Association patterns of bottlenose dolphins (Tursiops aduncus) off Point Lookout, Queensland, Australia

Abstract

The social structure of animal communities is usually measured through interactions or associations of individuals within the community. However, investigating and identifying association patterns for large communities of social animals can be difficult, given the logistical difficulties of identifying a large number of individuals within a given area and time period. In this study, over 550 individuals were identified within a large community of bottlenose dolphins (Tursiops aduncus) sampled intensively during the winters of 1998 and 1999 off Point Lookout, Queensland, Australia. Association patterns within this community were analysed using the half-weight index of association, including seven criteria for selecting individuals for inclusion in the analysis. Selection criteria were based on the number of times an individual was sighted during the entire study period. Overall, the community showed a highly fluid association pattern, with only two selection criteria showing association patterns that differed significantly from random. This type of association pattern is commonly reported for large communities of cetaceans. However, without the inclusion of other population information such as estimates of the proportion of identifiable individuals in the community and of community size, it appears that association patterns for these large communities may not be accurately assessed.