UBC Theses and Dissertations

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UBC Theses and Dissertations

Distribution and movements of Steller Sea lion cows, Eumetopias jubata Schreber, on a pupping colony Edie, Allan George 1977

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DISTRIBUTION AND MOVEMENTS OF STELLER SEA LION COWS (Eumetopias j u b a t a ) ON A PUPPING COLONY  by  A l l a n George E d i e  B . S c , U n i v e r s i t y of B r i t i s h Columbia, 1971  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE  i n the F a c u l t y of Graduate S t u d i e s i n the Department of Zoology  We a c c e p t t h i s t h e s i s a s conforming t o the required  standard  THE UNIVERSITY OF BRITISH COLUMBIA  A l l a n George E d i e , 1977  In p r e s e n t i n g  t h i s t h e s i s In p a r t i a l f u l f i l m e n t of the r e q u i r e m e n t s f o r  the 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 t h a t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e f u r t h e r agree t h a t p e r m i s s i o n s c h o l a r l y purposes may representatives..  f o r extensive  be granted by the head of my  Department or by  I t i s understood t h a t c o p y i n g or p u b l i s h i n g of  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, B r i t i s h Columbia, Canada 1W5  study.  I  c o p y i n g of t h i s t h e s i s f o r  t h e s i s f o r f i n a n c i a l g a i n s h a l l not be allowed without my  V6T  and  written  this  his  ii  ABSTRACT  Eumetopias jiibata i s h i g h l y polygynous, move where they choose on pupping  colonies.  but cows a r e f r e e t o  Consequently,  the s p a t i a l  p r e f e r e n c e s of p r e ^ e s t r o u s cows g r e a t l y i n f l u e n c e the r e p r o d u c t i v e success of e s t a b l i s h e d t e r r i t o r i a l b u l l s .  In t h i s study, I have observed  large  numbers of i n d i v i d u a l l y r e c o g n i z a b l e cows on an u n d i s t u r b e d pupping to i d e n t i f y environmental  colony  and other f a c t o r s t h a t i n f l u e n c e s p a t i a l p r e f -  erences of p r e - e s t r o u s cows.  R e s u l t s i n d i c a t e t h a t movements and d i s t r i b u t i o n of p r e - e s t r o u s cows p r i m a r i l y r e f l e c t  t r a d e o f f s between s i t e s *  sea, p r o t e c t i o n from waves, and degrees  a c c e s s i b i l i t i e s from the  of crowding.  Cows without pups  g e n e r a l l y t r a v e l o n l y f a r enough i n l a n d t o f i n d a vacant r e s t s p l a s h e d by waves.  spot n o t  Cows w i t h pups use r e s t spots t h a t a r e f a r t h e r  inland  and more p r o t e c t e d from waves.  Other  s i g n i f i c a n t i n f l u e n c e s i n s p a t i a l p r e f e r e n c e s of p r e -  e s t r o u s cows a r e ruggedness o f t e r r a i n , t h e tendency  t o "home", p a t t e r n s  of a c c e s s on the c o l o n y , and a v a i l a b i l i t y of water f o r use i n thermoregulation.  Cows tend s t r o n g l y t o occupy l e v e l , f l a t a r e a s away from  p r e c i p i c e s or deep c l e f t s i n the r o c k s u b s t r a t e of the c o l o n y .  Some cows  a p p a r e n t l y a r e bred i n t r a n s i t by b u l l s who have t e r r i t o r i e s t h a t i n c l u d e h i g h l y p r e f e r r e d access routes.  Cows tend t o home to the same v i c i n i t y  of the c o l o n y i n s u c c e s s i v e y e a r s . w i t h ready a c c e s s t o water used  Cows tend somewhat t o f r e q u e n t  i n thermoregulation.  areas  iii  I propose an e v o l u t i o n a r y  sequence  i n which the extreme  con-  c e n t r a t i o n of b r e e d i n g O t a r i i d s i n space can be accounted f o r by p o s i t i v e feedback mechanisms i n s e x u a l F i s h e r i n 1929.  s e l e c t i o n t h a t were f i r s t proposed by R. A.  iv  TABLE OF CONTENTS Page Abstract L i s t of T a b l e s L i s t of F i g u r e s L i s t of Appendices  i i v i viii ix  1.  Introduction  1  2.  M a t e r i a l s and Methods 2.1 The Study Area 2.2 C l a s s i f i c a t i o n of Sea L i o n s by S i z e and Sex 2.3 Data C o l l e c t i o n 2.3.1 G e n e r a l Procedures 2.3.2 I n d i v i d u a l l y R e c o g n i z a b l e Cows 2.3.3 B i r t h s and C o p u l a t i o n s 2.3.4 Access P a t t e r n s 2.3.5 Censuses 2.3.6 Weather 2.3.7 T e r r i t o r i a l Boundaries of B u l l s  4 4 4 6 6 7 9 9 9 10 11  3.  Results 3.1 Chronology o f t h e Breeding Season 3.2 Composition of the Cow P o p u l a t i o n : Presence of Suckling Offspring 3.3 P r e f e r e n c e f o r D i f f e r e n t L o c a t i o n s on the Colony: Cows With Pups v s . Cows Without 3.4 Access Routes 3.5 Homing of Cows t o t h e Same P a r t o f the Colony from Year t o Year 3.6 S p a t i a l D i s t r i b u t i o n of B i r t h s 3.6.1 G e n e r a l Comments 3.6.2 E f f e c t s of P r o t e c t i o n from Waves, A c c e s s i b i l i t y , A v a i l a b i l i t y of Water, and Roughness of T e r r a i n on S p a t i a l D i s t r i b u t i o n of B i r t h s 3.6.3 E f f e c t s of Waves and Thermal C o n d i t i o n s on Cows' Choices of B i r t h S i t e s 3.7 R e l a t i o n s h i p s Between L o c a t i o n s Where Cows Bore Pups and Where They Copulated 3.8 S p a t i a l D i s t r i b u t i o n of C o p u l a t i o n s 3.8.1 G e n e r a l Comments 3.8.2 E f f e c t s of Exposure t o Waves, A c c e s s i b i l i t y , A v a i l a b i l i t y o f Water, and Roughness of T e r r a i n on t h e S p a t i a l D i s t r i b u t i o n of Copulations 3.8.3 E f f e c t s of Waves and Thermal C o n d i t i o n s on Cows' Choices of C o p u l a t i o n L o c a t i o n s 3.9 Summary of R e s u l t s  12 12 12 15 15 18 23 23  26 30 32 37 37  41 47 47  V  4.  Discussion 4.1 Comparison With Other S t u d i e s 4.1.1 Ease of A c c e s s From the Sea 4.1.2 P r o t e c t i o n of S i t e s From Sea Waves 4.1.3 Ruggedness of T e r r a i n 4.1.4 A v a i l a b i l i t y of C o o l i n g Water 4.2 R e l a t i v e Importance of F a c t o r s I n f l u e n c i n g Where Cows C o p u l a t e a t Cape S t . James 4.3 Sexual S e l e c t i o n and Polygyny  Acknowledgements Literature Cited  52 52 53 55 58 60 63 65 70 71  LIST OF TABLES  C o p u l a t i o n s i t e s of known cows: degree of e x r posure v s . whether o r not cows had pups. C o p u l a t i o n s i t e s o f u n i d e n t i f i e d cows: degree of exposure t o waves v s . whether or not t h e cows were seen t o j o i n a pup a f t e r c o p u l a t i n g . C o p u l a t i o n s i t e s of u n i d e n t i f i e d cows: degree of exposure t o waves v s . whether or n o t cows were seen t o j o i n a j u v e n i l e a f t e r c o p u l a t i n g . L o c a t i o n o f l a n d i n g v s . whether or not a cow was observed l e a v i n g the b u l l ' s t e r r i t o r y t h a t she landed on. L o c a t i o n of c o p u l a t i o n v s . whether or not a cow was observed l e a v i n g t h e Area t h a t she c o p u l a t e d on. L o c a t i o n of c o p u l a t i o n s v s . whether or not a cow was observed l e a v i n g the Area she c o p u l a t e d on: a n a l y s i s of Areas 6, 8, and 13. Tendency of cows t o r e t u r n t o t h e same s i d e of the c o l o n y from year t o y e a r . B i r t h l o c a t i o n s v s . s i t e s ' a c c e s s i b i l i t i e s and p r o t e c t i o n from waves. B i r t h l o c a t i o n s v s . roughness of s i t e s '  terrains.  M u l t i p l e c l a s s i f i c a t i o n a n a l y s i s of s p a t i a l t r i b u t i o n of b i r t h s .  dis-  Areas on which b i r t h s o c c u r r e d v s . maximum wave i n t e n s i t y on days t h a t b i r t h s o c c u r r e d . D i s t a n c e s from shore a t which b i r t h s o c c u r r e d v s . maximum wave i n t e n s i t y on days t h a t b i r t h s o c c u r r e d Areas on which b i r t h s o c c u r r e d v s . maximum s u b s t r a t temperature on days t h a t b i r t h s o c c u r r e d . Movements of 11 cows t o c o p u l a t i o n . s i t e s from the s i t e s where they bore t h e i r pups.  Moves made by cows v s . i n t e n s i t y  of waves.  Moves made by cows v s . s u b s t r a t e temperature. C o p u l a t i o n l o c a t i o n s v s . s i t e s ' a c c e s s i b i l i t i e s and p r o t e c t i o n from waves. C o p u l a t i o n l o c a t i o n s v s . roughness of s i t e s '  terrains.  C o p u l a t i o n l o c a t i o n s v s . s i t e s ' water a v a i l a b i l i t i e s . M u l t i p l e c l a s s i f i c a t i o n a n a l y s i s of s p a t i a l u t i o n of c o p u l a t i o n s .  distrib-  D i s t r i b u t i o n of c o p u l a t i o n s among Areas 6, 4, and 5 v s . i n t e n s i t y of waves.  Vlll  LIST OF FIGURES Figure  Page  1  The c o l o n y .  2  Number of cows ashore and v i s i b l e from the b l i n d i n 1972 and 1973.  13  Temporal d i s t r i b u t i o n of b i r t h s d u r i n g 1972 and 1973.  14  3  4  5  and c o p u l a t i o n s  S p a t i a l d i s t r i b u t i o n of s i g h t i n g s of cows w i t h and without  pups.  16  5  Landing  6  Tendency f o r cows t o r e t u r n t o the same p a r t of the c o l o n y from year t o y e a r .  21  S p a t i a l d i s t r i b u t i o n of b i r t h s 1973.  24  7  8  9  10  11  s i t e s on t h e n o r t h s i d e of the c o l o n y .  19  on the c o l o n y i n  D i s t a n c e s between l o c a t i o n s where cows bore pups and l o c a t i o n s where they c o p u l a t e d .  33  D i s t a n c e s between cows' c o p u l a t i o n s i t e s and the s i t e s where cows where l a s t seen w i t h t h e i r pups.  34  Number of cows counted wave i n t e n s i t y .  39  on Areas 8, 9, and 13 v s .  S p a t i a l d i s t r i b u t i o n of c o p u l a t i o n s on the c o l o n y i n 1973.  40  I X  LIST OF APPENDICES Appendix  Page  A  Sample s k e t c h e s from cow i d e n t i f i c a t i o n f i l e .  76  B  Sampling proceedure used t o o b t a i n s i g h t i n g s shown i n F i g u r e 4.  78  S p a t i a l d i s t r i b u t i o n of b i r t h s v s . a v a i l a b i l i t y of water  79  S p a t i a l d i s t r i b u t i o n of b i r t h s v s . s u b s t r a t e temperature  80  E f f e c t s of temperature on cows c h o i c e s of copulation sites.  81  C  D  E  X  "The success of an organism i n l e a v i n g a numerous p o s t e r i t y i s not measured o n l y by the number of i t s s u r v i v i n g o f f s p r i n g , but a l s o by the q u a l i t y or p r o b a b l e success of those o f f s p r i n g . " "There i s thus i n any bionomic s i t u a t i o n i n which s e x u a l s e l e c t i o n i s capable of conf e r r i n g a g r e a t r e p r o d u c t i v e advantage... the p o t e n t i a l i t y of a runaway p r o c e s s , which, however s m a l l the b e g i n n i n g s from which i t a r o s e , must, u n l e s s checked, produce g r e a t e f f e c t s , and i n the l a t t e r stages w i t h g r e a t rapidity." (R.A. F i s h e r ,  1956)  1  1.  INTRODUCTION  S t e l l e r sea l i o n s  (Eumetopias j u b a t a Schreber)  c o a s t s of the P a c i f i c Ocean, from Japan, through  i n h a b i t the n o r t h e r n  the A l e u t i a n I s l a n d s , and  south a l o n g the c o a s t of N o r t h America to southern C a l i f o r n i a . g r e g a r i o u s and form c o l o n i e s when hauled out on l a n d . cows bear pups and c o p u l a t e d u r i n g the b r e e d i n g  P r e s e n t knowledge of pupping  They are  At pupping  colonies,  season.  c o l o n i e s stems m a i n l y from  i g a t i o n s by Sandegren (1970) and Gentry  (1970).  These two  invest-  s t u d i e s and  the  p r e s e n t one p r o v i d e the i n f o r m a t i o n f o r the f o l l o w i n g i n t r o d u c t i o n t o the n a t u r a l h i s t o r y of a pupping  colony.  A d u l t b u l l s b e g i n t o a r r i v e i n e a r l y May  and  over the f o l l o w i n g  two weeks p a r t i t i o n the c o l o n y i n t o c o n t i g u o u s t e r r i t o r i e s .  Bulls  defend  t h e i r t e r r i t o r i e s a g a i n s t t r e s p a s s by any male sea l i o n o l d e r than approxi m a t e l y t h r e e y e a r s of age, and do so w i t h v i o l e n t f i g h t i n g  i f necessary.  They remain on t h e i r t e r r i t o r i e s almost c o n t i n u o u s l y from l a t e May early  until  July.  Cows b e g i n t o gather i n l a r g e numbers on the c o l o n y i n l a t e They a r e g r e g a r i o u s but not t e r r i t o r i a l . without  r e s p e c t to b u l l s '  As they a r r i v e , they form groups  t e r r i t o r i a l boundaries.  a c c e s s i b l e a r e a s of the c o l o n y f i r s t ,  and  Cows occupy the most  sequentially f i l l  a c c e s s i b l e a r e a s as the season p r o g r e s s e s . days of her a r r i v a l a t the c o l o n y , a cow  May.  the  less  T y p i c a l l y , w i t h i n about t h r e e  b e a r s a s i n g l e pup,  e l e v e n days l a t e r c o p u l a t e s once w i t h a t e r r i t o r i a l  bull.  and  then about  2  Although t e r r i t o r i a l  b u l l s perform v i r t u a l l y a l l c o p u l a t i o n s ,  they do not a s a r u l e c o n f i n e cows w i t h i n t e r r i t o r i a l a r e e f f e c t i v e l y f r e e t o move about t h e c o l o n y t h e i r a r r i v a l s at the colony time on s e v e r a l b u l l s '  boundaries.  Cows  as they wish, and between  and t h e i r c o p u l a t i o n s ,  they t y p i c a l l y  spend  territories.  Thus, f a c t o r s t h a t i n f l u e n c e t h e d i s t r i b u t i o n and movements of pre-estrous  cows on the c o l o n y  among e s t a b l i s h e d t e r r i t o r i a l  determine the d i s t r i b u t i o n of c o p u l a t i o n s bulls.  In t h i s study, I i n v e s t i g a t e t h e  i n f l u e n c e of e n v i r o n m e n t a l f a c t o r s on the d i s t r i b u t i o n and movements of pre-estrous  cows on a pupping c o l o n y .  My o b j e c t i v e s a r e t o i d e n t i f y t h e  major f a c t o r s t h a t i n f l u e n c e where cows c o p u l a t e ,  and t o suggest the  r e l a t i v e importance of these f a c t o r s a t Cape S t . James. standing  A b e t t e r under-  of the i n f l u e n c e s on b r e e d i n g Eumetopias cows may  elucidate  f a c t o r s or p r o c e s s e s t h a t have a f f e c t e d the e v o l u t i o n of polygyny i n O t a r i i d s and other  animal groups.  In t h i s study, I am p r i m a r i l y concerned w i t h cows d u r i n g to e s t r u s .  Consequently, my i n t e r e s t i n any cow l i e s  the time i n t e r v a l between her a r r i v a l on t h e c o l o n y This r e s t r i c t i o n necessitates observation  specifically  or p r i o r within  and her c o p u l a t i o n .  of i n d i v i d u a l l y r e c o g n i z a b l e  because o n l y they can be observed i n t e r m i t t e n t l y throughout t h e time between a r r i v a l and c o p u l a t i o n .  cows, interval  Cows t h a t a r e not i n d i v i d u a l l y r e c o g n i z a b l e  c o n t r i b u t e u s e f u l d a t a o n l y when "observed g i v i n g b i r t h or c o p u l a t i n g , because o n l y d u r i n g  these two events can an o b s e r v e r determine t h a t  such  cows a r e w i t h i n the time, i n t e r v a l between t h e i r a r r i v a l s and c o p u l a t i o n s .  3  T h e r e f o r e I emphasize o b s e r v a t i o n s of i d e n t i f i a b l e cows, and complement t h e s e o b s e r v a t i o n s w i t h r e c o r d s of the s p a t i a l d i s t r i b u t i o n and c o p u l a t i o n s .  of b i r t h s  4  2.  2.1  MATERIALS AND  The  METHODS  Study Area  The pupping  c o l o n y t h a t I s t u d i e d i s on an i s l a n d i n the  group a t Cape S t . James, B r i t i s h Columbia  ( L a t . 52° 55', Long. 131°  S t e l l e r sea l i o n s have bred here f o r a t l e a s t the l a s t h a l f (Newcombe e t a l , 1918). a cliff  I observed  on  on the c o l o n y ' s p e r i p h e r y ( F i g u r e 1 ) .  conditions.  From e i t h e r of two  p o s s i b l e o n l y d u r i n g calm  sea  landing l o c a t i o n s , observers could climb  the b l i n d w i t h o u t d i s t u r b i n g the c o l o n y .  Boat l a u n c h i n g f a c i l i t i e s ,  accommodation,'. and  support were o b t a i n e d a t a weather s t a t i o n 1.5  2.2  00').  century  the c o l o n y from a b l i n d perched  Boat a c c e s s to the i s l a n d was  to  Kerouard  C l a s s i f i c a t i o n of Sea L i o n s by S i z e and  I classified  on my  logistic  km n o r t h of the study  island.  Sex  sea l i o n s as pups, j u v e n i l e s , subadult b u l l s , a d u l t  b u l l s , and a d u l t cows. e s t i m a t e s based  other  Ages g i v e n i n the d e s c r i p t i o n s below a r e e x p e r i e n c e o b s e r v i n g the animals and  my  on age-growth  c u r v e s p r e s e n t e d by Pike"*". Pups - sea l i o n s of e i t h e r sex, born d u r i n g the summer i n which they were observed.  Pups were obvious because of t h e i r s m a l l s i z e and  black pelage.  '''Unpublished m a n u s c r i p t ,  1966,  F i s h e r i e s Research  Board, Nanaimo, B.  C.  almost  F i g u r e 1.  The  Colony.  Legend:  Non-tidal pools Tidal  Shoreline  Area number  12  5a  6  J u v e n i l e s - sea l i o n s of e i t h e r sex, w i t h i n the s i z e range of s u b a d u l t s seen s u c k l i n g .  J u v e n i l e s p r o b a b l y ranged from one t o t h r e e  y e a r s of age. A d u l t cows - females l a r g e r than j u v e n i l e s .  Small cows c o u l d be m i s t a k e n  f o r s m a l l subadult b u l l s under c e r t a i n c i r c u m s t a n c e s .  Adult  cows p r o b a b l y ranged from f o u r t o about twenty y e a r s of age. A d u l t b u l l s - males w i t h i n the s i z e range t h a t h e l d t e r r i t o r i e s and copulated.  A d u l t b u l l s were obvious because  extremely muscular jaws.  of t h e i r l a r g e  size,  neck, and d i s p r o p o r t i o n a t e l y l a r g e head and  A d u l t b u l l s p r o b a b l y ranged from seven t o about  twelve  y e a r s of age. Subadult b u l l s - males l a r g e r than j u v e n i l e s , but s m a l l e r than a d u l t Large subadult b u l l s had secondary  sexual c h a r a c t e r i s t i c s  s i m i l a r t o but l e s s h i g h l y developed  than those of a d u l t  bulls.  These c h a r a c t e r i s t i c s made l a r g e s u b a d u l t b u l l s immediately tinguishable.  bulls.  dis-  When l y i n g q u i e t l y , s m a l l subadult b u l l s c o u l d be  m i s t a k e n f o r s m a l l cows, but were always d i s t i n g u i s h a b l e when active.  2.3  2.3.1  Data  Collection  G e n e r a l Procedures  A l l d a t a were r e c o r d e d i n or near the o b s e r v a t i o n b l i n d by e i t h e r an a s s i s t a n t or m y s e l f .  In 1972, we r e c o r d e d l o c a t i o n s as e s t i m a t e d  d i s t a n c e s and d i r e c t i o n s ' from prominent  landmarks on the c o l o n y .  In 1973,  7  we  r e c o r d e d them as C a r t e s i a n c o - o r d i n a t e s read from a g r i d drawn onto  l a r g e s c a l e a e r i a l photograph (1 cm =3.8 the c o l o n y u n d e r o b s e r v a t i o n -  May  27 u n t i l J u l y 6, 1973.  and  0630 hours  from May  m)  of the study i s l a n d .  19 u n t i l August 7, 1972,  We  and  a kept  from  We u s u a l l y began o b s e r v a t i o n s between 0500  and c o n t i n u e d them u n t i l about 2130  hours.  We  used  b i n o c u l a r s when n e c e s s a r y .  2.3.2  I r i d i v i d u a l l y R e c o g n i z a b l e Cows  Many cows were d i s t i n c t i v e l y marked w i t h s c a r s or w i t h patches of bare s k i n from 2 to 15 cm a p p a r e n t l y r e s u l t from u n i d e n t i f i e d  i n diameter.  circular  These c i r c u l a r marks  skin disorders.  When I n o t i c e d a  cow  w i t h r e c o g n i z a b l e markings, I sketched her and p l a c e d the s k e t c h i n t o a Examples of f i l e  sketches a r e shown i n Appendix A.  Cows i n t h i s f i l e  file.  will  h e n c e f o r t h i n t h i s t h e s i s be r e f e r r e d t o as known cows.  We of  a known  1)  i n c l u d e d the f o l l o w i n g i n f o r m a t i o n i n each r e c o r d e d o b s e r v a t i o n cow:  the cow's i d e n t i t y , her l o c a t i o n on the c o l o n y , and  the date  and  time of the o b s e r v a t i o n . 2)  her a c t i v i t y - Cows were r e c o r d e d as l a n d i n g from the sea, moving on the c o l o n y , s t a t i o n a r y w i t h head r a i s e d , s t a t i o n a r y and or  engaged i n p e r i e s t r o u s behaviour  A cow  All  (term a f t e r Sandegren, 1970).  e x h i b i t i n g p e r i e s t r o u s behaviour moves w i t h a l i m p ,  times i n t h i s t h e s i s a r e P a c i f i c Standard  prone,  Time.  exaggerated  8  g a i t , s a l i v a t e s p r o f u s e l y , and b i t e s , rubs a g a i n s t , and over the b u l l whose a t t e n t i o n her behaviour i n g t h i s behaviour 3)  whether she was whether i t was  arouses.  crawls  Cows show-  were sometimes r e c e p t i v e to c o p u l a t i o n .  accompanied by a pup  or j u v e n i l e , and  i f she  s u c k l i n g - Accompanied means t h a t b e h a v i o u r a l  i n t e r a c t i o n s between the cow  and  t h a t the two were mother and  offspring.  young i n d i c a t e d to the  observer  Cows l i e i n p r e f e r e n t i a l  c o n t a c t w i t h and a r e s o l i c i t o u s toward t h e i r a p p a r e n t l y own s p r i n g , and a r e a g g r e s s i v e and lions. and  was,  Observations  i n t o l e r a n t of other young  off-  sea  of mother-pup p a i r s i n which both the cows  t h e i r pups were i n d i v i d u a l l y r e c o g n i z a b l e i n d i c a t e t h a t  Eumetopias cows s u c k l e o n l y t h e i r own  offspring  (Sandegren, 1970).  S i m i l a r o b s e r v a t i o n s i n d i c a t e the same of C a l l o r h i n u s u r s i n u s (Bartholomew and H o e l , 1953)  and  of Zalophus c a l i f o r n i a n u s  (Peterson and Bartholomew, 1967). 4)  5)  whether she was  wet  or d r y  (1973  d r y , a l l wet,  i e . a l l pelage  miscellaneous  comments.  We  s y s t e m a t i c a l l y searched  began o b s e r v a t i o n s throughout the day.  o n l y ) - Cows were c l a s s e d as  soaked, p a r t l y wet,  or wet  from r a i n .  the c o l o n y f o r known cows when we  i n the morning, and  on s e v e r a l a d d i t i o n a l o c c a s i o n s  A f t e r n o t i c i n g a known cow,  a c t i v i t i e s as c o n t i n u o u s l y as p o s s i b l e .  we  tried  to monitor  her  9  2.3.3  B i r t h s and C o p u l a t i o n s  We r e c o r d e d the d a t e s , t i m e s , and l o c a t i o n s of a l l observed b i r t h s and c o p u l a t i o n s .  A f t e r a cow f i n i s h e d c o p u l a t i n g , we r e c o r d e d  where she went, whether she j o i n e d a pup or j u v e n i l e , whether she was d i r t y or c l e a n , and whether she was wet or d r y .  T h i s i n f o r m a t i o n helped  i d e n t i f y the c i r c u m s t a n c e s under which the cow came t o c o p u l a t i n g i n the l o c a t i o n she d i d .  2.3.4  Access  Patterns  Whenever we n o t i c e d a known cow l a n d i n g , we r e c o r d e d where she landed and where she subsequently went.  From June 24 t o June 30, 1972,  we r e c o r d e d t h i s i n f o r m a t i o n f o r a l l cows observed  l a n d i n g r e g a r d l e s s of  whether they were known or n o t .  2.3.5  Censuses  1972:  At 0800, 1200, 1600, and 2000 hours on each day from May 28 t o June 25 i n c l u s i v e we counted  by age and sex c l a s s a l l sea l i o n s p r e s e n t on  each b u l l ' s t e r r i t o r y , and those p r e s e n t on s e v e r a l d i s c r e t e a r e a s not defended  by b u l l s .  From June 26 t o August 8 we counted  0800, 1200, and 2000 hours and counted  o n l y a d u l t cows a t  a l l c l a s s e s a t 1600 hours.  1973:  I d i v i d e d the c o l o n y i n t o 16 a r e a s a c c o r d i n g t o my s u b j e c t i v e i m p r e s s i o n s of t h e i r r e l a t i v e exposure to waves, ease of a c c e s s from the  10  sea, and  topographic  t o J u l y 3, I counted  irregularity  On each day from June 3  the number of cows p r e s e n t a t 0700 and  on these a r e a s , and counted  2.3.6  ( F i g u r e 1) .  a l l c l a s s e s a t 1600  2000 hours  hours.  Weather  The  Cape S t . James weather s t a t i o n p r o v i d e d semi-hourly measure-  ments of a i r temperature,  wind speed and d i r e c t i o n , and p e r c e n t  cloud  cover.  I r e c o r d e d an index of s o l a r r a d i a t i o n i n 1973. t h e r m i s t e r of a telethermometer island.  The  t h e r m i s t e r was  I attached  d i r e c t l y to the r o c k s u b s t r a t e of the  the warming e f f e c t s of s o l a r r a d i a t i o n .  index of the thermal c o n d i t i o n s e x p e r i e n c e d I recorded  s u b s t r a t e temperature semi-hourly  In 1973,  study  exposed to a l l weather elements, so temperature  r e a d i n g s from i t c r u d e l y i n t e g r a t e d the c o o l i n g e f f e c t s of wind and and  the  rain,  Thus, the r e a d i n g s were an by the sea l i o n s on the  colony.  (0600, 0800, ... 2000 h o u r s ) .  I r e c o r d e d o b s e r v a t i o n s on the s e v e r i t y of wave a c t i o n  at the same time t h a t I r e c o r d e d  s u b s t r a t e temperature.  I rated  severity  a c c o r d i n g to the f i v e p o i n t s c a l e below:  1 - A l l a r e a s on the c o l o n y except  the i n t e r t i d a l zone a r e d r y .  2 - Area  6 i s b e i n g s p l a s h e d by waves ( F i g u r e 1 ) .  3 - Area  6 i s l i g h t l y awash.  4 - Waves a r e washing Area adult  cow.  6 s t r o n g l y enough to p h y s i c a l l y d i s l o d g e an  11  5 - Waves a r e washing over Areas i n a d d i t i o n t o A r e a 6 s t r o n g l y enough to move an a d u l t cow.  When waves were grade 5, I r e c o r d e d which  Areas i n a d d i t i o n t o Area 6 were awash.  2.3.7  T e r r i t o r i a l Boundaries df B u l l s  A d j a c e n t t e r r i t o r i a l b u l l s engaged i n border d i s p l a y s  (described  by Gentry, 1970) f r e q u e n t l y and o n l y a t the b o u n d a r i e s s e p a r a t i n g the adjacent t e r r i t o r i e s .  These d i s p l a y s , p l u s t h e tendency o f b o u n d a r i e s t o  f o l l o w t o p o g r a p h i c i r r e g u l a r i t i e s , made the boundaries o b v i o u s .  In 1972 b o u n d a r i e s were monitored by r e c o r d i n g l o c a t i o n s of border displays.  In 1973, I d i d not r e c o r d these l o c a t i o n s , I simply noted the  l o c a t i o n s o f b o u n d a r i e s a t t h e b e g i n n i n g o f t h e season, and noted boundary changes as they o c c u r r e d .  12  3.  3.1  RESULTS  Chronology of the Breeding  When we f i r s t  Season  a r r i v e d a t t h e study i s l a n d on May 13, 1972, 5 a d u l t  b u l l s had a l r e a d y a c q u i r e d t e r r i t o r i e s . l a t e r were observed  c o p u l a t i n g had a c q u i r e d  In 1972, t h e f i r s t  territories.  cows a r r i v e d a t t h e c o l o n y on about May 18.  In b o t h y e a r s , cows t h a t a r r i v e d f i r s t (Figure 1).  By June 4, 1972, a l l b u l l s t h a t  o c c u p i e d Area  7 and i t s v i c i n i t y  Then, as t h e season p r o g r e s s e d and the c o l o n y became more  crowded, cows s e q u e n t i a l l y occupied more i n l a n d l o c a t i o n s .  L a t e r , the  c o l o n y emptied i n the r e v e r s e sequence, the more i n l a n d l o c a t i o n s b e i n g abandoned f i r s t .  F i g u r e 2 shows t h e t o t a l number of cows ashore  from the b l i n d d u r i n g the two seasons of t h e study. temporal  3.2  d i s t r i b u t i o n of observed  Composition  F i g u r e 3 shows the  b i r t h s and c o p u l a t i o n s f o r b o t h  o f t h e Cow P o p u l a t i o n :  Presence  and v i s i b l e  years.  of S u c k l i n g O f f s p r i n g  Of 95 known cows s i g h t e d t e n or more times i n 1973, 12.6% were a l o n e , 9.5% were accompanied o n l y by j u v e n i l e s , 55.8% were accompanied o n l y by pups, and 22.1% were accompanied by both j u v e n i l e s and pups. p o r t i o n of cows accompanied by j u v e n i l e s d i f f e r s markedly w i t h o b t a i n e d i n other a r e a s .  The p r o results  On Ano Nuevo I s l a n d i n C a l i f o r n i a , o n l y 2% of  Eumetopias cows a r e accompanied by j u v e n i l e s (Gentry, 1970), whereas 80% a r e accompanied on Lewis I s l a n d i n A l a s k a i n Gentry,  1970).  (Sandegren, p e r s o n a l communication  Thus, the 31.6% f i g u r e f o r Cape S t . James i s i n t e r m e d i a t e  between f i g u r e s o b t a i n e d a t t h e n o r t h e r n and southern range.  extremes of Eumetopias'  13  30(D  o  4  1  1  27  1  10  MAY  '•  1  20  §~  1  JUNE  1  10 JULY  DATE  F i g u r e 2.  Number of cows ashore and v i s i b l e from the b l i n d and 1973.  Each d a i l y v a l u e i n the f i g u r e t h a t day. Legend: Storm i n 1973 - S Storm i n 1972 - St  i n 1972  i s t h e mean of the f o u r censuses taken  1  20  14  50,  Sg 40. r-  30  m  u.  O cc 20 UJ 03  s  10.  Z  41  0. 50..  z g 5c  40..  _j  0_  O o u. o rr UJ  m 5 =»  30.. 20.. 10.. 0._ 1^  CN 1  CN  4L ,  00 1  CO  1 00  CN  JO  1  1  O  CN  MAY  CO  o  CN 1  "—  ***  CN 1 r—  CN  CO CN 1  <o CN  CN  -O  o  CN  cn  i N.  1  1  CN  JUNE  JULY  DATE F i g u r e 3.  Temporal d i s t r i b u t i o n of b i r t h s and c o p u l a t i o n s d u r i n g and 1973.  Legendi 1972  -  1973  -  I  1  1972  1 i—  ^—  15  3.3  P r e f e r e n c e f o r D i f f e r e n t L o c a t i o n s on the Colony: v s . Cows Without  Cows w i t h young pups tended  t o occupy d i f f e r e n t a r e a s of t h e c o l o n y  than d i d cows without pups ( F i g u r e 4 ) . never  Cows w i t h Pups  Cows w i t h young pups were almost  seen on Area 6, whereas cows without pups were f r e q u e n t l y seen t h e r e .  The o p p o s i t e was t r u e of Area 13, where cows w i t h pups were f r e q u e n t l y seen and cows without pups were r a r e l y  seen.  These t r e n d s i n s p a t i a l p r e f e r e n c e were r e f l e c t e d  i n the s p a t i a l  d i s t r i b u t i o n of c o p u l a t i o n s of cows w i t h and without pups ( T a b l e s 1, 2, and 3 ) .  The d i f f e r e n c e i n s p a t i a l p r e f e r e n c e of cows w i t h and w i t h o u t pups may r e l a t e t o t h e s a f e t y of pups.  U n t i l they a r e a c o u p l e of weeks  o l d , pups a r e v e r y weak swimmers and u s u a l l y drown i f washed i n t o the sea by waves.  D u r i n g one storm i n 1973, 30% (N = 44) of the known cows w i t h  pups l o s t them.  A slightly less violent  storm o c c u r r e d i n 1972, and a more  v i o l e n t one i n 1974, so such m o r t a l i t y from storms  i s probably  typical.  P r e f e r e n c e e x h i b i t e d by cows without pups f o r l e s s p r o t e c t e d a r e a s may simply i n d i c a t e t h a t these cows u s u a l l y t r a v e l no f u r t h e r i n l a n d necessary t o f i n d a vacant r e s t  3.4  than  spot.  A c c e s s Routes  Cows p r e f e r r e d t o use c e r t a i n l o c a t i o n s on the s h o r e l i n e f o r l a n d i n g from the s e a .  Of 216 l a n d i n g s r e c o r d e d f o r the n o r t h s i d e of  the c o l o n y i n 1972, 87% o c c u r r e d on A r e a 6, 13% on Area 4, and 0% on Area "'.  16  F i g u r e 4.  S p a t i a l d i s t r i b u t i o n of s i g h t i n g s  of cows w i t h and without pups.  Legend: S i g h t i n g l o c a t i o n of known cow who had a pup  O  S i g h t i n g l o c a t i o n o f known cow who d i d not have a pup  Note:  F o r d e t a i l s o f procedure used t o o b t a i n t h i s sample o f s i g h t i n g s , see Appendix B.  16a  T a b l e 1.  C o p u l a t i o n s i t e s of known cows: degree of exposure t o waves v s . whether or not cows had pups Cow had a pup  Cow had no pup  P r o t e c t e d Area"*"  24  5  Exposed Area  19_  15  56  20  P e r c e n t on P r o t e c t e d Area (x T a b l e 2.  2  = 5.23,  df = 1, p <0.01)  C o p u l a t i o n s i t e s of u n i d e n t i f i e d cows: degree of exposure to waves v s . whether or n o t t h e cows were seen t o j o i n pup a f t e r copulating Cow seen w i t h pup  Cow not seen w i t h pup  Protected Area  54  38  Exposed Area  213  74  66  34  P e r c e n t on P r o t e c t e d Area (x T a b l e 3.  2  = 19.35, d f = 1, p <0.001)  C o p u l a t i o n s i t e s of u n i d e n t i f i e d cows: degree of exposure t o waves v s . whether or not cows were seen t o j o i n a j u v e n i l e after copulating  P r o t e c t e d Area Exposed A r e a  Cow seen w i t h juvenile  Cow not seen with juvenile  1  91  __8  94  11  49  P e r c e n t on P r o t e c t e d Area  ( F i s h e r ' s Exact P r o b a b i l i t y = 0 . 0 2 3 )  "^For a l l the above t a b l e s , Areas 8, 12, 2, 9, 1, 3, 11, 10, and 12 a r e p r o t e c t e d ; Areas 7, 4, 5, and 6 a r e exposed.  18  1 ( F i g u r e 5 ) . A l s o , cows l a n d i n g a t some p o i n t s tended  to continue  travel-  l i n g t o other p a r t s of the c o l o n y more o f t e n than d i d cows l a n d i n g a t other p o i n t s (Table 4 ) .  Thus, b u l l s ' t e r r i t o r i e s on Area 6 i n c l u d e d a c c e s s p o i n t s t o much of the r e s t of the c o l o n y . advantage t o these b u l l s .  T h i s may have imparted r e p r o d u c t i v e  S e v e r a l times i n b o t h y e a r s I observed  l a n d from the s e a , c o p u l a t e immediately  cows  w i t h the b u l l whose t e r r i t o r y i n c l u d e d  the l a n d i n g p o i n t , and then c o n t i n u e on t o other p a r t s of the c o l o n y . e n t l y , some cows a r r i v e a t the c o l o n y i n e s t r u s and c o n s e q u e n t l y  Appar-  copulate  w i t h a b u l l who owns a good l a n d i n g s p o t .  The above h y p o t h e s i s i s supported by the f a c t t h a t , a f t e r c o p u l a t i n g , cows l e f t e a s i l y a c c e s s i b l e a r e a s more f r e q u e n t l y than they d i d l e s s a c c e s s i b l e areas  3.5  (Tables 5 and 6 ) .  Homing of Cows t o t h e Same P a r t of the Colony from Year t o Year  T h i r t y - t w o known cows were observed w i t h pups i n both 1972 and 1973.  Of t h e s e cows, 4 were observed  y e a r , and 13 i n n e i t h e r y e a r . t h e s e cows were f i r s t  pupping  i n b o t h y e a r s , 15 i n o n l y one  The d i s t a n c e s between the l o c a t i o n s where  seen w i t h t h e i r pups i n the two y e a r s i n d i c a t e t h a t cows  tend t o r e t u r n t o the same v i c i n i t y of the c o l o n y  (Figure 6 ) .  I s t a t i s t i c a l l y a n a l y s e d the d a t a i n F i g u r e 6 i n two ways. first  The  and s i m p l e s t was to d i v i d e the c o l o n y i n t o n o r t h and south h a l v e s , and  then c l a s s i f y each o f t h e 32 cows as t o on which h a l f of t h e c o l o n y she was seen w i t h her pup i n each year  (Table 7 ) .  19  F i g u r e 5.  Landing s i t e s  on the n o r t h s i d e of the c o l o n y .  Legend: Landing s i t e w i t h number of l a n d i n g s observed  19a  20  T a b l e 4.  L o c a t i o n of l a n d i n g v s . whether or not a cow was observed i n g the b u l l ' s •: t e r r i t o r y t h a t she landed on Landing A&B  C&D  E&F  stayed  43  33  19  Cow  left  90  21  10  32  61  66  (x  T a b l e 5.  points  Cow  P e r c e n t of cows t h a t stayed 2  leav-  = 19.24, df = 2, p<0.001)  L o c a t i o n of c o p u l a t i o n v s . whether or not a cow was l e a v i n g the Area t h a t she c o p u l a t e d on  observed  Copulation Location Areas 4,5,6, 7,10, and 12 Cow stayed  43  54  Cow l e f t  50  2_9_  46  65  Percent  of cows  t h a t stayed (x  Table 6.  Areas 1,2,3,8, 9,11, and 13  2  = 6.289, d f = 1, p < 0 . 0 1 )  L o c a t i o n o f c o p u l a t i o n s v s . whether o f not cowwas observed l e a v i n g t h e Area t h a t she c o p u l a t e d on: a n a l y s i s of Areas 6, 8, and 13 Copulation Location Area 6 Cow stayed Cow l e f t Percent  2  9  32  19  ' _1  32  97  of cows  t h a t stayed (x  Areas 8 & 13  = 28.88, df = 1, p<0.001)  21  o o u. O CC LU CO  S  Z  14 12. 10 . 8. 6. 4. 2. 0  0 -10  >10 -20  >20 -30  DISTANCE F i g u r e 6.  >30 -40 IN  >40 -50  >50 -60  METERS  Tendency f o r cows t o r e t u r n to t h e same p a r t of the c o l o n y from year t o y e a r .  Legend: D i s t a n c e s between s i t e s where cows bore pups i n 1972 and 1973. D i s t a n c e s between s i t e s where cows bore pups i n one year and s i t e s where they were f i r s t seen w i t h pups i n the other year. D i s t a n c e s between s i t e s where cows were f i r s t seen w i t h pups i n 1972 and 1973.  mm  Tendency of cows t o r e t u r n t o t h e same s i d e of the c o l o n y from year t o year :  L o c a t i o n of f i r s t s i g h t i n g i n 1973 North side L o c a t i o n of f i r s t s i g h t i n g i n 1972  (x  2  South  side  North side  17  4  South side  1  10  = 15.14, d f = 1, p<0.001)  23  In  the second a n a l y s i s , I compared the d i s t a n c e s used i n F i g u r e 6  w i t h "randomized d i s t a n c e s " . I o b t a i n e d t h e randomized d i s t a n c e s as f o l l o w s . In  F i g u r e 6, each df the d i s t a n c e s between year t o year s i g h t i n g s was  c a l c u l a t e d from the c o - o r d i n a t e s of the s i g h t i n g s .  Four d i s t a n c e s were  from b i r t h s i t e to b i r t h s i t e , 15 from b i r t h s i t e to the s i t e where the pup was f i r s t  seen, and 13 were from pup s i g h t i n g t o pup s i g h t i n g .  In  order to o b t a i n the randomized d i s t a n c e s , I wrote the c o - o r d i n a t e s of each 1972 s i g h t i n g on a c a r d and kept the b i r t h s i g h t i n g s s e p a r a t e from the f i r s t pup s i g h t i n g s .  Then f o r each of the 32 cows, I p i c k e d a t random a c a r d  w i t h a 1972 l o c a t i o n on i t .  I f the cow was a c t u a l l y seen pupping i n 1972,  I p i c k e d a b i r t h l o c a t i o n , i f n o t , I p i c k e d a f i r s t pup s i g h t i n g  location.  Then f o r each cow, I c a l c u l a t e d the d i s t a n c e between the a c t u a l 1973 s i g h t i n g and the randomly chosen 1972 s i g h t i n g .  I compared these randomized d i s t a n c e s w i t h the a c t u a l year t o year d i s t a n c e s shown i n F i g u r e 6.  I f cows demonstrated no tendency t o r e t u r n  to  the same v i c i n i t y , t h e r e should be no d i f f e r e n c e between the two s e t s  of  distances.  However, the a c t u a l d i s t a n c e s  (median = 10.1 m) were  s i g n i f i c a n t l y s h o r t e r than the randomized d i s t a n c e s p < 0 . 0 5 , s i g n t e s t ; Campbell,  3.6 3.6.1  (median = 20.8 m;  1967).  S p a t i a l D i s t r i b u t i o n of B i r t h s G e n e r a l Comments  The s p a t i a l d i s t r i b u t i o n of b i r t h s observed i n 1973 i s shown i n F i g u r e 7.  Births  were n o t observed i n Areas 6, 14, 15, and 16, and  v e r y few were observed i n n o r t h e r n p o r t i o n s of Area 4, and the n o r t h e a s t e r n  24  F i g u r e 7.  S p a t i a l d i s t r i b u t i o n of b i r t h s  Legend: L o c a t i o n of one observed b i r t h  ®  Area number  4  on the c o l o n y i n  1973  24a  25  ends of Areas 5 and Area  6 was  7.  p a r t i c u l a r l y so; i t was  d i s l o d g e an a d u l t cow any  These v i c i n i t i e s were f r e q u e n t l y washed by waves. being washed by waves s t r o n g enough to  i n t h r e e times as many weather o b s e r v a t i o n s as  other Area of the c o l o n y .  Areas 14,  15, and  was  16 were a l s o s p e c i a l i n  t h a t the c r e v a s s e s e p a r a t i n g them from the r e s t of the c o l o n y was  difficult  f o r sea l i o n s to n e g o t i a t e , and would have been p a r t i c u l a r l y so f o r cows w i t h young pups.  Thus, cows appear t o a v o i d pupping i n l o c a t i o n s where  waves c o u l d be a danger to pups.  T h i s t r e n d i s apparent i s l a n d s i n the Kerouard  on a d i f f e r e n t  s c a l e as w e l l .  At l e a s t  group a t Cape S t . James were o c c u p i e d by a d u l t  cows d u r i n g the summers of t h i s study.  Of t h e s e 11, o n l y 3 had  apparent  a c c e s s t o ground h i g h enough to a f f o r d p r o t e c t i o n from waves d u r i n g These 3 were the o n l y i s l a n d s on which pups were observed i n which b i r t h s were observed.  B i r t h s were not observed  born after  i n Area  13.  These a r e a s had  1 i n 1972  storms.  d u r i n g the p e r i o d s  T h i s s e l e c t i o n of pupping s i t e s seems v e r y  a d a p t i v e i n l i g h t of the heavy pup  11, 12, and  11  m o r t a l i t y observed  i n Area  i n this  study.  1 or i n the western ends of Areas  rugged, p r e c i p i t o u s t e r r a i n .  The  f e l l about f o u r meters onto a r o c k ledge  one  pup  immediately  birth.  The  l i k e l i h o o d of cows g i v i n g b i r t h on a c e r t a i n a r e a  a l s o depends on the number of cows a l r e a d y occupying Through the season,  cows populated  probably  alternative  areas.  the c o l o n y r o u g h l y i n order of  e a s e , of a c c e s s , w i t h Area 7 b e i n g o c c u p i e d f i r s t , and Areas 8 and  apparent 13  last.  26  T h i s s e q u e n t i a l o c c u p a t i o n of the c o l o n y s t r o n g l y suggests t h a t cows p r e f e r e n t i a l l y o c c u p i e d more a c c e s s i b l e a r e a s , but a f t e r t h e s e were crowded, cows moved f u r t h e r i n l a n d to l e s s a c c e s s i b l e a r e a s .  Hence, a c u r s o r y examination  of b i r t h d i s t r i b u t i o n i n d i c a t e s t h a t  p r o t e c t i o n from waves, ruggedness of t e r r a i n , and ease of a c c e s s from sea may  be important  to bear pups.  the  f a c t o r s i n d e t e r m i n i n g where on the c o l o n y cows choose  D e t a i l e d examination  of these and other i n f l u e n c e s f o l l o w s  i n the next s e c t i o n s .  3.6.2  E f f e c t s of P r o t e c t i o n From Waves, A c c e s s i b i l i t y , A v a i l a b i l i t y of Water, and Roughness of T e r r a i n on S p a t i a l D i s t r i b u t i o n of B i r t h s  Preliminary observations indicated  t h a t exposure t o waves, a c c e s s -  i b i l i t y , and roughness of t e r r a i n might be important of b i r t h s i t e s by cows, and Gentry water might be important.  influences i n selection  (1970) i n d i c a t e d t h a t a v a i l a b i l i t y of  I t e s t e d the e f f e c t s of these f o u r f a c t o r s w i t h  c o n t i n g e n c y a n a l y s e s and a m u l t i p l e c l a s s i f i c a t i o n a n a l y s i s a l , 1969)  of the s p a t i a l d i s t r i b u t i o n of b i r t h s .  I used m u l t i p l e c l a s s -  i f i c a t i o n a n a l y s i s t o i n d i c a t e the r e l a t i v e importance  of the f a c t o r s ,  c o n t i n g e n c y a n a l y s e s t o t e s t the s i g n i f i c a n c e of observed  To perform  (Andrews e_t  trends.  these a n a l y s e s , I drew a g r i d on an a e r i a l  thereby d i v i d i n g the c o l o n y i n t o 171 a r e a s , each 4.6  and  m square.  photograph, I then  class-  i f i e d each of t h e s e a r e a s as b e l o n g i n g to one of f i v e c l a s s e s of exposure t o waves and a c c e s s i b i l i t y , f o u r c l a s s e s of t e r r a i n roughness, of water a v a i l a b i l i t y . b i r t h s observed  F i n a l l y , I o b t a i n e d from my  on each a r e a .  and  four c l a s s e s  r e c o r d s the number of  27  I hypothesized  t h a t a r e a s w i t h more p r o t e c t i o n from waves, b e t t e r  a c c e s s i b i l i t y , f l a t t e r and  l e s s rugged t e r r a i n , and b e t t e r a v a i l a b i l i t y of  water should have had more b i r t h s occur on them than should a r e a s of posite characteristics.  I expected  op-  t h a t numbers of b i r t h s should be c o r -  r e l a t e d i n a simple manner w i t h t e r r a i n roughness and water  availability,  but i n a more complex manner w i t h p r o t e c t i o n from waves and  accessibility.  These l a t t e r two  f a c t o r s are n e g a t i v e l y c o r r e l a t e d .  More p r o t e c t e d areas  were v i r t u a l l y always l e s s a c c e s s i b l e because t h e i r p r o t e c t i o n a r o s e t h e i r d i s t a n c e and h e i g h t from the sea. two  f a c t o r s l e d me  The  between these  t o expect v e r y few b i r t h s on the l e a s t p r o t e c t e d , most  a c c e s s i b l e a r e a s ; many b i r t h s on moderately a r e a s ; and  interdependence  from  p r o t e c t e d , moderately  accessible  few b i r t h s on the most p r o t e c t e d , l e a s t a c c e s s i b l e a r e a s .  R e s u l t s of the c o n t i n g e n c y a n a l y s e s of a c c e s s i b i l i t y and p r o t e c t i o n from waves, and  of roughness of terrainr.appear i n T a b l e s 8 and  s i m i l a r a n a l y s i s of water a v a i l a b i l i t y was and  i s shown i n Appendix C.  not s t a t i s t i c a l l y  9.  A  significant  T a b l e 8 f a i l s t o r e j e c t the h y p o t h e s i s t h a t  areas of moderate a c c e s s i b i l i t y and p r o t e c t i o n should have r e l a t i v e l y more b i r t h s than should a r e a s of more extreme a c c e s s i b i l i t y . t h a t a r e a s of l e v e l ,  T a b l e 9 shows s t r o n g l y  smooth t e r r a i n had more b i r t h s occur on them than d i d  areas of s t e e p e r , more rugged  terrain.  M u l t i p l e c l a s s i f i c a t i o n a n a l y s i s y i e l d s e s s e n t i a l l y the same p i c t u r e t h a t c o n t i n g e n c y a n a l y s i s d i d (Table 10). 2 est predictor  (B  T e r r a i n i s by f a r the s t r o n g -  1 =0.321)  compared t o a c c e s s i b i l i t y and p r o t e c t i o n  1 2 B p r o v i d e s a measure of the a b i l i t y of the p r e d i c t o r (eg. T e r r a i n roughness) to e x p l a i n v a r i a t i o n i n the dependent v a r i a b l e ( i e . number of b i r t h s per gr,id area) a f t e r a d j u s t i n g f o r ' t h e e f f e c t s of a l l other p r e d i c t o r v a r i a b l e s . B i s not i n terms of p e r c e n t v a r i a n c e e x p l a i n e d , the term s e r v e s s i m p l y t o compare the r e l a t i v e p r e d i c t i v e power of the t h r e e p r e d i c t o r v a r i a b l e s examined h e r e , i e . t e r r a i n roughness, a c c e s s i b i l i t y - p r o t e c t i o n , and a v a i l a b i l i t y of F o r f u r t h e r i n f o r m a t i o n on B see Andrews e t a l (1969, pages 22 water. and 117).  28 T a b l e 8.  B i r t h l o c a t i o n s v s . s i t e s ' a c c e s s i b i l i t i e s and from waves ''' '  protection  C l a s s e s of a c c e s s i b i l i t y and most a c c e s s i b l e 1 < Number of b i r t h s per g r i d area >  1  13  most p r o t e c t e d  2 +*  protection  3  4  5  15  -  17  -  23  +  35  +  13  +  1-3.5  2  -  8  +  8  -  6  -  3.5  1  -  9  +  13  +  1  -  7 -  ,2 2 (x = 18.96, df = 8, p<0.05; x = 13.28, df = 6, p<0.05 w i t h a c c e s s i b i l i t y - p r o t e c t i o n c l a s s e s 1 and 2 combined to e l i m i n a t e expected v a l u e s of 2.90 and 3.46 i n c e l l s 1/ 3.5 and 1/1-3.5) T a b l e 9.  B i r t h l o c a t i o n s v s . roughness of  sites' terrains C l a s s e s of  Terrain  flattest  roughest  1 Number of b i r t h s per g r i d area  ^ >  (x  3.5  2  3  4  5  -  21  -  37  +  40  +  6  -  19  +  9  -  3  -  18 4-  12  +  1  -  0  -  = 78.42, df = 6, p < 0.001)  In both of the above t a b l e s , the + and - s i g n s i n each c e l l i n d i c a t e whether the observed number i n t h a t c e l l was g r e a t e r (+) or l e s s (-) than expected.  Note:  In the above a n a l y s e s , and i n f o l l o w i n g c o n t i n g e n c y and m u l t i p l e c l a s s i f i c a t i o n a n a l y s e s of the s p a t i a l d i s t r i b u t i o n of b i r t h s and c o p u l a t i o n s , t h e r e e x i s t s the p o s s i b i l i t y of i n t e r a c t i o n between g r i d a r e a s . For example, cows might be a t t r a c t e d to pupping s i t e s because other cows had pupped nearby. U n f o r t u n a t e l y , d i s c u s s i o n w i t h Dr. P.A. L a r k i n i n d i c a t e d t h a t normal t e s t s f o r such i n t e r a c t i o n a r e not f e a s i b l e w i t h the d a t a a v a i l a b l e h e r e . However, I f e e l t h a t the e f f e c t s of i n t e r a c t i o n , i f i t e x i s t s , are g r e a t l y outweighed by the e f f e c t s of the s i t e c h a r a c t e r i s t i c s b e i n g analysed. F u r t h e r , i n t e r a c t i o n would tend to a f f e c t the a n a l y s e s i n opposing d i r e c t i o n s on d i f f e r e n t p a r t s of the c o l o n y . Hence, I do not t h i n k t h i s p o t e n t i a l i n t e r a c t i o n s h o u l d a f f e c t i n f e r e n c e from these a n a l y s e s .  T a b l e 10.  M u l t i p l e c l a s s i f i c a t i o n a n a l y s i s of s p a t i a l d i s t r i b u t i o n of b i r t h s  Predictor variable and i t s B  Class  Number of areas i n class  A c t u a l mean number of b i r t h s per a r e a  Adjusted mean number o f b i r t h s p e r area  1  16  0.44  0.01  AccessibilityProtection  2  32  2.04  1.73  3  38  2.35  1.94  B  4  30  0.59  1.08  5.  55  1.12  1.37  1  29  3. 79  3.59  2  52  1.98  1.97  3  47  0. 47  0.55  4  43  0. 15  0.21  1  38  0. 48  0.76  2  77  1.51  1.46  3  36  1.67  1.45  4  20  2.33  2.39  2  = 0.063  Terrain B  2  =.0.321  A v a i l a b i l i t y of Water B  2  = 0.046  O v e r a l l mean number of b i r t h s per a r e a = 1.41 O v e r a l l standard d e v i a t i o n i n number o f b i r t h s per area = 2.15 M u l t i p l e R = 0.435 A d j u s t e d means have been c o r r e c t e d f o r the e f f e c t s of t h e o t h e r two v a r i a b l e s (Andrews e t a l , 1969)  ho  30  (B  A  = 0.063) and a v a i l a b i l i t y of water  by c o n t i n g e n c y  (B  Z  =0.046).  As was  a l s o shown  a n a l y s i s , more b i r t h s o c c u r r e d on a r e a s of moderate a c c e s s -  i b i l i t y and p r o t e c t i o n than on a r e a s of more extreme a c c e s s i b i l i t y protection.  M u l t i p l e c l a s s i f i c a t i o n a g a i n i n d i c a t e s s t r o n g l y t h a t more  b i r t h s o c c u r r e d on g e n t l e than on rugged  3.6.3  and  terrain.  E f f e c t s of Waves and Thermal C o n d i t i o n s on Cows' C h o i c e s of Birth Sites  I f , as T a b l e s 8, 9, and  10 suggest,  danger from waves a f f e c t e d  cows' s e l e c t i o n of b i r t h s i t e s , then cows should have borne t h e i r pups i n more p r o t e c t e d l o c a t i o n s d u r i n g p e r i o d s w i t h h i g h waves than they d i d d u r i n g p e r i o d s w i t h low waves. of water were important,  S i m i l a r l y , i f hot weather and  availability  cows should have borne pups c l o s e r to water  d u r i n g hot weather than they d i d d u r i n g c o o l e r weather.  T a b l e 11 i n d i c a t e s t h a t b i r t h s d i d occur on more p r o t e c t e d s i t e s d u r i n g p e r i o d s w i t h h i g h waves, and T a b l e 12 shows t h a t b i r t h s o c c u r r e d f u r t h e r from the sea d u r i n g p e r i o d s w i t h h i g h waves.  S i m i l a r l y , T a b l e 13 shows t h a t b i r t h s o c c u r r e d on wetter d u r i n g h o t t e r weather. temperature was  areas  However, s i m i l a r a n a l y s e s showed t h a t s u b s t r a t e  not s i g n i f i c a n t l y c o r r e l a t e d w i t h the d i s t a n c e s t h a t b i r t h s  o c c u r r e d from water, or w i t h the d i s t r i b u t i o n of b i r t h s between Area which was  e x p e r i m e n t a l l y d r i e d , and Area 11 which a c t e d as a c o n t r o l .  t i n g e n c y t a b l e s f o r these n o n - s i g n i f i c a n t a n a l y s e s appear i n Appendix  13 ConD.  31  T a b l e 11.  Areas on which b i r t h s o c c u r r e d v s . maximum wave i n t e n s i t y on days t h a t b i r t h s o c c u r r e d Wave I n t e n s i t y Calm-High P r o t e c t e d Areas (1,2,8,9,11, and 13)  92  Exposed Areas (4,5,6,7,10, and 12)  40  Percent on P r o t e c t e d Areas  70,  (x  T a b l e 12.  V e r y High 45  88  =6.72, df = 1, p<0.01)  D i s t a n c e s from shore a t which b i r t h s o c c u r r e d v s . maximum wave i n t e n s i t y on days t h a t b i r t h s o c c u r r e d Wave I n t e n s i t y Calm-Low  Medium  High  D i s t a n c e < 18.2 m from ^ 18.2 m shore  20  19  29  16  13  15  36  35  ^ 18.2 m  39  44  55  69  Percent (x  T a b l e 13.  2  V e r y High  = 8.62, d f = 3, p<0.05)  Areas on which b i r t h s o c c u r r e d v s . maximum s u b s t r a t e temperature on days t h a t b i r t h s o c c u r r e d Substrate  Temperature  < 17°C  » 17°C  28  46  27  82  51  36  Dryer Areas (7,9,10,12, and 13) Wetter  Areas  (2,3,4,5,8,  and 11)  Percent on Dryer Areas (x  2  = 3.58, df = 1, p<0.05)  32  3.7  R e l a t i o n s h i p Between L o c a t i o n s Where Cows Bore Pups and Where They Copulated ^ •  Cows c o p u l a t e d an average of 11.1 f i d e n c e l i m i t s , n = 35) a f t e r  days (+6.4  they bore t h e i r pups.  days, 95%  During t h i s  conperiod,  most cows were extremely sedentary, and o f t e n l a y i n v i r t u a l l y the same spot f o r s e v e r a l days a t a time. may  be the pup's s a f e t y .  a week o l d .  The r e a s o n f o r t h i s sedentary behaviour  Pups a r e v i r t u a l l y h e l p l e s s u n t i l they a r e over  Any unnecessary movement about  the c o l o n y by t h e i r mothers  would s u b j e c t the pups to i n c r e a s e d r i s k of b e i n g harmed by i r a t e cows, falling  i n t o a c r a c k or over a p r e c i p i c e , or f a l l i n g  into  the sea and  drowning.  Sedentary behaviour of post-partum c o p u l a t i n g near the b i r t h s i t e s .  cows r e s u l t e d i n most of them  Of 34 known cows, 68% c o p u l a t e d w i t h i n  10 meters, and 82% w i t h i n 15 meters of the l o c a t i o n s where they bore pups ( F i g u r e 8 ) .  their  Of 49 known cows, 80% c o p u l a t e d w i t h i n 10 meters of  the s i t e where they were l a s t seen w i t h t h e i r pups p r i o r  to c o p u l a t i n g  (Figure 9).  As i n d i c a t e d  i n F i g u r e 8, 11 cows moved more than 10 meters t o  t h e i r c o p u l a t i o n s i t e s from the s i t e s where they bore t h e i r pups. p r o v i d e s a d d i t i o n a l i n f o r m a t i o n about  these 11 cows and the moves they  made between c o p u l a t i o n and pups* b i r t h s i t e s . w i t h her pup  T a b l e 14  to a l e s s protected l o c a t i o n  Only 1 of the 11 cows moved  before copulating.  Four cows  moved w i t h t h e i r pups to more p r o t e c t e d s i t e s i n apparent response t o waves d u r i n g storms, and two cows c o p u l a t e d on more a c c e s s i b l e s i t e s w h i l e  33  20 15 . CC Ul CQ  10.  S z  5.  0 -5  >5 -10  DISTANCE F i g u r e 8.  >10 -15 IN  >15 -20  >20  METERS  D i s t a n c e s b e t w e e n l l o c a t i o n s where cows bore pups and l o c a t i o n s where they c o p u l a t e d  34  30.  20 J oc UJ CQ  10 J  _E3  0 -5  >5 -10  >10 -15  DISTANCE  F i g u r e 9.  >15 -20 IN  >20 -25  E2L  >25 -30  >30  METERS  D i s t a n c e s between cows' c o p u l a t i o n s i t e s and the s i t e s where cows were l a s t seen w i t h t h e i r pups  Table  14.  Movements of 11 cows t o c o p u l a t i o n s i t e s from the s i t e s where they bore t h e i r  Cow  Distance between sites i n meters  C h a r a c t e r i s t i c s of c o p u l a t i o n s i t e s as compared t o b i r t h s i t e s Water availability  pups  Comments  Accessibilityprotection  126  13.3  dryer  more p r o t e c t e d  5  15.2  wetter  more p r o t e c t e d  51  12.0  dryer  s l i g h t l y more protected  1  14.8  same  s l i g h t l y more protected  122  33.4  wetter  more a c c e s s i b l e  158  44.0  slightly wetter  more a c c e s s i b l e _  These cows c o p u l a t e d on a c c e s s i b l e s i t e s w h i l e t h e i r pups remained on p r o t e c t e d sites.  7  11.3  dryer  s l i g h t l y more accessible  T h i s i s the o n l y cow t h a t moved w i t h her pup t o a l e s s p r o t e c t e d s i t e .  114  14.2  wetter  more p r o t e c t e d  25  18.0  dryer  more a c c e s s i b l e  These cows moved w i t h t h e i r pups t o the v i c i n i t y o f t h e i r c o p u l a t i o n s i t e s i n apparent response t o l a r g e waves d u r i n g storms.  115  26.1  dryer  more a c c e s s i b l e  142  26.5  dryer  more a c c e s s i b l e  Before c o p u l a t i n g , these cows l o s t t h e i r pups d u r i n g storms o r abandoned them i n favour of j u v e n i l e s .  u>  36  t h e i r pups remained i n p r o t e c t e d l o c a t i o n s .  The remaining  4 cows l o s t  or abandoned t h e i r pups, and 3 of these cows moved t o more a c c e s s i b l e areas before c o p u l a t i n g .  I f u r t h e r examined cow movements t o c o p u l a t i o n s i t e s from pups' b i r t h s i t e s by c o r r e l a t i n g moves w i t h weather.  I reasoned t h a t i f waves  caused cows t o move, cows would move t o more p r o t e c t e d l o c a t i o n s more f r e q u e n t l y d u r i n g p e r i o d s of h i g h waves than they would d u r i n g p e r i o d s of low waves.  S i m i l a r l y , i f hot weather caused cows t o move nearer  cows would move t o wetter  t o water,  l o c a t i o n s more f r e q u e n t l y d u r i n g hot weather  than they would d u r i n g p e r i o d s of c o o l e r weather.  I considered  a cow as having moved i f i n any r e c o r d e d  she was l o c a t e d more than 10 meters from her p r e v i o u s l o c a t i o n .  observation Since I  wished t o examine moves made d u r i n g the time i n t e r v a l between when a cow bore her pup and when she c o p u l a t e d , o n l y moves t h a t cows made w i t h i n 11 days of t h e i r pups' b i r t h s o r f i r s t appearances were i n c l u d e d i n the analysis.  To i n s u r e independence between moves used i n the a n a l y s i s , I  used o n l y one randomly s e l e c t e d move from those wise c o n t r i b u t e .  t h a t each cow would  F i n a l l y , I excluded moves t h a t o c c u r r e d over more  otherthan  a 3 day i n t e r v a l because such moves f r e q u e n t l y encompassed a l l the extremes of weather and hence p r o v i d e d over  s h o r t e r time  l e s s i n f o r m a t i o n than moves t h a t o c c u r r e d  intervals.  Cows moved t o more p r o t e c t e d l o c a t i o n s more f r e q u e n t l y d u r i n g p e r i o d s w i t h high, waves than they d i d d u r i n g p e r i o d s w i t h low waves  37  (Table 1 5 ) .  Cows moved t o wetter  l o c a t i o n s , or got wetter  during  their  moves, more f r e q u e n t l y d u r i n g h o t t e r weather than they d i d d u r i n g c o o l e r weather  (Table 1 6 ) .  I mentioned e a r l i e r t h a t cows o c c u p i e d t h e c o l o n y s e q u e n t i a l l y , w i t h more a c c e s s i b l e l o c a t i o n s b e i n g occupied f i r s t and the most p r o t e c t e d locations last.  The manner i n which the most p r o t e c t e d areas were occupied  i n d i c a t e s the importance of l a r g e waves and the r e l a t i v e unimportance of water a v a i l a b i l i t y i n movements of cows w i t h young pups.  Areas 8, 9, and  13 were the most p r o t e c t e d , l e a s t a c c e s s i b l e a r e a s on the c o l o n y , and they were a l s o the d r i e s t .  Area 8 had a s m a l l p o o l on i t , Area  9 had no water,  and Area:13 had been e x p e r i m e n t a l l y d r i e d , a l t h o u g h a s m a l l amount o f water was a v a i l a b l e i n c r a c k s a f t e r r a i n . t h e s e A r e a s d u r i n g storms,  F i g u r e 10 shows t h a t cows moved onto  and t h a t t h e numbers of cows on t h e Areas r e -  mained h i g h f o r a t l e a s t two weeks a f t e r the major storm on June 11.  Thus,  l a r g e waves induced cows t o occupy these d r y , i n a c c e s s i b l e a r e a s , and most cows chose t o remain t h e r e f o r a t l e a s t two weeks i n s p i t e of 7 days of hot weather d u r i n g t h a t p e r i o d . s t r a t e temperature r e c o r d e d  I n f a c t , June 19 had the h o t t e s t sub-  i n 1973, but no exodus from the d r y a r e a s  occurred  as a r e s u l t .  3.8  3.8.1  S p a t i a l D i s t r i b u t i o n of C o p u l a t i o n s  G e n e r a l Comments  The  s p a t i a l d i s t r i b u t i o n of c o p u l a t i o n s observed  i n F i g u r e 11, and i s g e n e r a l l y s i m i l a r t o t h a t o f b i r t h s  i n 1973 i s shown  (Figure 7).  Only  38 T a b l e 15.  Moves made by cows v s . i n t e n s i t y of waves Maximum wave i n t e n s i t y d u r i n g move Calm-High Move t o location with:  (x  T a b l e 16.  More protection  8  L e s s or same protection  18  Percent of moves to more p r o t e c t e d location  31  Very  High 9  69  = 5 . 2 1 , d f = 1, p <0.05)  Moves made by cows v s . s u b s t r a t e temperature . Maximum s u b s t r a t e temperature d u r i n g move < 20°C Move t o location  t h a t was wetter or where cow'was wetter a f t e r move  ^ 20°C  9  9  t h a t was l e s s or s i m i l a r l y wet or where cow was n o t wetter a f t e r move  1_6_  __5  Percent of moves to wetter l o c ation  36  64  2.89,  df = 1, p < 0 . 0 5 )  80,  JUNE gure 10.  Numbers of: cows counted on Areas 8, 9, and 13 v s . wave (Stippled  JULY intensity  a r e a i n d i c a t e s d a t e s on whicb wave i n t e n s i t y was grade 5)  40  F i g u r e 11.  S p a t i a l d i s t r i b u t i o n of c o p u l a t i o n s on the c o l o n y  Legend: L o c a t i o n of observed copulation Area number  0  one  O  4  in  1973  40a  41  1 c o p u l a t i o n and no b i r t h s o c c u r r e d i n Areas 14, 15, and 16.  Similarly,  b o t h c o p u l a t i o n s and b i r t h s were i n f r e q u e n t or absent from Area 1, the west s i d e of A r e a 13, and the southwest  s i d e of A r e a  11.  Areas 6 and 4 were the o n l y l o c a t i o n s where the numbers of b i r t h s and c o p u l a t i o n s d i f f e r e d markedly.  These Areas had many more c o p u l a t i o n s  than b i r t h s , p o s s i b l y because Area 6 was ( F i g u r e 5 ) , Area 4 was  a major a c c e s s r o u t e from the sea  a minor a c c e s s r o u t e , and both Areas were h e a v i l y  f r e q u e n t e d by cows w i t h o u t pups ( F i g u r e s 4 and 5 ) .  3.8.2  E f f e c t s of Exposure t o Waves, A c c e s s i b i l i t y , A v a i l a b i l i t y of Water, Roughness of T e r r a i n on the S p a t i a l D i s t r i b u t i o n of C o p u l a t i o n s  Preliminary observations indicated  t h a t s p a t i a l d i s t r i b u t i o n of  c o p u l a t i o n s as w e l l as b i r t h s might be i n f l u e n c e d by r e l a t i v e exposure t o waves, a c c e s s i b i l i t y , and roughness  of t e r r a i n .  A l s o , Gentry  (1970) i n -  d i c a t e d t h a t a v a i l a b i l i t y of water f o r use i n t h e r m o r e g u l a t i o n might be i m p o r t a n t .  also  To t e s t the e f f e c t s of these f o u r f a c t o r s , I d i d the same  c o n t i n g e n c y and m u l t i p l e c l a s s i f i c a t i o n a n a l y s e s t h a t I d i d f o r b i r t h s .  I expected more c o p u l a t i o n s to occur on s i t e s w i t h more p r o t e c t i o n from waves, b e t t e r a c c e s s from the sea, l e s s rugged t e r r a i n ,  and  b e t t e r a v a i l a b i l i t y of water than I expected on s i t e s w i t h o p p o s i t e c h a r a c t e r istics.  As I d i d f o r b i r t h s , I expected simple c o r r e l a t i o n s w i t h t e r r a i n  roughness and water a v a i l a b i l i t y .  However, because  of t h e i M n t e r p l a y  between a c c e s s i b i l i t y and p r o t e c t i o n from waves, I expected more copu l a t i o n s on m o d e r a t e l y a c c e s s i b l e , m o d e r a t e l y p r o t e c t e d s i t e s than on a r e a s  42  of extreme a c c e s s i b i l i t y or p r o t e c t i o n .  R e s u l t s o f the c o n t i n g e n c y  analyses  appear i n T a b l e s 17, 18, and 19, and r e s u l t s of the m u l t i p l e c l a s s i f i c a t i o n a n a l y s i s appear i n T a b l e 20.  More c o p u l a t i o n s o c c u r r e d on more a c c e s s i b l e , l e s s p r o t e c t e d than on s i t e s t h a t were l e s s a c c e s s i b l e and more p r o t e c t e d .  The  sites  expected  peak i n numbers of c o p u l a t i o n s on a r e a s of moderate c h a r a c t e r i s t i c s does not appear i n T a b l e 17, p r o b a b l y because a c c e s s i b i l i t y - p r o t e c t i o n c l a s s e s 1 and 2 were combined because of inadequate  sample s i z e .  T h i s peak i s  e v i d e n t i n the m u l t i p l e c l a s s i f i c a t i o n a n a l y s i s (Table 20) which shows t h a t the maximum number of c o p u l a t i o n s per a r e a o c c u r r e d on c l a s s 2 a r e a s .  How-  e v e r , c l a s s 1 areas had o n l y s l i g h t l y fewer c o p u l a t i o n s than d i d c l a s s 2 a r e a s , so the peaking  t r e n d i s not n e a r l y as s t r o n g f o r c o p u l a t i o n s as i t  is for births.  The number of c o p u l a t i o n s per area i s s t r o n g l y c o r r e l a t e d w i t h ruggedness of t e r r a i n  (Table 18); t h a t i s , more c o p u l a t i o n s o c c u r r e d on a r e a s  w i t h l e v e l , g e n t l e t e r r a i n than on a r e a s w i t h steep or rugged  terrain.  More c o p u l a t i o n s o c c u r r e d on wet a r e a s than on d r y ones .(Table 19).  M u l t i p l e c l a s s i f i c a t i o n a n a l y s i s (Table 20) g i v e s r e s u l t s b a s i c a l l y s i m i l a r t o the c o n t i n g e n c y  a n a l y s e s i n T a b l e s 17, 18, and 19.  One  e x c e p t i o n i s t h a t m u l t i p l e c l a s s i f i c a t i o n a n a l y s i s shows t h a t t h e number o f c o p u l a t i o n s per a r e a peaked on a r e a s of c l a s s 2 a c c e s s i b i l i t y and p r o t e c t i o n , whereas c o n t i n g e n c y  a n a l y s i s does not demonstrate t h i s peak.  As i t i s f o r  43  T a b l e 17.  C o p u l a t i o n l o c a t i o n s v s . s i t e s ' a c c e s s i b i l i t i e s and p r o t e c t i o n from waves C l a s s e s of a c c e s s i b i l i t y and p r o t e c t i o n most p r o t e c t e d  Number of copulations per g r i d area  1 & 2  3 & 4  < 1  25 -  45 +  34 +  1-3.5  11 -  17 -  18 -  ••• 12 +  6 -  3 -  > 3.5 (x  T a b l e 18.  2  most a c c e s s i b l e 5  = 11.09, df = 4, p < 0 . 0 5 )  C o p u l a t i o n l o c a t i o n s v s . roughness of s i t e s ' t e r r a i n s C l a s s e s of t e r r a i n flattest 1 & .2 Number of copulations per g r i d area  <  3  4  1  35 -  30 +  39 +  1-3.5  28 +  14 +  4 -  18 +  3 -  0 -  > 3.5 (x  roughest  = 30.48, d f = 4, p<0.005)  44  T a b l e 19.  Copulation  l o c a t i o n s v s . s i t e s ' water  availabilities  C l a s s e s of water driest 1 Number of copulations per g r i d area  < 1 1-3.5 > 3.5  (x  2  = 13.54, df = 4, p < 0 . 0 1 )  availability wettest  2  3 & 4  30 +  49 +  25 -  7 -  20 -  19 +  1 -  8 -  12 +  Table 20. Multiple classification analysis of spatial distribution of copulations Class  Number of areas in class  Actual mean number of copulations per area  Adjusted mean number of copulations per area  1  16  2.44  2.14  2  32  2.84  2.57  3  38  1.56  1.37  4  30  0.54  0.91  "'. 5  55  0.91  1.11  1  29  3.56  3.44  Terrain  2  52  1.71  1.56  B = 0.124  3  47  1.20  1.19  4  43  0.16  0.46  1  38  0.53  1.14  2  77  1.32  1.19  3  36  2.35  2.15  4  20  Predictor variable and i t s B  Accessibilityprotection B = 0.049 z  2  Availability of water B = 0.030 2  :  2.47  .  2.23  Overall mean number of copulations per area - 1.50 Overall standard deviation in number of copulations per area = 2.76 Multiple R = 0.197 Adjusted means have been corrected for the effects of the other two variables (Andrews et a l , 1969) -o Ln  46  b i r t h s , t e r r a i n roughness i s by f a r the s t r o n g e s t 2 (B = 0 . 1 2 4 ) .  copulations (B  2  predictor variable for  A c c e s s i b i l i t y - p r o t e c t i o n i s next s t r o n g e s t 2 = 0.049), and water a v a i l a b i l i t y i s weakest (B = 0.030). Together,  the t h r e e p r e d i c t o r v a r i a b l e s a r e c o n s i d e r a b l y ulations  (multiple R  2  l e s s p r e d i c t i v e f o r cop-  = 0.197) than they a r e f o r b i r t h s ( m u l t i p l e R  2  =  0.435).  The copulations copulation  weaker c o r r e l a t i o n between the p r e d i c t o r v a r i a b l e s and  p r o b a b l y r e s u l t s from a combination of f a c t o r s .  Cows whose  l o c a t i o n s were used f o r a n a l y s i s v a r i e d enormously i n t h e i r  m a t e r n a l s t a t u s a t the time of t h e i r c o p u l a t i o n .  Some cows had borne  pups, some had n o t ; some s t i l l had l i v e pups, some had l o s t them i n storms or f o r other r e a s o n s ; most cows w i t h l i v e pups c o p u l a t e d few  cows c o p u l a t e d  copulated  away from t h e i r pups f o r v a r i o u s  near them, but a  r e a s o n s ; and some cows  w h i l e t h e i r pups were r e l a t i v e l y young, whereas o t h e r s  w h i l e t h e i r pups were o l d e r .  Also,  copulated  the l o c a t i o n s where cows c o p u l a t e d  pended not o n l y on the cows' s p a t i a l p r e f e r e n c e s ,  de-  but a l s o on those of the  cows' mates.  In c o n t r a s t , cows whose pupping l o c a t i o n s were used f o r a n a l y s i s had  by d e f i n i t i o n the same m a t e r n a l s t a t u s .  a t the b i r t h s i t e , and t h e i r c h o i c e s  These cows were w i t h t h e i r pups  of l o c a t i o n were n o t i n f l u e n c e d by the  p r e f e r e n c e s of mates.  A l l of the above d i f f e r e n c e s between c o p u l a t i o n and b i r t h d a t a a r e " r e a s o n s t o expect much more i n h e r e n t v a r i a b i l i t y i n a c o r r e l a t i o n u s i n g copulations  than i n one u s i n g b i r t h s .  47  3.8.3  E f f e c t s of Waves and Thermal C o n d i t i o n s on Cows' Choices Copulation Locations  If,  as T a b l e s 17 and  of  20 suggest, danger from waves a f f e c t e d  cows' s e l e c t i o n of c o p u l a t i o n s i t e s , c o p u l a t i o n s should have o c c u r r e d i n more p r o t e c t e d a r e a s d u r i n g p e r i o d s w i t h h i g h waves. a v a i l a b i l i t y of water f o r use  Similarly, i f  i n t h e r m o r e g u l a t i o n were important,  cop-  u l a t i o n s should have o c c u r r e d c l o s e r to water d u r i n g hot weather. expected  These  c o r r e l a t i o n s would be p a r t i c u l a r l y s t r o n g i f many p r e - e s t r o u s cows  moved f r e q u e n t l y i n d i r e c t response  to changes i n weather.  Such  response  would enable weather changes to d i r e c t l y i n f l u e n c e cows' l o c a t i o n s when cows became e s t r o u s . of  For example, p r e - e s t r o u s cows might abandon d r y  the c o l o n y i n f a v o u r of wet  areas  ones d u r i n g hot weather, or they might l e a v e  exposed a r e a s i n f a v o u r of p r o t e c t e d ones d u r i n g p e r i o d s of h i g h waves.  As p r e d i c t e d , fewer c o p u l a t i o n s than expected  o c c u r r e d on Area  d u r i n g h i g h waves when compared t o the more p r o t e c t e d Areas 4 and 21).  5  6  (Table  S i m i l a r a n a l y s e s showed no s i g n i f i c a n t e f f e c t of s u b s t r a t e temperature  oh c o p u l a t i o n ; l o c a t i o n s s e l e c t e d by cows- (Appendix E ) .  3.9  Summary of R e s u l t s  During May,  the f i r s t  t h i s study, the f i r s t  cows i n l a t e May.  e a r l y to mid-June, and l a t e May,  b u l l s a r r i v e d on the c o l o n y i n mid-  B i r t h s s t a r t e d i n l a t e May,  continued u n t i l l a t e June.  peaked i n l a t e June, and c o n t i n u e d u n t i l  peaked i n  Copulations started i n mid-July.  48  T a b l e 21.  D i s t r i b u t i o n of c o p u l a t i o n s among Areas 6, 4, and 5 v s . i n t e n s i t y o f waves: Wave, i n t e n s i t y low t o moderate  h i g h and v e r y  Area 6 (very exposed) •  24  7  Area 4  16  17  22  20  ( l e s s exposed) Area 5 (x  2  = 6.58, df = 2, p< 0.05)  high  49  At Cape S t . James, a p p r o x i m a t e l y  13% of cows a r e a l o n e , 10% a r e  accompanied o n l y by j u v e n i l e s , 56% o n l y by pups, and 22% by both and pups.  Cows w i t h pups tended  juveniles  t o occupy and c o p u l a t e on more p r o t e c t e d  s i t e s than d i d cows w i t h no pups.  T h i s l i k e l y r e l a t e s t o the s a f e t y of  pups who a r e v e r y v u l n e r a b l e t o b e i n g washed away and drowned by waves. Approximately 1973,  30% of the pups on the c o l o n y were k i l l e d  and such storms a r e p r o b a b l y  i n one storm i n  typical.  Cows used p r e f e r r e d l a n d i n g l o c a t i o n s as a c c e s s p o i n t s from the sea.  This resulted  i n newly landed e s t r o u s cows c o p u l a t i n g w i t h b u l l s whose  t e r r i t o r i e s i n c l u d e d the l a n d i n g s i t e s .  Cows tended  t o home to t h e same g e n e r a l l o c a t i o n of the c o l o n y  annually.  More b i r t h s o c c u r r e d on g e n t l e than on rugged t e r r a i n , and on a r e a s of moderate than on a r e a s of extreme a c c e s s i b i l i t y and p r o t e c t i o n from waves.  S p a t i a l d i s t r i b u t i o n of b i r t h s was n o t s i g n i f i c a n t l y  w i t h a v a i l a b i l i t y of water f o r use i n t h e r m o r e g u l a t i o n .  Multiple  correlated class-  i f i c a t i o n a n a l y s i s showed s p a t i a l d i s t r i b u t i o n of b i r t h s to be c o r r e l a t e d s t r o n g e s t w i t h ruggedness of t e r r a i n , next  s t r o n g e s t w i t h a c c e s s i b i l i t y and  p r o t e c t i o n from waves, and weakest w i t h a v a i l a b i l i t y of water.  During  stormy p e r i o d s when waves were h i g h , cows s e l e c t e d more  p r o t e c t e d s i t e s t o bear were low.  t h e i r pups on than they d i d d u r i n g times when waves  One a n a l y s i s i n d i c a t e d t h a t cows s e l e c t e d pupping  a r e a s d u r i n g h o t weather.  However, other a n a l y s e s f a i l e d  s i t e s on wet  t o demonstrate  50  a s i g n i f i c a n t e f f e c t of hot weather on the d i s t a n c e s from water t h a t cows chose to bear pups, or on whether cows chose to bear pups on a wet  area i n  p r e f e r e n c e to an a d j a c e n t area t h a t had been e x p e r i m e n t a l l y d r i e d .  Because of the sedentary h a b i t s of cows w i t h young pups, most cows t h a t bore pups c o p u l a t e d near the b i r t h s i t e . observed  t o c o p u l a t e more than 10 meters from t h e i r pups' b i r t h s i t e s , f o u r  had moved to more p r o t e c t e d s i t e s i n apparent storms,  Of the m i n o r i t y of cows  response  to waves d u r i n g  f o u r o t h e r s had moved to more a c c e s s i b l e a r e a s a f t e r l o s i n g  abandoning t h e i r pups, two  had  c o p u l a t e d on s i t e s removed from t h e i r pups,  p o s s i b l y en r o u t e to or from them, and i b l e , d r i e r l o c a t i o n w i t h her pup  one cow  had moved t o a more a c c e s s -  p r i o r to c o p u l a t i n g .  cows w i t h young pups i n d i c a t e d t h a t moves tended a r e a s d u r i n g p e r i o d s w i t h h i g h waves, and weather.  Moves made by known  to be to more p r o t e c t e d  to w e t t e r  l o c a t i o n s d u r i n g hot  However, the p a t t e r n i n which the d r y , l e a s t a c c e s s i b l e a r e a s  were p o p u l a t e d by cows i n d i c a t e d s t r o n g l y t h a t response waves was  or  of cows to l a r g e :  c o n s i d e r a b l y g r e a t e r than t h a t to hot weather.  S p a t i a l d i s t r i b u t i o n of c o p u l a t i o n s was b i r t h s , except  t h a t many more c o p u l a t i o n s than b i r t h s o c c u r r e d on the  p r o t e c t e d , most a c c e s s i b l e a r e a s . by cows without  s i m i l a r to t h a t of  pups and  good a c c e s s i b i l i t y and  These v i c i n i t i e s were h e a v i l y f r e q u e n t e d  served as a c c e s s p o i n t s to the r e s t of the  More c o p u l a t i o n s tended  least  colony.  to occur on g e n t l e r t e r r a i n , on a r e a s of  poor t o moderate p r o t e c t i o n from waves, and  a r e a s w i t h h i g h a v a i l a b i l i t y of water.  on  Multiple classification analysis  51  i n d i c a t e d t h a t s p a t i a l d i s t r i b u t i o n of c o p u l a t i o n s was c o r r e l a t e d w i t h ruggedness of t e r r a i n , next  strongest  s t r o n g e s t w i t h a c c e s s i b i l i t y and p r o t e c t i o n ,  and weakest w i t h a v a i l a b i l i t y of water.  D u r i n g p e r i o d s of h i g h waves, ".cows s e l e c t e d more p r o t e c t e d a r e a s of  the c o l o n y t o c o p u l a t e on than they d i d d u r i n g p e r i o d s of low waves.  Hot weather d i d not r e s u l t d u r i n g c o o l e r weather.  i n cows c o p u l a t i n g on wetter  a r e a s than they d i d  52  4.  4.1  DISCUSSION  Comparison w i t h Other  A b a s i c premise c o n f i n e cows i n harems.  Studies  i n t h i s study i s t h a t Eumetopias b u l l s do not T h i s assumption  has been s u b s t a n t i a t e d by e x t e n s i v e  o b s e r v a t i o n of i n d i v i d u a l l y r e c o g n i z a b l e cows i n t h i s study, and supported i n o t h e r r e c e n t s t u d i e s of Eumetopias (Gentry, 1973, Sandegren, 1970;  Orr and P o u l e t e r , 1967).  i s strongly 1970;  A l l these s t u d i e s and  the p r e s e n t  one agree t h a t Eumetopias b u l l s g a i n a c c e s s t o cows not by c o n f i n i n g harems, but by e s t a b l i s h i n g and d e f e n d i n g t e r r i t o r i e s i n a r e a s where cows congregate. T h i s b a s i c p a t t e r n seems common t o a l l O t a r i i d s s t u d i e d t o d a t e , Zalophus c a l i f o r n i a n u s a l u s spp.  ( P e t e r s o n and  ( M i l l e r , 1974;  (Hamilton, 1939,  1934;  Rand, 1967;  Bartholomew, 1967; P a u l i a n , 1964),  O r r , 1967), A r c t o c e p h -  Otaria flavescens  Vas F e r r e i r a , 1975), Neophoca c i n e r e a ( S t i r l i n g ,  Marlow, 1975), P h o c a r c t o s h o o k e r i (Marlow, 1975), and (Bartholomew, 1953;  including  Bartholomew and H o e l , 1953;  1972;  Callorhinus ursinus  P e t e r s o n , 1965,  1968).  Al-  though C a l l o r h i n u s b u l l s herd cows, p e r s i s t e n t cows can move where they choose (Bartholomew, 1953;  Bartholomew and H o e l , 1953;  P e t e r s o n , 1965,  1968).  Hence, as seems t r u e of most o t a r i i d s , the number of cows occupying a b u l l ' s t e r r i t o r y depends more on the p r e f e r e n c e of cows f o r the v i c i n i t y than on b u l l ' s a b i l i t y t o r e t a i n a harem.  The b a s i c p a t t e r n i n which b u l l s compete  f o r a p o s i t i o n among cows r a t h e r than attempt among the, polygynous P e t e r s o n , 1969;  (Boyd and Campbell, 1960).  p h o c i d s Mirounga spp.  Bartholomew, 1952; 1971;  the  t o c o n f i n e cows i s a l s o  (Le Boeuf, 1972;  found  Le Boeuf and  Laws, 1956), and H a l i c h o e r u s grypus  Cameron, 1967;  C o u l s o n and H i c k l i n g , 1964;  Hewer,  53  Hence, as  seems t y p i c a l among polygynous p i n n i p e d s ,  cows are f r e e to choose t h e i r  l o c a t i o n s on b r e e d i n g c o l o n i e s .  i n t u r n determines where and w i t h whom the cows c o p u l a t e . of the f a c t o r s t h a t i n f l u e n c e cows' p r e f e r e n c e s  Eumetopias This  choice  Thus, knowledge  f o r l o c a t i o n on c o l o n i e s i s  c r u c i a l to an u n d e r s t a n d i n g of the polygynous b r e e d i n g system i n Eumetopias.  T h i s study has i n f l u e n c e d by  demonstrated t h a t cows' l o c a t i o n s and  s e v e r a l f a c t o r s i n c l u d i n g , among o t h e r s ,  movements were  ease of a c c e s s from  the sea, p r o t e c t i o n of s i t e s from sea waves, ruggedness of t e r r a i n , a v a i l a b i l i t y of c o o l i n g water. the p i n n i p e d  1970), and  4.1.1  q u a n t i t a t i v e analyses  By f a r the b e s t d a t a have been p u b l i s h e d  even these a r e of l i m i t e d use  where they d i d . in this  A l l these f a c t o r s have been d i s c u s s e d  l i t e r a t u r e , but u n f o r t u n a t e l y ,  e f f e c t s are r a r e .  and  i n d i s c e r n i n g why  of  copulated  Below, I b r i e f l y r e v i e w each of the major f a c t o r s examined  Ease of A c c e s s From the  Sea  l i o n s ' l a n d i n g at the study c o l o n y were f a c e d w i t h a broken  p r e c i p i t o u s r o c k s h o r e l i n e , waves t h a t were f r e q u e n t l y v i o l e n t , and almost continuous t i d a l c u r r e n t . s k i l l and  ashore.  s e r i o u s l y h u r t or even k i l l e d  waves were h i g h .  calm water c o n d i t i o n s .  a d u l t cows make r e p e a t e d u n s u c c e s s f u l  f i n a l l y scrambling  I t appeared to me  strong,  D u r i n g h i g h waves,  attempts a t  landing  t h a t a sea l i o n  could  i f i t e r r e d i n a l a n d i n g attempt w h i l e  Such mishaps may  common on Eumetopias cows.  a  and  S u c c e s s f u l l a n d i n g appeared to r e q u i r e  e x p e r i e n c e under a l l but  I sometimes saw  be  (1973,  study.  Sea  before  their  by Gentry cows  in  account f o r some of the many l a r g e  scars  54  G i v e n these sometimes hazardous l a n d i n g c o n d i t i o n s , and t h e extreme h e t e r o g e n e i t y of the c o l o n y s h o r e l i n e , t h e h i g h p r e f e r e n c e t h a t cows showed f o r a few l a n d i n g spots was i n e v i t a b l e . two consequences f o r b r e e d i n g a c t i v i t y on the c o l o n y .  T h i s p r e f e r e n c e had First,  i t meant t h a t  cows r e t u r n i n g i n e s t r u s to the c o l o n y were p r o b a b l y s e r v i c e d by t h e few b u l l s whose t e r r i t o r i e s i n c l u d e d the f a v o u r e d l a n d i n g l o c a t i o n s . e s t a b l i s h e d t h e observed  p a t t e r n i n which cows a r r i v i n g f i r s t  settled i n  areas c l o s e s t t o f a v o u r e d l a n d i n g s p o t s , and cows a r r i v i n g l a t e r occupied areas f u r t h e r and f u r t h e r  sequentially  inland.  S e q u e n t i a l o c c u p a t i o n of a c c e s s i b l e s i t e s f i r s t  and l e s s a c c e s s -  i b l e ones l a t e r i s a common p a t t e r n among polygynous p i n n i p e d s . been r e c o r d e d f o r Eumetopias  Second, i t  I t has  (Gentry, 1970), C a l l o r h i n u s (Bartholomew, 1953;  P e t e r s o n , 1965, 1968), H a l i c h o e r u s (Cameron, 1969; C o u l s o n and H i c k l i n g , 1964), and Mirounga  ( C a r r i c k e t a l , 1962).  Although d e t a i l s d i f f e r .among s p e c i e s , a c c e s s p a t t e r n s have been found  t o i n f l u e n c e where cows of s e v e r a l polygynous p i n n i p e d s c o p u l a t e .  example,  For  i n C a l l o r h i n u s , cows sometimes c o p u l a t e on t h e i r way t o t h e s e a .  T h i s f a c t a p p a r e n t l y r e s u l t e d i n b u l l s who owned t e r r i t o r i e s a l o n g r o u t e s of  d e p a r t u r e c o p u l a t i n g more f r e q u e n t l y than would be expected  of  the s i z e of t h e i r harems (Bartholomew and H o e l , 1953).  on the b a s i s  Halichoerus  cows a l s o c o p u l a t e en r o u t e t o the sea (Boyd and Campbell, 1971), so a c c e s s p a t t e r n s may a l s o a f f e c t where cows of t h i s s p e c i e s c o p u l a t e .  In Mirounga,  d e p a r t i n g cows f r e q u e n t l y r u n a g a u n t l e t of sub-dominant b u l l s , and a r e bred by s e v e r a l o f them b e f o r e e s c a p i n g t o sea (Le Boeuf, 1972).  In  55  Leptonychotes  w e d d e l l i , mature b u l l s e s t a b l i s h underwater t e r r i t o r i e s t h a t  a p p a r e n t l y permit the b u l l s t o i n t e r c e p t and c o p u l a t e w i t h cows i n t r a n s i t to and from b r e a t h i n g h o l e s i n f a s t  ice (Stirling,  1975).  Thus, i n summary, i t seems t h a t a c c e s s from the sea i s p r o b a b l y important  i n t h e o r g a n i z a t i o n of b r e e d i n g c o l o n i e s of many polygynous  species.  Although p a t t e r n s i n other s p e c i e s d i f f e r  Eumetopias, t h e p r i n c i p l e s seem the same.  In v i r t u a l l y a l l s t u d i e d s p e c i e s ,  cows occupy r e l a t i v e l y a c c e s s i b l e a r e a s f i r s t , later.  i n d e t a i l from those i n  and l e s s a c c e s s i b l e  areas  In s e v e r a l s p e c i e s , e s t r o u s cows i n t r a n s i t a r e s u b j e c t t o b e i n g  bred by b u l l s who own a c c e s s r o u t e s , or who by v i r t u e of s o c i a l rank a r e a b l e t o i n t e r c e p t cows on those r o u t e s .  4.1.2  P r o t e c t i o n of S i t e s from Sea Waves  D u r i n g one storm i n 1973, 30% of the pups b e l o n g i n g t o known cows d i s a p p e a r e d .  I s t r o n g l y suspect t h a t  t h i s 30% i s a c o n s e r v a t i v e  e s t i m a t e of o v e r a l l pup m o r t a l i t y d u r i n g t h e storm because my known cows p r o b a b l y tend to be those r e s i d e n t i n t h e more p r o t e c t e d areas near t h e observation b l i n d .  Cows l o c a t e d out of s i g h t a t the n o r t h e r n end of the  c o l o n y p r o b a b l y s u f f e r e d g r e a t e r pup l o s s , and because they were u s u a l l y out of s i g h t from t h e b l i n d , they were l e s s l i k e l y t o have been i n c l u d e d i n my c a t a l o g u e of known cows.  Pup counts b e f o r e and a f t e r the storm  a m o r t a l i t y of a p p r o x i m a t e l y  50%.  indicated  Hence, s i n c e about h a l f of the observed  b i r t h s had o c c u r r e d p r i o r t o t h e storm, r o u g h l y between 15% and 25% o f all  the pups born on the c o l o n y i n 1973 were k i l l e d  i n the one storm  event.  56  D u r i n g t h i s storm I saw waves sweep more than a dozen pups i n t o the s e a .  Once i n the s e a , the pups were q u i c k l y c a r r i e d away by t h e s w i f t  t i d a l current.  Many more pups were tumbled  over t h e c o l o n y s u r f a c e by  r u s h i n g water and dumped i n t o c r e v i c e s o r steep s i d e d p o o l s t o d i e . r e g u l a r l y sent water over e i g h t y  f e e t h i g h i n t o t h e a i r and broke  a p p r o x i m a t e l y h a l f the c o l o n y a r e a w i t h f o r c e s u f f i c i e n t b u l l s v i o l e n t l y through the a i r . Almost  Waves over  t o knock a d u l t  a l l the r e s t of the c o l o n y was  h i t p e r i o d i c a l l y w i t h waves s u f f i c i e n t l y p o w e r f u l to p h y s i c a l l y move a d u l t cows.  Furthermore,  l a t e r at night. S t . James. one  I d i d n ' t see the worst  of the storm because i t happened  I suspect t h a t such v i o l e n t  storms a r e commonplace a t Cape  A s l i g h t l y l e s s severe one .-.occurred i n 1972, and a much worse  i n 1974.  The g i s t of the above i s t h a t waves k i l l many pups a t Cape S t . James.  T h i s f a c t was r e f l e c t e d  i n many ways i n the r e s u l t s o f t h i s  Young pups were seen o n l y on i s l a n d s i n the Kerouard p a r e n t a c c e s s to h i g h ground.  study.  group t h a t had ap-  A l t h o u g h t e r r i t o r i a l b u l l s and numerous  a d u l t cows were seen on i s l a n d s without  such a c c e s s , pups were n o t .  the study i s l a n d , cows w i t h pups tended  t o occupy and c o p u l a t e on more  p r o t e c t e d areas than d i d cows without pups.  The d r i e s t , l e a s t  On  accessible  a r e a s were p o p u l a t e d by cows d r i v e n t h e r e by l a r g e waves, and, i n s p i t e of the h o t t e s t temperature  r e c o r d e d , these cows chose t o remain and cop-  u l a t e i n these a r e a s r a t h e r than move w i t h t h e i r pups to l e s s p r o t e c t e d locations.  The d i f f e r e n c e between s p a t i a l p r e f e r e n c e s of cows w i t h pups and cows without  them was n e a t l y demonstrated  by a n a t u r a l  "experiment"  57  performed by the A l a s k a earthquake i n 1964. Eumetopias  P r i o r to the earthquake,  cows pupped m a i n l y on the n o r t h s i d e of Lewis I s l a n d .  The  s o u t h s i d e of the i s l a n d had an a r e a of s m a l l r o c k i s l e t s i n h a b i t e d by about 100 cows and t h e i r y e a r l i n g s  (Sandegren, 1970).  D u r i n g the e a r t h -  quake, the former pupping a r e a on the n o r t h s i d e of the i s l a n d was by a r o c k l a n d s l i d e , and i s no l o n g e r used by b r e e d i n g cows. a l s o caused the i s l a n d  The  covered earthquake  t o r i s e about 5 meters, thereby t r a n s f o r m i n g t h e r o c k  i s l e t s on the south s i d e of the i s l a n d beach i s now  only  i n t o a rugged bedrock beach.  the main pupping a r e a on the i s l a n d .  This  The i n f e r e n c e i s t h a t  p r i o r t o the earthquake, the a r e a of r o c k i s l e t s was u n s a f e f o r pups and c o n s e q u e n t l y was  used o n l y by cows e i t h e r a l o n e or w i t h j u v e n i l e s .  r a i s e d 5 meters, the a r e a was  s a f e and was  However, the "experiment" would  then used by cows f o r pupping.  have been more c o n c l u s i v e i f the beach on  the n o r t h s i d e of the i s l a n d had remained by  Once  i n t a c t i n s t e a d of b e i n g covered  landslides.  I t has l o n g been suspected t h a t storms k i l l many Eumetopias Everman (1921) d e s c r i b e d severe m o r t a l i t y on the Ano Nuevo c o l o n y . and P o u l t e r  pups.  Orr  (1967) concluded i n s t u d i e s a t Ano Nuevo t h a t Eumetopias  pups  s u f f e r e d s e r i o u s m o r t a l i t y d u r i n g t h e i r f i r s t month of l i f e , and t h a t the p r i n c i p l e cause of death was  drowning.  P i k e and Maxwell  t h a t e a r l y m o r t a l i t y i n B r i t i s h Columbia was s p o r a d i c h i g h m o r t a l i t y would  (1958) thought  g e n e r a l l y s l i g h t , but t h a t  o c c u r d u r i n g storms, e s p e c i a l l y a t c e r t a i n  rookeries.  My  o b s e r v a t i o n s s t r o n g l y c o n f i r m Orr and P o u l t e r ' s  (1967) con-  c l u s i o n t h a t pups drown not because they cannot swim, but because  they  58  cannot climb back out of the sea once swept i n t o washed i n t o  I saw many pups  the sea, but I d i d not see one land a g a i n .  away q u i c k l y by the s t r o n g t i d a l c u r r e n t . retrieve  it.  They were  I never observed  carried  an a d u l t cow  a pup from the s e a .  Pups of other p i n n i p e d s p e c i e s a r e a l s o k i l l e d i n s i g n i f i c a n t numbers by waves.  Boyd e_t a l (1962) f e l t  that v i r t u a l l y a l l Halichoerus  pups born on the r o c k y f o r e s h o r e of North Rona were washed away by waves. However, a l a t e r study  (Summers e t a l , 1975) f a i l e d to demonstrate  m o r t a l i t y , perhaps because l i t t l e work was done on the f o r e s h o r e .  such Carrick  e t a l (1962) mentioned t h a t some Mirounga pups were washed away by waves, but t h a t t h i s  source of m o r t a l i t y was s l i g h t .  t h a t a c c e s s t o h i g h ground was important not say whether he had observed  S t i r l i n g (1971) c o n s i d e r e d  t o A r c t o c e p h a l u s cows, but d i d  pups b e i n g k i l l e d by waves.  In summary, pups of s e v e r a l polygynous p i n n i p e d s a r e k i l l e d by waves d u r i n g storms.  Such m o r t a l i t y seems p a r t i c u l a r l y  severe i n Eumetopias,  so i t i s no s u r p r i s e t h a t p r o t e c t i o n of s i t e s from waves should be i n f l u e n t i a l i n the s p a t i a l o r g a n i z a t i o n of the Cape S t . James c o l o n y .  4.1.3  Ruggedness of T e r r a i n  The  study i s l a n d  The western h a l f  of the i s l a n d  j u t t i n g up out of the s e a . where the animals  a t Cape S t . James has extremely v a r i a b l e t e r r a i n . i s largely  j u s t a jumble of r o c k p i n n a c l e s  T h i s a r e a has extremely  can h a u l out of the sea.  few f l a t ,  The e a s t e r n h a l f  l e v e l surfaces of the i s l a n d i s  thus the o n l y a r e a t h a t c o n t a i n s s i g n i f i c a n t amounts of f l a t o r g e n t l y sloping terrain. activity  occurs.  Consequently,  i t i s on t h i s e a s t e r n s i d e t h a t a l l b r e e d i n g  59  Even t h i s e a s t e r n s i d e has h i g h l y v a r i a b l e t e r r a i n .  A t one  extreme, Area 1 ( F i g u r e 1) and p a r t s of Area 13 a r e v e r y rugged and a r e d i s s e c t e d by deep c r a c k s and steep  s i d e d p o o l s i n t o which pups can f a l l .  A t t h e o p p o s i t e extreme, Areas 3, 5, and p a r t s of 13 and 11 a r e v e r y and  flat  c o n t a i n no dangerous c r a c k s or p o o l s .  T h i s study demonstrated s t r o n g c o r r e l a t i o n s between t h e roughness of a s i t e ' s t e r r a i n and the number of b i r t h s and c o p u l a t i o n s t h a t there.  occurred  Cows p r e f e r r e d a r e a s w i t h g e n t l y s l o p i n g or l e v e l s u r f a c e s and an  absence of deep c r a c k s or c l i f f s t h a t would endanger pups.  In v i e w of the s t r o n g r e s u l t s found i n t h i s study,  there i s  s u r p r i s i n g l y l i t t l e mention of the importance of t e r r a i n roughness i n the literature.  S t u d i e s on Eumetopias a t Ano Nuevo I s l a n d  (Gentry, 1970;  Orr and P o u l t e r , 1967) make v i r t u a l l y no mention of t e r r a i n roughness. I t was my i m p r e s s i o n  during a v i s i t  c o l o n y i s f a r more u n i f o r m  t o Ano Nuevo t h a t the t e r r a i n i n t h i s  and l e s s rugged than i t i s a t Cape S t . James.  Under such c o n d i t i o n s , t h e i n f l u e n c e of t e r r a i n might be l e s s and  l e s s obvious than i t i s a t Cape S t . James.  t e r r a i n roughness t o be important a t i v e a n a l y s i s of the s u b j e c t . on h i s c o l o n y o c c u r r e d  important  Sandegren (1970) found  a t Lewis I s l a n d , but he d i d no q u a n t i t -  However, he d i d mention t h a t most b i r t h s  i n two s m a l l f l a t  areas about 8 by 10 and 5 by  8 meters i n s i z e .  S t u d i e s on p i n n i p e d s  other  than Eumetopias a l s o make  little  mention o f the e f f e c t of t e r r a i n i n d i s t r i b u t i o n o f cows i n b r e e d i n g colonies.  I n h i s s t u d i e s on A r c t o c e p h a l u s ,  Stirling  (1971)  concluded  60  t h a t a c c e s s t o areas a f f o r d i n g p r o t e c t i o n from storm waves was important, so t e r r a i n roughness i s important to-:this a n i m a l a t l e a s t i n s o f a r a s i t can p e r m i t or prevent  such a c c e s s .  C o u l s o n and H i c k l i n g  (1964) found i n  s t u d i e s of H a l i c h o e r u s t h a t c o l o n i e s i n which t e r r a i n p e r m i t t e d fewer or more r e s t r i c t e d a c c e s s r o u t e s t o and from the sea had h i g h e r pup m o r t a l i t y . However, these a u t h o r s d i d not q u a n t i t a t i v e l y a n a l y s e the e f f e c t s of t e r r a i n per se on the s e a l s .  C a r r i c k e t a l (1962) f e l t  t h a t Mirounga tended t o  choose b r e e d i n g a r e a s on beaches t h a t a f f o r d e d easy a c c e s s f o r pregnant cows.  Bartholomew (1952) p o i n t e d out t h a t Mirounga i s rendered  immobile by rough, b o u l d e r strewn t e r r a i n .  virtually  Hence, the p r e f e r e n c e elephant  s e a l s show f o r sandy beaches may r e s u l t from t h e i n f l u e n c e of rugged r a i n on the animal's  ter-  mobility.  In summary, the l a r g e i n f l u e n c e of t e r r a i n roughness found i n t h i s study has n o t been r e p o r t e d i n o t h e r s t u d i e s . other s t u d i e s have not performed  I t h i n k t h i s i s p a r t l y because  the a p p r o p r i a t e q u a n t i t a t i v e a n a l y s e s ,  and p a r t l y because the extremely rugged  r o c k i s l e t s t h a t Eumetopias i n -  h a b i t s make t h e i n f l u e n c e of t e r r a i n more important and apparent  i n this  species.  4.1.4  A v a i l a b i l i t y of C o o l i n g Water  P i n n i p e d s a r e h i g h l y adapted  to aquatic l i f e  T y p i c a l l y , they a r e v e r y w e l l i n s u l a t e d , they produce  i n c o l d sea water. 1.7 t o 2.6 times as  much m e t a b o l i c heat as t e r r e s t r i a l mammals of t h e same weight do  (Matsuura  and Whittow, 1973), and they have l e s s body s u r f a c e a r e a than p r e d i c t e d by  61  g e n e r a l mammalian r e l a t i o n s h i p s  ( I v e r s o n and Krog,  1973).  Consequently,  p i n n i p e d s a r e v e r y s u s c e p t i b l e t o o v e r h e a t i n g w h i l e on l a n d . example, many f u r s e a l s have d i e d of hyperthermia i n l a n d d u r i n g the P r i b i l o f  seal harvest  For  grim  while being slowly  (Bartholomew and W i l k e ,  herded  1956).  Because of t h e i r a d a p t a t i o n t o c o l d water, a l l p i n n i p e d s p r o b a b l y e x h i b i t b e h a v i o u r a l mechanisms f o r t h e r m o r e g u l a t i o n w h i l e on l a n d ( f o r examples see Gentry, 1971,  1972;  O d e l l , 1974;  White and O d e l l , 1971;  W i l k e , 1956).  Whittow e t a l , 1972;  Fay and Ray,  1968;  Stirling,  and Bartholomew and  B e h a v i o u r a l t h e r m o r e g u l a t i o n i n Eumetopias i s more or  t y p i c a l and was heat  1973;  d e s c r i b e d i n d e t a i l by Gentry  (1970, 1973).  G e n e r a l l y , as  l o a d i n g from: i n s o l a t i o n i n c r e a s e s , the sea l i o n s i n c r e a s e t h e i r  l o s s by exposing more body s u r f a c e a r e a t o c o o l a i r or r o c k , and w e t t i n g t h e i r f l i p p e r s and other p a r t s of t h e i r b o d i e s .  t h e i r time i n i t . by Gentry  heat  later  When thermal  d i t i o n s become too s e v e r e , the sea l i o n s move to water and  less  by con-  spend most of  A l l of the v a r i o u s t h e r m o r e g u l a t o r y b e h a v i o u r s d e s c r i b e d  (1970, 1973)  f o r Eumetopias were observed  to some degree i n cows  a t Cape St. James.  However, Gentry t h e r m o r e g u l a t i o n was c o p u l a t e d a t Ano  (1970) concluded  the most important  t h a t a v a i l a b i l i t y of water f o r  f a c t o r i n f l u e n c i n g where cows  Nuevo I s l a n d , whereas i n t h i s study I conclude  f a c t o r i s s i g n i f i c a n t , but r e l a t i v e l y unimportant apparent  a t Cape S t . James.  d i f f e r e n c e between the f i n d i n g s of the two  and p a r t l y a r e s u l t  of methodology.  that t h i s  studies i s partly  This real  62  Gentry  (1970) concluded  that a v a i l a b i l i t y of water i n f l u e n c e d  where cows c o p u l a t e d because he found d r y i n l a n d l o c a t i o n s d u r i n g low high.  H i s argument c o n t a i n s two  f e r e n c e from r e c o r d e d  t h a t cows on h i s study a r e a  i n s o l a t i o n and wet important  occupied  s h o r e l i n e areas  flaws.  during  F i r s t , he drew h i s i n -  l o c a t i o n s of a l l cows on the c o l o n y , not j u s t  pre-  e s t r o u s cows.  As pups get o l d e r , cows g r a d u a l l y move toward the s h o r e l i n e  of  so t h a t by the l a t t e r p a r t of J u l y , most animals  the c o l o n y ,  to the s h o r e l i n e .  have moved  Hence, i n c l u s i o n of many p o s t - e s t r o u s cows may  bias  results.  Second, he c o l l e c t e d h i s t h e r m o r e g u l a t o r y August 3.  About h a l f of the c o p u l a t i o n s he observed  d a t a from June 21 to occurred p r i o r to t h i s  time p e r i o d , presumably d u r i n g somewhat c o o l e r weather. time p e r i o d i n c l u d e d more than two c o p u l a t i o n was  observed.  Further,  this  presumably warmer weeks a f t e r the  Thus, Gentry's i n f e r e n c e was  last  based on a l a r g e  p r o p o r t i o n of p o s t - e s t r o u s cows, perhaps under warmer c o n d i t i o n s than would be r e p r e s e n t a t i v e of those me  to suspect  availability  The  t h a t he may  have o v e r - e s t i m a t e d  i n determining  Nuevo l i e s over  where cows c o p u l a t e d .  a t Ano  water a v a i l a b i l i t y may  Nuevo than i t was  at Cape St. James.  15° i n l a t i t u d e south of Cape S t . James, so mid-day  p r o b a b l y much more i n t e n s e t h e r e .  Hence, Gentry  s u b s t r a t e temperatures as h i g h as 36°C, whereas I r e c o r d e d 24 C.  These b i a s e s l e a d  the importance of water  above arguments n o t w i t h s t a n d i n g ,  have been more important  a t i o n was  i n f l u e n c i n g p r e - e s t r o u s cows.  A l s o , Gentry observed  still Ano insol-  (1970) r e c o r d e d them o n l y up  to  mass movements of a l l cows to water when i n -  s o l a t i o n changed a b r u p t l y , whereas I never observed  such mass movements  63  even from the d r i e s t a r e a s on the c o l o n y temperatures I r e c o r d e d .  during  At Ano Nuevo, l a r g e numbers of  cows r e s o r t e d t o water o n l y a f t e r s u b s t r a t e 26 C.  My s u b s t r a t e  temperatures reached approx-  temperatures never got t h a t h o t .  In summary, cows a t my study c o l o n y r e g u l a t o r y b e h a v i o u r , but i t a p p a r e n t l y copulated.  This observation  Eumetopias.  substrate  The l a c k of such movements a t Cape S t . James i s  q u i t e c o n s i s t e n t with Gentry's r e s u l t s .  imately  the h o t t e s t  d i d demonstrate thermo-  d i d not g r e a t l y i n f l u e n c e where they  d i f f e r s from Gentry's c o n c l u s i o n s  (1970) f o r  The d i f f e r i n g r e s u l t s between the two s t u d i e s r e f l e c t  differences  i n methods of i n f e r e n c e , and d i f f e r e n c e s i n c l i m a t e between the two study areas.  4.2  R e l a t i v e Importance of F a c t o r s Cape S t . James  Several  I n f l u e n c i n g Where Cows Copulated a t  site characteristics including a c c e s s i b i l i t y ,  from waves, and t e r r a i n roughness, and other and  protection  f a c t o r s such as a c c e s s  routes  the tendency f o r cows t o home a l l s i g n i f i c a n t l y i n f l u e n c e where cows  copulate  on Cape S t . James c o l o n y .  which of these v a r i o u s  My d a t a cannot q u a n t i t a t i v e l y prove  f a c t o r s was most i n f l u e n t i a l .  However, the d a t a  warrant s p e c u l a t i v e comment, so i n t h i s s e c t i o n I w i l l d i s c u s s my  general  impressions.  I t h i n k t h a t the g e n e r a l colony  d i s t r i b u t i o n of c o p u l a t i o n s  over the study  p r i m a r i l y r e f l e c t s the t r a d e o f f between s i t e s ' a c c e s s i b i l i t i e s and  t h e i r p r o t e c t i o n from sea waves.  Cows without pups g e n e r a l l y move o n l y f a r  64  enough from the sea t o ensure far  t h e i r own  comfort, and  cows w i t h pups move  enough i n l a n d t o p r o t e c t t h e i r pups from sea waves.  As the more  a c c e s s i b l e s i t e s become o c c u p i e d , cows move f u r t h e r i n l a n d t o f i n d able locations. r e a s o n why  T h i s a c c e s s - p r o t e c t i o n - c r o w d i n g t r a d e o f f i s the main  cows f i l l e d  the c o l o n y s e q u e n t i a l l y from more a c c e s s i b l e t o l e s s  a c c e s s i b l e a r e a s and why  cows without pups p r e f e r r e d more a c c e s s i b l e  l o c a t i o n s than d i d cows w i t h pups. of  accept-  The d i f f e r e n c e between the p r e f e r e n c e s  cows w i t h and w i t h o u t pups has been documented i n o t h e r s t u d i e s  1970;  T h o r s t e i n s o n and L e n s i n k , 1962), and  the s e q u e n t i a l f i l l i n g of c o l o n i e s  i s t y p i c a l among c o l o n i a l l y b r e e d i n g p i n n i p e d s  ( f o r examples see  1970;  1964).  Bartholomew, 1953;  My  Coulson and H i c k l i n g ,  i m p r e s s i o n of the importance  e s t i m a t e t h i s importance  Gentry,  of the a c c e s s - p r o t e c t i o n - c r o w d i n g  t r a d e o f f d i f f e r s somewhat from r e s u l t s of my d i s t r i b u t i o n of b i r t h s and c o p u l a t i o n s .  (Sandegren,  statistical  a n a l y s e s of  F r a n k l y , I t h i n k my  spatial  a n a l y s e s under-  because they express the i n t e g r a t e d end r e s u l t of  the whole b r e e d i n g season.  The  a n a l y s e s i g n o r e the important  imparted by the s e q u e n t i a l manner i n which the c o l o n y was  information  occupied.  The  i n t e g r a t e d p i c t u r e e f f e c t i v e l y masks the p r o c e s s e s whereby the cows ended up where ^hey d i d .  I t h i n k the o t h e r i n f l u e n c e s on cows operated p r i m a r i l y w i t h i n the c o n f i n e s of the g e n e r a l p a t t e r n e s t a b l i s h e d by the a c c e s s - p r o t e c t i o n crowding  tradeoff.  The most important  secondary  James would appear t o be ruggedness of t e r r a i n .  i n f l u e n c e a t Cape S t . Thus, as cows f i l l e d  the  c o l o n y i n a manner p r i m a r i l y d i c t a t e d by a c c e s s , p r o t e c t i o n from waves, and  65  crowding,  they tended t o choose r e l a t i v e l y f l a t ,  c r a c k s or p r e c i p i c e s .  The remainder  l e v e l a r e a s away from  of i n f l u e n c e s on cows, a l t h o u g h  sig-  n i f i c a n t , were c o n s i d e r a b l y l e s s important than the a c c e s s - p r o t e c t i o n crowding  t r a d e o f f and t e r r a i n roughness.  Thus, a few cows were inseminated  i n t r a n s i t a t l a n d i n g s p o t s or a l o n g a c e s s r o u t e s , a few more i n l o c a t i o n s chosen f o r t h e r m o r e g u l a t o r y r e a s o n s , and no doubt i n t h i s study.  a few f o r reasons missed  Cows tended t o home, but somewhere i n p r e v i o u s y e a r s , t h e r e  must have been an o r i g i n a l c h o i c e of s i t e t h a t depended on i n f l u e n c e s o t h e r than homing.  These o r i g i n a l i n f l u e n c e s probably:..included the f a c t o r s found  to a f f e c t d i s t r i b u t i o n and movements o f cows i n t h i s  study.  In summary, I t h i n k the t r a d e o f f between a c c e s s , p r o t e c t i o n waves, and crowding was  the most important f a c t o r d e t e r m i n i n g s p a t i a l  t r i b u t i o n of c o p u l a t i o n s on the study c o l o n y .  T e r r a i n roughness  was  most important, and operated p r i m a r i l y w i t h i n c o n f i n e s e s t a b l i s h e d by tradeoff.  disnext this  The r e m a i n i n g f a c t o r s i n c l u d i n g a c c e s s p a t t e r n s , a v a i l a b i l i t y of  water, and homing, a l t h o u g h s i g n i f i c a n t , were of r e l a t i v e  4.3  from  Sexual S e l e c t i o n and  unimportance.  Polygyny  In t h i s study, I have c o n c e n t r a t e d almost e x c l u s i v e l y on  factors  t h a t i n f l u e n c e movements and d i s t r i b u t i o n of cows w i t h i n the s p a t i a l of one pupping c o l o n y . t h e r e remains  Beyond c o n s i d e r a t i o n of these f a c t o r s , however,  the p e r p l e x i n g q u e s t i o n of why  p i n n i p e d s choose  limits  Eumetopias and other  t o breed i n such extremely dense a g g r e g a t i o n s .  polygynous The same  q u e s t i o n i n p r i n c i p l e can be l i k e w i s e asked of numerous other s p e c i e s  66  i n c l u d i n g l e k breeders  such as the Uganda kob, Adenota kob  1966), the sage grouse, C e n t r o c e r c u s urophasianus  (Leuthold,  (Wiley, 1973), and  the  r u f f , Philomachus pugnax (Hogan-Warburg, 1966), and c o l o n i a l b r e e d e r s as weaver b i r d s , P l o c e u s spp.  (Crook,  such  1965).  There has been much d i s c u s s i o n of t h i s t o p i c i n the  literature,  and much of i t has aimed a t i d e n t i f y i n g f u n c t i o n a l or a d a p t i v e r o l e s f o r polygyny  i n s p e c i e s t h a t use the system.  Wynne-Edwards  (1962), Armitage  (1962), and Coulson and H i c k l i n g (1964) have argued t h a t polygyny h e l p s keep s p e c i e s ' p o p u l a t i o n s w i t h i n the c a p a b i l i t y of a v a i l a b l e food s u p p l i e s . V a r i o u s a u t h o r s have s t r o n g l y c o n t e s t e d t h i s group s e l e c t i o n argument and have proposed Peterson  alternatives  (1968) suggested  p i n n i p e d s may and  (Crook, 1965;  McLaren, 1967;  O r i a n s , 1969).  t h a t the dense a g g r e g a t i o n s found among b r e e d i n g  f a c i l i t a t e communication between b r e e d i n g a n i m a l s .  Bartholomew (1967) suggested  t h a t polygyny  to get the sexes t o g e t h e r a t the r i g h t mentioned t h a t polygyny  i n p i n n i p e d s might  time of y e a r .  Stirling  serve  (1975)  i n p i n n i p e d s might r e l i e v e p r e s s u r e on l o c a l  supplies while b u l l s are f a s t i n g .  C a r r i c k e_t a l (1962) suggested  b r e e d i n g a g g r e g a t i o n s of elephant s e a l s may  food  that  have, a t l e a s t a t some time  i n the p a s t , have served as p r o t e c t i o n of pups from p r e d a t o r s . proposed  Peterson  t h a t t e r r i t o r i a l Galapagos sea l i o n s , Zalophus  Barlow (1972)  californianus  co-  o p e r a t e i n d r i v i n g sharks from the v i c i n i t y of the c o l o n y , thus p r o t e c t i n g cows and  pups.  My  p o i n t i s t h a t much d i s c u s s i o n has f o c u s s e d on proposed  functional  or a d a p t i v e advantages of the dense b r e e d i n g a g g r e g a t i o n s found among p i n -  67  nipeds. of  Peterson  (1968) e x e m p l i f i e d t h e p h i l o s o p h y t h a t may  t h i s p r e o c c u p a t i o n when he s t a t e d , "There can be l i t t l e  the  u n d e r l i e much  doubt t h a t  e l a b o r a t e systems of s o c i a l o r g a n i z a t i o n seen i n p i n n i p e d s have appeared,  first  and f o r e m o s t , as a d a p t a t i o n s t o an amphibious mode of l i f e . "  (my  emphasis).  T h i s statement, and much d i s c u s s i o n i n the l i t e r a t u r e a  illustrate  fundamental m i s u n d e r s t a n d i n g and u n d e r e s t i m a t i o n of the p r o c e s s of s e x u a l  selection.  McLaren  (1967) and Crook (1965) b o t h emphasized the f r e q u e n t l y  underestimated p o t e n t i a l c a p a c i t y of s e x u a l s e l e c t i o n to d r a s t i c a l l y a  alter  s p e c i e s u n t i l s t r o n g c o u n t e r s e l e c t i o n h a l t s the p r o c e s s of change.  The magnitude of the i n f l u e n c e t h a t s e x u a l s e l e c t i o n may i n c i s i v e l y p o i n t e d out by F i s h e r male b i r d s as an example.  (1958).  have  was  He used plumage development i n  B r i e f l y , he argued t h a t i f t h e r e e x i s t s a plumage  c h a r a c t e r i n males t h a t imparts a r e p r o d u c t i v e advantage over males w i t h o u t it,  females w i l l be s e l e c t e d f o r the p r o p e n s i t y to mate w i t h males w i t h  the  s u c c e s s f u l plumage p a t t e r n .  Thus, female p r e f e r e n c e f o r the plumage  p a t t e r n f u r t h e r enhances i t s r e p r o d u c t i v e advantage t o males, and t h e r e b y a c c e l e r a t e s s e l e c t i o n f o r the p a t t e r n i n males.  The more advantageous the  plumage c h a r a c t e r becomes t o males, the more advantageous to females becomes the  p r o p e n s i t y t o choose i t .  The more the females choose i t , the more  advantageous i t becomes t o males.  Thus plumage development and female  p r e f e r e n c e f o r i t e v o l v e a t an e v e r a c c e l e r a t i n g pace u n t i l r e s u l t i n g f o r example the  counterselection,  from p r e d a t i o n on the more c o n s p i c u o u s males, a r r e s t s  p r o c e s s a t an e q u i l i b r i u m between  the opposing s e l e c t i v e  forces.  68  Thus, F i s h e r become trapped  (1958) i d e n t i f i e d the p o t e n t i a l f o r a s p e c i e s to  i n a p o s i t i v e feedback i n t e r a c t i o n between s e l e c t i o n f o r any  c h a r a c t e r i n one  sex, and p r e f e r e n c e f o r t h a t c h a r a c t e r i n the o t h e r .  c r u c i a l importance here  i s the d i s t i n c t p o s s i b i l i t y t h a t t h i s  Of  positive  feedback c o u l d a r i s e from female p r e f e r e n c e f o r c h a r a c t e r i s t i c s dr  sit-  u a t i o n s other than simple a n a t o m i c a l f e a t u r e s of p o t e n t i a l mates.  For  example, the feedback may  be p o s s i b l e between t e r r i t o r i a l i t y i n males, and  p r e f e r e n c e t o occupy crowded t e r r i t o r i e s i n females. probably  l i e s the o r i g i n of the extremely  T h e r e i n , I submit,  dense b r e e d i n g a g g r e g a t i o n s  polygynous p i n n i p e d s , and perhaps a l s o of v a r i o u s l e k b r e e d e r s gynous c o l o n i a l  and  of  poly-  breeders.  I propose t h a t the extreme polygyny  seen today  i n O t a r i i d s began  when e s t r o u s cows became c o n c e n t r a t e d , f o r whatever r e a s o n s , a l l y d e f e n s i b l e (term a f t e r Brown, 1964)  i n economic-  groups on c o a s t a l b r e e d i n g  areas.  T e r r i t o r i a l i t y i n males would then be i n e v i t a b l e , and males would compete h a r d e s t f o r a r e a s t h a t , by v i r t u e of t h e i r a c c e s s i b i l i t y , p r o t e c t i o n from sea waves, or other c h a r a c t e r i s t i c s , had e s t r o u s cows.  the g r e a t e s t c o n c e n t r a t i o n s of  Bulls that successfully appropriated favourable locations  w i t h many cows would be r e p r o d u c t i v e l y more s u c c e s s f u l t h a t b u l l s t h a t d i d not.  Consequently,  cows would be s e l e c t e d f o r the p r e f e r e n c e to breed  in  a r e a s a l r e a d y c o n t a i n i n g many cows, because these p l a c e s a r e where the h i g h l y c o m p e t i t i v e and  s u c c e s s f u l b u l l s would be.  The  b u l l s t h a t had  suc-  c e s s f u l l y e s t a b l i s h e d themselves w i t h i n these c o n c e n t r a t e d groups of cows would be more l i k e l y to s i r e c o m p e t i t i v e l y s u c c e s s f u l sons than  bulls  69  elsewhere would.  Hence cows t h a t chose to breed  defended by v i g o r o u s b u l l s would be more l i k e l y  i n concentrated  groups  to have s u c c e s s f u l sons.  Thus, female p r e f e r e n c e f o r a r e a s w i t h c o n c e n t r a t i o n s of cows, i e . female g r e g a r i o u s n e s s , would enhance the r e p r o d u c t i v e advantage o b t a i n e d by males t h a t were h i g h l y t e r r i t o r i a l , and even more advantageous f o r females  t h i s enhancement would i n t u r n make i t to become more g r e g a r i o u s .  So i t would  go, w i t h b r e e d i n g a c t i v i t i e s becoming more and more c o n c e n t r a t e d o u r a b l e l o c a t i o n s and becoming f i e r c e r and would have reached it  in fav-  c o m p e t i t i o n between ever more s e x u a l l y dimorphic fiercer.  I f F i s h e r ' s concept  i s correct, this  i t s l i m i t s v e r y q u i c k l y i n e v o l u t i o n a r y time.  males  process  Hence,  i s i n t e r e s t i n g t h a t even f o s s i l s from the a n c e s t r a l group common to  O t a r i i d s and Odobeniids  may  a l r e a d y demonstrate s e x u a l dimorphism  indicative  of a polygynous h a b i t (Repenning, 1975).  Thus, c o n t r a r y to some p u b l i s h e d d i s c u s s i o n , I do not b e l i e v e t h a t the extreme form of polygyny  among p i n n i p e d s e v o l v e d as a  a d a p t a t i o n to the a n i m a l s ' ways of l i f e .  Rather,  I think this  functional breeding  system i n polygynous p i n n i p e d s r e f l e c t s p o s i t i v e feedback mechanisms f i r s t proposed by F i s h e r (1958) and  l a t e r supported  extreme development of polygyny spectacular, a r t i f a c t The  f a c t o r s found  study may  by McLaren (1967).  i n modern p i n n i p e d s i s a s i m p l e ,  The albeit  of s e x u a l s e l e c t i o n and n a t u r a l s e l e c t i o n combined.  to i n f l u e n c e d i s t r i b u t i o n and movements of cows i n t h i s  have been r e s p o n s i b l e f o r the v a r i a b i l i t y i n s p a t i a l c o n c e n t r a t i o n  of e s t r o u s cows t h a t o r i g i n a l l y set o f f the p o s i t i v e feedback between the e v o l u t i o n of male t e r r i t o r i a l i t y and  female  gregariousness.  70  ACKNOWLEDGEMENTS  T h i s study c o u l d n o t have been accomplished without t h e generous a s s i s t a n c e and keen i n t e r e s t of many p e r s o n s .  I p a r t i c u l a r l y wish t o  thank my s u p e r v i s o r , Dr. H.D. F i s h e r , f o r support and encouragement  through-  out t h e study.  I a l s o wish::to thank A l t o n Harestad f o r many i n t e r e s t i n g and i n f o r m a t i v e d i s c u s s i o n s and f o r c o n s t a n t encouragement d u r i n g of the study.  I a l s o g r a t e f u l l y acknowledge t h e l o g i s t i c  from the Departments of Environment  a l l phases  support r e c e i v e d  and T r a n s p o r t , and the generous  assist-  ance r e c e i v e d by many departmental s t a f f , e s p e c i a l l y Messrs. Dave K u p i l l a s , N e i l W i l s o n , K i t Godin, Hugh Ashworth, and t h e C a p t a i n and crew of t h e S i r Alexander  Mackenzie.  Finally,  I extend v e r y s p e c i a l thanks t o my two f i e l d a s s i s t a n t s ,  Dan C l a r k and Stacey T e s s a r o . times extremely hazardous  Without  t h e i r w i l l i n g a s s i s t a n c e under some-  c o n d i t i o n s , t h i s study would not have been  feasible.  T h i s study was supported w i t h funds from the N a t i o n a l  Research  C o u n c i l of Canada, t h e U n i v e r s i t y Grants O f f i c e of the F i s h e r i e s Research Board of Canada, and t h e U.S. N a t i o n a l Geographic  Society.  71  LITERATURE CITED  Andrews, F., J . Morgan, and J . S o n q u i s t . 1969. M u l t i p l e C l a s s i f i c a t i o n Analysis: A Report on a Computer Program f o r M u l t i p l e R e g r e s s i o n U s i n g C a t e g o r i c a l P r e d i c t o r s . U n i v e r s i t y of M i c h i g a n , Ann A r b o r , Michigan. 131 pp.  Armitage,  K.B. 1962. 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The grey s e a l H a l i c h o e r u s grypus a t North Rona 1959 - 1968. J . Z o o l . Lond. 164:469-512.  Boyd, J.M., J.D. J o c k i e , and H.R. Hewer. 1962. The b r e e d i n g c o l o n y of grey s e a l s on North Rona. Proc. Z o o l . Soc. Lond. 138:257-277.  Cameron, A.W. 1967. Breeding Behaviour i n a c o l o n y of Western A t l a n t i c Grey S e a l s . Can. J . Z o o l . 45:161-173.  Cameron, A.W. 1969. Behaviour of a d u l t grey s e a l s ( H a l i c h o e r u s grypus) i n the e a r l y stages of the b r e e d i n g season. Can. J . Z o o l . 47:229-233.  72  Campbell, R.C. 1967. London.  Statistics forBiologists.  Cambridge U. P r e s s ,  C a r r i c k , R., S.E. Csordas, S.E. Ingham, and K. K e i t h . 1962. S t u d i e s on the s o u t h e r n elephant s e a l , Mirounga l e o n i n a ( L . ) . IV Breeding and development. C.S.I.R.O. W i l d l . Res. 7:161-197.  Coulson, J.C. and G. H i c k l i n g . 1964. 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Dover,  Ph.D. t h e s i s ,  Behaviour 46:  Hamilton, J . E . 1934. The s o u t h e r n sea l i o n , O t a r i a b y r o n i a (de B l a i n v i l l e ) A D i s c . Rep. 8:269-318.  1939. A second r e p o r t on the southern sea l i o n , O t a r i a b r y o n i a (de Blainville). D i s c . Rep. 19:121-164.  Hewer, H.R. 1960. Behaviour of t h e g r e y s e a l ( H a l i c h o e r u s grypus, Fab.) i n b r e e d i n g season. Mammalia 24:400-431.  73  Hogan-Warburg, A . J . 1966. S o c i a l behaviour L. Ardea 54:109-229.  of the R u f f , Philomachus pugnax  I v e r s o n , J.A. and J . Krog. 1973. Heat p r o d u c t i o n and body s u r f a c e a r e a i n s e a l s and sea o t t e r s . Norw. J . Z o o l . 21:51-54.  Laws, R.M.  1956. The elephant s e a l (Mirounga s o c i a l , and r e p r o d u c t i v e b e h a v i o u r .  leonina Linn.) I I General, F.I.D.S. S c i . Rep. #13. 88 p.  LeBoeuf, B.J. 1972. Sexual behaviour i n the n o r t h e r n elephant Mirounga a n g u s t i f b s t f i s . Beh. 41:1-26.  seal,  LeBoeuf, B.J. and R.S. P e t e r s o n . 1969. S o c i a l s t a t u s and mating i n elephant s e a l s . S c i e n c e 163:91-93.  L e u t h o l d , W.  1966.  V a r i a t i o n s i n t e r r i t o r i a l behaviour  Beh. 27:214-257.  McLaren, I.A.  1967.  S e a l s and group s e l e c t i o n .  Ecology  activity  of the Uganda kob.  48:104-110.  Marlow, B . J . 1975. The comparative behaviour of the A u s t r a l i a n sea l i o n s , Neophoca c i n e r e a and P h o c a r c t o s h o o k e r i . ( P i n n i p e d i a : O t a r i i d a e ) . Mammalia 39:159-230.  Matsuura, D.T. and G.C. Whittow. 1973. Oxygen uptake of the C a l i f o r n i a sea l i o n and harbour s e a l d u r i n g exposure t o heat. Am. J . P h y s i o l . 225:711-715.  M i l l e r , E.H. 1974. S o c i a l behaviour between a d u l t male and female New Zealand f u r s e a l s , A r c t o c e p h a l u s f b r s t e r i (Lesson) d u r i n g the b r e e d i n g season. Aus. J . Z o o l . 22:155-173.  Newcombe, C.F., W.H. Greenwood, and C. F r a s e r . 1918. The sea l i o n q u e s t i o n i n B.C. C o n t r . t o Can. B i o l , f o r 1914-17, Sess. Pap 33a:l-51.  O d e l l , D.K. 1974. B e h a v i o u r a l t h e r m o r e g u l a t i o n of the C a l i f o r n i a sea l i o n . Beh. B i o l . 10:231-237.  74  O r i a n s , G.H. 1969. On the e v o l u t i o n of mating systems i n b i r d s and mammals. Am. Nat. 103:589-603.  O r r , R.T.  1967.  The Galapagos sea l i o n .  J . Mamm. 48:62-69.  O r r , R.T. and T.C. P o u l t e r . 1967. Some o b s e r v a t i o n s on r e p r o d u c t i o n , growth, and s o c i a l behaviour i n the S t e l l e r sea l i o n . Proc. C a l i f . Acad. S c i . 35:193-226.  P a u l i a n , P. 1964. C o n t r i b u t i o n a l ' e t u d e de l ' o t a r i e de l ' i s l e Mammalia 28;1-146.  Amsterdam.  P e t e r s o n , R.S. 1965. Behaviour of t h e n o r t h e r n f u r s e a l . Ph.D. t h e s i s , Johns Hopkins Univ., B a l t i m o r e , M a r y l a n d . 214 p.  P e t e r s o n , R.S. 1968. S o c i a l behaviour i n p i n n i p e d s w i t h p a r t i c u l a r r e f e r e n c e t o the n o r t h e r n f u r s e a l , pp 3-51 IN: Behaviour and p h y s i o l o g y of p i n n i p e d s . R . J . H a r r i s o n e d . , A p p l e t o n , Centuryc r o f t s , N.Y., N.Y. 411 p.  P e t e r s o n , R.A. and G.A. Bartholomew. 1967. The N a t u r a l H i s t o r y and Behaviour of t h e C a l i f o r n i a Sea L i o n . S p e c i a l Pub. #1, Am. Soc. Mammalogists. 79 p.  P i k e , G.C. and B.E. Maxwell. 1958. The abundance and d i s t r i b u t i o n o f the n o r t h e r n sea l i o n (Eumetopias j u b a t a ) on the c o a s t o f B r i t i s h Columbia. J . F i s h . Res. Bd. Can. 15:5-17.  Rand, R.W.  1967. The Cape f u r s e a l , 3. G e n e r a l behaviour on l a n d and a t sea. I n v e s t i g a t i o n a l Report, D i v . Sea F i s h e r i e s S. A f r i c a 60:1-39.  Repenning, C.A. 1975. O t a r i o i d e v o l u t i o n . E x p l o r . Mer. 169:27-33.  Rapp. P.-v. Reun. Cons.  int.  Sandegren, F.E. 1970. Breeding and m a t e r n a l behaviour of the S t e l l e r sea l i o n (Eumetopias j u b a t a ) i n A l a s k a . M.Sc. T h e s i s , U n i v e r s i t y of A l a s k a , F a i r b a n k s , A l a s k a .  75  Stirling,  I . 1971. S t u d i e s on t h e behaviour of t h e south A u s t r a l i a n f u r s e a l , A r c o t o c e p h a l u s f b r s t e r i ( L e s s o n ) . I Annual c y c l e , p o s t u r e s , c a l l s , and a d u l t males d u r i n g t h e b r e e d i n g season. Aust. J . Z o o l . 19:243-266.  1972. O b s e r v a t i o n s on the A u s t r a l i a n sea l i o n , Neophoca c i n e r e a (Peron). A u s t . J . Z o o l . 20:271-279.  '  1975. F a c t o r s a f f e c t i n g t h e e v o l u t i o n of s o c i a l b e h a v i o u r i n t h e P i n n i p e d i a . Rapp. P.-v. Reun. Cons. i n t . E x p l o r . Mer. 169:205-212.  Summers, C.F., R.W. Burton, and S.S. Anderson. 1975. Grey s e a l ( H a l i c h o e r u s grypus) pup p r o d u c t i o n a t N o r t h Rona: A study of b i r t h and s u r v i v a l s t a t i s t i c s c o l l e c t e d i n 1972. J . Z o o l . Lond. 175:439-451.  T h o r s t e i n s o n , F.V. and C . J . L e n s i n k . 1962. B i o l o g i c a l o b s e r v a t i o n s of S t e l l e r sea l i o n s taken d u r i n g an e x p e r i m e n t a l h a r v e s t . J . W i l d l . Mgmt. 24:353-359.  Vas F e r r e i r a , R. 1975. Behaviour of t h e s o u t h e r n sea l i o n , O t a r i a f l a v e s c e n s (Shaw) i n t h e Uruguayan I s l a n d s . Rapp. P.-v. Reun. Cons. i n t . E x p l o r . Mer. 169:219-227.  Whittow, G.C., D.T. Matsuura, and Y.C. L i n . 1972. Temperature i n the C a l i f o r n i a sea l i o n (Zalophus c a l i f o r n i a n u s ) . Z o o l . 45:68-77.  regulation Physiol.  White, F.N. and D.K. O d e l l . 1971. Thermoregulatory behaviour of the n o r t h e r n e l e p h a n t s e a l , Mirounga a n g u s t i r o s t r i s . J . Mammal. 52:758-774.  Wiley, R.H. 1973. T e r r i t o r i a l i t y and non-random mating C e n t r o c e r c u s u r o p h a s i a n u s . Anim. Beh. Mono.  i n sage grouse,  Wynne-Edwards, V.C. 1962. Animal D i s p e r s i o n i n R e l a t i o n t o S o c i a l O l i v e r and Boyd, Edinburgh. 653 p.  Behaviour.  76 Appendix A.  Sample sketches from cow  identification  file.  77  S4  E 2.f«o€/  B3^iy^  Legend: D.B. dk It M.B. M.D.B.  -  dark brown dark light medium brown medium dark brown  Notes a t top r i g h t of each c a r d a r e coded i n f o r m a t i o n d e s c r i b i n g the f i r s t s i g h t i n g made of the cow.  ^  78  Appendix B.  Sampling procedure used t o o b t a i n s i g h t i n g s shown i n F i g u r e  The  l o c a t i o n s of s i g h t i n g s used i n F i g u r e 4 a r e a  4.  systematic  sample of s i g h t i n g s of known cows observed i n 1973.  S i g h t i n g s of known cows w i t h no pups were s e l e c t e d simply by i n c l u d i n g the f i r s t  and e v e r y subsequent f i f t h  s i g h t i n g f o r each cow f o r  the e n t i r e summer.  S e l e c t i o n of s i g h t i n g s of cows w i t h pups was more complex. concerned w i t h how a young pup might a f f e c t where i t s mother So,  I was  copulated.  o n l y s i g h t i n g s on o r p r i o r to the e l e v e n t h day a f t e r the pup was  first  seen, and i n which the cow was w i t h her pup were e l i g i b l e f o r s e l e c t i o n . Of the e l i g i b l e s i g h t i n g s f o r a g i v e n cow, the f i r s t t h r i t e e n t h s i g h t i n g was i n c l u d e d i n F i g u r e  No s i g h t i n g s made a f t e r t a g g i n g  and e v e r y subsequent  4.  operations  occurred  were i n c l u d e d  in this analysis.  Records f o r 68 cows w i t h pups were used i n the f i g u r e . 68 cows, 48 c o n t r i b u t e d contributed  1 or 2 s i g h t i n g s , 10 c o n t r i b u t e d 3 or 4, and 10  5 or 6.  Records f o r 21 cows w i t h o u t pups were used. contributed and  Of these  Of these cows, 2  1 or 2 s i g h t i n g s , 9 c o n t r i b u t e d 3 o r 4, 4 c o n t r i b u t e d  6 c o n t r i b u t e d from 7 to 11.  5 or 6,  Appendix C.  Spatial distribution  of b i r t h s v s . a v a i l a b i l i t y  C l a s s e s of water driest 1 Number of Copulations  1 1-3.5 3.5  (x  2  1  = 8.58, d f = 4, p > 0 . 0 5 )  of water.  availability wettest  2  3 & 4  29 +  44 -  30 -  8 -  17 +  12 +  •1 -  16 +  14 +  80  Appendix D.  Table D - l .  S p a t i a l d i s t r i b u t i o n of b i r t h s v s . s u b s t r a t e temperature.  D i s t a n c e s t h a t b i r t h s o c c u r r e d from water v s . s u b s t r a t e temperature Substrate <17°C  Table D-2.  2  >17°C •  0 - 5m  17  49  5 - 15m  32  68  6  11  15m (x  temperature  = 0.965, df = 2,  p>0.05)  D i s t r i b u t i o n of b i r t h s between Areas 11 and 13 v s . s u b s t r a t e temperature ' Substrate  temperature  o < 17 C  ^ o £ 17 C  Area 11 (wet)  7  31  Area 13 ( e x p e r i m e n t a l l y d r a i n e d )  9  33  (x  2  = 0.113, d f = 1,  p>0.05)  81  Appendix E.  E f f e c t s of temperature on cows' c h o i c e s of c o p u l a t i o n s i t e s .  Table E - l .  Areas on which cows c o p u l a t e d v s . s u b s t r a t e temperature a t the time of c o p u l a t i o n Substrate  temperature  < 17°C  *17°C  52  17  127  30  D r y e r Areas (1,3,7,8,9,10,13) Wetter Areas (2,4,5,6,11,12) (x T a b l e E-2.  2  = 0.899, df = 2, p > 0 . 0 5 )  D i s t r i b u t i o n of c o p u l a t i o n s between Areas 11 and 13 v s . subs t r a t e temperature a t time of c o p u l a t i o n Substrate  temperature  < 17°C  £ 17°C  Area 11 (wet)  17  12  Area 13 ( e x p e r i m e n t a l l y d r a i n e d )  21  6  (x  T a b l e E-3.  2  = 2.35, df = 1, p>0.05)  D i s t a n c e s cows c o p u l a t e d from water v s . s u b s t r a t e at time of c o p u l a t i o n Substrate  temperature  < 17°C  » 17°C  0 - 5m  41  15  5 - 15m  89  22  49  10  15m (x  2  temperature  = 1.81, df = 2, p > 0 . 0 5 )  

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