e are no o u t s i d e d a t a w i t h which to compare t h i s f i g u r e . p o p u l a t i o n was  The percentage  h i g h e r d u r i n g 1961,  1962,  o f a d u l t s i n the  and 1963  ( T a b l e 12),  but o n l y because t h e r e were fewer s u b - a d u l t s i n the p o p u l a t i o n . Most o f the 47 b e a r s k i l l e d on the study a r e a were a d u l t s o f b o t h sexes  (89 p e r c e n t ) .  The younger animals were not a s t a b l e p a r t of the population.  Table 13 shows t h a t 20 per c e n t of the cubs  remained i n the p o p u l a t i o n u n t i l two  two  y e a r s o f age, but o n l y  s u b - a d u l t females remained i n the p o p u l a t i o n u n t i l  years o l d . she was  One  still  3-1/2  cub became a permanent r e s i d e n t on the a r e a as  t h e r e i n 1965  a t 5-1/2  y e a r s of age.  numbers are low compared w i t h the 60.4  These  p e r c e n t of the a d u l t s  t h a t remained t h r e e or more y e a r s and w i t h the 10.4  per  cent  of the a d u l t s t h a t remained i n the p o p u l a t i o n s i x to e i g h t years.  T h i s t o p i c was  t r e a t e d e a r l i e r i n the s e c t i o n on  death  r a t e s and i n F i g u r e 13• Except  f o r those shot by h u n t e r s , a d u l t bears were  l o n g - l i v e d once they became e s t a b l i s h e d members of the  105  VIRGINIA  MICHIGAN  No.  %  No.  2  2  44  28  18  12  1-1/2  27  29  29  18  26  17  5  11  Total Cub & Yearling  29  21  73  46  44  29  5  11  Sub-Adult  47  30  10  21  Adult  64  41  32  68  Age Group Cub  %  B I G T o t a l o f 155 Bears Captured No. %  C R E E K T o t a l o f 47 Known Dead No. %  Total Older Bears  65  6°,  85  5±  111  2 1 4 - 2  82  T a b l e 11.  Age s t r u c t u r e o f the B i g Creek bear p o p u l a t i o n as compared w i t h t h a t found i n o t h e r s t u d i e s .  Number of Marked Bears on B i g Creek Year  Total  No.  of A d u l t s  Per Cent A d u l t s  1959  37  17  45.9  I960  75  32  42.7  1961  63  35  55.6  1962  42  33  76.2  1963  46  29  63.0  1964  47  25  53.2  1965  49  23  46.9*  *This f i g u r e i s low because i t i s based on d a t a from o n l y one y e a r .  Table 12.  The number and p e r c e n t a g e of a d u l t s i n the B i g Creek b e a r p o p u l a t i o n . The I960 and 1962 d a t a show the extremes i n the numbers of a d u l t s p r e s e n t i n the p o p u l a t i o n .  Alive 1 yr. Later  Alive 2 yrs. Later  Alive 3 yrs. Later  6-8  Alive yrs. Later  No.  No.  No.  No.  % Surv.  No.  % Surv,  15  13  86.6  3  2  13.3  0  0.0  7  6  85.6  —  —  —  —  —  Total*  22  19  86.4  3  20.0  2  13.3  0  0.0  Yearlings  26  10  38.4  6  23.0  0  0.0  0  0.0  Sub-Adults (2-1/2 5-1/2)  31  15  48.3  12  38.7  7  22.6  2  6.5  Adults  48  36  75-0  33  68.8  29  60.4  5  10.4  Age  % Surviving  % Surv.  Cubs Marked With, marked Females  20.0  —  * 0 n l y d a t a on marked cubs were used a f t e r one y e a r . T a b l e 13.  The s u r v i v a l o f i n d i v i d u a l b e a r s tagged between June, 1959, and September, 1963. Only 1959-1963 d a t a were used to a l l o w s u f f i c i e n t time to determine i f b e a r s were p r e s e n t o r not. K i l l e d bears a r e not i n c l u d e d i n the t a b l e .  108 population.  One  female  tagged as an a d u l t i n 1959  male tagged as an a d u l t i n I960 were s t i l l in  Four o t h e r s tagged i n 1959  1966.  were on the a r e a i n 1965 ages o f the two  and  seen i n 1966  and  one  on t h e s t u d y a r e a  and s i x tagged i n I960  are p r o b a b l y s t i l l  there.  The  were unknown a t the time o f  c a p t u r e , b u t b o t h were a t l e a s t 5-1/2  first  y e a r s o l d i n 1959  a c c o r d i n g t o t h e i r s i z e and b r e e d i n g c o n d i t i o n .  The  t h e r e f o r e , was  and the male  a minimum of 12-1/2 y e a r s of age,  a minimum of 11-1/2 y e a r s of age i n 1966. study a r e a are no doubt even o l d e r . s o u t h e a s t of the study a r e a was  Some b e a r s on the  A female from 10 m i l e s  23 y e a r s o l d , as  determined  by the number of cemental r i n g s i n h e r lower canine and J o n k e l , 1966).  (Stoneberg  Another bear k i l l e d on L o l o Creek i n s o u t h -  western Montana had molars gum  female,  and premolars worn l e v e l w i t h the  l i n e and had 24 r i n g s i n the cementum of an upper  premolar,  making her a t l e a s t 23 y e a r s o l d . Growth and It  Nutrition i s h a r d t o g e n e r a l i z e about  the development of w i l d  animals s i n c e t h e y have i n d i v i d u a l , s e a s o n a l , and s e x u a l d i f f e r e n c e s which v a r y w i t h time and p l a c e and which have r e l a t i o n s h i p t o the development o f c a p t i v e a n i m a l s .  I t would  be u s e f u l , however, i n management and i n u n d e r s t a n d i n g p o p u l a t i o n parameters weight  little  other  i f such e a s i l y measured c h a r a c t e r s as  and r a t e of g a i n i n weight  c o u l d be used as an  t i o n of n u t r i t i o n and growth l e v e l s .  indica-  I have t r i e d to e v a l u a t e  n u t r i t i o n and growth l e v e l s f o r the B i g Creek b e a r p o p u l a t i o n  109 and r e l a t e are  them t o o t h e r p o p u l a t i o n  characteristics.  p r e s e n t e d b y g r o u p i n g segments o f t h e p o p u l a t i o n . Adult  higher  elevations  ( T a b l e 14-). and  fall  spring  Females.  The a v e r a g e w e i g h t  o f 76 a d u l t  o n t h e s t u d y a r e a was 125 p o u n d s , b u t t h o s e  captured  were s i g n i f i c a n t l y  Weight  weights  or f a l l  the weights  all  adult  of bears from other  of adult  than other females  a t t h e same t i m e  showed a s l i g h t  each y e a r  (Figure 14),  and the a v e r a g e w e i g h t s o f  decline during  1959 t o 1965  As shown i n F i g u r e s 16 a n d 17,  seasonal  i n the weights  of adult  changed  from e a r l y  Weight  summer, b u t f r o m (Figure  16).  individuals comparing  (Figure  related  changes  i n the weight  June  August  o f 1959 t o 116 p o u n d s i n J u l y  change i n weight  to early  rapidly  were  often  condition of the i n d i v i d u a l ; f o r i n 1961;  No. 36  o f 1959 t o 88 p o u n d s i n  w h i l e f e m a l e No. 1 d r o p p e d  Adult Males.  spring  of selected  fluctuations  f r o m 140 p o u n d s i n t h e f a l l  o f I960,  were  t h e c a u t i o n n e c e s s a r y when  example b o t h f e m a l e s No. 1 a n d 36 h a d c u b s decreased  females  areas i f t h e time o f the year  The most p r o n o u n c e d  to the reproductive  however,  time females g a i n e d  17) i l l u s t r a t e  bears from d i f f e r e n t  not noted.  little  then to denning  The g r e a t  early  elevations.  ( F i g u r e s 14 a n d 1 5 ) . fluctuations  spring  f e m a l e s d i d n o t c h a n g e much a n n u a l l y  o f some i n d i v i d u a l s  females  considerable.  from  f r o m one e l e v a t i o n were c o m p a r e d w i t h  when t h e y w e r e w e i g h e d but  lighter  females  d i f f e r e n c e s were g r e a t e s t when e a r l y  weights  Weights  is  The d a t a  f r o m 200 p o u n d s i n  o f I960.  A d u l t m a l e s do n o t show a m a r k e d s e a s o n a l  (Figure  14).  They a p p a r e n t l y endure t h e  110  June Elevation  n  4,400' +  July  x  Aug.-Oct.  n  x  n  x  A l l Seasons n  x  "  ^  -  17  112  8  118  15  138  41  122*  18  14  120  7  120  11  147  35  128  23  184*  56  3,400_ 4,400' Less  than  4,000' (Outside of B i g Creek)  *No. 1 and 3 a r e s i g n i f i c a n t l y l e v e l by Student's t t e s t .  T a b l e 14.  5  -  different  a t the 5 per cent  The a v e r a g e w e i g h t i n p o u n d s o f a d u l t f e m a l e b e a r s c a p t u r e d a t v a r i o u s e l e v a t i o n s b e t w e e n 1959 and 1965 o n B i g C r e e k and i n a p o n d e r o s a p i n e f o r e s t o u t s i d e of the B i g Creek d r a i n a g e .  1959  Figure  14.  15.  1961  1962  1963  1964  1965  I n d i v i d u a l weights o f a d u l t females c a p t u r e d . i n the same month i n d i f f e r e n t y e a r s .  1959 Figure  1960  1960  1961  1962  1963  1964  1965  Average weights o f - a d u l t females from 1959 t h r o u g h 1965• Numbers i n d i c a t e sample s i z e .  112  '"'•288  MAY Figure  16.  JUNE  17.  AUG.  SEPT.  O C T . NOV.  S e a s o n a l g r o w t h o f a d u l t males and a d u l t females. Numbers i n d i c a t e s a m p l e s i z e .  '59 Figure  JULY  lbs.  '60  '61  '62  '63  '64  '65  Weights o f i n d i v i d u a l a d u l t females a t v a r i o u s times of•the year. The numbers i d e n t i f y t h e i n d i v i d u a l b e a r s and a r e d i s c u s s e d i n t h e t e x t .  113 winter  denning  and  have  so  on  Big  i n  J u l y  adult  The  female  area  with  (Figure  18),  weights  a f t e r  the  p h y s i c a l  but  reached  was  5-1/2  1965. who  f o r  f o r  that  year,  4,400  feet  and were  the  b e r r y  188  by  and  and  Student's  the  production  pounds  October,  d e c l i n e  to  15),  (Figure  years,  during  d e c l i n e  i s on  also the  recorded  5-1/2  l e a s t  weights  i n  corstudy  to  agree  with  growth  of  males  increased  sexual  19).  Bears  I960,  1965*  Bear  to  pounds  of  bears  i n  50  No.  and  those  i n  and  o l d  increased  captive  increase  years  1964  i n  tend  260  Rausch  and  4,400  feet  by  (I960),  continued  g i r t h  7  No.  u n t i l  t o t a l  the  weight  thereafter. males with  averaged Student's  males  breeding  at  males  a f t e r  (Figure  but  compared  the  were  reached  1961,  a d u l t  by  been  adult  even  i n  that  t h a t  some  age  bone  years  s i g n i f i c a n t females,  of  but  s e v e r a l  pounds  1959  a  bears  males  June,  September,  show  other  Adult  and  corresponds  f o r  maximum  data  Nine  202  May  d i d  i n d i v i d u a l  has  t h e i r  years  found  males  poor  year.  s i g n i f i c a n t  females,  example,  These  s i x t h  the  maturity  62,  not  which  of  i n  than  15).  annually  and  were  each  during  pounds  adult  years  back  pounds 225  and  s p r i n g b e t t e r  gain  211  of  (Table  weight  to  differences  Unlike i n  early  weights  1963  r e l a t e d  weight  August,  The  to  and  averaged  and  test.  1961  less  Creek  November. t  p e r i o d  moved  season,  from  higher  captured  above  34  captured  males  214 t  pounds.  test.  to and  lower only  The  Unlike  averaged  3,400  between  d i f f e r e n c e the  more  e l e v a t i o n s  small i n  number  the  was  not  stationary  e l e v a t i o n s during a  and  of  spring.  the  s p r i n g  weights Males  are  114,  a. 160-  '59 Figure  18.  19.  '61  '62  '63  '64  '65  A v e r a g e w e i g h t s o f a d u l t males on t h e B i g C r e e k study area. Numbers i n d i c a t e t h e sample s i z e .  '59 Figure  '60  '60  '61  '62  The w e i g h t o f i n d i v i d u a l .Creek.  '63 a d u l t males  '64 on B i g  '65  TP•_• E l e v a t i o n  Relative  Abundance  of  Huckleberries  in  1957  Feet  3,500-4,000  1958  very  common  1959 few  I960 abundant  1961  1962  few  few  1963 abundant  1964  1965  few  very  abundant  4,000-4,500  "  scarce abundant  common  few  "  very  "  "  "  scarce  4,500-5,000  "  "  5,000-6,000  "  '»  6,000-7,000  "*  *«  *Two  feet  Table  15.  of  snow  f e l l  September  few  "  "  "  "  "  few  "  "  "  "  "  "  "  "  "  "  "  common  common  8.  Huckleberry production on the B i g Creek p l o t s and annual estimates.  study  area  as  determined  by  sample  "  116 s c a t t e r e d widely throughout the  fall,  the e x t e n s i v e h i g h country  making c a p t u r e s p a r t i c u l a r l y d i f f i c u l t  Sub-adults.  The w e i g h t s  sub-adults  at that time.  of the sub-adults  Creek study are a d i f f e r e n t matter.  As  i n the  shown i n F i g u r e  increase i n weight slowly i n t h e i r f i r s t  m e r s , w e i g h i n g o n l y 60 pounds of gain corresponds In  a t 2-1/2  during  years.  to t h e i r s u r v i v a l r a t e s  the w i l d there i s v e r y l i t t l e  20,  four  This  sum-  slow r a t e  (see F i g u r e  13).  d i f f e r e n c e i n the  a p p e a r a n c e o f a 4 5 p o u n d y e a r l i n g a n d a 60 p o u n d 2 - 1 / 2 old,  Big  b u t F i g u r e 21 shows t h a t w i t h i n t h e s t u d y  year  area the  w e i g h t s o f young b e a r s have a d e f i n i t e range f o r i n d i v i d u a l age c l a s s e s  when o n l y t h e w e i g h t s f o r e a c h m o n t h a r e c o m p a r e d .  T h e r e was no o v e r l a p w i t h i n t h e f i r s t  f o u r age g r o u p s o f  from the B i g Creek study a r e a , but the weights of f i v e a n d two 2 - 1 / 2  year o l d bears captured o f f the area i n  cubs the  Douglas f i r type completely overlapped w i t h the weights B i g C r e e k b e a r s 1-1/2  and 3-1/2  years  The w e i g h t s o f 37 y e a r l i n g s 49 pounds  of  d e c l i n e d from a high  (n = 3 ) , but the weights of 1964-1965 bears  little two  of  38 p o u n d s  showed  (n » 9 ) «  and 3-1/2  Bears  of 1963  some was  i n the  first  y e a r o l d males were o f t e n  h e a v i e r t h a n f e m a l e s o f t h e same a g e Rate of Gain.  in  There  d i f f e r e n c e i n t h e w e i g h t o f t h e two s e x e s  summers, b u t 2-1/2  of  age.  a v e r a g e i n 1959-1961 ( n = 25) t o 27 p o u n d s  i n c r e a s e w i t h an average  bears  (Figure  20).  o f a l l age c l a s s e s  either  gained  w e i g h t s l o w l y o r l o s t w e i g h t d u r i n g t h e s p r i n g and e a r l y summer.  Bears  foraged extensively during t h i s period,  and  .5  1.5  2.5  3.5  AGE CLASS  F i g u r e 20. Average w e i g h t s o f known-age s u b - a d u l t b e a r s on B i g Creek. Numbers i n d i c a t e sample s i z e .  MAY F i g u r e 21.  JUNE  JULY  AUG.  SEPT.  OCT.  NOV.  S e a s o n a l changes i n t h e average w e i g h t s o f knownage s u b - a d u l t s o n t h e B i g Creek s t u d y a r e a 19591965.  118 t h e y a t e a g r e a t v a r i e t y o f f o r b s and g r a s s e s ( T i s c h ,  1961).  However, 22 b e a r s g a i n e d o n l y 0.08 pounds p e r day over an average p e r i o d of 21 days d u r i n g t h i s time individual rates).  ( s e e Table 16 f o r  The g r e a t e s t l o s s was 0.64 pounds p e r day  over a 14 day p e r i o d by a s u b - a d u l t female.  Gerstell  (1939)  r e p o r t s c a p t i v e cubs g a i n i n g 0.208 pounds p e r day d u r i n g e a r l y s p r i n g , and E r i c k s o n and N e l l o r (1964) s a i d b e a r s a r e l i g h t e s t s h o r t l y a f t e r t h e y l e a v e t h e den i n A p r i l ;  some b e a r s i n t h i s  study, however, r e a c h e d t h e i r lowest weights i n l a t e June o r early  July. The one e x c e p t i o n when a B i g Greek b e a r g a i n e d weight  r a p i d l y d u r i n g t h i s p e r i o d i l l u s t r a t e s the e f f e c t f o o d c a n have i n a l t e r i n g bear weight  supplemental  and development.  This  b e a r , a s u b - a d u l t female, f e d a t a c o n s t r u c t i o n camp i n the c e n t r e o f t h e study a r e a d u r i n g 1959 and g a i n e d 25 pounds i n 30 days from June 6 t o J u l y 14.  A more a r t i f i c i a l case was  a penned y e a r l i n g male t h a t grew from a p p r o x i m a t e l y 50 pounds i n e a r l y s p r i n g t o 185 pounds on September 24.  This bear  would have weighed about 60 pounds i n September under w i l d c o n d i t i o n s on B i g Creek. From m i d - J u l y u n t i l sexes g a i n e d weight r a p i d l y .  October a l l age c l a s s e s o f b o t h I n an average o f 30 days,  14 b e a r s g a i n e d 0.84 pounds p e r day, w i t h one a d u l t g a i n i n g 1.55 pounds f o r 22 days ( T a b l e 1 7 ) . season i n c l u d e s many k i n d s o f f r u i t s  female  Food d u r i n g t h i s  ( T i s c h , 1961).  Black  (1958) r e p o r t e d t h a t i n New York two b e a r s w i t h a c c e s s t o garbage g a i n e d an average o f f o u r pounds p e r day f o r t h r e e  119 weeks d u r i n g t h i s same p e r i o d . Discussion Population Characteristics.  Changes i n bear numbers  have i n t e r e s t e d people f o r many y e a r s .  S c o t t (194-7) s a i d t h a t  "bear p o p u l a t i o n s f l u c t u a t e as do those o f o t h e r game," and Schorger  (194-9) c i t e d a number o f a l l e g e d b l a c k bear  irrup-  t i o n s i n the e a r l y p a r t of the n i n e t e e n t h c e n t u r y i n the upper M i s s i s s i p p i d r a i n a g e .  He concluded they were  emigra-  t i o n s t h a t r e s u l t e d from the c o i n c i d e n c e o f a c o r n f a i l u r e a h i g h bear p o p u l a t i o n .  T r o y e r and Hensel  and  (1954-) found t h a t  Kodiak bear p o p u l a t i o n d e n s i t y i n A l a s k a changed from y e a r to y e a r and t h a t numbers were h i g h e s t wherever f o o d was Lawrence ( i n B l a c k , 1958) 0.25  abundant.  r e p o r t e d a d e n s i t y of one bear  per  square m i l e s as measured i n a bear removal p r o j e c t i n  Washington.  T h i s f i g u r e was  no doubt augmented, however, by  movement of s u b - a d u l t b e a r s i n t o the a r e a as r e s i d e n t b e a r s were k i l l e d .  U s i n g marked-unmarked r a t i o s o f b e a r s k i l l e d  by  h u n t e r s , E r i c k s o n and P e t r i d e s (1964) c a l c u l a t e d the p o p u l a t i o n d e n s i t y a t one bear p e r 3.4  square m i l e s of bear range i n  Michigan. D e n s i t y o f 1.0 p e r 0.8  square m i l e i n 1961  that i n Michigan. another  b e a r s p e r square m i l e i n I960 and  one  on B i g Creek i s h i g h compared w i t h  Comparisons of numbers from one a r e a to  are incomplete, however, u n l e s s o t h e r components of  the environment such as topography and timber type are a l s o compared c l o s e l y .  For example, the 1960-1961 d e n s i t y f o r B i g  120 Creek does not take i n t o account t h a t a s i g n i f i c a n t , but  un-  measured p a r t of the 80 square m i l e study a r e a i s seldom  used  by the b e a r s , as i t i s e i t h e r o u t s i d e the permanent bear  range  or i n a stage o f p l a n t s u c c e s s i o n not used by the b e a r s . E s t i m a t e s of bear d e n s i t y from o t h e r s t u d i e s may  include  larger  unused a r e a s of t h i s k i n d . The bear d e n s i t y on B i g Creek d e c l i n e d to a p p r o x i m a t e l y one p e r two  square m i l e s through 1966.  The r a t i o of a d u l t  to  young animals on B i g Creek those y e a r s a l s o i n d i c a t e s the popul a t i o n had d e c l i n e d .  Furthermore,  the i n c r e a s e d c l e a r - c u t  l o g g i n g i n the a r e a and the poor b e r r y crops from 1961 a l l l e a d one t o expect such a d e c l i n e .  to  Density declined  1963 faster  t h a n expected, however, and u n l e s s c l e a r - c u t l o g g i n g a f f e c t s b e a r s i n some way  o t h e r t h a n t h r o u g h the amount of h a b i t a t  o t h e r causes f o r the d e c l i n e must be i n v o l v e d . a v o i d e d the a r e a i n which I was  working  became a d d i c t e d t o the t r a p s i t e s .  lost,  C e r t a i n bears  j u s t as c e r t a i n o f them  This could i n f l a t e  the  d e n s i t y e s t i m a t e s based on c a p t u r e s i f o t h e r b e a r s moved i n , or d e f l a t e the e s t i m a t e s i f they remained a v o i d e d the t r a p s i t e a r e a .  on t h e i r home ranges but  I do n o t c o n s i d e r t h i s an important  v a r i a b l e i n t h i s study, however.  There must be  additional  causes f o r the changes i n bear d e n s i t y , and these causes  will  be d i s c u s s e d i n t h e s e c t i o n on p o p u l a t i o n r e g u l a t i o n (p. 124). E r i c k s o n and P e t r i d e s (1964) found t h a t a M i c h i g a n s e r i e s o f 158 b l a c k b e a r s was  composed of 46 p e r c e n t cubs and  y e a r l i n g s , and S t i c k l e y (1961) l i s t e d 31 p e r cent of 94 b l a c k bears i n V i r g i n i a i n the same group.  T r o y e r and Hensel  (1964)  121 reported fied and  that  o f 163 K o d i a k  on Kodiak  Island  yearlings age  (Ursus m i d d e n d o r f f i )  classi-  i n A l a s k a , 48 p e r c e n t were i n t h e c u b  1-1/2 y e a r a g e g r o u p s ,  o f brown b e a r s  bears  and t h e y a l s o  reported that  o n t h e A l a s k a n P e n i n s u l a showed t h a t  made up 4 3 p e r c e n t o f t h e p o p u l a t i o n .  o f cubs and y e a r l i n g s  i n the B i g Creek  c u b s and  The p e r c e n t -  p o p u l a t i o n compares  c l o s e l y with the black bear p o p u l a t i o n s t r u c t u r e but i s c o n s i d e r a b l y lower  a survey  than the percentage  i n Virginia,  of that  group  i n the Michigan population. Some b i a s since  those based  can be expected  on c a p t u r e d a t a a r e b i a s e d a g a i n s t  w i t h cubs.  The c u b s r e s t r i c t  during part  of t h e f i r s t  as prone tions  to capture.  t h e movements  a r e more  y e a r , and t h e females  a t a minimum  thus  Conversely, estimates based  easily  seen than s i n g l e  i n this  females  of the females  alone a r e s u b j e c t t o chance d i s t o r t i o n  groups kept  i n any o f t h e e s t i m a t e s ,  on observa-  since  animals.  a r e not  family B i a s was  study by trapping i n t e n s i v e l y  over  a long period. M o s t o f t h e 47 b e a r s k i l l e d which agrees w i t h the r e s u l t s showing t h a t h u n t e r s u s u a l l y tion  structure  therefore  less  based  reliable.  hunted  more  plains  the l a r g e r  populations. that  solely  than  those  o n t h e a r e a were  o f Troyer and Hensel select  larger  on b e a r s k i l l e d  adults,  (1964)  animals.  Popula-  by hunters i s  The A l a s k a n a n d M i c h i g a n b e a r s a r e  on B i g Creek,  cub and y e a r l i n g  and t h i s p r o b a b l y ex-  group  observed  i n those  The V i r g i n i a p o p u l a t i o n , w h i c h i s s i m i l a r t o  o f B i g Creek  i n structure,  i s a l s o hunted  extensively,  122 however, s i n c e S t i c k l e y  (1961) r e p o r t s t h a t 33 per cent of the  b e a r s he tagged were shot the same f a l l .  Y e a r l i n g s and  sub-  a d u l t s a r e s m a l l e r on B i g Creek than they are on o t h e r areas and are seldom s h o t . kill are  Perhaps  V i r g i n i a h u n t e r s , by u s i n g dogs,  g r e a t e r numbers of the younger animals, even though small.  The  average weight  males i s low (157 sub-adults i n t h i s  that S t i c k l e y  they  reports f o r adult  pounds), which i n d i c a t e s he i n c l u d e d many group.  Average weights of a d u l t females r e p o r t e d from o t h e r areas were 119 in  Virginia  in  New  pounds i n V i r g i n i a  (Stickley,  (Stickley,  1957), 189 pounds i n F l o r i d a , 183 pounds  Hampshire, and 200 pounds i n New  None of t h e s e weights was the f i r s t  I 9 6 0 ) , 149 pounds  York  (Harlow,  1961:488).  c l a s s i f i e d by season, but, except f o r  s e t o f d a t a from V i r g i n i a , they were p r o b a b l y m o s t l y  f a l l weights.  The a d u l t female b e a r s on B i g Creek appear to  be l i g h t e r than females from most o t h e r a r e a s . A d u l t male weights r e p o r t e d elsewhere  are a l s o h e a v i e r  than those on B i g Creek.  Stickley  a d u l t males a v e r a g i n g 157  pounds i n V i r g i n i a , and i n an e a r l i e r  paper  (1957) he l i s t s  ( I 9 6 0 ) , however, r e p o r t s  375 males as a v e r a g i n g 175 pounds.  These  f i g u r e s a g a i n must i n c l u d e c o n s i d e r a b l e numbers of s u b - a d u l t s , as he a l s o r e p o r t s males t h a t weigh as h i g h as 475 pounds. Harlow (1961:448) r e p o r t s average a d u l t male weights i n F l o r i d a o f 304 pounds, i n New New  York 324 pounds.  Hampshire 263 pounds, and i n  These are m o s t l y l a t e f a l l  B e r s i n g (1956) r e p o r t s i n d i v i d u a l pounds maximum i n W i s c o n s i n .  weights.  a d u l t males of 400 t o 500  123 The w e i g h t s  r e p o r t e d f o r c u b s i n most o t h e r  overlapped w i t h the weights from  B i g Creek.  t o 90  and  2-1/2  year  olds  (1954) r e p o r t e d t h e w e i g h t o f c u b s i n  Matson  November a t 70  of yearlings  studies  p o u n d s i n P e n n s y l v a n i a , and  Knudsen  (1961) l i s t e d c u b w e i g h t s i n t h e f a l l a t 95 p o u n d s i n W i s c o n s i n . Beatty  ( i n Schorger,  Park,  California,  w e i g h e d 120 garbage.  New  York,  Bersing  year o l d animals adult  weights  of t h i s  months.  five  yearling  i n Saskatchewan. p h a s e w e i g h e d 25.0,  other studies  He  found 27.7,  Sub-adult bears  eastern North America.  that and  Hausch older that  that  access  pounds i n  to  subthose  (1963)  of the  brown  pounds. s t u d y a r e a and  than bears be  1-1/2  only  r e p o r t e d by M i l l e r  on t h e B i g Creek  I t may  The  Saskatchewan  of the  significant  that  of food potential Food c a n be  ( s e e A p p e n d i x 2). be  to  yearling  in  same age  important  a r e a s compared i n this  the  Alterna-  s m a l l e r as a r e s u l t  i n these  in  the brown  a major p o r t i o n o f the p o p u l a t i o n i n b o t h  a r e a and  eastern areas.  a s 74  three yearlings  28.5  h o w e v e r , t h e b e a r s may  difference  females  t h a t were s i m i l a r  weights  Saskatchewan are s m a l l e r , then,  tively,  Yosemite  a male cub  a n i m a l s had  pounds i n W i s c o n s i n .  s t u d y were y e a r l i n g  B i g Creek  in  (1956) r e p o r t e d t h e w e i g h t o f two  a s 102  from  p h a s e makes up  Both  cub  (1958) g a v e t h e a v e r a g e w e i g h t o f f i v e  p o u n d s and  and  r e p o r t e d a female  t h a t w e i g h e d 80 p o u n d s and  p o u n d s a t 10  Black  m a l e s a s 65  1949)  regard,  of  a  with since  (1961) f o u n d t h a t c a p t i v e b e a r s a r e p h y s i o l o g i c a l l y than wild  bears, that  t h e y become l a r g e r  t h e y make more r a p i d  adults.  This w i l l  growth,  be d i s c u s s e d  and  124 f u r t h e r on page 131. D u r i n g the summer and autumn b e a r s on B i g Creek g a i n e d i n weight r a p i d l y i n a l l types of h a b i t a t .  Cowan e t a l . (1957)  found an autumn change i n the r a t e of g a i n f o r a c a p t i v e b e a r , w i t h a r a t e as h i g h as 1.1 study, but as low as 0.06  pounds p e r day a t the s t a r t of the p e r day l a t e r i n the f a l l .  They sug-  g e s t t h i s i n d i c a t e s a s l o w i n g of the m e t a b o l i c p r o c e s s e s , even i n penned b e a r s , as the denning p e r i o d approaches. Big to  Creek b e a r s do not r e a c h the n u t r i t i o n a l l e v e l slow the m e t a b o l i c p r o c e s s e s b e f o r e denning  Apparently necessary  i n the  fall,  but t h e y are l e s s a c t i v e d u r i n g bad weather ( u n u s u a l l y wet c o n d i t i o n s e i t h e r from snow or r a i n ) , and the r a t e of g a i n thereby sometimes be slowed i n the l a t e f a l l .  may  Most B i g Creek  b e a r s f e d u n t i l severe weather f o r c e d them to den, and a t l e a s t one a d u l t male c o n t i n u e d to g a i n r a p i d l y u n t i l November i n I960. Two had weights weights  The weather was  unusually mild that  normal f o r l a t e autumn cubs, which suggests  are m a i n t a i n e d w e l l i n t o the w i n t e r .  weight  fall.  y e a r l i n g s c a p t u r e d i n February near the s t u d y a r e a  l o s s through the w i n t e r months.  r e p o r t e d a c o n s t a n t weight  examination  E r i c k s o n (1961:300)  l o s s d u r i n g w i n t e r i n penned b e a r s  and s a i d t h a t , l i k e woodchucks (Marmota s p p . ) , t h e y l o s e 20 per c e n t of t h e i r  about  weight.  Population Regulation. of  that  I do not have  a s i g n i f i c a n t number of o b s e r v a t i o n s t o p e r m i t an of  early  The topography  and the c l i m a t e  the B i g Creek s t u d y a r e a c r e a t e good bear h a b i t a t and  doubt s e t u l t i m a t e l i m i t s to the numbers of animals t h a t  no can  125 l i v e  there,  neither  more  k i l l e d part  but  those  the  seen per  were  surplus  drainages  the  not  at  female  hunted  lower  to  also  been  i n previous  reproductive  success  e s p e c i a l l y  since  production  a l l 34  study  were  area  d i r e c t l y are  not  15),  (Table  adult  to  conclusive  external  area  and  survival  from  year  to  Dispersal involved any  mainly  stable  of  number  since  of  there  Surrounding  study on  Huckleberries  young,  at  of  i n  any  were  data  c o r r e l a t e of  or  supply i n  other  i t does  v a r i a t i o n s  unusually  same  to  and to  on  the  therefore  be  C o r r e l a t i o n s causes  seem i n  had  huckleberry  observed would  that  well,  low  bears.  and  the  way  1959,  young  r e l a t e d  bears  since  area  i s  control  of  i n  p r i o r  however,  causes  area  s e v e r a l years  captured Food  f o r  the  s u r v i v a l  f o l l o w i n g years  evidence,  search  the  the  these  population  to  l o s s .  i n  with  reduced  density,  on  and  i f food  cubs.  Nonetheless,  the  bears  accounts  compared  present  f o r  females  involved.  rates  Range  the  be  f o r  high  years.  i n bears,  without  r e l a t e d  were  and  during  f o r  of  are  l i t t l e .  reproduction  Whitefish  1963  numbers  number  hunters  this  sub-adults  that  1959  counter  very  indicates  during  to  the  f o r  time  the  1961  why  The  by  or  of  i n  Creek  not  l a r g e  abundant  time.  but  r a t e s  high  completely  l a t e r ,  Reproductive number  Big  during  sub-adults  were  given  on  cubs or  e x p l a i n  any  1963  to  fewer  adult  do  less  e a r l i e r  cubs  and  nor  I960  from  f o r  they  might  appropriate  reproductive  adults  are  on  the  year. of  the  sub-adults males.  p o p u l a t i o n  can  from  the  D i s p e r s a l of be  expected,  area young  but  was  common  animals  d i s p e r s a l  and  from  becomes  126  far  more l i k e l y  this  Flathead  the  implication i s that  Valley,  an  range o u t s i d e  the  part  statement  w i t h the forced  while  the  species  it  Big  population  the  dispersing  i n extensively  area  not  are  sub-adults  good b e a r  t h e y w e r e somehow f o r c e d  to  or  others  could  search  for  These r e s u l t s agree  areas of  serai  in  animals  vegetation,  climax f o r e s t to which  the  D i s p e r s a l of young males i s a permanent  Creek p o p u l a t i o n  s i n c e much o f  probably d i e from other  not  of  habitat,  (1963) t h a t y o u n g  of Margelef  r e m a i n i n the  terri-  farmed areas  considered  normal b e a r h a b i t a t .  i s adapted. the  the  the  movement  i n t o a r e a s o f p o o r b e a r h a b i t a t where some b e a r s a r e  and I  of  into marginal habitat adults  d r a i n on is  Two  s t u d y were r e c a p t u r e d  the  are  members o f  ( E r r i n g t o n , 1956).  torial in  i f the  determine i f t h i s  reasons  at  dispersal rate  changes under d i f f e r e n t l e v e l s of  shot  a faster rate. i s constant  density  or with  or i f  food  shortages. The population c u b s and  causes of  r e g u l a t i o n remain obscure, but  adults  were so  density  changes.  rapidly  disappeared  population trol  of  rate,  n a t u r a l m o r t a l i t y and  (41  the  other  low  they can  A f t e r 1-1/2  per  from the cent  on  be  The  than that  caused by  and  live  study  shows some b e a r s do  the  a n n u a l 14.0  per  cent  20  the  i s quite - 30 that  adult  for  i n annual  stable  Once b e a r s become a d u l t s , hunting,  in  however, b e a r s  habitat.  to  E v e n some o f  disregarded  adult  Big Creek) i s thereby l e f t  z o o s b e a r s h a v e b e e n known t o l i v e this  role  mortality rates  y e a r s o f age, population.  their  i n con-  death  low.  In  years of long  age,  i n the  mortality  wild.  measured  127 was no d o u b t c a u s e d  by poaching  a c t u a l n a t u r a l death five  rate f o r adults i s probably  years  o f age and t h e 14.0 p e r c e n t  measured f o r a d u l t s . populations, follicle deaths  maturation  of animals  deserve  tially, year;  additional  with  differences  sexually  years.  season  and p h y s i c a l l y . 5-1/2  -  nutritionally  and y e a r l y The l a s t  than w i l d bears. have l i t t e r s  50 p e r c e n t  Poten-  every  other  skipped  two a n d  of the adult  females  Although  reduced  the q u a l i t y  of the  a high population density, the  causes  years  animals  p r e n a t a l and e a r l i e r  bears  t o m a t u r e more s l o w l y  o f age.  have  This short  especially  shown t h a t p o o r  to bears,  which  (1961) f o r p e n n e d b e a r s .  season  i n certain  reproductive failure.  c o u l d be extended  c o n c l u s i o n s o f Rausch  mature  b u t some f o r c e d r a s t i c a l l y  the adults n u t r i t i o n a l l y ,  the assumption  two  Females a r e n o t s u c c e s s f u l i n r e p r o -  7-1/2  S t u d i e s on o t h e r  affect  data, the  bears  of t h i s p o t e n t i a l .  growing  even r e s t r i c t s  i n size,  on B i g Creek d i d , b u t o t h e r s  Theoretically,  duction u n t i l  Consumption o f  comment.  h a b i t a t on B i g Creek a l l o w s annual  group.  s u p p l y may a l l b e i n v o l v e d .  good n u t r i t i o n ,  realization  to  i n natural  ( 1 9 6 1 ) h a s shown t h a t p e n n e d b l a c k b e a r s  some b e a r s  short  fluctuations  i n p l a n t s (see Appendix 3),  s h o u l d have young each y e a r ,  can  1/2  as'changes i n the r a t e s of  and p h y s i c a l l y much s o o n e r  three years.  bear  between t h e  annual m o r t a l i t y  i n the o l d e r sub-adult  i n food  The  numbers), p r e n a t a l m o r t a l i t y , o r  controlled  Rausch sexually  (total  substances  genetically  differences  Any l a r g e a n n u a l  t h e r e f o r e , must o c c u r  hormone-like  the  hunters.  p e r c e n t n a t u r a l m o r t a l i t y r a t e f o r t h e young from  1-1/2  or  or uncooperative  nutrition With  my  supports  Part of  128  this  restriction  female  t h r o u g h the  at high and  i n the  food  supply  can  act  nutrition  of the  young.  e l e v a t i o n s s o m e t i m e s s u c k l e up  this  stimulus  may  be  inhibiting  s e c o n d a r i l y on Smaller  t o 16  the  yearlings  months o f  e s t r u s f o r two  age,  consecutive  years. Mortality annually adults the  i n response  are  i n poor  energy l o s t  increased and  and  The the  June  drugged.  Erickson their  t h i n and  to  This  this  weak t h e y  i n the  This  and  limiting  the  As  of  of  late April, during  weight  years  of  d i d not  rapidly. age  vulnerable factors,  access  in  May be  to " c l i m a t i c  any  of  which  under  to garbage  weight  May, this  need to  or  rapidly.  t h a t penned b e a r s  regained  d e n s i t y , though l e s s  are  study  likely  d i f f e r e n c e s i n behaviour was  begun w i t h  largely  p r o b l e m u n d e r t a k e n was  f o r c e s were.  because  sub-  spring.  t h a t p o p u l a t i o n r e g u l a t i o n was tors,  a result  i n weight i s not  t h a t had  found  annually,  composition.  must be  loss  Other f o r c e s t h a t l i m i t affect populations  3-1/2  same p e r i o d g a i n e d  (1961:200), too,  lost  decimating  c o n t r o l since bears  weight r a p i d l y  genetic  feed during  change Younger  i s poor f o r bears  2-1/2  a number o f o t h e r  were f e d d u r i n g  s p r i n g as  i n particular  some b e a r s  change a n n u a l l y .  endocrine  they  apparently  sub-adults  supply.  d e n n i n g p e r i o d and  In t h a t c o n d i t i o n they  c h a n g e s and could  d u r i n g the  t h a t were so  apparently  changes i n f o o d  condition in late  food  I have handled and  to  e n e r g y demands as  June.  time,  rates f o r sub-adults  through  the  and  assumption  extrinsic  t o d e t e r m i n e what  shown i n t h e  to  fac-  those  s e c t i o n s on m o r t a l i t y  129 and  b e h a v i o u r  i n  and  i n t r i n s i c  c a u s e s  b e a r  p o p u l a t i o n  causes f r o m  t h o s e  i n  appear  f o r c e s ;  p o o r  a n t a g o n i s m , a n t a g o n i s m some  t o  f o r  b e a r s  p r o b a b l y  o t h e r  i s  These  C r e e k  e a s t e r n not  an  and  s i z e  was  A l s o  c o r p o r a  and  t h e  i f  c o n s t a n t l u t e a  Washington  l i t t e r  s i z e s  N e l l o r  (1964)  are  p e r i o d s .  The  seem  i n  the  q u i t e  of  of  e x t r i n s i c  up  d i s p e r s a l  of  Creek  major  seem  and  These  i n t r i n s i c  f o r c e ,  and  male  f o r c e .  groups,  young,  c e n t r e d  group.  i n t r i n s i c  f a m i l y  B i g  p o p u l a t i o n  change  e x t r i n s i c  e x t r i n s i c  d i f f e r e n t  s u b - a d u l t  i m p o r t a n t  have  Male  r e s u l t s  s e t t i n g  i n  i n  the  and  mature  were f o r  the  West,  s i n c e  b e a r s  l o w e r  average  l i t t e r  t h e  p o p u l a t i o n  k i l l e d , s t a t e  f o l l i c l e same  w i t h  as  f r o m  c o u n t s the  b l a c k t h o s e  nor  s i n c e  and  b e a r s  by  B i g  on  t h a n s i z e  w o u l d  t h e  i s the  l i t t e r  y e a r  f r o m  l i t t e r  of  p o p u -  e v o l u t i o n a r y  l i t t e r s  A l a s k a n  comparable  l o n g - t e r m  s m a l l e r  were  but  b e h a v i o u r a l  have  u n e x p l o i t e d b e a r s  the  be  d e n s i t y ,  and  m a i n t a i n i n g  of  Montana t h i s  b e a r  r e p r o d u c t i v e  f o r e s t  t h r o u g h o u t  r e p o r t e d were  an  more  b e a r s  d e t e r m i n i n g  c h a r a c t e r i s t i c s may  s p r u c e  o f  i n  unique  A p p a r e n t l y  i n d i c a t i o n change  l o n g  p o p u l a t i o n  b r e a k  a l s o  t h r o u g h o u t  b e a r s .  average  most  f o r c e s  Creek  l a t i o n  B i g  the  p r i m a r y  i m p o r t a n t  t h a t  to  the  b o t h  r e g u l a t i n g  r e g u l a t i o n  l o s s  h e l p s  and  c h a r a c t e r i s t i c s  a d a p t a t i o n s  of  t h a t  i n  f l u c t u a t i o n s  and  the  appears  c o n t r o l s .  B i g  l e v e l s .  over  c o m b i n a t i o n  a p p a r e n t l y  on  t o g e t h e r  c a u s e s  a  now  l o n g - t e r m  n u t r i t i o n ,  H a b i t a t the  be  i t  and  f a i l u r e  c a n n i b a l i s m ,  stage  i n  a n n u a l  r e p r o d u c t i v e  causes  work  annual  i n v o l v e d The  p a p e r ,  a n n u a l l y  i n v o l v e d  d e n s i t y . on  t h i s  to  y e a r .  Montana  c o u n t s ,  and  E r i c k s o n C r e e k  b e a r s  and  130 rather  than  with  season  might  those  also  be  p o s s i b l y  the  measured  adequately  contact  with  large  home  case,  and  stress the of  pods  of  e s p e c i a l l y Tanner,  the  bears  allows  data  are  exclude they  are  this  has  not  the  area,  but  been  by  dispersed  have  i n  i s  are  i n c r e a s i n g and  or  the  opposed  crowded.  on  this  shown  increases  adversely  (Cheatum  into  reproduction  this  adults  come  developed  (1959)  but  density  must  bears  more  i n s t a r s  or  g r i z z l y  bears.  about  to  share  a  have  minimum  functions  to  i n number  by I t  an i s  a f f e c t s m o r t a l i t y  rates, 1950;  Severinghaus,  two a  bears  even  the  years, s o c i a l  range  r e g u l a t e  bears  while  they  maintaining Creek.  a  This  i n  an  t o l e r a t e  do  some-  s i g n i f i c a n t l y ,  which form  large  generation  groups  population  r e s i d e n t  form  more  order  while  not  several  but,  bears  B i g  do  Family  but  thereby on  Creek  of  a l .  animals  area  density  et  conditions black  f o r  non-resident  population  i n  breeding  1965).  to  complete,  i s  adults,  high  given  f a m i l i a r ,  longer  than  terms  l a r v a l  when  a  s t i l l not  common i n t a c t  i n  i n  o f f s p r i n g  herbivorous  them  r i a l i t y  the  n a t u r a l  remain  mean  populations  Under  groups  times  that  B i g  behaviour  of  l a y i n g  P e r r i n s ,  family  season  often  Albrecht  1966;  l i k e  A  bears  l i k e  more  ensuing  avian  among  groups  f a r  might  h e l d  and  area  S o c i a l  by  egg  of  breeding  an  crowding  l a i d  commonly  mammalian  i n  unmeasured.  i n h i b i t i o n also  the  other  this  that  bears.  elsewhere.  ranges.  l o c u s t egg  each  Eastern  adaptation  of  l i v i n g  what  i s  an  l e n g t h  Bears  of  apparently  of  t e r r i t o -  density.  My  area  tend  to  bears  with  whom  c o n t i n u a l l y  a  higher  f a m i l i a r i t y  stems  at  131 l e a s t  i n part  extend  to  from  adults  o f  Contrary  evidence  dumps  o r  salmon  could  be  explained  ance.  e a r l i e r  f a m i l y  t h e same  of bears  streams by  Comparative  sex, a t l e a s t  moving  through  learned  data  r e l a t i o n s h i p s ,  from  long  among  behaviour  o f  o r  areas  t o  garbage  strange  c u l t u r a l  could  even  females.  distances  the ranges  other  a n d may  bears i n h e r i t -  c l a r i f y  t h i s  point. I f , the  colour  evidence  a s my  of bears  that  dynamics  t i o n  o f the brown  continental  the by the  a  brown almost  America, i n the  phase  the central  of  i n North o f  black  that  area.  America.  phases  Rocky  eastern  the brown  be  value  The  Mountain along  and  coast  d i s t r i b u -  bears  f a m i l y  groups  occurrence  of  area,  surrounded coast,  southeastern  f o r gene areas  i n  North  i s somehow  opportunity  popula-  of black  the west  phenotype  and Northwest  and  p e c u l i a r  w i t h i n high  i n  f u r t h e r  f o r the  phases  r e l a t i v e l y  ample  may  accounts  populations  The  this  the colour  The  i s survival  i n the n u t r i t i o n  the various  cause.  Minnesota-Manitoba  out  favoured  flow  probably  i n r u l e s  i s o l a t i o n . The  black  bears  graphical bears, and  phase  and throughout  i n d i c a t e s  2),  thereby  i n the central  e n t i r e l y  A r c t i c ,  and  d i s t r i b u t i o n  genetic  there  i s involved  o f bears,  the occurrence  denotes  i n d i c a t e ,  (see Appendix  climate  t i o n  and  data  concluding a r e t h a t  other  because  conditions,  b u t because  i m p l i c a t i o n s  of  shortcomings,  o f my  o f v a r i e d  B i g Creek c l i m a t i c  population  vegetational  i s e x c e l l e n t extremes,  i t i s an h o s t i l e  high  and  h a b i t a t bear  studies  on  topo-  f o r a d u l t  density,  environment f o r  132 sub-adults. of  Annual  sub-adults  Though  the  density Big  cause  h a b i t a t ,  higher  Creek  bears  that  reduce  with  n u t r i t i o n ,  this,  the  because care  of  from  apparently  changes  the  than do  the their  changes  and  some  have  size  s u r v i v a l  i n  to  hierarchy  i n  b a s i c a l l y  t e r r i t o r i a l  i n  frequency  of  l i t t e r f o r  the  areas,  North and  of  longer  allowing  periods.  species.  a  allow  of  greater  areas,  These,  are the  along  Countering increased young  This a  a  adaptations  l e v e l s .  because  s u r v i v a l  density.  genetic  young  establishment  the  American  l i t t e r s .  i n d i v i d u a l and  i n  behaviour,  population  sizes  and  population  degree  behavioural  r a t e s  rates  eastern  long-term  mothers  l o c a l  to  and  small  extends  b i r t h  annual  those  set  i n  receive  care  s t r i c t density  s o c i a l i n  a  PART  CONCLUDING  III  REMARKS  133  CHAPTER NINE CONCLUSIONS AND SUMMARY 1.  The m u l t i t u d e o f d i f f e r e n t exposures  throughout  and s l o p e s  B i g Creek p r o v i d e s a patchwork o f h a b i t a t  that  ranges from d e s e r t - l i k e c o n d i t i o n s t o permanent snow f i e l d s . There were two major types o f bear h a b i t a t on B i g  Creek;  areas t h a t were h e a v i l y f o r e s t e d and lower i n e l e v a t i o n , and areas t h a t were t h i n l y f o r e s t e d , h i g h i n e l e v a t i o n , and f r e e of  snow o n l y d u r i n g summer and f a l l .  Bears had permanent  home ranges i n the f o r e s t e d lower type, and most b e a r s d i d not move i n t o o t h e r p o r t i o n s o f t h i s type under any c i r c u m s t a n c e s , except d i s p e r s a l . support b e a r s permanently,  The s e a s o n a l l y used areas d i d not b u t when f o o d was abundant t h e r e ,  b e a r s from a d j a c e n t areas moved t o i t f r e e l y . 2.  The P i c e a - A b i e s / P a c h i s t i m a a s s o c i a t i o n was an impor-  t a n t component o f bear h a b i t a t d u r i n g a l l seasons.  Other  types o f h a b i t a t were important s e a s o n a l l y : d r y meadow areas in  e a r l y s p r i n g , s n o w s l i d e s and stream "bottoms i n e a r l y and  mid-summer, and t h e P i c e a - A b i e s / M e n z i e s i a and P i c e a - A b i e s / Xerophylum a s s o c i a t i o n s i n the f a l l .  C l e a r - c u t l o g g e d areas  were a v o i d e d . 3.  Home ranges o f B i g Creek b e a r s were v e r y s m a l l compared  w i t h those elsewhere. for  G r e a t e s t movements averaged  a d u l t females and 3.9 f o r a d u l t males.  1.6 m i l e s  Home range  estimates  134 based  on m e a s u r e d movements were c o n s i d e r e d b e s t f o r B i g  bears because of  of the l i n e a r i t y  e l e v a t i o n on  the  of the h a b i t a t  study area.  with adult  female  a d u l t m a l e i n c r e a s e d as he m a l e was 4.  but  ranges.  extremes  of the  sub-adult ranges The  ranges  matured, perhaps  usually  o f one  because  same  sub-  an  adjacent  killed. There  were no  congregate  on  was  i n their  shared  their  the  Ranges o f a d u l t s  sex o v e r l a p p e d o n l y o c c a s i o n a l l y , coincided  and  Creek  slides  home r a n g e s  "migrations" of bears, but bears d i d o r d r y meadow a r e a s when s u c h a n  ranges.  Bears  t o t h e f o o d on  area  a l s o moved r e a d i l y  seeded  strips  within  along logging  roads. 5.  Bears  longer is  than bears  s e v e r e , and  state. this and  on B i g Creek  a l l bears  They seem t o be  most o f  building  den  the b e a r s .  den  and  Winter  adapted,  to that  behaviour  comes e a r l y  active  like  quite  Dispersal  o f s u b - a d u l t s was  nutritional  such  as  during this  an  extended  a r o u s e d by  are o f t e n  and  even  curling  of true h i b e r n a t o r s , but  observed  They are e a s i l y  months  however, t o s u r v i v e  Some o f t h e i r b e h a v i o u r  that winter i s rather  for  o f 1-1/2  r e g a r d l e s s of t h e i r  well  i s similar  the denning  indicates  average  r e p o r t e d elsewhere.  longer period. den  denned an  i n the den  any  study  waiting period  approach  when u n d e r  to  the  obser-  vation. 6.  mostly males. persal  from  the  Territoriality  No  estimate of the  a r e a was imposed by  involved  t r u e magnitude of t h i s  made, b u t the  common and  adult  13  dis-  movements were r e c o r d e d .  m a l e s seemed t o be  involved,  135 but  dispersal  7.  The  was  r a t e s may  sex r a t i o  of the  e v e n , a s were t h e  groups. fied  sub-adults  total  sex r a t i o s  1-1/2  Bears  increase with  o r 2-1/2  food  bears  captured  f o r the  years  shortages.  cub  o f age  deviated significantly  and  and  from  on  adult  other  an  F e m a l e s on  B i g C r e e k were i n e s t r u s f r o m  e a r l y August, w i t h female  pairs  females  J u n e 27,  and on  June  9. in  from  mature f o l l i c l e s  and  from  bears  e s t r u s on  female  The  litters  average  o f M o n t a n a i t was  and  mature f o l l i c l e s  Washington b e a r s .  2.2  and  eastern North 11.  some b e a r s two  cent  o f 96  1964  almost  on  size  1.6. was  The 1.8  are  low  corpora lutea  l a t e May  to  Malefive 9  corpora  lutea  years  o f age  on  were  those  observed  average  of  1.7  on  1.9  age. and  for  o f 2.4  lutea  for  B i g Creek  compared w i t h l i t t e r counts  success-  number o f c o r p o r a  f o r B i g C r e e k and sizes  was  years  B i g C r e e k was  observed  averaged  counts  f o r bears  of  in  America.  Potentially,  skipped  area.  between June  t o 7-1/2  6-1/2  Yearling l i t t e r  These averages t o 2.6  none o f  before  litter  all  1.6.  the  July,  Washington had  y o u n g e r t h a n 4-1/2  B i g C r e e k , and  in raising  10.  one  ratio,  14. No  ful  o n l y d u r i n g J u n e and  Washington had  age  unclassi-  a peak from mid-June to m i d - J u l y .  were o b s e r v e d  Creek  even sex  p r o b a b l y b e c a u s e many s u b - a d u l t m a l e s moved t h r o u g h 8.  Big  bears  can have l i t t e r s  every  other  B i g Creek d i d have young t h a t o f t e n , b u t  years  and  two  a d u l t females 50 p e r  skipped  three years.  examined had  c e n t had  litters,  litters. but  from  Only  16  I n 1959 1961  year; some per and  through  136 1963  no marked females had young, a l t h o u g h a few unmarked  females on t h e area d i d have cubs those y e a r s .  Reproductive  r a t e s d e c l i n e d when t h e abundance o f h u c k l e b e r r i e s and  i n c r e a s e d when h u c k l e b e r r y  production  declined,  increased,  but this  may be a mere c o r r e l a t i o n . 12. 1959,  Hunters k i l l e d  t h r e e p e r cent  b u t by 1961 t h e k i l l  animals marked t h a t y e a r . natural population 13-  Little  t o 10 p e r cent o f t h e  Some of the f o r c e s i n v o l v e d i n  c o n t r o l remain obscure, however.  evidence o f the causes o f p r e n a t a l  m o r t a l i t y was found. small  increased  o f the b e a r s tagged i n  Ultimate  or early  causes appear r e l a t e d t o the  s i z e o f the females, consumption of e s t r o g e n - l i k e  sub-  s t a n c e s i n p l a n t s , or g e n e t i c a l l y c o n t r o l l e d b e h a v i o u r . B i o assays showed t h a t cow p a r s n i p , which some b e a r s e a t i n the spring, i s powerfully  anti-estrogenic.  The p o t e n t i a l f o r  d e l a y i n g o r i n h i b i t i n g the m a t u r a t i o n o f f o l l i c l e s i s o b v i o u s . S i m i l a r l y , whitebark p i n e nuts have an e s t r o g e n - l i k e  action  t h a t c o u l d t e r m i n a t e pregnancy i n t h e f a l l . ( A p p e n d i x 3 ) . 14.  Cub and a d u l t m o r t a l i t y r a t e s were low and no n a t u r a l  m o r t a l i t y was observed. from the p o p u l a t i o n ,  Older sub-adults  disappeared r a p i d l y  b u t p a r t o f t h i s l o s s was from d i s p e r s a l .  Annual v a r i a t i o n s i n sub-adult  m o r t a l i t y r a t e s from e x t r i n s i c  f a c t o r s a r e q u i t e p r o b a b l e s i n c e many b e a r s of t h a t age group are i n e x t r e m e l y poor c o n d i t i o n i n l a t e s p r i n g . during 15.  the denning p e r i o d was r e c o r d e d  No m o r t a l i t y  f o r 31 b e a r s .  I n t e r n a l and e x t e r n a l p a r a s i t e s were found i n B i g  Creek b e a r s , b u t o n l y t i c k s were abundant.  No d i s e a s e d  animals  137 were f o u n d .  P r e d a t i o n by a d u l t b l a c k and g r i z z l y b e a r s on  s m a l l b l a c k b e a r s was r e c o r d e d i n B i g G r e e k a n d v i c i n i t y , b u t t h e i n c i d e n c e was l o w . 16.  Climate influences  period  and b y c r e a t i n g  Climate  seems t h u s  17.  Agonistic  developed  annual  indirectly behaviour  involved  18.  are elaborate.  then break  through  up i n l a t e  The f a m i l y g r o u p  t h e breeding season  i n permanent Seasonal  two y e a r s .  21. by  away f r o m  Territorial this  study,  that  the family  group  Some f a m i l y g r o u p s  Some f a m i l y  Males and females  This aids  frightened  y e a r s and  may  females  relationships  associations.  travel  dispersion of  side by side  of the year  bears  o r more.  sensitivity  i n survival,  to danger from since  autumn  they are not  t h e p r o t e c t e d a r e a o f t h e i r den.  behaviour  though  influence  but the r e s t  have a r e d u c e d  through winter.  sometimes  males.  a t h i g h e l e v a t i o n s because  the b r e e d i n g season,  Bears  easily  Females  t h e male d i s r u p t s  k e e p a m u t u a l d i s t a n c e o f 50 y a r d s 20.  benefits  My o b s e r v a t i o n s s u g g e s t  changes i n b e h a v i o u r  bear p o p u l a t i o n s . during  highly  also  e n d u r e 1-1/2  a g g r e s s i o n towards t h e young.  the estrous cycle  19.  period.  usually  June.  endure l o n g e r t h a n normal  result  quality.  i s more  t h e y o u n g a g a i n s t man a n d a g a i n s t a d u l t Family relationships  during  i n food  i n mortality.  i n black bears  c o o p e r a t i o n d u r i n g the denning  defend  skip  fluctuations  t h a n was f o r m e r l y r e c o g n i z e d , a n d f a m i l y b e h a v i o u r a l  relationships from  n u t r i t i o n by extending the denning  i n bears  i s strongly  i t i s masked b y " s o c i a l  indicated  groups"  of bears  138 t h a t t o l e r a t e each o t h e r , but exclude o t h e r b e a r s . evidence  of bears moving l o n g d i s t a n c e s to garbage dumps or  salmon streams might be 22.  Contrary  e x p l a i n e d by l e a r n e d  I n d i v i d u a l v a r i a t i o n i n behaviour  from d o c i l e to v e r y a g g r e s s i v e t y p e s .  behaviour.  i s great, ranging  S u r v i v a l r a t e s may  be  a f f e c t e d by these d i f f e r e n c e s . 23.  The  d e n s i t y e s t i m a t e s of a p p r o x i m a t e l y  one bear  per  square m i l e on the B i g Creek study a r e a were h i g h compared w i t h e s t i m a t e s from elsewhere. d e c l i n e d from I960 to 1966, 1965 24.  and 1966 Cub  The  d e n s i t y on B i g Creek  but r e c o v e r y was  noted  during  as r e p r o d u c t i v e r a t e s i n c r e a s e d .  s u r v i v a l was  h i g h from 1/2  to 1-1/2  y e a r s of  age,  but the young t h e n r a p i d l y d i s a p p e a r from the p o p u l a t i o n through d e a t h and d i s p e r s a l .  A d u l t s are s t a b l e i n the  popula-  t i o n because t h e i r s u r v i v a l r a t e i s h i g h , and they do not p e r s e from the 25.  area.  A d u l t females  from h i g h e l e v a t i o n s on B i g Creek were  l i g h t e r i n weight than those from lower  e l e v a t i o n s , and  i n d i v i d u a l s showed a g r e a t s e a s o n a l change i n weight.  Sub-  a d u l t s on B i g Creek were s m a l l e r t h a n b e a r s of the same elsewhere,  dis-  age  p r o b a b l y because they had poor f o o d f o r a l o n g e r  p e r i o d i n the s p r i n g .  A g e n e t i c cause cannot y e t be  ruled  out, however, s i n c e s m a l l s i z e c o u l d be r e l a t e d to the c o l o u r of bears. 26.  The weights of the s u b - a d u l t s were d i s t i n c t i n t h e i r  range i f c a r e was  taken to compare o n l y the weights of  c a p t u r e d d u r i n g the same month of the  year.  animals  139 27.  During  April  only  just  they  denned t h e y  inclement  maintained  t o e a r l y J u l y most b e a r s l o s t w e i g h t o r their  gained  weight, b u t from mid-July  up t o 1.5  weather probably  pounds p e r day.  until  On B i g C r e e k  slows the r a t e o f g a i n near  time, b u t bears d i d n o t cease f e e d i n g  as has been  denning  reported  elsewhere. 28.  The b r o w n p h a s e makes up o n e - t h i r d o f t h e B i g C r e e k  population,  and brown b e a r s  Rocky Mountain r e g i o n . ically  Colour  Annual  the c e n t r a l  i s no d o u b t c o n t r o l l e d g e n e t -  changes i n p o p u l a t i o n  a d e c l i n e i n average weights  adult  throughout  i n t h e b l a c k b e a r , b u t t h e mechanism r e m a i n s  29. with  a r e found  t o young animals, 1961-1963,  during  increased  logging  1963.  Trapping  lation  density  population  a virtual  of bears;  operations slightly.  are correlated a lower r a t i o o f  absence o f r e p r o d u c t i o n  increased hunting activity,  density  obscure.  pressure  and poor b e r r y  t h r o u g h 1963,  crops  from  may a l s o h a v e c u r t a i l e d The number o f s u b - a d u l t s  1961-  the popui n the  d e c l i n e d a s d e n s i t y d e c l i n e d , b u t t h e number o f  adults d i dnot vary  s i g n i f i c a n t l y during  because  are l o n g - l i v e d , are strongly attached to  their  adult bears  home r a n g e a r e a ,  30.  t h e study,  and have a low annual m o r t a l i t y r a t e .  Long-term c o n t r o l o f p o p u l a t i o n  density  seems  dependent on t h e h a b i t a t o f B i g Creek and on unique ductive  and b e h a v i o u r a l  there.  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S c r i b e r s ' Sons, 127 pp. . . . .  ne-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. O l i v e r and Boyd, L t d . E d i n b u r g h x i + 653 pp.  APPENDIX 1  149  Bear Uo7~Sex 174 56 160 170 163 172 169 170 61 157 31 10 48 51 203 168 49 50 62 162 87 50  M M M M M M F M F M M F F F M F M M M F F M  F i r s t Capture  Second  Date  Date  6-19-64 6-4-60 6-26-64 6-4-64 6-28-64 6-15-64 6-4-64 6-8-65 5-27-63 6-7-65 6-30-60 6-4-60 5-21-60 5-22-60 6-27-65 6-4-64 5-22-60 5-22-60 6-28-61 6-23-65 6-4-65 6-5-65  Table 16.  Weight (lbs.)  13 42 55 38 53 39 52 80 65 72 56 103 52 107 62 67 195 190 173 114 115 263  6-30-64 6-29-60 7-1-64 6-15-64 7-16-64 7-9-64 6-29-64 7-16-65 5-31-63 7-13-65 7-7-60 7-21-60 6-5-60 6-5-60 7-13-65 6-12-64 7-7-60 6-20-60 7-25-61 7-9-65 6-23-65 6-26-65  Capture . Weight (lbs.) 15 40 52 37 66 46 51 91 69 82 56 92 52 98 65 65 187 190 175 120 125 270  Loss  Q  Gain (lbs.) +2 -2 -3 -1 +13 +7 -1 +11 +4 +10 0 -11 0 -9 +3 -2 -8 0 +2 +6 +10 +7  r  No. of Days 11 22 5 11 18 24 25 38 4 36 7 47 13 14 16 8 47 29 27 16 19 21  G a i n or l o s s i n weight f o r 22 b e a r s over v a r i o u s periods during the spring.  150  First Date  Bear Sex No.  17 18 72 69 120 8 18 2 1 25 75 75 77 62  F F F F F M F F F F F F M M  8-7-59 8-7-59 7-20^60 7-19-60 7-13-61 7-25-59 8-7-61 7-21-60 7-14-59 8-11-59 7-13-61 8-4-61 8-4-60 7-10-64  T a b l e 17.  Capture Weight (lbs.)  25 25 18 41 49 40 73 103 155 141 114 148 198 235 '  Second Date  8-25-59 8-22-59 8-20-60 8-4-60 8-7-61 8-26-59 8-18-61 9-12-60 8-26-59 8-27-59 8-4-61 8-7-61 11-6-60 9_4_64-  Capture Weight (lbs.)  42 35 22 44 59 58 80 170 200 152 148 151 288 265  Gain (lbs.)  No. o: Days  18 15 30 14 25 31 11 53 40 16 22 3 94 45  +17 +10 +4 +3 +10 +18 +7 +67 +45 +11 +34 +3 +90 +30  G a i n i n w e i g h t o f 14 b e a r s d u r i n g l a t e and autumn.  summer  Figure  23.  Newhouse 150 s t e e l t r a p , c a n v a s f o r w e i g h i n g b e a r s , and a r e c o v e r i n g black bear.  Figure  24.  Cubby t y p e  trapsite  showing s t e p p i n g  sticks.  F i g u r e 26.  F i g u r e 27.  Snowslide  Open f o r e s t  type.  through a mature s p r u c e - f i r  forest.  Figure  28.  D r y meadow t y p e  Figure  29.  Seeded s t r i p  i n the s p r u c e - f i r  along the B i g Creek  forest.  road.  155  APPENDIX 2 COLOUR PHASE The b l a c k bear i s one of s e v e r a l N o r t h  American  s p e c i e s known f o r t h e e x i s t e n c e o f d i f f e r e n t c o l o u r phases i n the p o p u l a t i o n .  The r e l a t i v e abundance of t h e s e v e r a l  d i f f e r s i n a b r o a d r e g i o n a l p a t t e r n throughout (Cowan, 1938).  phases  the range  N o t h i n g i s known o f the g e n e t i c s o f c o l o u r  phase i n the b l a c k b e a r , b u t the o c c u r r e n c e of the l i g h t brown phase as an abundant element Mountain  throughout t h e C e n t r a l Rocky-  a r e a over a p e r i o d of more than a c e n t u r y suggests a  s e l e c t i v e f o r c e f u n c t i o n i n g t o m a i n t a i n a b a l a n c e d polymorphism. S p e c u l a t i o n on t h e p o s s i b l e g e n e t i c mechanisms i n f o r c e a r e beyond t h e scope o f the p r e s e n t study, but some of my  observa-  t i o n s suggest a p o s s i b l e mechanism whereby the brown phase may e x p e r i e n c e a t l e a s t p e r i o d i c and l o c a l s e l e c t i v e  advantages.  On B i g Creek 32.3 p e r cent o f 158 b e a r s were brown, and 8 . 2 p e r cent o f these were o f the l i g h t brown phase. A l l l i g h t brown b e a r s ( f i v e ) were f e m a l e s .  Of 75 cubs and y e a r l i n g s  examined, 44.0 p e r c e n t were brown, w h i l e 31•2 p e r cent o f 77 a d u l t s were brown.  Females of the b l a c k phase had m o s t l y b l a c k  cubs (80.0 p e r c e n t ) , w h i l e brown females had m o s t l y brown cubs (86.2 p e r c e n t ) ; each had a low i n c i d e n c e o f mixed ( T a b l e s 18 and 1 9 ) .  litters  156  JTemale  L i t t e r s  Colour  No.  Black  29  22  Browm  16  1  Total  45  (23)  Table  18.  The  colour  composition  and  Cubs  Black  of  female  of  and  Y e a r l i n g s  Brown  Mixed  4  3  13  2  (17)  bears  and  (5)  the  colour  l i t t e r s .  Animal  Cubs  of  Black  Brown  Light  Y e a r l i n g s  Black  Mother  Brown  Mother  36 3  Total  9  0  19  (39)  (28)  5 (5)  A l l  Sub-adults  54  20  7  A l l  Adults  53  19  5  (39)  (12)  Total  Table  19.  Brown  ( a l lbears)  Colour phases study area.  (107)  of  bears  captured  on  the  B i g  Creek  157 A r e v i e w o f the l i t e r a t u r e and a survey m a i l e d t o Game Departments showed t h a t the "brown phase i s common i n b l a c k bears from c e n t r a l B r i t i s h Columbia to  Colorado and C a l i f o r n i a ( F i g u r e 3 0 ) .  Mountain  and A l b e r t a  south  The c e n t r a l Rocky  a r e a harbours the g r e a t e s t numbers of brown b e a r s ,  but t h e y a r e abundant i n the S i e r r a Nevadas i n C a l i f o r n i a i n the Cascade Mountains Hamilton, 194-3; E l l i o t ,  i n s o u t h e r n Washington ( B l a c k , 1901;  Cowan, 1938;  R. F. Harlow, and L. E. B r u n n e t t , p e r s o n a l  A. W.  1958;  Erikson,  communication).  The b e a r s i n t h i s a r e a are o f t e n c o n s i d e r e d t o be of the s p e c i e s U. a. cinnamomum. bears l e f t  A r i z o n a and Texas have too  today t o determine  any  and  sub-  few  ratios.  The brown phase seems most common a l o n g a l i n e  running  from c e n t r a l C a l i f o r n i a t o Saskatchewan ( G r i n n e l l e t a l . , Cowan, 1938;  M i l l e r , 1963;  C. E. Kebbe, p e r s o n a l  1937;  communication).  P i e r s o n (1964) r e p o r t e d t h a t of 517 b e a r s t r a p p e d i n western Washington i n 1964, Mt.  31 p e r c e n t of those taken i n the  S t . Helens a r e a were brown, w h i l e those t a k e n on the  Olympic  P e n i n s u l a 100 m i l e s northwest were a l l b l a c k . In  many s p e c i e s c o l o u r i s r e l a t e d t o d i f f e r e n t i a l  p r e d a t i o n or t o s e x u a l b e h a v i o u r . in  some s p e c i e s c o l o u r i s an a d a p t a t i o n to c l i m a t i c  C o l o u r i n b e a r s was of  G l o g e r ' s Rule s t a t e s  i n v e s t i g a t e d t o t e s t whether the  d i f f e r e n t c o l o u r e d animals was  and i f they were r e l a t e d ,  r e l a t e d t o the  i n what way.  that  conditions. survival  environment,  Natural mortality i n  b e a r s seems h i g h e s t i n the s u b - a d u l t group  i n s p r i n g when  they are i n poor p h y s i c a l c o n d i t i o n and are f e e d i n g on the  158.  500  Figure  50.  miles  The d i s t r i b u t i o n o f the. b r o w n p h a s e i n b l a c k bears. D i s t r i b u t i o n o f the s p e c i e s i s b a s e d on A F i e l d G u i d e t o t h e Mammals. W. H. B u r t a n d R. P. G r o s s e n h e i d e r . 1964. Houghton M i f f l i n Co., B o s t o n x x i i i + 284 pp.  159 o p e n d r y meadow a r e a s . if  c o l o u r was  during  this  period,  operating. referring in  related  i n some way  as  bears p r i m a r i l y  the  areas.  mechanism  the observations  l e n g t h of time  spent f e e d i n g  O b s e r v a t i o n s were made  d u r i n g May  and  June.  that  to obtain food  a selective  A c c o r d i n g l y , I have assembled t o c o l o u r p h a s e and  therefore,  to c a p a c i t y  t h e r e c o u l d be  the c h o i c e exposed  276  I t seemed p o s s i b l e ,  The  on  results  were  follows:  No. Time  1:00  A.M.  8 : 0 0 A.M. 5:00 P.M. 10:00 P.M. 8:00 5:00  have an  (8:00 was  110  40  32.3  26.7  126  72  54  32.3  42.8  the  observed  t o 5:00  this  t h e c o l o u r o f 158 brown b e a r s  of being captured.  from  bears and  The  per cent  level  black bears of  d i d not  d u r i n g midday  t h e number o f b r o w n b e a r s (five  captured  number  evenings  the expected, b u t  of  observed  significance  test).  (1933) says b e a r s  s u c h as b l a c k b e c a u s e  Expected  d u r i n g m o r n i n g s and  P.M.)  Chi-square  Hingston  on  on the assumption  higher than expected  using  Actual  150  significantly  A.M.  Brown  Brown  equal p r o b a b i l i t y  brown b e a r s deviate  and  Percentage  Black  E x p e c t e d v a l u e s were b a s e d on B i g Creek  Observed  Total  to and to  A.M. to P.M.  of Bears  c a n be  t h e y have l i t t l e  i s the i m p l i c a t i o n  an o b v i o u s c o l o u r  to f e a r .  t h a t brown phases  Inherent i n  w o u l d be  selected  160  for i s  under  heavy  scanty,  but  g r i z z l y Clark  and  1805  and  t h i s  the  implies  past.  Brown  i n d u s t r i a l  melanism a  of  more A  the  Rule.  what  r a i n  Chapter  phase On  i s  2),  those  early  summer  the  v e g e t a t i o n on  and  completed  p h y s i c a l r i g o u r s  to  a  are  black  bears  i n  1961)  i n  these  sub-adult  winter have  the  sedges,  at  well-known but  and  and  on  most  s i g n i f i c a n t h i l l s i d e s , of  would  be  pro-  b l a c k  since  bears  apparently  scale,  most  bear,  or use  areas  of  the  t i c k  and  are  w i t h  this  bears  i n  By  are i n  spring  mid-June f r u i t e d ,  e s p e c i a l l y extremely  following  i n f e s t a t i o n s . adequate  l i e s  (see  flowered,  year  they  area  Despite  area  areas.  openings which  of  my  to  has  maintenance  Desert.  w i t h i n  "desert"  the  i n part  American  obtaining  grasses,  and  common,  adult  c r i t i c a l  These  heavy  and  now  an  concurs  Great  time  are  open  t h i s  and  Dakota  phenomena  whether  r e g i o n  animals,  bears  hunting.  exposed  d i f f i c u l t y  see  explanation f o r  e f f e c t  the  to  g r i z z l y ,  their  the  that  been  the  continental as  have  bears  g r i z z l y  i n North they  on  Lewis  the  where  harder  t h i s  i t s growth.  apparently forbs,  i n  habitats  c o n d i t i o n of  few  c o n d i t i o n s e x i s t i n g  and  important  bears.  are  alternate  known  f o r e s t  i n  black  black  e s p e c i a l l y  v i s i o n  adult  M i s s o u r i River  predatory  p o s s i b l e  brown  Gloger's w i t h i n  than  p r e d a t i o n  small  i n moths,  is.another matter,  scent  the  reverse  against  both  p r e d a t i o n might  bears  on  on  (Burroughs,  that  the  of  saw  l i t t l e  R i v e r  suggesting  man  e a r l i e r ,  1804  between  t e c t i o n  noted  predators  Columbia  the  I  are  the  i n  as  Information  bears  i n  country  predation.  poor the  They  nutrients  either  lose  or  from barely  161 maintain  their  time they noted  can  weight. feed  earlier,  over a longer food.  By  c o u l d be  e a c h day  during period  feeding  Under t h e s e  s p r i n g b e a r s o f the on  the  longer  brown phase d i d g a i n an black  period  i n the  tically  open a r e a s  i n e a c h 24  s p r i n g , but  significant.  no  I t has  ( G e r s h e n s o n , 194-5) t h a t  o f c o l o u r p h a s e s o f mammals, and found  that  the  absorption  g r e a t l y when t h e y Finches  polymorphic  (1955) s a y s  species  a change i n form o f jurtina) an  that for  i n one  area. genetic  c a n be the  year  a three  feathers  the  nine  week statisspecies  differential  survival  Heppner  (1967)  increased  of white  up  t o 30  (I960) and  p r o p e r t i e s can  through a greater arid  per  Zebra  advantage  cent  cattle  others  seldom be time.  brown phase i n b e a r s ,  i n maintaining  phase to  selective  and  meadow b r o w n b u t t e r f l y  seems p o s s i b l e f r o m my  tion  of  pounds, w h i l e  H a m i l t o n and  the  more t h a n a s h o r t p e r i o d o f  volved  be  when g r a z i n g b y  Sheppard  advantage of the It  the  thereby  (Poephila castanotis). Dowdeswell  in  three  of r a d i a n t s o l a r energy  dyed b l a c k  feed  Seven sub-adults  b e e n shown f o r o t h e r can  I  they  d i f f e r e n c e s were n o t  there  of  w h i c h p r o d u c e more  weight during  the  As  brown phase  hour p e r i o d ,  spring.  average of  phase gained  length  c o u l d become c r i t i c a l .  selected for during  o f the  c o n d i t i o n s , the  the  observations  describes (Maniola discontinued  have p o i n t e d  out  neutral i n their Whatever the  i t n e e d o n l y be that climate  during  sub-adults  s p r i n g and  of  effect  selective slight.  is in-  c e n t r a l S o c k y M o u n t a i n brown  t o l e r a n c e by  conditions  was  in  the  populabrown  e a r l y summer.  It  162  would of  be  l i g h t  i n t e r e s t i n g  to  and  these  heat  by  experiment two  with  colour  the  phases  r e l a t i v e i n  the  tolerance bear.  163  APPENDIX 3 HORMONAL ACTIVITY OP CERTAIN BEAR POODS Many p l a n t s f e d t o domestic l i v e s t o c k c o n t a i n e s t r o g e n i c substances ( K i t t s , I960; B i c k o f f , 1961) and a n t i e s t r o g e n i c substances  ( A d l e r , 1962; Cook and K i t t s ,  1964),  and b o t h compounds a t c e r t a i n times of the y e a r have d e l e t e r i o u s e f f e c t s on t h e r e p r o d u c t i o n o f l a b o r a t o r y  animals.  The compounds a r e r e a d i l y t a k e n i n through t h e d i g e s t i v e system,  and t h e i r presence c a n be e a s i l y d e t e c t e d w i t h  bioassays.  S i n c e b e a r s on B i g Creek a r e almost  exclusively  v e g e t a r i a n s ( T i s c h , 1961) and c o n c e n t r a t e on c e r t a i n p l a n t foods a t each season of the y e a r , I p o s t u l a t e d t h a t some o f t h e s e foods might p l a y a r o l e i n d e t e r m i n i n g bear r e p r o d u c t i v e r a t e s as has been shown t o be the case i n sheep by Bennetts e t a l . (1946).  My h y p o t h e s i s was t h a t  similar  e x t e r n a l hormones c o u l d be p r e s e n t i n p l a n t s eaten by b e a r s and t h a t they might d i s r u p t t h e c r i t i c a l  endocrine b a l a n c e  n e c e s s a r y e i t h e r f o r o v u l a t i o n , i m p l a n t a t i o n , o r maintenance of  pregnancy  before implantation.  can be p r e v e n t e d and pregnancy  Experimentally, ovulation  c a n be t e r m i n a t e d w i t h  i n j e c t i o n s o f s y n t h e t i c hormones (see page 166).  The p e r i o d  d u r i n g which the unimplanted b l a s t o c y s t s a r e c a r r i e d l o o s e i n the u t e r u s has been suggested as a c r i t i c a l p e r i o d f o r  the p i n e marten by Enders and P e a r s o n (1943). was  The assumption  made i n t h i s study t h a t t h i s might a l s o be a v u l n e r a b l e  p e r i o d f o r b e a r s , and b i o a s s a y s were made o f foods  abundant  i n t h e d i e t s o f b e a r s d u r i n g t h e b r e e d i n g season, d u r i n g t h e d e l a y p e r i o d , and near i m p l a n t a t i o n time. S e v e r a l bear f o o d s were c o l l e c t e d , and b i o a s s a y s were made t o determine t h e i r e s t r o g e n i c and a n t i - e s t r o g e n i c activity.  The samples were c o l l e c t e d on t h e s t u d y a r e a a t  the time t h e p l a n t s were b e i n g e a t e n and t h e y were t h e n frozen u n t i l  the b i o a s s a y s c o u l d be made.  The b i o a s s a y s o f  f o r a g e p l a n t s were undertaken on female r a t s u s i n g the t e c h nique d e s c r i b e d by B i e l y and K i t t s Kitts  (1964).  G s t r o v a s k y and  (1963) have shown t h a t s i m i l a r substances a r e r e a d i l y  absorbed through the d i g e s t i v e system o f r a t s and t h e assumption was made t h a t they would be s i m i l a r l y  absorbed  i n bears. Pour bear foods t h a t a r e eaten i n l a r g e  quantities  d u r i n g p e r i o d s t h a t c o u l d be c r i t i c a l were t e s t e d .  Chloro-  form ( a n t i - e s t r o g e n i c ) and e t h e r ( e s t r o g e n i c ) e x t r a c t s from h u c k l e b e r r i e s were h i g h l y t o x i c when i n j e c t e d i n t o mental r a t s ( T a b l e 2 0 ) .  experi-  I n the 1965 experiments a l l r a t s  d i e d w i t h i n a few minutes a f t e r t h e h u c k l e b e r r y i n j e c t i o n s , b u t i n t h e 1966 experiments enough of t h e r a t s l i v e d t o show t h a t the b e r r i e s had no hormone-like a c t i v i t y .  Even  though  attempts had been made to p u r i f y t h e e x t r a c t s , t h e y caused massive hemorrhages and i n f l a m m a t i o n o f t h e v i s c e r a .  Treatment Control  Plant  (saline)  E s t r a d i o l - 1 7 -  F r a c t i o n  .0.  ( N = 6 )  Groups  -Fraction  A  (estrogenic)  Species M.U.W.as B.W.  U.W.  P e r Cent  U.W.  P e r Cent  B.W.  B.W.  U.W.  +  (anti-estroKenic)  M.U.W.as  M.U.W.as B.W.  B  e s t r a d i o l - 1 7 - - f  P e r Cent  M.U.W.as B.W.  U.W.  P e r Cent  B.W.  B.W.  B.W.  Pinus a l b i c a u l i s Whole ± Meat ±  49.7  S.D.  II  n  n  II  n  S.D.  -  S.D.  I I  n It  * **N  ±  = 4  Table  2 0 .  49.9  4 0 . 4  n  8 0 . 8  5 3 . 4  0 . 1 4 8 5 1 . 5  It  0 . 0 8 1 48.8  § 9 . 3  ±0.041  t i  11  48.3  0  .  1  3  5 2 . 0  5  i t  5 3 . 8 * * 4 8 . 9  I t  3 8 . 3 0 . 0 7 8 ±0.020 2 7 . 6  4 0 . 9 * 3 2 . 0  0 . 0 5 4  5 2 . 3  0 . 0 9 2  0 . 0 7 6  ±0.018  ±0.018 11  0 . 0 7 8  ±0.012  0 . 1 0 849.3  5 2 . 1  3 6 . 8 ±0.017  3 6 . 8 0 . 0 6 9 ±0.002  11  Vaccinium membranaceum  i  ± 0 . 0 2 3 tt  II  t  i t  5 5 - 0  A n g e l i c a dawsoni  11  4 7 . 5  2 4 . 4 0 . 0 4 8 ±0.010 ±0.016  5 0 . 9 * 6 6 . 7 0 . 1 3 1 - 0 . 0 1 0  Heracleum -  n  ti  only  0 . 0 7 1 5 1 . 3  3 3 . 9 ±0.008  11  S.D.  lanatum  0 . 0 4 6  ± 0 . 0 0 5  only  S h e l l ±  4 6 . 6 * 2 1 . 5  seeds  S.D.  5 6 . 7 0 . 1 1 4 ±0.028 7 7 . 2  0 . 1 4 8  ±0.013  ± 0 . 0 1 5  S.D. * N =  5  The e f f e c t ( F r a c t i o n  o f subcutaneous B)  extracts  weight  i n grams  uterine  weight  The  meat  when  estrogenic.  s a c r i f i c e d ,  expressed  o f Pinus  i n j e c t i o n s  on the uterine  seeds  U.W.  o f ether weight = mean  a s a. p e r c e n t a g e was h i g h l y  ( F r a c t i o n  A)  o f laboratory uterine  o f body  estrogenic;  weight  weight  Heracleum  -  and  r a t s  chloroform  (B.W.  i n mg.,  standard was  = mean  M.U.W.  body = mean  d e v i a t i o n ) .  strongly  a n t i -  166  Two  of  the  plants  n e e d f u r t h e r comment: bark pine entire  estrogenic. over the  of  cow  Neither  study area  each food.  a  short  of  seeds  was  these  (Figure  found  species  31);  would have a c c e s s on  the  of  cow  c e r t a i n Big  a l s o b e e n shown b y  t o be  of  and  white-  (2)  the  extremely  only  anti-  a portion  of  quantities  of  extensively i n  whitebark pine  ( T i s c h , 1961).  Kitts  the  cones  White  Creek bears d u r i n g  B i e l y and  the  and  to l a r g e  parsnip on  results  i s distributed generally  therefore  e a r l y summer and  food  (meat o n l y )  highly estrogenic,  time i n e a r l y September  a favoured has  t o be  Bears feed  s p r i n g and  the  parsnip  the b e a r p o p u l a t i o n  late  (1)  were f o u n d  plant  t e s t e d gave s i g n i f i c a n t  clover,  late  ( 1 9 6 4 ) t o be  for  spring,  anti-  estrogenic. The domestic the  consumption of  stock  onset of  has  during  e s t r u s by  the  inhibiting  breeding  w h i t e c l o v e r and  great  which contain powerful tial  for upsetting  from the  in distribution, food  throughout  these  maturation of  s t u d y has  q u a n t i t i e s o f cow anti-estrogenic  that  these  and the  i t has  Big  Creek  parsnip,  compounds.  substances,  probably  Cow  too,  both The  parsnip  been an bears.  matter requires  eat of potenmy  are r e a d i l y is  circumpolar  important I t could  t h a t b e a r s would have a c q u i r e d The  before  i s obvious, p r o v i d i n g  evolution of black  substances.  prevent  follicles  shown t h a t  s e a s o n some b e a r s on  digestive tract.  argued, t h e r e f o r e , to  This  reproduction  assumption i s v a l i d absorbed  by  b e e n shown s o m e t i m e s t o d i s r u p t o r  (Bennetts et a l . , 1946). and  a n t i - e s t r o g e n i c compounds  further  bear be  tolerance experimental  Figure  31.  The Big  approximate Creek study  d i s t r i b u t i o n area.  of  whitebark  pine  and  cow  parsnip  on  the  H  168 study, however, as t h e r e i s some i n d i c a t i o n t h a t cow does d i s r u p t the e s t r o u s c y c l e .  F o r example, one  parsnip  female  (No. 61) r e s i d e n t i n an a r e a on L a n g f o r d Creek where  cow  p a r s n i p i s abundant had not y e t produced  when  she was  5-1/2  years o l d .  She was  i n the b r e e d i n g season of 1965,  i n e s t r u s l a t e r t h a n normal  hut u n f o r t u n a t e l y I was  a b l e to l o c a t e h e r i n the s p r i n g of 1966 she had young.  Cow  cubs i n 1965  to determine  p a r s n i p sometimes forms almost  not  whether  the  total  d i e t f o r days or weeks a t times when a bear's r e p r o d u c t i v e c y c l e c o u l d be v u l n e r a b l e to i n t e r f e r e n c e .  In a r e l a t e d  study P i n t e r and Negus (1965) f e d d r y or s p r o u t e d wheat t o d i f f e r e n t groups of M i c r o t u s montanus, and w i t h t h e i r they proposed  data  t h a t compounds p r e s e n t i n the green shoots were  r e s p o n s i b l e f o r b e t t e r r e p r o d u c t i v e performance by the t i m i n g of e s t r u s .  controlling  Bears l i v i n g i n an a r e a abundant i n  p a r s n i p s h o u l d be compared w i t h bears i n n e i g h b o r i n g  cow  areas  eating other foods. E s t r o g e n - l i k e substances  which may  contribute to  e x t e n s i v e r e p r o d u c t i v e f a i l u r e by c a u s i n g the l o s s of young are a l s o p r e s e n t i n bear f o o d s .  Data o b t a i n e d by Wimsatt  (1963) i n d i c a t e t h a t d u r i n g the d e l a y p e r i o d the b l a c k b e a r b l a s t o c y s t must be  i n a progestational uterus.  (1961) and E r i c k s o n and N e l l o r  (1964) thought  Both Wimsatt that corpora  l u t e a i n bears s t a y e d f u n c t i o n a l u n t i l p a r t u r i t i o n . i n c r e a s e d growth of o v a r i a n f o l l i c l e s  i n the f a l l  i m p l a n t a t i o n , a l s o r e p o r t e d by Wimsatt (1963),  An  before  suggests t h a t  t h e r e i s a d d i t i o n a l e s t r o g e n p r o d u c t i o n then.. Perhaps  this  169 i n c r e a s e i n e s t r o g e n t r i g g e r s i m p l a n t a t i o n of the b l a s t o c y s t s i n b e a r s j u s t as i t does i n the r a t and mouse ( N u t t i n g  and  Meyer, 1963;  Mayer, 1963;  others).  e a r l i e r or l a t e r surge o f e s t r o g e n - l i k e substances  An  Shelesnyak and K r a i c e r , 1963;  i n t o the system from p l a n t sources balance  necessary  Experimentally,  c o u l d e a s i l y d i s r u p t the  f o r i m p l a n t a t i o n or s u r v i v a l of b l a s t o c y s t s .  e s t r o g e n has been shown to i n t e r f e r e  with  i m p l a n t a t i o n i n r a t s when g i v e n i n l a r g e doses ( N u t t i n g Meyer, 1963).  Parkes and B e l l e r b y (1926) u s i n g mice  Greenwald (1957) u s i n g r a b b i t s have shown t h a t a t a t i o n i n c r e a s e i n n a t u r a l estrogens loss.  and  Brambell e t a l .  and  postimplan-  w i l l r e s u l t i n embryo  (1948) working w i t h r a b b i t s  B a l s e r (1964) u s i n g w i l d coyotes  and  and  ( C a n i s l a t r a n s ) showed  s i m i l a r e f f e c t s u s i n g the s y n t h e t i c e s t r o g e n i c compound stilbestrol. Whitebark p i n e nuts are eaten by b e a r s i n l a r g e quant i t i e s f o r a s h o r t p e r i o d i n the f a l l when they s t r o n g l y e s t r o g e n i c compounds.  contain  A l s o whitebark p i n e t r e e s grow  o n l y i n narrow s t r i p s o f the t o t a l b e a r range i n w e s t e r n N o r t h America, and  the n u t s are abundant o n l y on c e r t a i n f a l l s .  T h i s p e r i o d i c abundance of cones and t i o n of the t r e e s would p r e v e n t  any  the r e s t r i c t e d  g e n e t i c s e l e c t i o n i n the  b e a r p o p u l a t i o n to a v o i d hormonal u p s e t s There was  no heavy cone crop d u r i n g the  comparative d a t a c o u l d not be gathered The  distribu-  of  reproduction.  study,  and  on the study  therefore area.  p o s s i b i l i t y of a n t i - e s t r o g e n i c substances i n  p a r s n i p u p s e t t i n g the e s t r o u s c y c l e i n b e a r s o r of  cow  estrogenic  170 substances  i n whitebark p i n e nuts  t e r m i n a t i n g pregnancy by  u p s e t t i n g the u t e r i n e environment i s h i g h l y s p e c u l a t i v e . should be p o i n t e d out i n a study o f t h i s n a t u r e , o r d e r to emphasize t h a t these f a c t o r s may wild populations.  however, i n  be important  Animal p h y s i o l o g i s t s and  It  in  agricultural  s c i e n t i s t s have done much r e c e n t work i n t h i s f i e l d ,  but  s c i e n t i s t s working w i t h n a t u r a l p o p u l a t i o n s have l a r g e l y i g n o r e d t h i s p o t e n t i a l i n t e r f e r e n c e w i t h normal r e p r o d u c t i o n . T h i s n e g l e c t a p p a r e n t l y f o l l o w s from the assumption t h a t s i n c e f o o d s u p p l y does not change g r e a t l y d u r i n g p o p u l a t i o n changes (Rausch, 1950;  C h i t t y , I960; and Krebs, 1964), the change i n  food q u a l i t y probably  i s not  great.  

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