Social Structure and Life History of Bottlenose Dolphins Near Sarasota Bay, Florida: Insights from Four Decades and Five
Studies of social ecology can benefit from long-term observations, as these provide researchers with opportunities to distinguish between the relative contributions of life history, demographics, and ecological pressures to the development of social patte
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Social Structure and Life History of Bottlenose Dolphins Near Sarasota Bay, Florida: Insights from Four Decades and Five Generations Randall S. Wells
Abstract Studies of social ecology can benefit from long-term observations, as these provide researchers with opportunities to distinguish between the relative contributions of life history, demographics, and ecological pressures to the development of social patterns. Long-term study can provide the means of interpreting changes in stable social patterns relative to changes in environmental factors or availability of members of specific age-sex classes. The strength of social patterns
R.S. Wells (*) Chicago Zoological Society, c/o Mote Marine Laboratory 1600 Ken Thompson Parkway, Sarasota, FL 34236, USA e-mail: [email protected] J. Yamagiwa and L. Karczmarski (eds.), Primates and Cetaceans: Field Research and Conservation of Complex Mammalian Societies, Primatology Monographs, DOI 10.1007/978-4-431-54523-1_8, © Springer Japan 2014
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can be measured by their persistence from one generation to the next, and as individuals pass life history milestones. The Sarasota Dolphin Research Program has been engaged in studies of bottlenose dolphins along the central west coast of Florida, including Sarasota Bay, since 1970. The research includes focal animal behavioral observations, photographic identification surveys, biopsy darting for genetic and contaminant samples, and occasional capture–release efforts to examine the animals’ behavior, ecology, life history, population biology, health, and concentrations and effects of environmental contaminants. More than 4,800 individuals have been identified in the bays and coastal Gulf of Mexico waters of the region, including the approximately 160 dolphins using Sarasota Bay on a regular basis. A mosaic of adjacent, often slightly overlapping dolphin communities has been identified based on sighting locations and social associations, and genetic findings support these designations. These communities are genetically distinguishable but not isolated. The communities of dolphins residing in and around Sarasota Bay, the most intensively studied animals, are characterized by a high level of multigenerational site fidelity and low levels of emigration and immigration. The social structure includes three basic components: nursery groups built around females with young of similar age, juvenile groups, and adult males, mostly in strongly bonded, long-term male pairs or sometimes as single individuals. This overall structure has remained relatively stable through five generations; however, core area use, group size, and some social association patterns show variability over time. Paternity testing suggests that male pair-bonding may improve reproductive success. Female reproductive success appears to be related to mother’s age, experience, and environmental contaminant residues. Older, more experienced mothers are more successful in rearing young over the typical 3- to 6-year period of association; these females have also p
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