A multi‐scale synthesis of mousedeer habitat associations in Southeast Asia reveals declining abundance but few extirpations in fragments and edges

Abstract

AbstractHabitat loss and fragmentation profoundly impact Southeast Asian rainforest biodiversity and ecosystem functioning. While many larger herbivores are hunted and area‐demanding apex predators are lost from degraded forests (logged forests, forest fragments and forest edges), smaller herbivore species may be comparatively resilient or even benefit from a release from competition and predation in degraded forests. Mousedeer (or chevrotains) in the Tragulus genus are some of the world's smallest ungulates (1.5–4.5 kg) and are widespread in Southeast Asia. We evaluated mousedeer habitat associations at three spatial scales. At the regional scale, presence‐only species distribution modelling suggested mousedeer are negatively associated with aridity and elevation. At the landscape scale, variation capture rates among 186 published camera trapping studies suggested mousedeer are negatively associated with forest degradation and elevation. At the local scale (within landscapes), mousedeer abundance sampled with 1218 cameras at 10 landscapes and analysed with hierarchical abundance modelling suggested mousedeer are negatively associated with humans and elevation. Mousedeer diel activity patterns shifted towards increased nocturnality in degraded forests, possibly to avoid interactions with diurnal humans. Taken together, mousedeer prefer wet lowland forests and they persist – but decline – in degraded habitats and near humans. One exception was degraded forest fragments of Singapore where mousedeer are very abundant, likely due to the absence of hunting and predators. Our results emphasize that small herbivores persisting in fragmented rainforests decline relative to intact forests and thus are unlikely to be experiencing significant release from competition or predation. They also differ from small omnivorous generalists who experience beneficial foraging opportunities at edges. In degraded forests where larger wildlife has been lost, even low densities of small herbivores may perpetuate important ecological interactions such as herbivory, seed dispersal, or as prey for remaining predators.