OCCURRENCE AND GROUP ORGANIZATION OF ATLANTIC BOTTLENOSE PORPOISES (TURSIOPS TRUNCATUS) IN AN ARGENTINE BAY

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Abstract
During a 21-mo. study, individuals of T. truncatus in Golfo San Jose, Argentina, exhibited a 4 mo. occurrence cycle, but showed no seasonal migration. Subgroups numbering 8-22 animals included a small core unit of individuals consistently found together. Other animals appeared and disappeared in these subgroups on different days in a highly fluid manner which paralleled the open society of African chimpanzees, Pan troglodytes. Some adults showed weak and changing surfacing associations with other adults. Calves consistently surfaced together with a particular adult, except during apparent play or investigative behavior, when calves left adults for brief periods. The mean dive time per animal was 21.8 s. Of 7 calves, 6 were born in late summer. This calving peak coincided with the highest water temperatures of the year.