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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 jubata) ON A PUPPING COLONY B.Sc, 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 i n the Faculty of Graduate Studies i n the Department of Zoology We accept t h i s thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA by A l l a n George Edie MASTER OF SCIENCE A l l a n George Edie, 1977 In presenting t h i s t hesis In p a r t i a l f u l f i l m e n t of the requirements for the advanced degree at the U n i v e r s i t y of B r i t i s h Columbia, I agree that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e for reference and study. I further agree that permission f o r extensive copying of t h i s t hesis f o r scholarly purposes may be granted by the head of my Department or by h i s representatives.. I t i s understood that copying or publishing of t h i s t hesis for f i n a n c i a l gain s h a l l not be allowed without my written 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 V6T 1W5 i i ABSTRACT Eumetopias jiibata i s highly polygynous, but cows are free to move where they choose on pupping colonies. Consequently, the s p a t i a l preferences of pre^estrous cows greatly influence the reproductive success of established 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 recognizable cows on an undisturbed pupping colony to i d e n t i f y environmental and other f a c t o r s that influence s p a t i a l p ref-erences of pre-estrous cows. Results ind i c a t e that movements and d i s t r i b u t i o n of pre-estrous cows p r i m a r i l y r e f l e c t tradeoffs between s i t e s * a c c e s s i b i l i t i e s from the sea, protection from waves, and degrees of crowding. Cows without pups generally t r a v e l only f a r enough inland to f i n d a vacant r e s t spot not splashed by waves. Cows with pups use re s t spots that are farther inland and more protected from waves. Other s i g n i f i c a n t influences i n s p a t i a l preferences of pre-estrous cows are ruggedness of t e r r a i n , the tendency to "home", patterns of access on the colony, and a v a i l a b i l i t y of water f or use i n thermo-regulation. Cows tend strongly to occupy l e v e l , f l a t areas away from pr e c i p i c e s or deep c l e f t s i n the rock substrate of the colony. Some cows apparently are 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 that include highly preferred access routes. Cows tend to home to the same v i c i n i t y of the colony i n successive years. Cows tend somewhat to frequent areas with ready access to water used i n thermoregulation. i i i I propose an evolutionary sequence i n which the extreme con-centration of breeding O t a r i i d s i n space can be accounted f or by p o s i t i v e feedback mechanisms i n sexual s e l e c t i o n that were f i r s t proposed by R. A. Fisher i n 1929. i v TABLE OF CONTENTS Page Abstract i i L i s t of Tables v i L i s t of Figures v i i i L i s t of Appendices i x 1. Introduction 1 2. Ma t e r i a l s and Methods 4 2.1 The Study Area 4 2.2 C l a s s i f i c a t i o n of Sea Lions by Size and Sex 4 2.3 Data C o l l e c t i o n 6 2.3.1 General Procedures 6 2.3.2 I n d i v i d u a l l y Recognizable Cows 7 2.3.3 Births and Copulations 9 2.3.4 Access Patterns 9 2.3.5 Censuses 9 2.3.6 Weather 10 2.3.7 T e r r i t o r i a l Boundaries of Bu l l s 11 3. Results 12 3.1 Chronology of the Breeding Season 12 3.2 Composition of the Cow Population: Presence of Suckling Offspring 12 3.3 Preference for D i f f e r e n t Locations on the Colony: Cows With Pups vs. Cows Without 15 3.4 Access Routes 15 3.5 Homing of Cows to the Same Part of the Colony from Year to Year 18 3.6 S p a t i a l D i s t r i b u t i o n of Birt h s 23 3.6.1 General Comments 23 3.6.2 E f f e c t s of Protection from Waves, Access-i b i l i t y , A v a i l a b i l i t y of Water, and Rough-ness of Terrain on S p a t i a l D i s t r i b u t i o n of Births 26 3.6.3 E f f e c t s of Waves and Thermal Conditions on Cows' Choices of B i r t h Sites 30 3.7 Relationships Between Locations Where Cows Bore Pups and Where They Copulated 32 3.8 S p a t i a l D i s t r i b u t i o n of Copulations 37 3.8.1 General Comments 37 3.8.2 E f f e c t s of Exposure to 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 Ter 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 Copulations 41 3.8.3 E f f e c t s of Waves and Thermal Conditions on Cows' Choices of Copulation Locations 47 3.9 Summary of Results 47 V 4. Discussion 52 4.1 Comparison With Other Studies 52 4.1.1 Ease of Access From the Sea 53 4.1.2 Protection of Sites From Sea Waves 55 4.1.3 Ruggedness of Te r r a i n 58 4.1.4 A v a i l a b i l i t y of Cooling Water 60 4.2 Relative Importance of Factors Influencing Where Cows Copulate at Cape St. James 63 4.3 Sexual Selection and Polygyny 65 Acknowledgements 70 L i t e r a t u r e Cited 71 LIST OF TABLES Copulation s i t e s of known cows: degree of exr posure vs. whether or not cows had pups. Copulation s i t e s of u n i d e n t i f i e d cows: degree of exposure to waves vs. whether or not the cows were seen to j o i n a pup a f t e r copulating. Copulation s i t e s of u n i d e n t i f i e d cows: degree of exposure to waves vs. whether or not cows were seen to j o i n a j u v e n i l e a f t e r copulating. Location of landing vs. whether or not a cow was observed leaving the b u l l ' s t e r r i t o r y that she landed on. Location of copulation vs. whether or not a cow was observed leaving the Area that she copulated on. Location of copulations vs. whether or not a cow was observed leaving the Area she copulated on: an a l y s i s of Areas 6, 8, and 13. Tendency of cows to return to the same side of the colony from year to year. B i r t h l o c a t i o n s vs. s i t e s ' a c c e s s i b i l i t i e s and protection from waves. B i r t h l o c a t i o n s vs. roughness of s i t e s ' t e r r a i n 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 d i s -t r i b u t i o n of b i r t h s . Areas on which b i r t h s occurred vs. maximum wave i n t e n s i t y on days that b i r t h s occurred. Distances from shore at which b i r t h s occurred vs. maximum wave i n t e n s i t y on days that b i r t h s occurred Areas on which b i r t h s occurred vs. maximum substrat temperature on days that b i r t h s occurred. Movements of 11 cows to copula 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 vs. i n t e n s i t y of waves. Moves made by cows vs. substrate temperature. Copulation locations vs. s i t e s ' a c c e s s i b i l i t i e s and protection from waves. Copulation locations vs. roughness of s i t e s ' t e r r a i n s . Copulation locations vs. 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 alysis of s p a t i a l d i s t r i b -u t i o n of copulations. D i s t r i b u t i o n of copulations among Areas 6, 4, and 5 vs. i n t e n s i t y of waves. V l l l LIST OF FIGURES Figure Page 1 The colony. 5 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 3 Temporal d i s t r i b u t i o n of b i r t h s and copulations during 1972 and 1973. 14 4 S p a t i a l d i s t r i b u t i o n of sightings of cows with and without pups. 16 5 Landing s i t e s on the north side of the colony. 19 6 Tendency for cows to return to the same part of the colony from year to year. 21 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 on the colony i n 1973. 24 8 Distances between locatio n s where cows bore pups and locati o n s where they copulated. 33 9 Distances between cows' copulation s i t e s and the s i t e s where cows where l a s t seen with t h e i r pups. 34 10 Number of cows counted on Areas 8, 9, and 13 vs. wave i n t e n s i t y . 39 11 S p a t i a l d i s t r i b u t i o n of copulations on the colony i n 1973. 40 I X LIST OF APPENDICES Appendix Page A Sample sketches 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 to obtain sightings shown i n Figure 4. 78 C 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 vs. a v a i l a b i l i t y of water 79 D 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 vs. substrate temperature 80 E E f f e c t s of temperature on cows choices of cop-u l a t i o n s i t e s . 81 X "The success of an organism i n leaving a numerous p o s t e r i t y i s not measured only by the number of i t s surviving o f f s p r i n g , but also by the q u a l i t y or probable 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 sexual s e l e c t i o n i s capable of con-f e r r i n g a great reproductive advantage... the p o t e n t i a l i t y of a runaway process, which, however small the beginnings from which i t arose, must, unless checked, produce great e f f e c t s , and i n the l a t t e r stages with great r a p i d i t y . " (R.A. Fi s h e r , 1956) 1 1. INTRODUCTION S t e l l e r sea l i o n s (Eumetopias jubata Schreber) inhabit the northern coasts of the P a c i f i c Ocean, from Japan, through the Aleutian Islands, and south along the coast of North America to southern C a l i f o r n i a . They are gregarious and form colonies when hauled out on land. At pupping colonies, cows bear pups and copulate during the breeding season. Present knowledge of pupping colonies stems mainly from i n v e s t -igations by Sandegren (1970) and Gentry (1970). These two studies and the present one provide the information for the following introduction to the n a t u r a l h i s t o r y of a pupping colony. Adult b u l l s begin to a r r i v e i n e a r l y May and over the following two weeks p a r t i t i o n the colony into contiguous t e r r i t o r i e s . B u l l s defend t h e i r t e r r i t o r i e s against trespass by any male sea l i o n older than approx-imately three years of age, and do so with 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 continuously from l a t e May u n t i l e a rly July. Cows begin to gather i n large numbers on the colony i n l a t e May. They are gregarious but not t e r r i t o r i a l . As they a r r i v e , they form groups without respect to b u l l s ' t e r r i t o r i a l boundaries. Cows occupy the most accessible areas of the colony f i r s t , and sequentially f i l l the l e s s accessible areas as the season progresses. T y p i c a l l y , within about three days of her a r r i v a l at the colony, a cow bears a si n g l e pup, and then about eleven days l a t e r copulates once with a t e r r i t o r i a l b u l l . 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 copulations, they do not as a r u l e confine cows within t e r r i t o r i a l boundaries. Cows are e f f e c t i v e l y free to move about the colony as they wish, and between t h e i r a r r i v a l s at the colony and t h e i r copulations, they t y p i c a l l y spend time on several b u l l s ' t e r r i t o r i e s . Thus, f a c t o r s that influence the d i s t r i b u t i o n and movements of pre-estrous cows on the colony determine the d i s t r i b u t i o n of copulations among established t e r r i t o r i a l b u l l s . In t h i s study, I investigate the influence of environmental 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 colony. My objectives are to i d e n t i f y the major f a c t o r s that influence where cows copulate, and to suggest the r e l a t i v e importance of these factors at Cape St. James. A better under-standing of the influences on breeding Eumetopias cows may elucidate f a c t o r s or processes that have affected the evolution of polygyny i n Ot 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 with cows during or p r i o r to estrus. Consequently, my i n t e r e s t i n any cow l i e s s p e c i f i c a l l y within the time i n t e r v a l between her a r r i v a l on the colony and her copulation. This r e s t r i c t i o n necessitates observation of i n d i v i d u a l l y recognizable cows, because only they can be observed i n t e r m i t t e n t l y throughout the time i n t e r v a l between a r r i v a l and copulation. Cows that are not i n d i v i d u a l l y recognizable contribute u s e f u l data only when "observed giving b i r t h or copulating, because only during these two events can an observer determine that such cows are within 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 copulations. 3 Therefore I emphasize observations of i d e n t i f i a b l e cows, and complement these observations with records 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 copulations. 4 2. MATERIALS AND METHODS 2.1 The Study Area The pupping colony that I studied i s on an i s l a n d i n the Kerouard group at Cape St. James, B r i t i s h Columbia (Lat. 52° 55', Long. 131° 00'). S t e l l e r sea l i o n s have bred here for at l e a s t the l a s t half century (Newcombe et a l , 1918). I observed the colony from a b l i n d perched on a c l i f f on the colony's periphery (Figure 1). Boat access to the i s l a n d was possible only during calm sea conditions. From either of two landing l o c a t i o n s , observers could climb to the b l i n d without disturbing the colony. Boat launching f a c i l i t i e s , accommodation,'. and other l o g i s t i c support were obtained at a weather s t a t i o n 1.5 km north of the study i s l a n d . 2.2 C l a s s i f i c a t i o n of Sea Lions by Size and Sex I c l a s s i f i e d sea l i o n s as pups, j u v e n i l e s , subadult b u l l s , adult b u l l s , and adult cows. Ages given i n the descriptions below are my estimates based on my experience observing the animals and on age-growth curves presented by Pike"*". Pups - sea l i o n s of e i t h e r sex, born during the summer i n which they were observed. Pups were obvious because of t h e i r small si z e and almost black pelage. '''Unpublished manuscript, 1966, F i s h e r i e s Research Board, Nanaimo, B. C. Figure 1. The Colony. Legend: Non-tidal pools T i d a l Shoreline Area number 12 5a 6 Juveniles - sea l i o n s of either sex, within the siz e range of subadults seen suckling. Juveniles probably ranged from one to three years of age. Adult cows - females larger than j u v e n i l e s . Small cows could be mistaken for small subadult b u l l s under c e r t a i n circumstances. Adult cows probably ranged from four to about twenty years of age. Adult b u l l s - males within the siz e range that held t e r r i t o r i e s and cop-ulated. Adult b u l l s were obvious because of t h e i r large s i z e , extremely muscular neck, and disproportionately large head and jaws. Adult b u l l s probably ranged from seven to about twelve years of age. Subadult b u l l s - males larger than j u v e n i l e s , but smaller than adult b u l l s . 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 to but l e s s highly developed than those of adult b u l l s . These c h a r a c t e r i s t i c s made large subadult b u l l s immediately d i s -tinguishable. When l y i n g q u i e t l y , small subadult b u l l s could be mistaken f o r small cows, but were always dis t i n g u i s h a b l e when a c t i v e . 2.3 Data C o l l e c t i o n 2.3.1 General Procedures A l l data were recorded i n or near the observation b l i n d by either an a s s i s t a n t or myself. In 1972, we recorded locati o n s as estimated distances and directions' from prominent landmarks on the colony. In 1973, 7 we recorded them as Cartesian co-ordinates read from a g r i d drawn onto a large scale a e r i a l photograph (1 cm =3.8 m) of the study i s l a n d . We kept the colony under -observation from May 19 u n t i l August 7, 1972, and from May 27 u n t i l J u l y 6, 1973. We u s u a l l y began observations between 0500 and 0630 hours and continued them u n t i l about 2130 hours. We used binoculars when necessary. 2.3.2 Iridividually Recognizable Cows Many cows were d i s t i n c t i v e l y marked with scars or with c i r c u l a r patches of bare skin from 2 to 15 cm i n diameter. These c i r c u l a r marks apparently r e s u l t from u n i d e n t i f i e d skin disorders. When I noticed a cow with recognizable markings, I sketched her and placed the sketch into a f i l e . Examples of f i l e sketches are shown i n Appendix A. Cows i n t h i s f i l e w i l l henceforth i n t h i s t h e s i s be referred to as known cows. We included the following information i n each recorded observation of a known cow: 1) the cow's i d e n t i t y , her l o c a t i o n on the colony, and the date and time of the observation. 2) her a c t i v i t y - Cows were recorded as landing from the sea, moving on the colony, stationary with head r a i s e d , stationary and prone, or engaged i n periestrous behaviour (term a f t e r Sandegren, 1970). A cow e x h i b i t i n g periestrous behaviour moves with a limp, exaggerated A l l times i n t h i s t h e s i s are P a c i f i c Standard Time. 8 g a i t , s a l i v a t e s profusely, and b i t e s , rubs against, and crawls over the b u l l whose attention her behaviour arouses. Cows show-ing t h i s behaviour were sometimes receptive to copulation. 3) whether she was accompanied by a pup or j u v e n i l e , and i f she was, whether i t was suckling - Accompanied means that behavioural i n t e r a c t i o n s between the cow and young indicated to the observer that the two were mother and o f f s p r i n g . Cows l i e i n p r e f e r e n t i a l contact with and are s o l i c i t o u s toward t h e i r apparently own o f f -spring, and are aggressive and i n t o l e r a n t of other young sea l i o n s . Observations of mother-pup p a i r s i n which both the cows and t h e i r pups were i n d i v i d u a l l y recognizable i n d i c a t e that Eumetopias cows suckle only t h e i r own o f f s p r i n g (Sandegren, 1970). Similar observations i n d i c a t e the same of Callorhinus ursinus (Bartholomew and Hoel, 1953) and of Zalophus c a l i f o r n i a n u s (Peterson and Bartholomew, 1967). 4) whether she was wet or dry (1973 only) - Cows were classed as dry, a l l wet, i e . a l l pelage soaked, p a r t l y wet, or wet from r a i n . 5) miscellaneous comments. We systematically searched the colony for known cows when we began observations i n the morning, and on several a d d i t i o n a l occasions throughout the day. A f t e r n o t i c i n g a known cow, we t r i e d to monitor her a c t i v i t i e s as continuously as p o s s i b l e . 9 2.3.3 Birt h s and Copulations We recorded the dates, times, and locations of a l l observed b i r t h s and copulations. A f t e r a cow f i n i s h e d copulating, we recorded where she went, whether she joined a pup or j u v e n i l e , whether she was d i r t y or clean, and whether she was wet or dry. This information helped i d e n t i f y the circumstances under which the cow came to copulating i n the l o c a t i o n she d i d . 2.3.4 Access Patterns Whenever we noticed a known cow landing, we recorded where she landed and where she subsequently went. From June 24 to June 30, 1972, we recorded t h i s information f o r a l l cows observed landing regardless of whether they were known or not. 2.3.5 Censuses  1972: At 0800, 1200, 1600, and 2000 hours on each day from May 28 to 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 present on each b u l l ' s t e r r i t o r y , and those present on several d i s c r e t e areas not defended by b u l l s . From June 26 to August 8 we counted only adult cows at 0800, 1200, and 2000 hours and counted a l l classes at 1600 hours. 1973: I divided the colony into 16 areas according to my subjective impressions of t h e i r r e l a t i v e exposure to waves, ease of access from the 10 sea, and topographic i r r e g u l a r i t y (Figure 1) . On each day from June 3 to J u l y 3, I counted the number of cows present at 0700 and 2000 hours on these areas, and counted a l l classes at 1600 hours. 2.3.6 Weather The Cape St. James weather st a t i o n provided semi-hourly measure-ments of a i r temperature, wind speed and d i r e c t i o n , and percent cloud cover. I recorded an index of solar r a d i a t i o n i n 1973. I attached the thermister of a telethermometer d i r e c t l y to the rock substrate of the study i s l a n d . The thermister was exposed to a l l weather elements, so temperature readings from i t crudely integrated the cooling e f f e c t s of wind and r a i n , and the warming e f f e c t s of solar r a d i a t i o n . Thus, the readings were an index of the thermal conditions experienced by the sea l i o n s on the colony. I recorded substrate temperature semi-hourly (0600, 0800, ... 2000 hours). In 1973, I recorded observations on the s e v e r i t y of wave action at the same time that I recorded substrate temperature. I rated s e v e r i t y according to the f i v e point scale below: 1 - A l l areas on the colony except the i n t e r t i d a l zone are dry. 2 - Area 6 i s being splashed by waves (Figure 1). 3 - Area 6 i s l i g h t l y awash. 4 - Waves are washing Area 6 strongly enough to p h y s i c a l l y dislodge an adult cow. 11 5 - Waves are washing over Areas i n addi t i o n to Area 6 strongly enough to move an adult cow. When waves were grade 5, I recorded which Areas i n addition to 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 Adjacent t e r r i t o r i a l b u l l s engaged i n border displays (described by Gentry, 1970) frequently and only at the boundaries separating the adjacent t e r r i t o r i e s . These d i s p l a y s , plus the tendency of boundaries to follow topographic i r r e g u l a r i t i e s , made the boundaries obvious. In 1972 boundaries were monitored by recording locations of border displays. In 1973, I did not record these l o c a t i o n s , I simply noted the locations of boundaries at the beginning of the season, and noted boundary changes as they occurred. 12 3. RESULTS 3.1 Chronology of the Breeding Season When we f i r s t a r r i v e d at the study i s l a n d on May 13, 1972, 5 adult b u l l s had already acquired t e r r i t o r i e s . By June 4, 1972, a l l b u l l s that l a t e r were observed copulating had acquired t e r r i t o r i e s . In 1972, the f i r s t cows arri v e d at the colony on about May 18. In both years, cows that ar r i v e d f i r s t occupied Area 7 and i t s v i c i n i t y (Figure 1). Then, as the season progressed and the colony became more crowded, cows sequentially occupied more inland l o c a t i o n s . Later, the colony emptied i n the reverse sequence, the more inland locations being abandoned f i r s t . Figure 2 shows the t o t a l number of cows ashore and v i s i b l e from the b l i n d during the two seasons of the study. Figure 3 shows the temporal d i s t r i b u t i o n of observed b i r t h s and copulations f o r both years. 3.2 Composition of the Cow Population: Presence of Suckling Off spring Of 95 known cows sighted ten or more times i n 1973, 12.6% were alone, 9.5% were accompanied only by j u v e n i l e s , 55.8% were accompanied only by pups, and 22.1% were accompanied by both j u v e n i l e s and pups. The pro-portion of cows accompanied by j u v e n i l e s d i f f e r s markedly with r e s u l t s obtained i n other areas. On Ano Nuevo Island i n C a l i f o r n i a , only 2% of Eumetopias cows are accompanied by j u v e n i l e s (Gentry, 1970), whereas 80% are accompanied on Lewis Island i n Alaska (Sandegren, personal communication i n Gentry, 1970). Thus, the 31.6% f i g u r e f o r Cape St. James i s intermediate between f i g u r e s obtained at the northern and southern extremes of Eumetopias' range. 13 30(D o 4 1 1 '• 1 § ~ 1 1 2 7 1 10 20 1 10 20 MAY JUNE JULY DATE Figure 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. Each d a i l y value i n the fi g u r e i s the mean of the four censuses taken that day. Legend: Storm i n 1973 - S Storm i n 1972 - St 14 5 0 , Sg 40. r-m 30 20 u. O cc UJ 03 s Z z g 5c _ j 0_ O o u. o rr UJ m 5 =» 10. 0. 50. . 40 . . 30. . 20. . 10.. 0 . _ 41 4L 1^ , 00 CN JO o *** CO CN -O o CN 1 CO 1 1 1 1 CN 1 CN 1 CN 1 1 CN 1 c n i 1 00 O CO r — <o CN N. i— CN CN "— CN CN ^— MAY JUNE DATE JULY Figure 3. Temporal d i s t r i b u t i o n of b i r t h s and copulations during 1972 and 1973. Legend i 1972 -1973 - I 1 15 3.3 Preference for D i f f e r e n t Locations on the Colony: Cows with Pups vs. Cows Without Cows with young pups tended to occupy d i f f e r e n t areas of the colony than did cows without pups (Figure 4). Cows with young pups were almost never seen on Area 6, whereas cows without pups were frequently seen there. The opposite was true of Area 13, where cows with pups were frequently seen and cows without pups were r a r e l y seen. These trends i n s p a t i a l preference 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 copulations of cows with and without pups (Tables 1, 2, and 3). The d i f f e r e n c e i n s p a t i a l preference of cows with and without pups may r e l a t e to the safety of pups. U n t i l they are a couple of weeks old , pups are very weak swimmers and us u a l l y drown i f washed into the sea by waves. During one storm i n 1973, 30% (N = 44) of the known cows with pups l o s t them. A s l i g h t l y l e s s v i o l e n t storm occurred 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 t y p i c a l . Preference exhibited by cows without pups f o r l e s s protected areas may simply ind i c a t e that these cows us u a l l y t r a v e l no further inland than necessary to f i n d a vacant r e s t spot. 3.4 Access Routes Cows preferred to use c e r t a i n locations on the shoreline f o r landing from the sea. Of 216 landings recorded f o r the north side of the colony i n 1972, 87% occurred on Area 6, 13% on Area 4, and 0% on Area "'. 16 Figure 4. S p a t i a l d i s t r i b u t i o n of sightings of cows with and without pups. Legend: Sighting l o c a t i o n of known cow who had a pup Sighting l o c a t i o n of known cow who did not have a pup Note: For d e t a i l s of procedure used to obtain t h i s sample of sig h t -ings, see Appendix B. O 16a Table 1. Copulation s i t e s of known cows: degree of exposure to waves vs. whether or not cows had pups Cow had Cow had a pup no pup Protected Area"*" 24 5 Exposed Area 19_ 15 Percent on Protected Area 56 20 (x 2 = 5.23, df = 1, p <0.01) Table 2. Copulation s i t e s of u n i d e n t i f i e d cows: degree of exposure to waves vs. whether or not the cows were seen to j o i n pup a f t e r copulating Cow seen Cow not seen with pup with pup Protected Area 54 38 Exposed Area 213 74 Percent on Protected Area 66 34 (x 2 = 19.35, df = 1, p <0.001) Table 3. Copulation s i t e s of u n i d e n t i f i e d cows: degree of exposure to waves vs. whether or not cows were seen to j o i n a j u v e n i l e a f t e r copulating Cow seen with Cow not seen j u v e n i l e with j u v e n i l e Protected Area 1 91 Exposed Area __8 94 Percent on Protected Area 11 49 (Fisher's Exact P r o b a b i l i t y =0.023) "^For a l l the above tables, Areas 8, 12, 2, 9, 1, 3, 11, 10, and 12 are protected; Areas 7, 4, 5, and 6 are exposed. 18 1 (Figure 5). Also, cows landing at some points tended to continue t r a v e l -l i n g to other parts of the colony more often than did cows landing at other points (Table 4). Thus, b u l l s ' t e r r i t o r i e s on Area 6 included access points to much of the r e s t of the colony. This may have imparted reproductive advantage to these b u l l s . Several times i n both years I observed cows land from the sea, copulate immediately with the b u l l whose t e r r i t o r y included the landing point, and then continue on to other parts of the colony. Appar-ently, some cows a r r i v e at the colony i n estrus and consequently copulate with a b u l l who owns a good landing spot. The above hypothesis i s supported by the f a c t that, a f t e r copulat-ing, cows l e f t e a s i l y a ccessible areas more frequently than they did l e s s a c c e s s i b l e areas (Tables 5 and 6). 3.5 Homing of Cows to the Same Part of the Colony from Year to Year Thirty-two known cows were observed with pups i n both 1972 and 1973. Of these cows, 4 were observed pupping i n both years, 15 i n only one year, and 13 i n neither year. The distances between the locations where these cows were f i r s t seen with t h e i r pups i n the two years indicate that cows tend to return to the same v i c i n i t y of the colony (Figure 6). I s t a t i s t i c a l l y analysed the data i n Figure 6 i n two ways. The f i r s t and simplest was to divide the colony into north and south halves, and then c l a s s i f y each of the 32 cows as to on which h a l f of the colony she was seen with her pup i n each year (Table 7). 19 Figure 5. Landing s i t e s on the north side of the colony. Legend: Landing s i t e with number of landings observed 19a 20 Table 4. Location of landing vs. whether or not a cow was observed leav-ing the b u l l ' s •: t e r r i t o r y that she landed on Landing points A&B C&D E&F Cow stayed 43 33 19 Cow l e f t 90 21 10 Percent of cows that stayed 32 61 66 (x 2 = 19.24, df = 2, p<0.001) Table 5. Location of copulation vs. whether or not a cow was observed leaving the Area that she copulated on Copulation Location Areas 4,5,6, Areas 1,2,3,8, 7,10, and 12 9,11, and 13 Cow stayed 43 54 Cow l e f t 50 2_9_ Percent of cows that stayed 46 65 (x 2 = 6.289, df = 1, p<0.01) Table 6. Location of copulations vs. whether of not cowwas observed leaving the Area that she copulated on: analysis of Areas 6, 8, and 13  Copulation Location Area 6 Areas 8 & 13 Cow stayed 9 32 Cow l e f t 19 ' _1 Percent of cows that stayed 32 97 (x 2 = 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 >20 -10 -20 -30 >30 >40 >50 -40 -50 -60 DISTANCE IN METERS Figure 6. Tendency for cows to return to the same part of the colony from year to year. Legend: Distances between s i t e s where cows bore pups i n 1972 and 1973. Distances 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 with pups i n the other year. mm Distances between s i t e s where cows were f i r s t seen with pups i n 1972 and 1973. Tendency of cows to return to the same side of the colony from year to year : Location of f i r s t s ighting i n 1973 North side South side Location of f i r s t North sighting i n 1972 side 17 4 South side 1 10 2 (x = 15.14, df = 1, p<0.001) 23 In the second a n a l y s i s , I compared the distances used i n Figure 6 with "randomized distances". I obtained the randomized distances as follows. In Figure 6, each df the distances between year to year sightings was calculated from the co-ordinates of the sightings. Four distances 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 sighting to pup si g h t i n g . In order to obtain the randomized distances, I wrote the co-ordinates of each 1972 sighting on a card and kept the b i r t h sightings separate from the f i r s t pup sightings. Then f o r each of the 32 cows, I picked at random a card with a 1972 l o c a t i o n on i t . If the cow was a c t u a l l y seen pupping i n 1972, I picked a b i r t h l o c a t i o n , i f not, I picked a f i r s t pup sighting l o c a t i o n . Then f o r each cow, I calculated the distance between the act u a l 1973 sighting and the randomly chosen 1972 si g h t i n g . I compared these randomized distances with the actual year to year distances shown i n Figure 6. If cows demonstrated no tendency to return to the same v i c i n i t y , there should be no di f f e r e n c e between the two sets of distances. However, the actual distances (median = 10.1 m) were s i g n i f i c a n t l y shorter than the randomized distances (median = 20.8 m; p<0.05, sign t e s t ; Campbell, 1967). 3.6 S p a t i a l D i s t r i b u t i o n of Birt h s 3.6.1 General 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 Figure 7. B i r t h s were not observed i n Areas 6, 14, 15, and 16, and very few were observed i n northern portions of Area 4, and the northeastern 24 Figure 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 on the colony i n 1973 Legend: Location of one observed b i r t h ® Area number 4 24a 25 ends of Areas 5 and 7. These v i c i n i t i e s were frequently washed by waves. Area 6 was p a r t i c u l a r l y so; i t was being washed by waves strong enough to dislodge an adult cow i n three times as many weather observations as was any other Area of the colony. Areas 14, 15, and 16 were also s p e c i a l i n that the crevasse separating them from the r e s t of the colony was d i f f i c u l t f o r sea l i o n s to negotiate, and would have been p a r t i c u l a r l y so for cows with young pups. Thus, cows appear to avoid pupping i n lo c a t i o n s where waves could be a danger to pups. This trend i s apparent on a d i f f e r e n t scale as w e l l . At least 11 islands i n the Kerouard group at Cape St. James were occupied by adult cows during the summers of t h i s study. Of these 11, only 3 had apparent access to ground high enough to a f f o r d protection from waves during storms. These 3 were the only islands on which pups were observed during the periods i n which b i r t h s were observed. This s e l e c t i o n of pupping s i t e s seems very adaptive i n l i g h t of the heavy pup m o r t a l i t y observed i n t h i s study. Bir t h s were not observed i n Area 1 or i n the western ends of Areas 11, 12, and 13. These areas had rugged, precipitous t e r r a i n . The one pup born i n Area 1 i n 1972 f e l l about four meters onto a rock ledge immediately a f t e r b i r t h . The l i k e l i h o o d of cows giving b i r t h on a c e r t a i n area probably also depends on the number of cows already occupying a l t e r n a t i v e areas. Through the season, cows populated the colony roughly i n order of apparent ease, of access, with Area 7 being occupied f i r s t , and Areas 8 and 13 l a s t . 26 This sequential occupation of the colony strongly suggests that cows pre-f e r e n t i a l l y occupied more accessible areas, but a f t e r these were crowded, cows moved further inland to l e s s accessible areas. Hence, a cursory examination of b i r t h d i s t r i b u t i o n indicates that protection from waves, ruggedness of t e r r a i n , and ease of access from the sea may be important factors i n determining where on the colony cows choose to bear pups. Detailed examination of these and other influences follows i n the next sections. 3.6.2 E f f e c t s of Protection 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 Bi r t h s Preliminary observations indicated that exposure to waves, access-i b i l i t y , and roughness of t e r r a i n might be important influences i n s e l e c t i o n of b i r t h s i t e s by cows, and Gentry (1970) indicated that a v a i l a b i l i t y of water might be important. I tested the e f f e c t s of these four factors with contingency analyses 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 (Andrews e_t 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 multiple c l a s s -i f i c a t i o n a n alysis to 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 , and contingency analyses to t e s t the s i g n i f i c a n c e of observed trends. To perform these analyses, I drew a g r i d on an a e r i a l photograph, thereby d i v i d i n g the colony into 171 areas, each 4.6 m square. I then c l a s s -i f i e d each of these areas as belonging to one of f i v e classes of exposure to waves and a c c e s s i b i l i t y , four classes of t e r r a i n roughness, and four classes of water a v a i l a b i l i t y . F i n a l l y , I obtained from my records the number of b i r t h s observed on each area. 27 I hypothesized that areas with more protection from waves, better 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 better 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 areas of op-posite c h a r a c t e r i s t i c s . I expected that numbers of b i r t h s should be cor-r e l a t e d i n a simple manner with t e r r a i n roughness and water a v a i l a b i l i t y , but i n a more complex manner with protection from waves and a c c e s s i b i l i t y . These l a t t e r two f a c t o r s are negatively c o r r e l a t e d . More protected areas were v i r t u a l l y always l e s s accessible because t h e i r protection arose from t h e i r distance and height from the sea. The interdependence between these two f a c t o r s led me to expect very few b i r t h s on the l e a s t protected, most accessible areas; many b i r t h s on moderately protected, moderately accessible areas; and few b i r t h s on the most protected, l e a s t accessible areas. Results of the contingency analyses of a c c e s s i b i l i t y and protection from waves, and of roughness of terrainr.appear i n Tables 8 and 9. A s i m i l a r a nalysis of water a v a i l a b i l i t y was not s t a t i s t i c a l l y s i g n i f i c a n t and i s shown i n Appendix C. Table 8 f a i l s to r e j e c t the hypothesis that 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 areas of more extreme a c c e s s i b i l i t y . Table 9 shows strongly that areas of l e v e l , smooth t e r r a i n had more b i r t h s occur on them than did areas of steeper, more rugged t e r r a i n . M u l t i p l e c l a s s i f i c a t i o n analysis y i e l d s e s s e n t i a l l y the same picture that contingency a n a l y s i s did (Table 10). T e r r a i n i s by f a r the strong-2 1 est predictor (B =0.321) compared to a c c e s s i b i l i t y and protection 1 2 B provides a measure of the a b i l i t y of the predictor (eg. T e r r a i n roughness) to explain 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 adjusting for'the e f f e c t s of a l l other predictor v a r i a b l e s . B i s not i n terms of percent variance explained, the term serves simply to compare the r e l a t i v e p r e d i c t i v e power of the three predictor v a r i a b l e s ex-amined here, 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 water. For further information on B see Andrews et a l (1969, pages 22 and 117). 28 Table 8. B i r t h locations vs. s i t e s ' a c c e s s i b i l i t i e s and protection from waves ' ' ' ' Classes of a c c e s s i b i l i t y and protection most accessible most protected 1 2 3 4 5 < 1 13 +* 15 - 17 - 23 + 35 + Number of b i r t h s per 1-3.5 2 - 8 + 8 - 6 - 13 + g r i d area > 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 with a c c e s s i b i l i t y - p r o t e c t i o n classes 1 and 2 combined to eliminate expected values of 2.90 and 3.46 i n c e l l s 1/ 3.5 and 1/1-3.5) Table 9. B i r t h locations vs. roughness of s i t e s ' t e r r a i n s Classes of Terrain f l a t t e s t roughest 1 2 3 4 Number of 5 - 21 - 37 + 40 + b i r t h s per ^ g r i d area 6 - 19 + 9 - 3 -> 3.5 18 4- 12 + 1 - 0 -(x = 78.42, df = 6, p< 0.001) In both of the above tables, the + and - signs i n each c e l l i n d i c a t e whether the observed number i n that c e l l was greater (+) or l e s s (-) than expected. Note: In the above analyses, and i n following contingency and multiple c l a s s i f i c a t i o n analyses 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 copulations, there 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 areas. For example, cows might be attracted to pupping s i t e s because other cows had pupped nearby. Unfortunately, discussion with Dr. P.A. Larkin indicated that normal tests for such i n t e r -a c t i o n are not f e a s i b l e with the data a v a i l a b l e here. However, I f e e l that 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 being analysed. Further, i n t e r a c t i o n would tend to a f f e c t the analyses i n opposing d i r e c t i o n s on d i f f e r e n t parts of the colony. Hence, I do not think t h i s p o t e n t i a l i n t e r a c t i o n should a f f e c t inference from these analyses. Table 10. Multiple c l a s s i f i c a t i o n analysis 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 v a r i a b l e Class Number of areas Actual mean Adjusted mean and i t s B i n c l a s s number of number of b i r t h s per area b i r t h s per area 1 16 0. 44 0.01 A c c e s s i b i l i t y - 2 32 2. 04 1.73 Protection 3 38 2. 35 1.94 B 2 = 0.063 4 30 0. 59 1.08 5. 55 1. 12 1.37 1 29 3. 79 3.59 Terrain 2 52 1. 98 1.97 B 2 =.0.321 3 47 0. 47 0.55 4 43 0. 15 0.21 1 38 0. 48 0.76 A v a i l a b i l i t y of Water 2 77 1. 51 1.46 B 2 = 0.046 3 36 1. 67 1.45 4 20 2. 33 2.39 Overal l mean number of b i r t h s per area = 1.41 Overall standard deviation i n number of b i r t h s per area = 2.15 Mul t i p l e R = 0.435 Adjusted means have been corrected for the e f f e c t s of the other two v a r i a b l e s (Andrews et a l , 1969) ho 30 (B A = 0.063) and a v a i l a b i l i t y of water (B Z =0.046). As was also shown by contingency a n a l y s i s , more b i r t h s occurred on areas of moderate access-i b i l i t y and protection than on areas of more extreme a c c e s s i b i l i t y and protection. M u l t i p l e c l a s s i f i c a t i o n again indicates strongly that more b i r t h s occurred on gentle than on rugged t e r r a i n . 3.6.3 E f f e c t s of Waves and Thermal Conditions on Cows' Choices of B i r t h S i t e s I f , as Tables 8, 9, and 10 suggest, danger from waves affected 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 protected locations during periods with high waves than they did during periods with low waves. S i m i l a r l y , i f hot weather and a v a i l a b i l i t y of water were important, cows should have borne pups closer to water during hot weather than they did during cooler weather. Table 11 indicates that b i r t h s did occur on more protected s i t e s during periods with high waves, and Table 12 shows that b i r t h s occurred further from the sea during periods with high waves. S i m i l a r l y , Table 13 shows that b i r t h s occurred on wetter areas during hotter weather. However, s i m i l a r analyses showed that substrate temperature was not s i g n i f i c a n t l y correlated with the distances that b i r t h s occurred from water, or with the d i s t r i b u t i o n of b i r t h s between Area 13 which was experimentally d r i e d , and Area 11 which acted as a c o n t r o l . Con-tingency tables f o r these non-significant analyses appear i n Appendix D. 31 Table 11. Areas on which b i r t h s occurred vs. maximum wave i n t e n s i t y on days that b i r t h s occurred Protected Areas (1,2,8,9,11, and 13) Wave Intensity Calm-High Very High 92 45 Exposed Areas (4,5,6,7,10, and 12) Percent on Protected Areas 40 70, 88 (x =6.72, df = 1, p<0.01) Table 12. Distances from shore at which b i r t h s occurred vs. maximum wave i n t e n s i t y on days that b i r t h s occurred Wave Intensity Calm-Low Medium High Very High Distance < 18.2 m 20 19 29 16 from ^ 18.2 m shore 13 15 36 35 Percent ^ 18.2 m 39 44 55 69 (x 2 = 8.62, df = 3, p<0.05) Table 13. Areas on which b i r t h s occurred vs. maximum substrate temperature on days that b i r t h s occurred  Substrate Temperature < 17°C » 17°C Dryer Areas (7,9,10,12, and 13) 28 46 Wetter Areas (2,3,4,5,8, and 11) 27 82 Percent on Dryer Areas 51 36 (x 2 = 3.58, df = 1, p<0.05) 32 3.7 Relationship Between Locations Where Cows Bore Pups and Where They Copulated ^ • Cows copulated an average of 11.1 days (+6.4 days, 95% con-fidence l i m i t s , n = 35) a f t e r they bore t h e i r pups. During t h i s period, most cows were extremely sedentary, and often l ay i n v i r t u a l l y the same spot for several days at a time. The reason for t h i s sedentary behaviour may be the pup's safety. Pups are v i r t u a l l y helpless u n t i l they are over a week ol d . Any unnecessary movement about the colony by t h e i r mothers would subject the pups to increased r i s k of being harmed by i r a t e cows, f a l l i n g into a crack 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 cows resulted i n most of them copulating near the b i r t h s i t e s . Of 34 known cows, 68% copulated within 10 meters, and 82% within 15 meters of the locati o n s where they bore t h e i r pups (Figure 8). Of 49 known cows, 80% copulated within 10 meters of the s i t e where they were l a s t seen with t h e i r pups p r i o r to copulating (Figure 9). As indicated i n Figure 8, 11 cows moved more than 10 meters to t h e i r copulation s i t e s from the s i t e s where they bore t h e i r pups. Table 14 provides a d d i t i o n a l information about these 11 cows and the moves they made between copulation and pups* b i r t h s i t e s . Only 1 of the 11 cows moved with her pup to a l e s s protected l o c a t i o n before copulating. Four cows moved with t h e i r pups to more protected s i t e s i n apparent response to waves during storms, and two cows copulated on more accessible s i t e s while 33 20 15 . 10. 5 . 0 >5 >10 >15 >20 -5 -10 -15 -20 DISTANCE IN METERS Figure 8. Distances betweenllocations where cows bore pups and locations where they copulated CC U l CQ S z 34 3 0 . 20 J oc UJ CQ 10 J _E3 E2L 0 >5 >10 >15 >20 >25 >30 -5 -10 -15 -20 -25 -30 DISTANCE IN METERS Figure 9. Distances between cows' copulation s i t e s and the s i t e s where cows were l a s t seen with t h e i r pups Table 14. Movements of 11 cows to copulation s i t e s from the s i t e s where they bore t h e i r pups Cha r a c t e r i s t i c s of copulation Comments s i t e s as compared to b i r t h s i t e s Water 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 protection 126 13.3 dryer more protected 5 15.2 wetter more protected These cows moved with t h e i r pups to the v i c i n i t y of t h e i r copulation s i t e s 51 12.0 dryer s l i g h t l y more i n apparent response to large waves protected during storms. 1 14.8 same s l i g h t l y more protected 122 33.4 wetter more accessible These cows copulated on acc e s s i b l e s i t e s while t h e i r pups remained on protected 158 44.0 s l i g h t l y more accessible_ s i t e s . wetter 7 11.3 dryer s l i g h t l y more This i s the only cow that moved with her accessible pup to a l e s s protected s i t e . 114 14.2 wetter more protected 25 18.0 dryer more accessible Before copulating, these cows l o s t t h e i r - pups during storms or abandoned them i n 115 26.1 dryer more accessible favour of j u v e n i l e s . 142 26.5 dryer more accessible u> Cow Distance between s i t e s i n meters 36 t h e i r pups remained i n protected 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 to more accessible areas before copulating. I f u r t h e r examined cow movements to copulation 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 with weather. I reasoned that i f waves caused cows to move, cows would move to more protected locations more frequently during periods of high waves than they would during periods of low waves. S i m i l a r l y , i f hot weather caused cows to move nearer to water, cows would move to wetter l o c a t i o n s more frequently during hot weather than they would during periods of cooler weather. I considered a cow as having moved i f i n any recorded observation she was located more than 10 meters from her previous l o c a t i o n . Since I wished to examine moves made during the time i n t e r v a l between when a cow bore her pup and when she copulated, only moves that cows made within 11 days of t h e i r pups' b i r t h s or f i r s t appearances were included i n the an a l y s i s . To insure independence between moves used i n the a n a l y s i s , I used only one randomly selected move from those that each cow would other-wise contribute. F i n a l l y , I excluded moves that occurred over more than a 3 day i n t e r v a l because such moves frequently encompassed a l l the extremes of weather and hence provided l e s s information than moves that occurred over shorter time i n t e r v a l s . Cows moved to more protected l o c a t i o n s more frequently during periods with high, waves than they did during periods with low waves 37 (Table 15). Cows moved to wetter l o c a t i o n s , or got wetter during t h e i r moves, more frequently during hotter weather than they did during cooler weather (Table 16). I mentioned e a r l i e r that cows occupied the colony sequentially, with more accessible locations being occupied f i r s t and the most protected locations l a s t . The manner i n which the most protected areas were occupied in d i c a t e s the importance of large 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 with young pups. Areas 8, 9, and 13 were the most protected, l e a s t a ccessible areas on the colony, and they were also the d r i e s t . Area 8 had a small pool on i t , Area 9 had no water, and Area:13 had been experimentally d r i e d , although a small amount of water was a v a i l a b l e i n cracks a f t e r r a i n . Figure 10 shows that cows moved onto these Areas during storms, and that the numbers of cows on the Areas r e -mained high f o r at le a s t two weeks a f t e r the major storm on June 11. Thus, large waves induced cows to occupy these dry, ina c c e s s i b l e areas, and most cows chose to remain there f o r at le a s t two weeks i n s p i t e of 7 days of hot weather during that period. In f a c t , June 19 had the hottest sub-str a t e temperature recorded i n 1973, but no exodus from the dry areas occurred as a r e s u l t . 3.8 S p a t i a l D i s t r i b u t i o n of Copulations 3.8.1 General Comments The s p a t i a l d i s t r i b u t i o n of copulations observed i n 1973 i s shown i n Figure 11, and i s generally s i m i l a r to that of b i r t h s (Figure 7). Only 38 Table 15. Moves made by cows vs. i n t e n s i t y of waves Move to lo c a t i o n with: Maximum wave i n t e n s i t y during move More prot e c t i o n Less or same protection Percent of moves to more protected l o c a t i o n Calm-High 8 18 31 Very High 9 69 (x =5.21, df = 1, p <0.05) Table 16. Moves made by cows vs. substrate temperature . Maximum substrate temperature during move < 20°C ^ 20°C Move to that was wetter or lo c a t i o n where cow'was wetter a f t e r move 9 9 that was l e s s or s i m i l a r l y wet or where cow was not wetter a f t e r move 1_6_ __5 Percent of moves to wetter l o c -a t i o n 36 64 2.89, df = 1, p<0.05) 8 0 , JUNE JULY gure 10. Numbers of: cows counted on Areas 8, 9, and 13 vs. wave i n t e n s i t y (Stippled area indicates dates on whicb wave i n t e n s i t y was grade 5) 40 Figure 11. S p a t i a l d i s t r i b u t i o n of copulations on the colony i n 1973 Legend: Location of one observed copulation Area number O 4 0 40a 41 1 copulation and no b i r t h s occurred i n Areas 14, 15, and 16. S i m i l a r l y , both copulations and b i r t h s were infrequent or absent from Area 1, the west side of Area 13, and the southwest side of Area 11. Areas 6 and 4 were the only locations where the numbers of b i r t h s and copulations d i f f e r e d markedly. These Areas had many more copulations than b i r t h s , p o s s i b l y because Area 6 was a major access route from the sea (Figure 5), Area 4 was a minor access route, and both Areas were heavily frequented by cows without pups (Figures 4 and 5). 3.8.2 E f f e c t s of Exposure to 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 Te 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 Copulations Preliminary observations indicated that s p a t i a l d i s t r i b u t i o n of copulations as w e l l as b i r t h s might be influenced by r e l a t i v e exposure to waves, a c c e s s i b i l i t y , and roughness of t e r r a i n . Also, Gentry (1970) i n -dicated that a v a i l a b i l i t y of water f o r use i n thermoregulation might also be important. To test the e f f e c t s of these four f a c t o r s , I did the same contingency and m u l t i p l e c l a s s i f i c a t i o n analyses that I did f o r b i r t h s . I expected more copulations to occur on s i t e s with more pro-t e c t i o n from waves, better access from the sea, le s s rugged t e r r a i n , and better a v a i l a b i l i t y of water than I expected on s i t e s with opposite character-i s t i c s . As I did f o r b i r t h s , I expected simple c o r r e l a t i o n s with 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 theiMnterplay between a c c e s s i b i l i t y and protection from waves, I expected more cop-u l a t i o n s on moderately a c c e s s i b l e , moderately protected s i t e s than on areas 42 of extreme a c c e s s i b i l i t y or protection. Results of the contingency analyses appear i n Tables 17, 18, and 19, and r e s u l t s of the multiple 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 Table 20. More copulations occurred on more accessible, l e s s protected s i t e s than on s i t e s that were l e s s accessible and more protected. The expected peak i n numbers of copulations on areas of moderate c h a r a c t e r i s t i c s does not appear i n Table 17, probably because a c c e s s i b i l i t y - p r o t e c t i o n classes 1 and 2 were combined because of inadequate sample s i z e . This peak i s evident i n the multiple c l a s s i f i c a t i o n a n alysis (Table 20) which shows that the maximum number of copulations per area occurred on c l a s s 2 areas. How-ever, cl a s s 1 areas had only s l i g h t l y fewer copulations than did c l a s s 2 areas, so the peaking trend i s not nearly as strong f o r copulations as i t i s for b i r t h s . The number of copulations per area i s strongly correlated with ruggedness of t e r r a i n (Table 18); that i s , more copulations occurred on areas with l e v e l , gentle t e r r a i n than on areas with steep or rugged t e r r a i n . More copulations occurred on wet areas than on dry 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) gives r e s u l t s b a s i c -a l l y s i m i l a r to the contingency analyses i n Tables 17, 18, and 19. One exception i s that m u l t i p l e c l a s s i f i c a t i o n a n alysis shows that the number of copulations per area peaked on areas of c l a s s 2 a c c e s s i b i l i t y and protection, whereas contingency analysis does not demonstrate t h i s peak. As i t i s for 43 Table 17. Copulation l o c a t i o n s vs. s i t e s ' a c c e s s i b i l i t i e s and protection from waves Classes of a c c e s s i b i l i t y and protection most protected most accessible 1 & 2 3 & 4 5 Number of < 1 25 - 45 + 34 + copulations per g r i d 1-3.5 11 - 17 - 18 -area > 3.5 ••• 12 + 6 - 3 -( x 2 = 11.09, df = 4, p<0.05) Table 18. Copulation locations vs. roughness of s i t e s ' t e r r a i n s Classes of t e r r a i n f l a t t e s t roughest 1 & .2 3 4 Number of < 1 35 - 30 + 39 + copulations per g r i d 1-3.5 28 + 14 + 4 -area > 3.5 18 + 3 - 0 -(x = 30.48, df = 4, p<0.005) 44 Table 19. Copulation locations vs. s i t e s ' water a v a i l a b i l i t i e s Classes of water a v a i l a b i l i t y d r i e s t wettest 1 2 3 & 4 Number of < 1 30 + 49 + 25 -copulations per g r i d 1-3.5 7 - 20 - 19 + area > 3.5 1 - 8 - 12 + (x 2 = 13.54, df = 4, p<0.01) Table 20. Multiple classification analysis of spatial distribution of copulations Predictor variable Class Number of areas Actual mean Adjusted mean and its B in class number of cop-ulations per area number of cop-ulations per area 1 16 2.44 2.14 Accessibility- 2 32 2.84 2.57 protection 3 38 1.56 1.37 Bz = 0.049 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 B2 = 0.124 3 47 1.20 1.19 4 43 0.16 0.46 1 38 0.53 1.14 Availability of water 2 77 1.32 1.19 B2 = 0.030 3 36 2.35 2.15 4 20 : 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 al, 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 strongest predictor v a r i a b l e f o r 2 copulations (B =0.124). 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 strongest 2 2 (B = 0.049), and water a v a i l a b i l i t y i s weakest (B = 0.030). Together, the three predictor v a r i a b l e s are considerably l e s s p r e d i c t i v e f o r cop-2 2 ulat i o n s (multiple R = 0.197) than they are for b i r t h s (multiple R = 0.435). The weaker c o r r e l a t i o n between the predictor v a r i a b l e s and copulations probably r e s u l t s from a combination of f a c t o r s . Cows whose copulation locations were used for analysis varied enormously i n t h e i r maternal status at the time of t h e i r copulation. Some cows had borne pups, some had not; 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 reasons; most cows with l i v e pups copulated near them, but a few cows copulated away from t h e i r pups for various reasons; and some cows copulated while t h e i r pups were r e l a t i v e l y young, whereas others copulated while t h e i r pups were older. Also, the locations where cows copulated de-pended not only on the cows' s p a t i a l preferences, but also on those of the cows' mates. In contrast, cows whose pupping locations were used for analysis had by d e f i n i t i o n the same maternal status. These cows were with t h e i r pups at the b i r t h s i t e , and t h e i r choices of l o c a t i o n were not influenced by the preferences of mates. A l l of the above differences between copulation and b i r t h data are" reasons to expect much more inherent 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 using copulations than i n one using b i r t h s . 47 3.8.3 E f f e c t s of Waves and Thermal Conditions on Cows' Choices of Copulation Locations I f , as Tables 17 and 20 suggest, danger from waves affected cows' s e l e c t i o n of copulation s i t e s , copulations should have occurred i n more protected areas during periods with high waves. S i m i l a r l y , i f a v a i l a b i l i t y of water for use i n thermoregulation were important, cop-ula t i o n s should have occurred close r to water during hot weather. These expected 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 strong i f many pre-estrous cows moved frequently 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 influence cows' locations when cows became estrous. For example, pre-estrous cows might abandon dry areas of the colony i n favour of wet ones during hot weather, or they might leave exposed areas i n favour of protected ones during periods of high waves. As predicted, fewer copulations than expected occurred on Area 6 during high waves when compared to the more protected Areas 4 and 5 (Table 21). Similar analyses showed no s i g n i f i c a n t e f f e c t of substrate temperature oh copulation; locations selected by cows- (Appendix E). 3.9 Summary of Results During t h i s study, the f i r s t b u l l s a r r i v e d on the colony i n mid-May, the f i r s t cows i n l a t e May. Bi r t h s started i n l a t e May, peaked i n e a r l y to mid-June, and continued u n t i l l a t e June. Copulations started i n l a t e May, peaked i n l a t e June, and continued u n t i l mid-July. 48 Table 21. D i s t r i b u t i o n of copulations among Areas 6, 4, and 5 vs. i n t e n s i t y of waves: Wave, i n t e n s i t y low to moderate high and very high Area 6 (very exposed) • 24 7 Area 4 16 17 (less exposed) Area 5 22 20 (x 2 = 6.58, df = 2, p< 0.05) 49 At Cape St. James, approximately 13% of cows are alone, 10% are accompanied only by j u v e n i l e s , 56% only by pups, and 22% by both ju v e n i l e s and pups. Cows with pups tended to occupy and copulate on more protected s i t e s than did cows with no pups. This l i k e l y r e l a t e s to the safety of pups who are very vulnerable to being washed away and drowned by waves. Approximately 30% of the pups on the colony were k i l l e d i n one storm i n 1973, and such storms are probably t y p i c a l . Cows used preferred landing locations as access points from the sea. This resulted i n newly landed estrous cows copulating with b u l l s whose t e r r i t o r i e s included the landing s i t e s . Cows tended to home to the same general l o c a t i o n of the colony annually. More b i r t h s occurred on gentle than on rugged t e r r a i n , and on areas of moderate than on areas of extreme a c c e s s i b i l i t y and protection 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 not s i g n i f i c a n t l y correlated with a v a i l a b i l i t y of water f or use i n thermoregulation. 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 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 correlated strongest with ruggedness of t e r r a i n , next strongest with a c c e s s i b i l i t y and protection from waves, and weakest with a v a i l a b i l i t y of water. During stormy periods when waves were high, cows selected more protected s i t e s to bear t h e i r pups on than they did during times when waves were low. One an a l y s i s indicated that cows selected pupping s i t e s on wet areas during hot weather. However, other analyses f a i l e d to 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 distances from water that cows chose to bear pups, or on whether cows chose to bear pups on a wet area i n preference to an adjacent area that had been experimentally d r i e d . Because of the sedentary habits of cows with young pups, most cows that bore pups copulated near the b i r t h s i t e . Of the minority of cows observed to copulate more than 10 meters from t h e i r pups' b i r t h s i t e s , four had moved to more protected s i t e s i n apparent response to waves during storms, four others had moved to more acc e s s i b l e areas a f t e r l o s i n g or abandoning t h e i r pups, two had copulated on s i t e s removed from t h e i r pups, possibly en route to or from them, and one cow had moved to a more access-i b l e , d r i e r l o c a t i o n with her pup p r i o r to copulating. Moves made by known cows with young pups indicated that moves tended to be to more protected areas during periods with high waves, and to wetter locations during hot weather. However, the pattern i n which the dry, l e a s t a c c e s s i b l e areas were populated by cows indicated strongly that response of cows to large : waves was considerably greater than that to hot weather. S p a t i a l d i s t r i b u t i o n of copulations was s i m i l a r to that of b i r t h s , except that many more copulations than b i r t h s occurred on the l e a s t protected, most ac c e s s i b l e areas. These v i c i n i t i e s were heavily frequented by cows without pups and served as access points to the r e s t of the colony. More copulations tended to occur on gentler t e r r a i n , on areas of good a c c e s s i b i l i t y and poor to moderate protection from waves, and on areas with high a v a i l a b i l i t y of water. M u l t i p l e c l a s s i f i c a t i o n analysis 51 indicated that s p a t i a l d i s t r i b u t i o n of copulations was correlated strongest with ruggedness of t e r r a i n , next strongest with a c c e s s i b i l i t y and protection, and weakest with a v a i l a b i l i t y of water. During periods of high waves, ".cows selected more protected areas of the colony to copulate on than they did during periods of low waves. Hot weather did not r e s u l t i n cows copulating on wetter areas than they did during cooler weather. 52 4. DISCUSSION 4.1 Comparison with Other Studies A basic premise i n t h i s study i s that Eumetopias b u l l s do not confine cows i n harems. This assumption has been substantiated by extensive observation of i n d i v i d u a l l y recognizable cows i n t h i s study, and i s strongly supported i n other recent studies of Eumetopias (Gentry, 1973, 1970; Sandegren, 1970; Orr and Pouleter, 1967). A l l these studies and the present one agree that Eumetopias b u l l s gain access to cows not by confining harems, but by e s t a b l i s h i n g and defending t e r r i t o r i e s i n areas where cows congregate. This basic pattern seems common to a l l O t a r i i d s studied to date, including Zalophus c a l i f o r n i a n u s (Peterson and Bartholomew, 1967; Orr, 1967), Arctoceph- alus spp. ( M i l l e r , 1974; Rand, 1967; Paulian, 1964), Otaria flavescens (Hamilton, 1939, 1934; Vas F e r r e i r a , 1975), Neophoca cinerea ( S t i r l i n g , 1972; Marlow, 1975), Phocarctos hookeri (Marlow, 1975), and Callorhinus ursinus (Bartholomew, 1953; Bartholomew and Hoel, 1953; Peterson, 1965, 1968). A l -though Callorhinus b u l l s herd cows, persistent cows can move where they choose (Bartholomew, 1953; Bartholomew and Hoel, 1953; Peterson, 1965, 1968). Hence, as seems true 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 preference of cows for the v i c i n i t y than on the b u l l ' s a b i l i t y to r e t a i n a harem. The basic pattern i n which b u l l s compete for a p o s i t i o n among cows rather than attempt to confine cows i s also found among the, polygynous phocids Mirounga spp. (Le Boeuf, 1972; Le Boeuf and Peterson, 1969; Bartholomew, 1952; Laws, 1956), and Halichoerus grypus (Boyd and Campbell, 1971; Cameron, 1967; Coulson and H i c k l i n g , 1964; Hewer, 1960). 53 Hence, as seems t y p i c a l among polygynous pinnipeds, Eumetopias cows are free to choose t h e i r locations on breeding colonies. This choice i n turn determines where and with whom the cows copulate. Thus, knowledge of the f a c t o r s that influence cows' preferences for l o c a t i o n on colonies i s c r u c i a l to an understanding of the polygynous breeding system i n Eumetopias. This study has demonstrated that cows' locations and movements were influenced by several f a c t o r s including, among others, ease of access from the sea, protection of s i t e s from sea waves, ruggedness of t e r r a i n , and a v a i l a b i l i t y of cooling water. A l l these f a c t o r s have been discussed i n the pinniped l i t e r a t u r e , but unfortunately, quantitative analyses of t h e i r e f f e c t s are rare. By f a r the best data have been published by Gentry (1973, 1970), and even these are of l i m i t e d use i n discerning why cows copulated where they did. Below, I b r i e f l y review each of the major f a c t o r s examined i n t h i s study. 4.1.1 Ease of Access From the Sea Sea lions' landing at the study colony were faced with a broken and precipitous rock shoreline, waves that were frequently v i o l e n t , and a strong, almost continuous t i d a l current. Successful landing appeared to require s k i l l and experience under a l l but calm water conditions. During high waves, I sometimes saw adult cows make repeated unsuccessful attempts at landing before f i n a l l y scrambling ashore. It appeared to me that a sea l i o n could be s e r i o u s l y hurt or even k i l l e d i f i t erred i n a landing attempt while waves were high. Such mishaps may account for some of the many large scars common on Eumetopias cows. 54 Given these sometimes hazardous landing conditions, and the extreme heterogeneity of the colony shoreline, the high preference that cows showed for a few landing spots was i n e v i t a b l e . This preference had two consequences for breeding a c t i v i t y on the colony. F i r s t , i t meant that cows returning i n estrus to the colony were probably serviced by the few b u l l s whose t e r r i t o r i e s included the favoured landing l o c a t i o n s . Second, i t established the observed pattern i n which cows a r r i v i n g f i r s t s e t t l e d i n areas clo s e s t to favoured landing spots, and cows a r r i v i n g l a t e r sequentially occupied areas further and further inland. Sequential occupation of accessible s i t e s f i r s t and l e s s access-i b l e ones l a t e r i s a common pattern among polygynous pinnipeds. It has been recorded f o r Eumetopias (Gentry, 1970), Callorhinus (Bartholomew, 1953; Peterson, 1965, 1968), Halichoerus (Cameron, 1969; Coulson and H i c k l i n g , 1964), and Mirounga (Carrick et a l , 1962). Although d e t a i l s d i f f e r .among species, access patterns have been found to influence where cows of several polygynous pinnipeds copulate. For example, i n Callorhinus, cows sometimes copulate on t h e i r way to the sea. This f a c t apparently resulted i n b u l l s who owned t e r r i t o r i e s along routes of departure copulating more frequently than would be expected on the basis of the s i z e of t h e i r harems (Bartholomew and Hoel, 1953). Halichoerus cows also copulate en route to the sea (Boyd and Campbell, 1971), so access patterns may also a f f e c t where cows of t h i s species copulate. In Mirounga, departing cows frequently run a gauntlet of sub-dominant b u l l s , and are bred by several of them before escaping to sea (Le Boeuf, 1972). In 55 Leptonychotes weddelli, 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 that apparently permit the b u l l s to intercept and copulate with cows i n t r a n s i t to and from breathing holes i n f a s t i c e ( S t i r l i n g , 1975). Thus, i n summary, i t seems that access from the sea i s probably important i n the organization of breeding colonies of many polygynous species. Although patterns i n other species d i f f e r i n d e t a i l from those i n Eumetopias, the 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 studied species, cows occupy r e l a t i v e l y accessible areas f i r s t , and l e s s accessible areas l a t e r . In several species, estrous cows i n t r a n s i t are subject to being bred by b u l l s who own access routes, or who by v i r t u e of s o c i a l rank are able to intercept cows on those routes. 4.1.2 Protection of Site s from Sea Waves During one storm i n 1973, 30% of the pups belonging to known cows disappeared. I strongly suspect that t h i s 30% i s a conservative estimate of o v e r a l l pup m o r t a l i t y during the storm because my known cows probably tend to be those resident i n the more protected areas near the observation b l i n d . Cows located out of sight at the northern end of the colony probably suffered greater pup l o s s , and because they were usually out of sight from the b l i n d , they were les s l i k e l y to have been included i n my catalogue of known cows. Pup counts before and a f t e r the storm indicated a m o r t a l i t y of approximately 50%. Hence, since about half of the observed b i r t h s had occurred p r i o r to the storm, roughly between 15% and 25% of a l l the pups born on the colony i n 1973 were k i l l e d i n the one storm event. 56 During t h i s storm I saw waves sweep more than a dozen pups into the sea. Once i n the sea, the pups were quickly c a r r i e d away by the swift t i d a l current. Many more pups were tumbled over the colony surface by rushing water and dumped in t o crevices or steep sided pools to d i e . Waves r e g u l a r l y sent water over eighty feet high into the a i r and broke over approximately h a l f the colony area with force s u f f i c i e n t to knock adult b u l l s v i o l e n t l y through the a i r . Almost a l l the re s t of the colony was h i t p e r i o d i c a l l y with waves s u f f i c i e n t l y powerful to p h y s i c a l l y move adult cows. Furthermore, I didn't see the worst of the storm because i t happened l a t e r at night. I suspect that such v i o l e n t storms are commonplace at Cape St. James. A s l i g h t l y l e s s severe one .-.occurred i n 1972, and a much worse one i n 1974. The g i s t of the above i s that waves k i l l many pups at Cape St. James. This 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 of t h i s study. Young pups were seen only on islands i n the Kerouard group that had ap-parent access to high ground. Although t e r r i t o r i a l b u l l s and numerous adult cows were seen on islands without such access, pups were not. On the study i s l a n d , cows with pups tended to occupy and copulate on more protected areas than did cows without pups. The d r i e s t , l e a s t accessible areas were populated by cows driven there by large waves, and, i n sp i t e of the hottest temperature recorded, these cows chose to remain and cop-ulate i n these areas rather than move with t h e i r pups to l e s s protected l o c a t i o n s . The d i f f e r e n c e between s p a t i a l preferences of cows with pups and cows without them was neatly demonstrated by a natural "experiment" 57 performed by the Alaska earthquake i n 1964. P r i o r to the earthquake, Eumetopias cows pupped mainly on the north side of Lewis Island. The south side of the i s l a n d had an area of small rock i s l e t s inhabited only by about 100 cows and t h e i r yearlings (Sandegren, 1970). During the earth-quake, the former pupping area on the north side of the i s l a n d was covered by a rock l a n d s l i d e , and i s no longer used by breeding cows. The earthquake also caused the is l a n d to r i s e about 5 meters, thereby transforming the rock i s l e t s on the south side of the is l a n d into a rugged bedrock beach. This beach i s now the main pupping area on the i s l a n d . The inference i s that p r i o r to the earthquake, the area of rock i s l e t s was unsafe for pups and consequently was used only by cows either alone or with j u v e n i l e s . Once rais e d 5 meters, the area was safe and was then used by cows for pupping. However, the "experiment" would have been more conclusive i f the beach on the north side of the i s l a n d had remained i n t a c t instead of being covered by l a n d s l i d e s . I t has long been suspected that storms k i l l many Eumetopias pups. Everman (1921) described severe m o r t a l i t y on the Ano Nuevo colony. Orr and Poulter (1967) concluded i n studies at Ano Nuevo that Eumetopias pups suffered serious m o r t a l i t y during t h e i r f i r s t month of l i f e , and that the p r i n c i p l e cause of death was drowning. Pike and Maxwell (1958) thought that 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 generally s l i g h t , but that sporadic high m o r t a l i t y would occur during storms, e s p e c i a l l y at c e r t a i n rookeries. My observations strongly confirm Orr and Poulter's (1967) con-c l u s i o n that pups drown not because they cannot swim, but because they 58 cannot climb back out of the sea once swept into i t . I saw many pups washed into the sea, but I did not see one land again. They were c a r r i e d away quickly by the strong t i d a l current. I never observed an adult cow r e t r i e v e a pup from the sea. Pups of other pinniped species are also 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 rocky foreshore of North Rona were washed away by waves. However, a l a t e r study (Summers et a l , 1975) f a i l e d to demonstrate such m o r t a l i t y , perhaps because l i t t l e work was done on the foreshore. Carrick et a l (1962) mentioned that some Mirounga pups were washed away by waves, but that t h i s source of mo r t a l i t y was s l i g h t . S t i r l i n g (1971) considered that access to high ground was important to Arctocephalus cows, but did not say whether he had observed pups being k i l l e d by waves. In summary, pups of several polygynous pinnipeds are k i l l e d by waves during 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 surprise that protection 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 organization of the Cape St. James colony. 4.1.3 Ruggedness of Terrain The study i s l a n d at Cape St. James has extremely v a r i a b l e t e r r a i n . The western half of the is l a n d i s l a r g e l y j u s t a jumble of rock pinnacles j u t t i n g up out of the sea. This area has extremely few f l a t , l e v e l surfaces where the animals can haul out of the sea. The eastern half of the i s l a n d i s thus the only area that contains s i g n i f i c a n t amounts of f l a t or gently sloping t e r r a i n . Consequently, i t i s on t h i s eastern side that a l l breeding a c t i v i t y occurs. 59 Even t h i s eastern side has highly v a r i a b l e t e r r a i n . At one extreme, Area 1 (Figure 1) and parts of Area 13 are very rugged and are dissected by deep cracks and steep sided pools into which pups can f a l l . At the opposite extreme, Areas 3, 5, and parts of 13 and 11 are very f l a t and contain no dangerous cracks or pools. This study demonstrated strong c o r r e l a t i o n s between the 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 copulations that occurred there. Cows preferred areas with gently sloping or l e v e l surfaces and an absence of deep cracks or c l i f f s that would endanger pups. In view of the strong 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 l i t e r a t u r e . Studies on Eumetopias at Ano Nuevo Island (Gentry, 1970; Orr and Poulter, 1967) make v i r t u a l l y no mention of t e r r a i n roughness. It was my impression during a v i s i t to Ano Nuevo that the t e r r a i n i n t h i s colony i s f a r more uniform and l e s s rugged than i t i s at Cape St. James. Under such conditions, the influence of t e r r a i n might be less important and l e s s obvious than i t i s at Cape St. James. Sandegren (1970) found t e r r a i n roughness to be important at Lewis Island, but he did no quantit-a t i v e a nalysis of the subject. However, he did mention that most b i r t h s on h i s colony occurred i n two small f l a t areas about 8 by 10 and 5 by 8 meters i n s i z e . Studies on pinnipeds other than Eumetopias also make l i t t l e mention of 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 of cows i n breeding colonies. In his studies on Arctocephalus, S t i r l i n g (1971) concluded 60 that access to areas a f f o r d i n g protection from storm waves was important, so t e r r a i n roughness i s important to-:this animal at least insofar as i t can permit or prevent such access. Coulson and H i c k l i n g (1964) found i n studies of Halichoerus that colonies i n which t e r r a i n permitted fewer or more r e s t r i c t e d access routes to and from the sea had higher pup m o r t a l i t y . However, these authors did not q u a n t i t a t i v e l y analyse the e f f e c t s of t e r r a i n per se on the seals. Carrick et a l (1962) f e l t that Mirounga tended to choose breeding areas on beaches that afforded easy access for pregnant cows. Bartholomew (1952) pointed out that Mirounga i s rendered v i r t u a l l y immobile by rough, boulder strewn t e r r a i n . Hence, the preference elephant seals show f o r sandy beaches may r e s u l t from the influence of rugged t e r -r a i n on the animal's mo b i l i t y . In summary, the large influence of t e r r a i n roughness found i n t h i s study has not been reported i n other studies. I think t h i s i s p a r t l y because other studies have not performed the appropriate quantitative analyses, and p a r t l y because the extremely rugged rock i s l e t s that Eumetopias i n -habits make the influence of t e r r a i n more important and apparent i n t h i s species. 4.1.4 A v a i l a b i l i t y of Cooling Water Pinnipeds are highly adapted to aquatic l i f e i n cold sea water. T y p i c a l l y , they are very well insulated, they produce 1.7 to 2.6 times as much metabolic heat as t e r r e s t r i a l mammals of the same weight do (Matsuura and Whittow, 1973), and they have l e s s body surface area than predicted by 61 general mammalian r e l a t i o n s h i p s (Iverson and Krog, 1973). Consequently, pinnipeds are very susceptible to overheating while on land. For grim example, many fur seals have died of hyperthermia while being slowly herded inland during the P r i b i l o f seal harvest (Bartholomew and Wilke, 1956). Because of t h e i r adaptation to cold water, a l l pinnipeds probably exhibit behavioural mechanisms for thermoregulation while on land (for examples see Gentry, 1973; Odell, 1974; Whittow et a l , 1972; S t i r l i n g , 1971, 1972; White and Odell, 1971; Fay and Ray, 1968; and Bartholomew and Wilke, 1956). Behavioural thermoregulation i n Eumetopias i s more or l e s s t y p i c a l and was described i n d e t a i l by Gentry (1970, 1973). Generally, as heat loading from: i n s o l a t i o n increases, the sea l i o n s increase th e i r heat loss by exposing more body surface area to coo l a i r or rock, and l a t e r by wetting t h e i r f l i p p e r s and other parts of t h e i r bodies. When thermal con-d i t i o n s become too severe, the sea l i o n s move to water and spend most of t h e i r time i n i t . A l l of the various thermoregulatory behaviours described by Gentry (1970, 1973) for Eumetopias were observed to some degree i n cows at Cape St. James. However, Gentry (1970) concluded that a v a i l a b i l i t y of water for thermoregulation was the most important factor influencing where cows copulated at Ano Nuevo Island, whereas i n t h i s study I conclude that t h i s f actor 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 at Cape St. James. This apparent d i f f e r e n c e between the findings of the two studies i s p a r t l y r e a l and p a r t l y a r e s u l t of methodology. 62 Gentry (1970) concluded that a v a i l a b i l i t y of water influenced where cows copulated because he found that cows on h i s study area occupied dry inland locations during low i n s o l a t i o n and wet shoreline areas during high. His argument contains two important flaws. F i r s t , he drew his i n -ference from recorded locations of a l l cows on the colony, not just pre-estrous cows. As pups get older, cows gradually move toward the shoreline of the colony, so that by the l a t t e r part of July, most animals have moved to the shoreline. Hence, i n c l u s i o n of many post-estrous cows may bias r e s u l t s . Second, he c o l l e c t e d h i s thermoregulatory data from June 21 to August 3. About half of the copulations he observed occurred p r i o r to t h i s time period, presumably during somewhat cooler weather. Further, t h i s time period included more than two presumably warmer weeks a f t e r the l a s t copulation was observed. Thus, Gentry's inference was based on a large proportion of post-estrous cows, perhaps under warmer conditions than would be representative of those i n f l u e n c i n g pre-estrous cows. These biases lead me to suspect that he may have over-estimated the importance of water a v a i l a b i l i t y i n determining where cows copulated. The above arguments notwithstanding, water a v a i l a b i l i t y may s t i l l have been more important at Ano Nuevo than i t was at Cape St. James. Ano Nuevo l i e s over 15° i n l a t i t u d e south of Cape St. James, so mid-day i n s o l -a t i o n was probably much more intense there. Hence, Gentry (1970) recorded substrate temperatures as high as 36°C, whereas I recorded them only up to 24 C. Also, Gentry observed mass movements of a l l cows to water when i n -s o l a t i o n changed abruptly, whereas I never observed such mass movements 63 even from the d r i e s t areas on the colony during the hottest substrate temperatures I recorded. The lack of such movements at Cape St. James i s quite consistent with Gentry's r e s u l t s . At Ano Nuevo, large numbers of cows resorted to water only a f t e r substrate temperatures reached approx-imately 26 C. My substrate temperatures never got that hot. In summary, cows at my study colony did demonstrate thermo-regulatory behaviour, but i t apparently did not greatly influence where they copulated. This observation d i f f e r s from Gentry's conclusions (1970) for Eumetopias. The d i f f e r i n g r e s u l t s between the two studies r e f l e c t d i f f e r e n c e s i n methods of inference, and differences i n climate between the two study areas. 4.2 Relative Importance of Factors Influencing Where Cows Copulated at Cape St. James  Several s i t e c h a r a c t e r i s t i c s including a c c e s s i b i l i t y , protection from waves, and t e r r a i n roughness, and other factors such as access routes and the tendency f o r cows to home a l l s i g n i f i c a n t l y influence where cows copulate on Cape St. James colony. My data cannot q u a n t i t a t i v e l y prove which of these various factors was most i n f l u e n t i a l . However, the data warrant speculative comment, so i n t h i s section I w i l l discuss my general impressions. I think that the general d i s t r i b u t i o n of copulations over the study colony p r i m a r i l y r e f l e c t s the tradeoff 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 protection from sea waves. Cows without pups generally move only f a r 64 enough from the sea to ensure t h e i r own comfort, and cows with pups move far enough inland to protect t h e i r pups from sea waves. As the more accessible s i t e s become occupied, cows move further inland to f i n d accept-able lo c a t i o n s . This access-protection-crowding tradeoff i s the main reason why cows f i l l e d the colony sequentially from more acc e s s i b l e to le s s a ccessible areas and why cows without pups preferred more accessible locations than did cows with pups. The diffe r e n c e between the preferences of cows with and without pups has been documented i n other studies (Sandegren, 1970; Thorsteinson and Lensink, 1962), and the sequential f i l l i n g of colonies i s t y p i c a l among c o l o n i a l l y breeding pinnipeds (for examples see Gentry, 1970; Bartholomew, 1953; Coulson and H i c k l i n g , 1964). My impression of the importance of the access-protection-crowding tradeoff d i f f e r s somewhat from r e s u l t s of my s t a t i s t i c a l analyses 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 and copulations. Frankly, I think my analyses under-estimate t h i s importance because they express the integrated end r e s u l t of the whole breeding season. The analyses ignore the important information imparted by the sequential manner i n which the colony was occupied. The integrated p i c t u r e e f f e c t i v e l y masks the processes whereby the cows ended up where ^hey d i d . I think the other influences on cows operated p r i m a r i l y within the confines of the general pattern established by the access-protection-crowding tradeoff. The most important secondary influence at Cape St. James would appear to be ruggedness of t e r r a i n . Thus, as cows f i l l e d the colony i n a manner p r i m a r i l y dictated by access, protection from waves, and 65 crowding, they tended to choose r e l a t i v e l y f l a t , l e v e l areas away from cracks or p r e c i p i c e s . The remainder of influences on cows, although s i g -n i f i c a n t , were considerably le s s important than the access-protection-crowding tradeoff and t e r r a i n roughness. Thus, a few cows were inseminated i n t r a n s i t at landing spots or along acess routes, a few more i n locations chosen for thermoregulatory reasons, and no doubt a few for reasons missed i n t h i s study. Cows tended to home, but somewhere i n previous years, there must have been an o r i g i n a l choice of s i t e that depended on influences other than homing. These o r i g i n a l influences 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 of cows i n t h i s study. In summary, I think the tradeoff between access, protection from waves, and crowding was the most important factor determining s p a t i a l d i s -t r i b u t i o n of copulations on the study colony. Terrain roughness was next most important, and operated p r i m a r i l y within confines established by t h i s tradeoff. The remaining factors including access patterns, a v a i l a b i l i t y of water, and homing, although s i g n i f i c a n t , were of r e l a t i v e unimportance. 4.3 Sexual Selection and Polygyny In t h i s study, I have concentrated almost e x c l u s i v e l y on factors that influence movements and d i s t r i b u t i o n of cows within the s p a t i a l l i m i t s of one pupping colony. Beyond consideration of these f a c t o r s , however, there remains the perplexing question of why Eumetopias and other polygynous pinnipeds choose to breed i n such extremely dense aggregations. The same question i n p r i n c i p l e can be likewise asked of numerous other species 66 including lek breeders such as the Uganda kob, Adenota kob (Leuthold, 1966), the sage grouse, Centrocercus urophasianus (Wiley, 1973), and the r u f f , Philomachus pugnax (Hogan-Warburg, 1966), and c o l o n i a l breeders such as weaver b i r d s , Ploceus spp. (Crook, 1965). There has been much discussion of t h i s topic i n the l i t e r a t u r e , and much of i t has aimed at i d e n t i f y i n g f u n c t i o n a l or adaptive r o l e s for polygyny i n species that use the system. Wynne-Edwards (1962), Armitage (1962), and Coulson and H i c k l i n g (1964) have argued that polygyny helps keep species' populations within the c a p a b i l i t y of a v a i l a b l e food supplies. Various authors have strongly contested t h i s group s e l e c t i o n argument and have proposed a l t e r n a t i v e s (Crook, 1965; McLaren, 1967; Orians, 1969). Peterson (1968) suggested that the dense aggregations found among breeding pinnipeds may f a c i l i t a t e communication between breeding animals. Peterson and Bartholomew (1967) suggested that polygyny i n pinnipeds might serve to get the sexes together at the r i g h t time of year. S t i r l i n g (1975) mentioned that polygyny i n pinnipeds might r e l i e v e pressure on l o c a l food supplies while b u l l s are f a s t i n g . Carrick e_t a l (1962) suggested that breeding aggregations of elephant seals may have, at least at some time i n the past, have served as protection of pups from predators. Barlow (1972) proposed that t e r r i t o r i a l Galapagos sea l i o n s , Zalophus c a l i f o r n i a n u s co-operate i n d r i v i n g sharks from the v i c i n i t y of the colony, thus protecting cows and pups. My point i s that much discussion has focussed on proposed f u n c t i o n a l or adaptive advantages of the dense breeding aggregations found among p i n -67 nipeds. Peterson (1968) exemplified the philosophy that may underlie much of t h i s preoccupation when he stated, "There can be l i t t l e doubt that the elaborate systems of s o c i a l organization seen i n pinnipeds have appeared, f i r s t and foremost, as adaptations to an amphibious mode of l i f e . " (my emphasis). This statement, and much discussion i n the l i t e r a t u r e i l l u s t r a t e a fundamental misunderstanding and underestimation of the process of sexual s e l e c t i o n . McLaren (1967) and Crook (1965) both emphasized the frequently underestimated p o t e n t i a l capacity of sexual s e l e c t i o n to d r a s t i c a l l y a l t e r a species u n t i l strong counterselection h a l t s the process of change. The magnitude of the influence that sexual s e l e c t i o n may have was i n c i s i v e l y pointed out by Fisher (1958). He used plumage development i n male b i r d s as an example. B r i e f l y , he argued that i f there e x i s t s a plumage character i n males that imparts a reproductive advantage over males without i t , females w i l l be selected for the propensity to mate with males with the successful plumage pattern. Thus, female preference for the plumage pattern further enhances i t s reproductive advantage to males, and thereby accelerates s e l e c t i o n f o r the pattern i n males. The more advantageous the plumage character becomes to males, the more advantageous to females becomes the propensity to choose i t . The more the females choose i t , the more advantageous i t becomes to males. Thus plumage development and female preference f or i t evolve at an ever accelerating pace u n t i l counterselection, r e s u l t i n g f o r example from predation on the more conspicuous males, a r r e s t s the process at an equilibrium between the opposing s e l e c t i v e forces. 68 Thus, Fisher (1958) i d e n t i f i e d the p o t e n t i a l f or a species to become trapped 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 for any character i n one sex, and preference f o r that character i n the other. Of 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 that t h i s p o s i t i v e feedback could a r i s e from female preference f o r c h a r a c t e r i s t i c s dr s i t -uations other than simple anatomical features of p o t e n t i a l mates. For example, the feedback may be possible between t e r r i t o r i a l i t y i n males, and preference to occupy crowded t e r r i t o r i e s i n females. Therein, I submit, probably l i e s the o r i g i n of the extremely dense breeding aggregations of polygynous pinnipeds, and perhaps also of various lek breeders and poly-gynous c o l o n i a l breeders. I propose that the extreme polygyny seen today i n O t a r i i d s began when estrous cows became concentrated, for whatever reasons, i n economic-a l l y defensible (term a f t e r Brown, 1964) groups on c o a s t a l breeding 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 hardest for areas that, 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 , protection from sea waves, or other c h a r a c t e r i s t i c s , had the greatest concentrations of estrous cows. Bu l l s that s u c c e s s f u l l y appropriated favourable locations with many cows would be reproductively more successful that b u l l s that did not. Consequently, cows would be selected for the preference to breed i n areas already containing many cows, because these places are where the highly competitive and successful b u l l s would be. The b u l l s that had suc-c e s s f u l l y established themselves within these concentrated groups of cows would be more l i k e l y to s i r e competitively successful sons than b u l l s 69 elsewhere would. Hence cows that chose to breed i n concentrated groups defended by vigorous b u l l s would be more l i k e l y to have successful sons. Thus, female preference f o r areas with concentrations of cows, i e . female gregariousness, would enhance the reproductive advantage obtained by males that were highly t e r r i t o r i a l , and t h i s enhancement would i n turn make i t even more advantageous f o r females to become more gregarious. So i t would go, with breeding a c t i v i t i e s becoming more and more concentrated i n fav-ourable l o c a t i o n s and competition between ever more sexually dimorphic males becoming f i e r c e r and f i e r c e r . If Fisher's concept i s c o r r e c t , t h i s process would have reached i t s l i m i t s very quickly i n evolutionary time. Hence, i t i s i n t e r e s t i n g that 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 already demonstrate sexual dimorphism i n d i c a t i v e of a polygynous habit (Repenning, 1975). Thus, contrary to some published discussion, I do not believe that the extreme form of polygyny among pinnipeds evolved as a f u n c t i o n a l adaptation to the animals' ways of l i f e . Rather, I think t h i s breeding system i n polygynous pinnipeds 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 Fisher (1958) and l a t e r supported by McLaren (1967). The extreme development of polygyny i n modern pinnipeds i s a simple, a l b e i t spectacular, a r t i f a c t of sexual s e l e c t i o n and natural s e l e c t i o n combined. The f a c t o r s found to influence d i s t r i b u t i o n and movements of cows i n t h i s study may have been responsible for the v a r i a b i l i t y i n s p a t i a l concentration of estrous cows that 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 evolution of male t e r r i t o r i a l i t y and female gregariousness. 70 ACKNOWLEDGEMENTS This study could not have been accomplished without the generous assistance and keen i n t e r e s t of many persons. I p a r t i c u l a r l y wish to thank my supervisor, Dr. H.D. Fis h e r , f o r support and encouragement through-out the study. I also wish::to thank Alton Harestad f o r many i n t e r e s t i n g and informative discussions and for constant encouragement during a l l phases of the study. I also g r a t e f u l l y acknowledge the l o g i s t i c support received from the Departments of Environment and Transport, and the generous a s s i s t -ance received 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 Wilson, K i t Godin, Hugh Ashworth, and the Captain and crew of the Sir Alexander Mackenzie. F i n a l l y , I extend very s p e c i a l thanks to my two f i e l d a s s i s t a n t s , Dan Clark and Stacey Tessaro. Without t h e i r w i l l i n g assistance under some-times extremely hazardous conditions, t h i s study would not have been f e a s i b l e . This study was supported with funds from the National Research Council of Canada, the 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 the U.S. National Geographic Society. 71 LITERATURE CITED Andrews, F., J . Morgan, and J . Sonquist. 1969. 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Body temperature i n the northern fur se a l , Callorhinus ursinus. J . Mamm. 37:327-337. Boyd, J.M. and R.N. Campbell. 1971. The grey seal Halichoerus grypus at North Rona 1959 - 1968. J . Zool. Lond. 164:469-512. Boyd, J.M., J.D. Jockie, and H.R. Hewer. 1962. The breeding colony of grey seals on North Rona. Proc. Zool. Soc. Lond. 138:257-277. Cameron, A.W. 1967. Breeding Behaviour i n a colony of Western A t l a n t i c Grey Seals. Can. J . Zool. 45:161-173. Cameron, A.W. 1969. Behaviour of adult grey seals (Halichoerus grypus) i n the early stages of the breeding season. Can. J . Zool. 47:229-233. 72 Campbell, R.C. 1967. S t a t i s t i c s f o r B i o l o g i s t s . Cambridge U. Press, London. Car r i c k , R., S.E. Csordas, S.E. Ingham, and K. Keith. 1962. Studies on the southern elephant s e a l , Mirounga leonina (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. The breeding biology of the grey seal Halichoerus grypus (Fab.), on the Fame Islands, Northumber-land. J . Anim. E c o l . 33:485-512. Crook, J.H. 1965. The adaptive s i g n i f i c a n c e of avian s o c i a l organizations. Symp. Zool. Soc. Land. 14:181-218. Everman, B.W. 1921. The Ano Nuevo S t e l l e r sea l i o n rookery. J . Mammal 2:16-19. Fay, F.H. and C. Ray. 1968. Influence of climate on the d i s t r i b u t i o n of walrus. I. Evidence from thermoregulatory behaviour. Zoolog-i c a 53:1-18. Fisher, R.A, 1958. The Genetical Theory of Natural Selection. Dover, New York. 291 p. Gentry, R.L. 1970. S o c i a l behaviour of the S t e l l e r sea l i o n . Ph.D. th e s i s , Univ. of C a l i f o r n i a , Santa Cruz, C a l i f o r n i a . 1973. Thermoregulatory behaviour of eared seals. Behaviour 46: 73-93. Hamilton, J.E. 1934. The southern sea l i o n , Otaria byronia (de B l a i n v i l l e ) A Disc. Rep. 8:269-318. 1939. A second report on the southern sea l i o n , Otaria bryonia (de B l a i n v i l l e ) . Disc. Rep. 19:121-164. Hewer, H.R. 1960. Behaviour of the grey seal (Halichoerus grypus, Fab.) i n breeding season. Mammalia 24:400-431. 73 Hogan-Warburg, A.J. 1966. S o c i a l behaviour of the Ruff, Philomachus pugnax L. Ardea 54:109-229. Iverson, J.A. and J . Krog. 1973. Heat production and body surface area i n seals and sea o t t e r s . Norw. J . Zool. 21:51-54. Laws, R.M. 1956. The elephant seal (Mirounga leonina Linn.) II General, s o c i a l , and reproductive behaviour. F.I.D.S. S c i . Rep. #13. 88 p. LeBoeuf, B.J. 1972. Sexual behaviour i n the northern elephant s e a l , Mirounga a n g u s t i f b s t f i s . Beh. 41:1-26. LeBoeuf, B.J. and R.S. Peterson. 1969. So c i a l status and mating a c t i v i t y i n elephant seals. Science 163:91-93. Leuthold, 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 of the Uganda kob. Beh. 27:214-257. McLaren, I.A. 1967. Seals and group s e l e c t i o n . Ecology 48:104-110. Marlow, B.J. 1975. The comparative behaviour of the Au s t r a l i a n sea l i o n s , Neophoca cinerea and Phocarctos hookeri. (Pinnipedia:Otariidae). 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 seal during exposure to heat. Am. J . Phy s i o l . 225:711-715. M i l l e r , E.H. 1974. S o c i a l behaviour between adult male and female New Zealand f ur seals, Arctocephalus f b r s t e r i (Lesson) during the breeding season. Aus. J . Zool. 22:155-173. Newcombe, C.F., W.H. Greenwood, and C. Fraser. 1918. The sea l i o n question i n B.C. Contr. to Can. B i o l , f o r 1914-17, Sess. Pap 33a:l-51. Odell, D.K. 1974. Behavioural thermoregulation 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 Orians, G.H. 1969. On the evolution of mating systems i n bi r d s and mammals. Am. Nat. 103:589-603. Orr, R.T. 1967. The Galapagos sea l i o n . J . Mamm. 48:62-69. Orr, R.T. and T.C. Poulter. 1967. Some observations on reproduction, 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. Paulian, P. 1964. Contribution a l'etude de l ' o t a r i e de l ' i s l e Amsterdam. Mammalia 28;1-146. Peterson, R.S. 1965. Behaviour of the northern fur s e a l . Ph.D. t h e s i s , Johns Hopkins Univ., Baltimore, Maryland. 214 p. Peterson, R.S. 1968. S o c i a l behaviour i n pinnipeds with p a r t i c u l a r reference to the northern fur seal , pp 3-51 IN: Behaviour and physiology of pinnipeds. R.J. Harrison ed., Appleton, Century-c r o f t s , N.Y., N.Y. 411 p. Peterson, R.A. and G.A. Bartholomew. 1967. The Natural History and Behaviour of the C a l i f o r n i a Sea Lion. Special Pub. #1, Am. Soc. Mammalogists. 79 p. Pike, G.C. and B.E. Maxwell. 1958. The abundance and d i s t r i b u t i o n of the northern sea l i o n (Eumetopias jubata) on the coast of 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 fur s e a l , 3. General behaviour on land and at sea. I n v e s t i g a t i o n a l Report, Div. Sea F i s h e r i e s S. A f r i c a 60:1-39. Repenning, C.A. 1975. Ota r i o i d evolution. Rapp. P.-v. Reun. Cons. i n t . Explor. Mer. 169:27-33. Sandegren, F.E. 1970. Breeding and maternal behaviour of the S t e l l e r sea l i o n (Eumetopias jubata) i n Alaska. M.Sc. Thesis, U n i v e r s i t y of Alaska, Fairbanks, Alaska. 75 S t i r l i n g , I. 1971. Studies on the behaviour of the south A u s t r a l i a n fur s e a l , Arcotocephalus f b r s t e r i (Lesson). I Annual c y c l e , postures, c a l l s , and adult males during the breeding season. Aust. J . Zool. 19:243-266. 1972. Observations on the A u s t r a l i a n sea l i o n , Neophoca cinerea (Peron). Aust. J . Zool. 20:271-279. ' 1975. Factors a f f e c t i n g the evolution of s o c i a l behaviour i n the Pinnipedia. Rapp. P.-v. Reun. Cons. i n t . Explor. Mer. 169:205-212. Summers, C.F., R.W. Burton, and S.S. Anderson. 1975. Grey seal (Halichoerus  grypus) pup production at North 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 . Zool. Lond. 175:439-451. Thorsteinson, F.V. and C.J. Lensink. 1962. B i o l o g i c a l observations of S t e l l e r sea l i o n s taken during an experimental harvest. J . Wi l d l . Mgmt. 24:353-359. Vas F e r r e i r a , R. 1975. Behaviour of the southern sea l i o n , Otaria flavescens (Shaw) i n the Uruguayan Islands. Rapp. P.-v. Reun. Cons. i n t . Explor. Mer. 169:219-227. Whittow, G.C., D.T. Matsuura, and Y.C. L i n . 1972. Temperature re g u l a t i o n 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 ) . P h y s i o l . Zool. 45:68-77. White, F.N. and D.K. Odell. 1971. Thermoregulatory behaviour of the northern elephant 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 i n sage grouse, Centrocercus urophasianus. Anim. Beh. Mono. Wynne-Edwards, V.C. 1962. Animal Dispersion i n Rela t i o n to S o c i a l Behaviour. Oli v e r and Boyd, Edinburgh. 653 p. 76 Appendix A. Sample sketches from cow i d e n t i f i c a t i o n f i l e . 77 S4 E 2.f«o€/ B3^iy^ ^ Legend: D.B. - dark brown dk - dark I t - l i g h t M.B. - medium brown M.D.B. - medium dark brown Notes at top r i g h t of each card are coded information describing the f i r s t sighting made of the cow. 78 Appendix B. Sampling procedure used to obtain sightings shown i n Figure 4. The loca t i o n s of sightings used i n Figure 4 are a systematic sample of sightings of known cows observed i n 1973. Sightings of known cows with no pups were selected simply by including the f i r s t and every subsequent f i f t h sighting for each cow for the e n t i r e summer. Selection of sightings of cows with pups was more complex. I was concerned with how a young pup might a f f e c t where i t s mother copulated. So, only sightings on or p r i o r to the eleventh day a f t e r the pup was f i r s t seen, and i n which the cow was with 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 sightings f o r a given cow, the f i r s t and every subsequent t h r i t e e n t h sighting was included i n Figure 4. No sightings made a f t e r tagging operations occurred were included i n t h i s a n a l y s i s . Records f or 68 cows with pups were used i n the f i g u r e . Of these 68 cows, 48 contributed 1 or 2 sightings, 10 contributed 3 or 4, and 10 contributed 5 or 6. Records f or 21 cows without pups were used. Of these cows, 2 contributed 1 or 2 sightings, 9 contributed 3 or 4, 4 contributed 5 or 6, and 6 contributed from 7 to 11. Appendix C. 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 vs. a v a i l a b i l i t y of water. Classes of water a v a i l a b i l i t y d r i e s t wettest 1 2 3 & 4 Number 1 29 + 44 - 30 -of Copulations 1-3.5 8 - 17 + 12 + 3.5 1 • 1 - 16 + 14 + (x 2 = 8.58, df = 4, p>0.05) 80 Appendix D. 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 vs. substrate temperature. Table D - l . Distances that b i r t h s occurred from water vs. substrate temperature  Substrate temperature <17°C > 1 7 ° C • 0 - 5m 17 49 5 - 15m 32 68 15m 6 11 (x 2 = 0.965, df = 2, p>0.05) Table D-2. D i s t r i b u t i o n of b i r t h s between Areas 11 and 13 vs. substrate temperature '  Substrate temperature o ^ o < 17 C £ 17 C Area 11 (wet) 7 31 Area 13 (experimentally drained) 9 33 (x 2 = 0.113, df = 1, p>0.05) 81 Appendix E. E f f e c t s of temperature on cows' choices of copulation s i t e s . Table E - l . Areas on which cows copulated vs. substrate temperature at the time of copulation  Substrate temperature < 17°C *17°C Dryer Areas (1,3,7,8,9,10,13) 52 17 Wetter Areas (2,4,5,6,11,12) 127 30 (x 2 = 0.899, df = 2, p>0.05) Table E-2. D i s t r i b u t i o n of copulations between Areas 11 and 13 vs. sub-st r a t e temperature at time of copulation  Substrate temperature < 17°C £ 17°C Area 11 (wet) 17 12 Area 13 (experimentally drained) 21 6 (x 2 = 2.35, df = 1, p>0.05) Table E-3. Distances cows copulated from water vs. substrate temperature at time of copulation  Substrate temperature < 17°C » 17°C 0 - 5m 41 15 5 - 15m 89 22 15m (x 2 = 1.81, df = 2, p>0.05) 49 10 

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