Preliminary tolerance distances of Sri Lankan deer to humans: The effect of species, landscape use, and proximity to buildings

Disturbance of wildlife by humans is common worldwide and is prevalent in areas where local economies rely on ecotourism, which promotes close encounters between people and charismatic megafauna, e.g., deer. When ecotourists approach wildlife, maintaining adequate separation distances minimizes impacts on focal mammals while enhancing the ecotourism experience. We propose suitable separation distances by measuring deer Flight-Initiation Distances (FIDs) in the tourism and biodiversity hotspot, Sri Lanka. FIDs ( n = 139 non-alert individuals) differed between four species: Spotted Deer Axis axis (µ ± SE, 23.74 ± 3.59 m), Barking Deer Muntiacus muntjak (15.36 ± 1.69 m), Sambar Rusa unicolor (12.11 ± 1.92 m) and Hog Deer A. porcinus (10.44 ± 2.32 m). Barking Deer, Sambar and Spotted Deer exhibited positive associations between Starting Distance (the distance between the observer and focal deer when an approach began) and FID. This relationship is almost always modelled as a linear effect in studies of wildlife FIDs, however for Sambar and Spotted Deer it was non-linear. Spotted Deer and Sambar had longer FIDs in wilderness compared with non-wilderness areas. Sambar at Horton Plains National Park, which are subjected to intense depredation by Leopard Panthera pardus kotiya , tended to have shorter FIDs within c. 300 m of human infrastructure, perhaps at least partly because Leopards avoid humans. Minimum human-deer separation distances (95th percentiles of FIDs collected in wilderness areas) were: 31 m for Spotted Deer; 64 m for Sambar; 23 m for Barking Deer; and 15 m for Hog Deer (with limited sampling). Prescriptions based on these could be implemented into tourism operations via codes of conduct, for future validation and fine-tuning.