Long-term impacts of fish provisioning on the behavior and survival of wild bottlenose dolphins

To promote close encounters with wildlife, humans sometimes provision wild animals with food. However such practices can be harmful, and the impacts of human provisioning on wild animals can be difficult to determine, especially indirect effects such as those on the offspring of provisioned animals. In Shark Bay, Australia, a small subset of the resident population of bottlenose dolphins is regularly provisioned with fish handouts under the supervision of the West Australian Department of Environment and Conservation (DEC). Previous studies have shown that calves born to provisioned females experienced reduced care and higher mortality relative to calves of non-provisioned mothers. These results led to changes in the management practices in 1994, which we assessed the efficacy of by comparing (1) calf mortality before and after the intervention and (2) behavior of provisioned with non-provisioned dolphins in the population. Although calves born to provisioned females exhibited higher survivorship (86.7%) than before the intervention (23.1%, χ2 = 9.05, df = 1, p = 0.003, N = 28), group differences in maternal and calf activity budgets were still observed over the course of calf development. Provisioned mothers provided less care to their calves and their calves appeared to compensate by foraging more and separating more from their mothers compared to their non-provisioned counterparts (N = 114 calves). Our study shows that careful regulation and reduced wildlife provisioning can increase calf survivorship, but behavioral development continues to be affected.