Within both species of bottlenose dolphins, males and females seem to have different approaches to life. My PhD thesis, complete in August 2015, was undertaken through the South West Marine Research Program (SWMRP) in Bunbury, Western Australia. I completed an integrated analysis of a 6.5 year photo-identification study conducted across coastal and sheltered waters. The most pronounced sex-specific findings of my research were that 1) abundance estimates for males and females were seasonally dependent and influenced by large-scale environmental variables, such as El Niño, 2) abundance estimates and sighting frequencies were generally higher for adult females than adult males, 3) females typically had smaller home ranges than males, 4) both females and males clustered close to the coast in summer and autumn, and were more dispersed throughout the study area during winter and spring (including offshore waters), and 5) a subgroup of females was segregated from males in a shallow, sheltered estuary across all seasons apart from summer. We suggested that the documented sex-specific and seasonal patterns in dolphin movements and behavior ultimately reflect seasonal fluctuations in prey distribution coupled with mating priorities during the warmer months. Overall, this study enhances available knowledge of the variation in behavioral ecology found among bottlenose dolphin populations and between the sexes, and acts as a model and impetus for future sex-based studies.
Our research would not have been possible if it was not for the help from our dedicated assistants and funding bodies for the SWMRP: the Dolphin Discovery Centre, Bemax Cable Sands, BHP Billiton Worsley Alumina, Bunbury Port Authority, City of Bunbury, Cristal Global, Department of Environment and Conservation, Iluka, Millard Marine, Naturaliste Charters, Newmont Boddington Gold, South West Development Commission and WAPRES.
This article appeared on pages 23-24 of the 2017 SDRP Annual Report, Nicks n Notches.