Human food provisioning impacts the social environment, home range and fitness of a marine top predator

Abstract

Food provisioning promotes close interaction with wildlife but can negatively impact the targeted species. Repeated behavioural disruptions have the potential to negatively impact vital rates and have population level consequences. In Bunbury, Western Australia, food-provisioned female bottlenose dolphins, Tursiops aduncus, suffer reduced reproductive success via lower calf survival. However, the proximal causes of this long-term negative effect remain unknown. To infer processes that could lead to fitness costs, we combined network analyses, Markov Chain, regression models and kernel density estimates to evaluate the social environment, behavioural budget and home range size of provisioned dolphins relative to their nonprovisioned counterparts. We found that provisioned dolphins spent significantly less time socializing and had smaller home ranges and weaker social associations than the nonprovisioned dolphins. Overall, these findings suggest that provisioned dolphins experience a more restricted social environment among themselves, which likely results from investing time in an unnatural foraging tactic around the provisioning site, in proximity to human activities. This modified social environment associated with food provisioning and begging behaviour, reinforced by the limited time spent socializing, could affect the opportunities of calves of provisioned females to acquire fitness-enhancing skills and form essential social bonds. This study highlights the need to consider the potential impact of human activities on the social environment of animals.