COS 60-2 - Maximum temperatures determine the habitat affiliations of North American mammals

Abstract: Addressing the ongoing biodiversity crisis requires identifying the winners and losers associated with global change. Species have been historically categorized into groups based on how they respond to habitat loss; for example, species restricted to natural environments, those that now specialize on anthropogenic habitats, and habitat generalists. Yet, there is increasing evidence that species are not monolithic and may switch their habitat affiliations across time and space. For example, an organism may venture into human-modified areas in benign regions but retreat into thermally buffered forests in areas subject to temperature extremes. Here, we applied community occupancy models to a large-scale, mammal camera trapping dataset consisting of >150,000 mammal detections of 29 species at 2498 sites distributed across the continental United States, to ask three questions. First, are species’ responses to forest and anthropogenic habitats consistent across continental scales? Second, do macroclimatic conditions explain spatial variation in species’ responses to land-use? Third, can species traits elucidate which species are most likely to show climate-dependent habitat associations?

We found that all species exhibited significant spatial variation in how they respond to land-use, tending to avoid anthropogenic areas and increasingly use forest in hotter regions. Specifically, species occupancy was on average 50% higher in completely forested compared to open habitats in the hottest regions, whereas, in the coldest regions, species occupancy was 55% lower in completely forested habitats. Larger species with wider ranges, herbivores, and primary predators were more likely to change their habitat affiliations over macroclimatic gradients than top predators, which consistently affiliated with high forest cover across their ranges. Our findings suggest that climatic conditions may dictate species’ capacities to persist in anthropogenic landscapes. Looking forward, increasingly severe and frequent temperature spikes may thus impede efforts to conserve biodiversity in alongside people anthropogenic landscapes. Thus, our results suggest decisions about whether to enhance the conservation value of anthropogenic landscapes versus protect more natural areas should consider how species habitat affiliations are likely to shift under a changing climate.