Individual differences in responses to unmanned aerial vehicles among Weddell seals, Leptonychotes weddellii

Unmanned aerial vehicles (UAVs) offer invaluable contributions to wildlife observation, reducing costs and human risk while minimizing disturbance to animals during aerial surveys. However, within a population, individual animals can exhibit different responses to UAVs. This indicates that the level of UAV disturbance might differ between individuals even when the disturbance is mild at the population level. However, few studies have investigated UAV disturbance at the individual level. In this study, we explored the variation in response to UAVs among individual Weddell seals along the Terra Nova Bay coastline in Antarctica. We also examined how internal factors such as age, group composition and whether their eyes were open, as well as external factors such as UAV flight schemes, influenced responses. Our findings showed substantial variation among individual seals in both their overall response and changes in response to descending UAVs. Notably, seals were more sensitive to UAVs with vertical flight schemes than to those with horizontal flight schemes. When seals were in groups or had their eyes closed, their vigilance responses to UAVs decreased. Therefore, our findings highlight the importance of not only considering individual factors but also avoiding vertical flight patterns during UAV-based aerial surveys of Weddell seals, thus minimising disturbance. Additionally, we recommend developing more effective approaches for wildlife research that utilize UAVs by incorporating the consideration of individual differences in responses to UAVs.