Biology; of the Seal

7

PREFACE

The first International Symposium on the Biology papers were read by title and are included either in of the Seal was held at the University of Guelph, On­ full or abstract form in this volume. The 139 particip­ tario, Canada from 13 to 17 August 1972. The sym­ ants represented 16 countries, permitting scientific posium developed from discussions originating in Dub­ interchange of a truly international nature. lin in 1969 at the meeting of the Marine Mammals In his opening address, V. B. Scheffer suggested that Committee of the International Council for the Ex­ a dream was becoming a reality with a meeting of ploration of the Sea (ICES). The culmination of such a large group of pinniped biologists. This he felt three years’ organization resulted in the first interna­ was very relevant at a time when the relationship of tional meeting, and this volume. The president of ICES marine mammals and man was being closely examined Professor W. Cieglewicz, offered admirable support as on biological, political and ethical grounds. well as honouring the participants by attending the The scientific session commenced with a seven paper symposium. section on evolution chaired by E. D. Mitchell which The programme committee was composed of experts showed the origins and subsequent development of representing the major international sponsors. W. N. this amphibious group of higher vertebrates. Many of Bonner, Head, Seals Research Division, Institute for the arguments for particular evolutionary trends are Marine Environmental Research (IMER), represented speculative in nature and different interpretations can ICES; A. W. Mansfield, Director, Arctic Biological be attached to the same fossil material. Readers of this Station, Fisheries Research Board of Canada (FRB) volume should be aware of such differences when read­ represented the International Commission for North­ ing the papers in this section. The twelve papers of west Atlantic Fisheries (ICNAF); and K. S. Norris, S. H. Ridgway’s section on functional anatomy illus­ Director, Marine Mammal Council Executive Com­ trated the fundamental structure of the seal, as well mittee, represented the International Biological Pro­ as its associated control mechanisms. R. J. Schusterman gram (IBP). The Food and Agriculture Organization followed this theme by introducing ten papers on be­ of the United Nations (FAO) also offered its support haviour. He established a major focus on social or­ to the programme and ICNAF has contributed to the ganization and communication and their association financing of this volume. with the functional anatomy of the pinnipeds. D. E. Sponsors of national origin were the Fisheries Re­ Sergeant chaired the population dynamics section of search Board of Canada (FRB), the National Re­ seven papers, covering the modelling of populations search Council of Canada (NRCC), the Canadian and method of analysis of seal populations around the National Sportsmen’s Show (CNSS), the World Wild­ world. In the fifth section, J. R. Geraci, by means of life Fund (Canada) (WWF), and the University of papers and a panel discussion dealt with the care and Guelph. management of captive pinnipeds. W. N. Bonner co­ In his preliminary remarks Professor Ronald intro­ ordinated a presentation in the broad area of ecology, duced the representatives of these groups; namely J. R. and was able to bring together studies on environmen­ Weir, Chairman, Fisheries Research Board of Canada; tal factors and their associated behavioural and gene­ S. Bata, International Director and J. S. McCormack, tic control systems. The physiology section was chaired Director, World Wildlife Fund (Canada); and R. T. by H. T. Andersen, his introductory remarks forming D. Birchall, President, Canadian National Sportsmen’s the initial paper of the section. The other six papers Show and a Director of WWF (Canada). of his section emphasized the underwater responses of W. C. Winegard, President of the University of seals. The final and general section, chaired by J. E. Guelph, welcomed participants to the symposium and King, offered a broad coverage of several of the more commented particularly on how pleased he was to interesting areas in various disciplines. welcome representatives from so many countries. Later, A. W. Mansfield acted as rapporteur for the entire at a banquet sponsored by the Department of the En­ programme, and his report stressed the need for con­ vironment, Canada, he offered an invitation to the tinued cooperation by all biologists so that they might group to return in 1975 for a Second International understand seals and their importance to environmen­ Seal Symposium. tal studies. Altogether 62 papers were presented. A further 14 This volume includes with one exception, those pa- 8 K. Ronald pers either presented, read by title, or abstracted, but mammals of the world’ by D. W. Rice and V. B. the continuing discussion on the biology of the seals Scheffer (U.S. Fish and Wildlife Service, Washing­ led to one further paper that is included here. Some ton, 1968) has been used as the standard reference on of the discussion was formal and, where recordable, is nomenclature. included here, but by far the greater part of discussion The work of the chairmen of each of the seven sec­ was informal and hence must remain as extremely tions of this volume is especially recognized. As well, valuable, but merely mental recollections of the par­ the convenor wishes to thank the programme com­ ticipants in the symposium. mittee for their ability to support a somewhat unortho­ The symposium achieved its purpose of bringing dox procedural system, and particularly the sponsors together scientists interested in the Pinnipedia and it ICES, ICNAF, IBP, CNSS, FRB, NRCC, WWF (Ca­ offered leads into the international examination of nada), FAO, and the University of Guelph for their marine mammals. valuable financial assistance. The editors with little apology recognized that they The convenor is most grateful to Mr. H. Tambs- have not reached a completely uniform format in this Lyche, General Secretary of ICES, for his advice and volume since they have allowed use of both English encouragement from the embryonic stages of the sym­ and metric systems of measurement and both English posium to the publication of the proceedings; he also and North American word usage for the sake of har­ recognizes the considerable amount of expert help pro­ mony. The main editorial structure has been the con­ vided by A. W. Mansfield in co-editing this volume. sistency of usage throughout a particular paper. Finally, the effort put into both the symposium and Attempts have also been made to attain a fairly this volume by Mrs. Ginny Bandesen has been beyond uniform taxonomy for the species, but where there has measure, but I hope that she will accept the results of been any doubt caution has not overridden clarity. As the symposium recorded here as tangible proof of her in other mammalian groups, the systematics of the most valuable contribution. To the members of the Pinnipedia are still open to much interpretation. The Dean of the College of Biological Science’s office, the references are cited according to an Annotated Biblio- university support staff and our host Dr. W. C. Wine- praphy on the Pinnipedia*. The ‘List of the marine gard, I express on behalf of the participants and my­ self, our sincerest thanks. * Ronald, K., L. M. Hanly and P. J. Healey, College of Bio­ K. Ronald, logical Science, University of Guelph, Ontario, Canada. Convenor

The following have kindly acted as Discussion Care and Management Section Leaders of the different Sections and also assisted in J. R. Geraci the editing of the contributions: Department of Zoology, University of Guelph, Guelph, Ontario, Canada. Evolution Section Ecology Section E. D. Mitchell Arctic Biological Station, Fisheries Research Board W. N. Bonner of Canada, Ste. Anne de Bellevue, Quebec, Canada. Seals Research Division IMER, c/o Fisheries Labora­ tories, Lowestoft, Suffolk, England.

Functional Anatomy Section Physiology Section S. H. Ridgway H. T. Andersen School of Anatomy, University of Cambridge, Nutrition Institute, University of Oslo, Blindern, Cambridge, England. Oslo, Norway.

Behaviour Section General Session R. J. Schusterman J. E. King Department of Psychology, California State University Department of Zoology, University of New South Hayward, California 94542, U.S.A. Wales, Kensington, N.S.W., Australia.

Population Dynamics Section Summary D. E. Sergeant A. W. Mansfield (Rapporteur) Arctic Biological Station, Fisheries Research Board of Arctic Biological Station, Fisheries Research Board Canada, Ste. Anne de Bellevue, Quebec, Canada. of Canada, Ste. Anne de Bellevue, Quebec, Canada. 188

Rapp. P.-v. Réun. Cons. int. Explor. Mer, 169: 189-194. 1975.

COMPARATIVE SOCIAL BEHAVIOR OF EARED SEALS

R. L. G e n t r y Division of Natural Science, University of California, Santa Cruz, California 95060, U.S.A.*

INTRODUCTION Finally, this paper will suggest a standard research The eared seals studied to date seem fairly similar format for future studies on the behavior of eared in general social organization and social behaviour. seals. Using this or a similar format, comparable data They seem so like each other that by extrapolation we can be obtained on each species being studied. would expect more variations on existing themes than startlingly new concepts from the as-yet unstudied species. This realization dictates that we orient our METHODS future studies away from simple description, however The Steller sea lion was observed for approximately detailed, and move toword comparative studies. 3000 hour at Ano Nuevo Island, California during the The comparative approach, in which the same con­ reproducive seasons of 1967 through 1969. The South ceptual framework and the same study methods are Australian fur seal was observed at South Neptune applied to several species, allows us to emphasize the Islands, South Australia during the reproductive season differences that exist among living species. From these of 1970-71 for approximately 840 hours. At both sites, differences we get a perspective on evolution of the an observer, myself or an assistant, collected quantita­ group that one cannot obtain from study of a single tive data during all daylight hours from a blind si­ species. T hat is, the existing differences are seen as the tuated above the rookery. Individual animals were results of natural selection, and simultaneously as the identified by marks and scars, or by plastic identifica­ substrate for future selection. tion tags, and a history card was kept for each known Another benefit of the comparative method is that animal in each population. In addition separate sheets it provides input for constructing conceptual models, were kept for scoring specific behavioral events, such and permits empirical tests of existing models like that as aggressive encounters among territorial males, of Bartholomew (1970) and Stirling (in this volume). births, copulations, and maps were made showing the Conceptual models are a necessary step in the matura­ location of each event. These data were correlated tion of any scientific discipline. But modelers inadver­ with daily censuses of the rookery and with daily tently use terms like “territoriality” as unitary con­ weather conditions. cepts, and assume that they have similar effects in all species. Comparative studies can delineate species differences in these terms, and thus prevent their dissimilar impacts from being obscured by blanket RESULTS terminology. Female “gregariousness” To punctuate the above points this paper presents In both of these species, and presumably in all data on two components of social behavior in the Stel­ eared seals, females gather in large numbers on the ler sea lion (Eumetopias jubatus) and the South same sites used by territorial males. Early researchers Australian fur seal (Arctocephalus forsteri), namely believed that males controlled “harems” of females, female “gregariousness” and male “territoriality”. The but this concept with its erroneous evolutionary im­ data will show that the species differ in the expression plications has been abandoned (Peterson, 1968). The of these components, and that the reproductive con­ aggregative responses of females to each other (termed sequences of each may differ between the two popula­ “gregariousness”) probably produce the large num­ tions. In other words the data will show that neither bers typically seen on rookeries. The herding and of these terms should be considered a unitary concept territorial activities of males may create some dis­ in model-building since each may have a different re­ continuities in the female aggregation, but no evidence productive impact. has been offered that females prefer specific males or * Present address: NMFS, Marine M am m sl Div., NSA BIdg. 67, that their movements are controlled by males (that is, Sand Point, Seattle Washington 98115, USA. the discontinuities are not absolute). Comparative social behavior of eared seals 189

Figure 144. Relative spacing between (a) female Arctocephalusforsieri and (b) female Eumetopias jubatus.

It is clear at a glance that there are population In other words, to establish the exact link between differences in the spacing between “gregarious” fem­ female “gregariousness” and male reproductive suc­ ales. South Australian fur seal females do not permit cess we need more research on the factors that keep other females to approach more closely than about 1 males and females in close proximity. But in the inte­ meter. The only sustained body contact is between rim we are not justified in assuming that “gregarious­ females and their offspring. Steller sea lion females, ness” has equal form or equal evolutionary significance on the other hand, often huddle against one another, in females of all species because of the differences we and thus many more can use the same male’s territory. already know exist. Relative spacing between females is shown in Figure 144. O ther female fur seals (with the exception of Arctocephalus pusillus doriferus, Stirling and War- Male “territoriality” neke, 1971) are reported to maintain spacing similar There are broad similarities in the social organization to A. forsteri while other sea lions are said to space of males in both species. Males each establish and similar to Eumetopias. Maximum spacing between maintain a preserve, traditionally called a territory, females would apparently be reached in Callorhinus where copulation may occur. The territory is de­ females except for the strong herding tendencies of lineated by the male’s holding ceremonial threat dis­ males (Peterson, 1965). Thus there appear to be some plays with adjacent males at several points around the species differences in female gregariousness as meas­ periphery. Encroachment beyond a line joining the ured by spacing between individuals. points of display, usually thought of as the territorial Perhaps associated with the differences in spacing boundaiy, precipitates a fight. The form of both is the fact that the copulation frequency of males, boundary displays and of fights are similar, although discussed in the next section, is approximately four recognizably different in the two species. times higher in Steller sea lions than in A. forsteri. Figure 145 shows that when two Steller sea lion Possibly these differences result from the fact that males hold a boundary display they meet in the prone female fur seals each require more space, and there­ position with mouths open, then shift to a “facing fore fewer can coexist in each male’s territory. How­ away” or “oblique stare” position, then physically ever, we know that the number of females in each separate from each other. In Arctocephalus the males territory also depends on the location of the territory, meet erect with heads pointed high (see Figure 146), the aggressiveness of females (which reaches a peak then shift to a “facing away” posture, then return near parturition), environmental temperatures (Gen­ repeatedly to the head high position alternating with try, 1973), the herding tendency of the males, high “facing away” postures. Physical separation may occur surf, driving rain, and the ratio of females to males. after 10 or more head high postures. Thus the 190 R. L. Gentry

a

Figure 146. Boundary display posture in Arctocephalus males, the head high posture.

display of Arctocephalus resembles multiple single displays of the Steller sea lion chained together in sequence. Another display common to the two species is the submission display given by a subadult male to a terri­ torial male (and by females to adult males). Adult males rarely if ever give a boundary display toward subadult males but instead move toward them menac­ ingly. Juveniles of both species respond to these threats by opening the mouth, snapping it repeatedly, and sidling away. During submission Arctocephalus emit a b yelp like an injured dog, while sea lions remain silent. Figure 147 shows an intruding sea lion submitting to a territory holder. Adult males never give a submission display while on their territory unless they are de­ feated in a true fight. In subadult males of both species there is an in­ complete separation of the boundary display from the submission display. Young male fur seals that defend territories prior to and following the actual reproduc­ tive season will boundary-display to a larger neigh­ boring male, but if pressed will give the submission display and flee the territory. That is, the boundary displays of juveniles often terminate with submission whereas those of adults do not. Figure 148 shows the seasonal variation in number of male-male encounters that included both boundary display and submission display components. On the same graph appears the percentage of arrival of all males seen copulating. Note c that virtually all boundary displays ending with sub­ mission occurred before the fully adult males (defined Figure 145. Boundary display components in Eumetopias males, (a) Prone threat posture, (b) Facing away or oblique stare posture, as those seen copulating) arrived. Young Steller sea (c) Animals moving away from one another. lions go through a similar developmental pattern but Comparative social behavior of eared seals 191

Figure 147. Submission display being given by Eumetopias male on left. no quantitative data have been collected to substan­ more and had a slightly stronger tendency to restrict tiate the point. fighting to the time of establishing contact with a new- Despite similarities in the behavioral components of rival. territory maintenance there are many differences in the territorial systems in these two populations. Sea Boundary display lions formed territories in two rows parallel to the sea Quantitative comparisons of boundary displays were and averaged only four neighbors each. Fur seals based on the encounters between known pairs of formed territories five or six rows deep and averaged males. Table 29 shows the duration and number of 16 neighbors. Research on other rookeries of these two displays between one neighbor-pair of sea lions and species are needed to determine which of the diffe­ between one pair of fur seals. These examples were rences below resulted from dissimilar terrain or dif­ selected for their large N; the trends shown are typical ferences in population size, and which are “true” species differences.

Territory size 80 % Territory size varied throughout the reproductive Copulating 60 Males season for both species. I compared the species by Arrived 40 finding the mean territory size held during the week 20 of peak copulation numbers by males seen copulating. For 13 sea lion males the mean territory size was 205 m2 during this period. A comparable figure for 12 20 measurable fur seal territories was only 23 m2. % 16 Boundary Displays 12 Number of fights 8 Steller sea lions defended their territory by fighting more often than did fur seal males. For 13 sea lion 4 males that copulated the average was 3'2 fights, all 0 of which occurred within the first five days that the 2 3 4 56 7 8 9 10 11 12 13 opponents were neighbors. The 34 Arctocephalus W eeks males seen copulating averaged 2-2 fights each and Figure 148. Seasonal occurrence of boundary displays-with- 94 % of these occured within the first five days after submission, and percent of arrival of Arctocephalus males seen establishment of a neighbor-pair. Thus sea lions fought copulating. 192 R. L. Gentry

Table 29. Duration and number of boundary displays between one neighbor-pair each of Eumetopias and Arctocephalus

Sea lions Fur seals (WBW vs EP) (MA vs ZZ) Days Time (secs) Time (mins & secs)

1-5 ...... 22" (26) 3'28" (35) % of 6-10...... 14" (15) 4'39" (22) Displays 11-15...... 17" (13) 4'16" (27) 16-20...... 14" (5) 2'34" (41) 21-25...... 14" (4) 2' 13" (27) 26-30...... 8" (3) 2'28" (26) 31-35...... 3" (2)______of all data collected. Note that fur seal boundary dis­ plays averaged much longer in duration than sea lion displays, reflecting the “chained” nature of the display as described above. 0 The Table also shows a progressive decrease in 12 3 4 5 6 7 8 number and duration of sea lion displays with time, Time spent which I have previously interpreted as habituation as neighbors (Gentry, 1970). No such decreases are evident in the ( in eighths) fur seal data. I have shown elsewhere (Gentry, 1970) that boundary display activity increases with the Figure 149. Time course of biting during Eumetopias boundary displays. arrival of new neighbors. Since fur seal males had four times as many neighbors as sea lion males they may have been more constantly aroused to territorial possible to analyze for habituation tendencies between defense and therefore their boundary display perfor­ individual pairs as for sea lions. mance was less likely to show temporal declines than To summarize then, the Steller sea lion males had sea lions. Perhaps fur seals would show similar declines bigger territories and had more fights than did fur at lower population levels. seal males. But in boundary maintenance the sea lions had fewer boundary displays which were of shorter Biting during boundary displays duration and underwent rapid habituation. Steller For 13 sea lion males seen copulating, 14 % of 905 males did tend to bite each other more during boun­ recorded boundary displays involved one of the op­ dary displays, but even this biting underwent rapid ponents biting the other. In 13 Arctocephalus seen habituation. copulating only 5 % of 2412 displays recorded involved Aside from differences in the behavioral means of biting. Therefore not only did fur seals average more territorial defense the two territorial systems differed than twice as many displays per male, but they bit in their rigidity; sea lion territories were more endur­ each other only about one third as often as did sea ing and stable than Arctocephalus territories. The lions. quantifiable aspects of territorial stability summarized Biting also showed a different time-course in sea in Table 30 show that not only were Steller sea lions lions than in fur seals. Figure 149 shows that 44 % of present on their territories longer but, unlike fur seals, all biting between pairs of sea lions occurred during none of them changed territorial sites completely, and the first one eighth of the days they spent as neighbors, fewer of them had major changes in the territory and that virtually all biting has ceased by the end of boundaries throughout the season. The Table also the first half. No such habituation is evident among shows that sea lions which changed boundaries did so fur seals, perhaps because of the low absolute incidence only one fourth as often as fur seals. Viewed on the of biting and the large number of neighbors. A typical population level, the Arctocephalus rookery had al­ example is fur seal male “ER” for which we recorded most five times as many boundary changes per day of 30 displays with biting. Of these, 16 were in the first observation as did the sea lion rookery, and the com­ half and 14 were in the second half of his tenure on position of the male population changed more often. territory. However, since these instances were spread Thus, there are quantitative differences in both the over encounters with 15 different opponents it is im- behavioral components of territoriality and in the na- Comparative social behavior of eared seals 193

Table 30. Stability of territorial systems in sea lions would maintain rigid territorial systems like Callor­ and fur seals. hinus and that all sea lions would resemble the more plastic system of Zalophus. This prediction is not sup­ Eumetopias Arctocephalus ported by the results presented here. In fact the op­ posite was found; a sea lion system was more rigid X Days ashore...... 46 38 than a fur seal system. Thus in speculating on the % Males changing evolution of otariid subfamilies we must consider that territorial site...... 0 9 the groups have quantitative and qualitative differen­ % Males having ces in the expression of the same behavioral repertoire, boundary changes...... 61 97 rather than having different repertoires. X Boundary changes/male . 1-4 4-0 In selecting a behavioral basis for comparing species X Boundary change/day we should select the most stereotyped behavioral pat­ in population...... 0-4 2-8 terns available. No displays of eared seals are as highly X Copulations per male . . . 11-9 3-0 stereotyped as some bird displays, but many approach the redundancy of form needed for a behavioral “unit” (Barlow, 1968). These units are the most likely to re­ main species-typical and, since they do not intergrade ture of the territorial system as a whole in two diffe­ with other patterns, are the easiest to quantify. The rent populations. But are these differences related by widest possible range of behavioral units should be cause and effect to the large differences in mean selected for study since species differences may arise copulation frequency shown in the last line of Table in many components of social behavior. Below is a list 30.'' It is tempting to speculate so, but copulation fre­ of patterns that are useful in studying eared seal po­ quencies may equally depend on differences in po­ pulations. pulation size, habitat and other factors. Only more research can establish the determinants of copulation ( 1 ) Male boundary display. The boundary display is frequency in different populations. the basis of the territorial system and is probably the In summary, this section has shown that variations most stereotyped pattern to be seen. The form should in territorial systems exist among otariids, and that be recorded on film. Quantitative notes should be kept these variations occur along with very dissimilar con­ on the number, duration, time of day and especially tributions of males to the gene pools of their respective location of displays between known pairs of males breeding groups. That is, there is nothing unitary in throughout the season. the concept of male “territoriality” either as a system or as it relates to reproduction. This is especially im­ (2) Male fighting. Note the occurrence of biting portant to consider when speculating on the roles “strategies” or combinations of bites that recur. Also played by various components of social behavior dur­ note repeated postures, whether biting is prolonged, ing the evolution of pinniped groups, as in Bartholo­ and relate the timing of fights to the arrival of males. mew’s model (Bartholomew, 1970). (3) Male-female encounters. Note whether the male or the female initiates the encounter and the sequence of components such as biting, perineal licking, urina­ CONCLUSIONS tion, or licking the urine. Note especially the orienta­ The first point extractable from these data is that tion of the female to the male and the outcome (co­ we must operationally define our terms when dis­ pulation or the female departs the male’s territory). cussing pinniped behavior. “Territoriality” may mean Note the occurrence of these encounters relative to different things to different researchers depending on the date of copulation. their background. This becomes especially important in phocid seals whose social systems do not fit the (4) Copulation. Count the number of mounts, whe­ existing terminology as well as do otariid seals. ther the male performs a neck-bite, time the duration Also, it is becoming clear that no single behavioral of the initial non-thrusting and the terminal pelvic pattern exists by which the subfamilies of otariids can thrusting phases, measure thrusting rate and observe be differentiated. For instance, close body contact or which animal terminates the copulation. Note mul­ huddling is common to sea lions and does not occur in tiple copulations for known females. fur ssals with the important exception of A. p. dorife- rus. Also, based on observations of Callorhinus and (5) Female-female encounters. List the types of ag­ Zalophus, Peterson (1968) predicted that all fur seals gressive encounters seen (example: pushing chest to

13 194 R. L. Gentry chest, locking mouths). Quantify the relative fre­ I suggest that data be gathered on as many of the quencies of types during and outside the reproductive above patterns as possible, and on those unlisted pat­ season, and note whether one or both females have terns that seem appropriate to the situation. Such a pups. research format will produce a broad spectrum of in­ formation specific to each new species under study, (6) Parturition. Note vocal interchanges between and it will add to the growing body of standardized mother and newborn, the patterns of nuzzling or lifting information by which all the Otariidae will eventually the pup, and the postures related to suckling. Measure be compared. frequency and duration of these interchanges. (7) Female-young relations. Follow the pattern of female’s feeding trips to sea, duration of her absences REFERENCES and the behavioral sequences on reunion of the pair Barlow, G. W. 1968. Ethological units of behavior, pp. 217—32' such as vocalizing, sniffing the mouth or rubbing with In The Central Nervous System and Fish Behavior. Ed. by the vibrissae. Time the duration of suckling bouts and D. Ingle. Univ. of Chicago Press, Chicago, 111. Bartholomew, G. A. 1970. A model for the evolution of pinniped note their frequency relative to the female’s feeding polygyny. Evolution, (Lancaster, Pa.), 24:546-59. trips. Gentry, R. L. 1970. Social behavior of the Steller sea lion. Univ. Calif., Santa Cruz, Ph.D. Thesis. 113 pp. (8) Juvenile interactions. Mock-fighting patterns of Gentry, R. L. 1973. Thermoregulatory behavior of eared seals. pups and juveniles mimic those of adult males fight­ Behavior, 46:73-93. ing. Behavioral components become relatively stereo­ Peterson, R. S. 1965. Behavior of the northern fur seal. Johns Hopkins Univ., Baltimore, Md., D.Sc. Thesis. 214 pp. typed only after one month of age and may include Peterson, R. S. 1968. Social behavior in pinnipeds with particular chest to chest pushing, neck-fencing, hard biting and reference to the northern fur seal. pp. 3-53. In The Behavior shaking and the submission display. and Physiology of Pinnipeds. Ed. by R. J. Harrison, R. C. Hubbard, R. S. Peterson, C. E. Rice, and R. J. Schusterman. (9) Behavioral patterns related to thermoregulation. Appleton-Century-Crofts, New York. Note the rest postures of females at different tempera­ Stirling, I. & Warneke, R. M. 1971. Implications of a compa­ rison of the airborne vocalizations and some aspects of the tures, the occurrence of panting, flipper waving, and behavior of the two Australian fur seals (Arctocephalus spp.) urinating at high temperatures, the use of shade and on the evolution and present taxonomy of the genus. Aust. the movements to water of females and males. J. Zool., 19:227-41.