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.