Abstract
Understanding the way animals use space is essential to infer movements related to essential biological activities such as foraging, mating, and predator avoidance. However, these factors may change with warming waters and more frequent heatwaves. Changes in animals’ social and ecological environment can affect their movement, so it is important to examine how habitat use changes over time. Many studies have examined how invertebrates and fish communities are responding to changes in their habitat, but less it is known about how marine mammals adjust to such ecological alterations. This study investigates the long-term movements of bottlenose dolphins (Tursiops aduncus) in Shark Bay, Western Australia. We used linear mixed effect models and weighted home range on 21 years of seasonally collected survey data to examine the range shifts of individuals in a bisexually philopatric, resident population of adult male and female dolphins in Shark Bay. We also used changes in sightings proportions over time to detect changes in habitat use. Our results indicate that males and, to a lesser extent, females have shifted their range south over the northwest-southeast axis of the Peron peninsula. This shift might be explained by a response to a southerly shift in preferred preys or a change in predators’ abundance and distribution, and there is ample evidence of poleward shifts in the distribution of fish and invertebrates concomitant with ocean warming. There was a markedly stronger shift by males, suggesting that the pursuing of mating opportunities and male-male competition from the north might also play a role. Our long-term study shows the flexibility of range in bottlenose dolphins in response to ecological and social changes.