Between a rock and a hard place: rugged terrain features and human disturbance affect behaviour and habitat use of Sumatran elephants in Aceh, Sumatra, Indonesia

Abstract

Asian elephants are threatened throughout their range due to habitat loss, fragmentation, and conflict with humans. Limited data on spatial and temporal use of habitats in largely intact forests by elephants in Sumatra is a major hindrance for conservation and land use planning, and consequently human–elephant conflict mitigation. We analysed GPS data from collared elephants to investigate their use of habitat in relation to available land cover and human disturbance in Aceh, Sumatra, Indonesia. We applied remote sensing techniques to extract environmental variables to use in state-space Hidden Markov Models and integrated Step Selection Function to analyse foraging strategies and land use selectivity, while using dynamic Brownian Bridge Movement Models and Minimum Convex Polygons to determine used and available habitat features within their home ranges. Our results show that Sumatran elephants in Aceh preferred areas with lower elevation (< 200 m) and slopes (0–10°), with minimal terrain ruggedness, which also happen to be areas selected by humans. Elephants closely adhered to rivers and mountain valleys when utilizing homogenous dense natural forests, and expanded from the rivers in heterogenous forests toward open, resource-dense, land use types. Overall, slope, vegetation, and human disturbance had the largest impact on each of the clans’ foraging strategies. Areas closer to human settlements were used more by night and less by day, indicating that human presence and activities influence elephant habitat use and avoidance. Our findings conclude future management decisions should focus on protecting the remaining lowland forests and preventing further urban encroachment in areas with lower elevation and slope, particularly in proximity to rivers which act as corridors between natural habitats, in order to mitigate human-elephant conflict and protect the species from extinction.