Individual variation in red deer responsiveness towards human disturbance: A prospect for wildlife viewing in Europe’s national parks

Abstract

Animals adjust behavior to changes in perceived predation risk, their so called “landscape of fear”. However, individuals within populations can differ greatly in their plasticity towards perceived risk. In national parks, where animals are often protected from human hunting, wildlife may start losing their fear of humans and become more observable, a process that starts at the individual level. Here we aim to test whether ungulates in one of the only largely non-hunted populations in Europe show individual variation in behavioral plasticity towards gradients of human disturbance. We used random regression to dissolve the individual movement responses of 63 red deer (Cervus elaphus) to spatio-temporal variation in human recreation. We measured human disturbance as the number of recreationists on the closest trail on a given day. We quantified conditional repeatability, i.e., between-individual variation, along the perceived risk gradient. To avoid pseudoreplication, we fitted models to the hours of the day with peak activity or passivity. Diel activity patterns were conserved across individuals in our population, with peak activity in the early morning and late evening. When actively foraging during the morning, red deer responded to human disturbance with flight, i.e., longer hourly movement distances, while they reduced movement in response to disturbance when resting in the middle of the day. Between-individual variation increased with visitor frequentation, i.e., red deer behaved similarly when human disturbance was low, but with increasing human disturbance some deer adjusted movement while others responded little. Our results show that individuals varied greatly in their responsiveness towards human disturbance, with some resuming normal movement behavior. Flight responses are costly and may be selected against in non-hunted populations, leading to an increase in human-tolerant individuals over time. These are good news for national parks for which wildlife viewing is an effective tool to engage the public in conservation. Observing wildlife in Europe is difficult, likely due to a long persecution history and strong hunting pressure. Our results demonstrate that large non-hunting zones may, over time, successfully reduce wildlife’s extreme fear of humans.