Special Issue Survey of Cetaceans in Captive Care

296 Couquiaudbirth and in supervising calves while the motheris hunting or diving to great depths where calvescannot follow (Johnson & Norris, 1986; Evans,1987). In captivity, the oldest, parturient femaleoften is observed to be the “focal point on whichthe social activity of the tank is centred” (Tavolga,1966, quoted in Johnson & Norris, 1986, p. 338).Sexual segregation occurs commonly in dolphinschools (Norris & Dohl, 1980). Many oceanic cetaceanjuvenile males form separate groups, and adultmales travel alone, in tightly bonded pairs, or insmall groups, joining the basic social group for briefperiods, primarily for breeding purposes (Sweeney,1990; Wells & Scott, 1999). In some populations,bonds between males of similar age develop early inlife, and pair bonds may be maintained for 20 yearsor more (Wells & Scott, 1999). Males and femalesalso may form sex-segregated alliances when theyencounter resources and cooperate in competitionfor these resources with other conspecifics (Connoret al., 2000a, 2000b).Play, courtship, and sexual behaviours have animportant role in the social life of whales and dolphinsand are probably more developed in captivitysince the time dedicated to the feeding is reducedand traveling is suppressed. Play is commonly seenamong young animals and may serve as learningand practice progress. Adults also play with youngstersor among themselves. They frequently leap,chase each other, or engage in preludes of courtship.Social and sexual behaviours are carriedout throughout life, and they probably functionnot only in courtship, but as a means to maintainfamiliarity between group members (Evans, 1987).These behaviours are sometimes directed towardsother species and humans. Other social behavioursinclude altruistic and care-giving behaviours. Itmay take the form of cooperation such as collectivefood herding, assistance to a sick animal, “standingby” when a school mate is captured, rescueand defence of a threatened member of the group,and the assistance given by the mother to her calf(Johnson & Norris, 1986). Care-giving behaviourhas been observed in captivity among speciessuch as the bottlenose dolphin, the pilot whale, thecommon dolphin, and the Pacific white-sided dolphin,and between individuals of different species(Defran & Pryor, 1980; Johnson & Norris, 1986).For other detailed and recent sources on cetaceanlife, behaviour, and physiology, please refer toReeves et al. (1999), Reynolds & Rommel (1999),Mann et al. (2000), and Perrin et al. (2002).Possible Impact of Controlled Environment onBehaviourLife in a controlled environment may impede certainaspects of normal social dynamics. Aggressivehierarchical dominance may be naturallyoccurring in the wild, but in captivity, it can disruptthe group and harm subordinates (Geraci, 1986b).The situation in captivity is altered because adultmales interact permanently with the social unit.Dominance hierarchies can be established in bothsexes. Large adult males can dominate other poolmates,and the largest and oldest females maydominate younger or smaller males and females(Östman, 1991; Samuels & Gifford, 1997; Wells& Scott, 1999). In captivity, this male dominanceis often the source of many social and behaviouralproblems, especially related to juvenileswithin the social group (Johnson & Norris, 1986;Sweeney, 1990). The aggression often reportedin adult male bottlenose dolphins towards infantsand juveniles in captivity may reflect a tendencyon the part of such adults to herd the young whenthreatened in the wild. This behavior may escalateinto obsessive hostility in captivity where theyoung can neither escape nor be buffered from themale by a tightly packed crowd of adults (Johnson& Norris, 1986). Since they are unable to leavethe area to avoid the situation, stress, psychological,and physical trauma can occur. Attempts tosolve problems caused by dominance or othercompatibility problems in the enclosure are challenging.These disruptions also can be caused bythe fact that some of the animals may have beenremoved from their original social structure, separatedfrom family members or a social unit, andnow have to adjust to a new social environment.Many surveyed facilities emphasized the importanceof recreating an adequate social structurein captivity, especially by avoiding mixing adultmales together in the presence of females or adultmales with new juvenile males, and by providingample space and a multiple pool complex toallow separation and escape. In the wild, verticallyorganised swimming arrangements havebeen seen among groups of pantropical spotteddolphins, Pacific white-sided dolphins, and bottlenosedolphins, and in captivity, among spinnerdolphins. It has been hypothesised that these weredominance arrangements, expressed as priority ofaccess to the surface (Herman & Tavolga, 1980;Norris & Dohl, 1980; Johnson & Norris, 1986;Pryor, 1995). I have made similar observations ina dolphinarium in Japan about bottlenose dolphinsand false killer whales living in a restricted space.In a crowded square tank, the dominant animal, alarge adult male bottlenose dolphin, was alwaysseen swimming closer to the surface and to theedge of the tank, enjoying the optimal swimmingsurface available and having to make little effortto surface to breathe. Below him in the hierarchywas an adult female false killer whale that alsoenjoyed the upper layer and the outer peripheryof the tank. The lowest ranking animals, a