A tale of scale: different factors influence the range boundaries and habitat use of a generalist mammalian carnivore

Abstract

Context: Understanding how environmental factors shape species distributions at different spatial scales is crucial for predicting responses to global change. However, most studies conflate factors determining habitat use and range boundaries, lacking a clear distinction between them. Objective: This study examines the environmental determinants of a generalist species with a relatively small range, distinguishing factors that shape range boundaries from those affecting habitat use. Methods: Using IUCN-assembled brown hyena presence data, we systematically varied the spatial extent of background points to separate variables related to range boundaries and habitat use. We used ensemble species distribution models (SDMs), including climatic, landscape, biogeographic, and anthropogenic variables, to compare different spatial scales. Additionally, we compared our results to traditional SDMs, which randomly distribute background points, depicting geographic distribution in general. Results: Our findings indicate that range boundaries and habitat use can be explained by different environmental factors and that the traditionally used SDM approaches can be biased towards one of these scales, depending on the background points distribution. In the case of brown hyenas, range boundaries are mainly defined by climatic factors, while habitat use is influenced by carnivore diversity, prey biomass, and anthropogenic factors. With multiple variables driving habitat use but only a few limiting range, our results suggest that brown hyenas function as habitat generalists but range specialists. Conclusions: Our study highlights the importance of study design when making inferences about species distributions at different spatial scales. Our findings challenge traditional classifications of generalist and specialist species, showing that presumed generalists may be habitat generalists but range specialists, like brown hyenas. Our methodological framework can be applied to other species to refine predictions of distributional responses to environmental change at different scales.