Identifying appropriate management units is vital for wildlife management. Here we investigate one potential
management unit — resident communities of bottlenose dolphins — using information from ranging, occupancy, and
association patterns. We identify a resident community of Indo-Pacific bottlenose dolphins (Tursiops aduncus) in the
Swan Canning Riverpark, Western Australia based on: ranging patterns, sighting rates, Lagged Identification Rates
(LIR), and three measures of social affinity and structure (Simple Ratio Index, preferred dyadic association analyses,
and Lagged Association Rates (LAR)). The analyses yielded an estimated ‘community size’ of 17–18 individuals
(excluding calves). High seasonal sighting rates (> 0.75 sightings per season) and a long mean residence time (ca.
nine years) indicated year-round residency. The model best-fitting the LIR (emigration and mortality) also supported
this. The social structure of dolphins was species-typical, characterized by significant dyadic associations within agesex
classes (permutation test; P < 0.001), stronger associations among adult males than among adult females (LAR
males > LAR females), and temporally stable associations (LAR > null LAR). Constant companions or long-lasting
association models best explained adult male and female LARs. While behavioural information identified a resident
community in the Riverpark, genetic and demographic information is needed to assess its appropriateness as a
management unit.
Matching Signature Whistles with Photo-Identification of Indo-Pacific Bottlenose Dolphins (Tursiops aduncus) in the Fremantle Inner Harbour, Western Australia
