The social structure of bottlenose dolphins, Tursiops truncatus, in the Bahamas

This study reports on a community of bottlenose dolphins found >27 km from Grand Bahama Island. Observations were conducted from May--September, 1993--2002. The half weight index determined coefficients of association (COA) between dolphins for each year and from pooled data over the 10-year period. Long-term site fidelity of up to 17 years occurred. Resident and non-resident dolphins occurred in the area. Some dolphins traveled 333 km between communities. Average group size was 3--5, and significantly larger with calves. Traveling groups were significantly smaller than feeding or socializing. Mother-calf associations were the strongest. Male-male COAs were low (x = .34), however, some individuals formed strong associations. Female-female COAs were low (x = .35), and affected by female reproductive status. Mixed-gender COAs were significantly lower (x = .31) than same sex associations. Pooled data revealed lower COA values, however, the same trends were evident. The long-term associations revealed from yearly COAs were not seen when data were pooled.