Maximum temperatures determine the habitat affiliations of North American mammals

Abstract

Addressing the ongoing biodiversity crisis requires identifying the winners and losers of global change. Species are often categorized based on how they respond to habitat loss; for example, species restricted to natural environments, those that most often occur in anthropogenic habitats, and generalists that do well in both. However, species might switch habitat affiliations across time and space: an organism may venture into human-modified areas in benign regions but retreat into thermally buffered forested habitats in areas with high temperatures. Here, we apply community occupancy models to a large-scale camera trapping dataset with 29 mammal species distributed over 2,485 sites 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 taxa 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 forests in hotter regions. In the hottest regions, species occupancy was 50% higher in forested compared to open habitats, whereas in the coldest regions, the trend reversed. Larger species with larger ranges, herbivores, and primary predators were more likely to change their habitat affiliations than top predators, which consistently affiliated with high forest cover. Our findings suggest that climatic conditions influence species’ space-use and that maintaining forest cover can help protect mammals from warming climates.

Habitat alteration or climate: What drives the densities of an invading ungulate?

“…Even over a small geographic area relative to the overall distribution of white-tailed deer, we found a large increase in deer densities (from 0 to 2 animals/km 2 ), which suggests that even a small change in winter severity over time could trigger a substantial increase in deer densities in northern areas. However, forecasting future deer distribution and abundance using retrospective relationships (see ex- When seeking to understand the drivers of a species' abundance and distribution, it is important to consider that ecological processes are often hierarchical (Tourani et al, 2023). Our finding that climate drives the population density of white-tailed deer, aligns with studies on factors affecting deer distribution (Dawe & Boutin, 2016;Kennedy-Slaney et al, 2018).…”

“…Localized habitat-driven processes are nested within a larger scale framework that dictates overall population dynamics (Tourani et al, 2023). Climate may set the envelope within which whitetailed deer can persist in the boreal forests of western Canada, while habitat alteration may influence their abundance or finer scale spatial distribution within this climatic envelope (Elmhagen et al, 2017;Kennedy-Slaney et al, 2018).…”

“…For most species, anthropogenic habitat alteration (hereafter termed habitat alteration) is considered to have a stronger effect (Caro et al, 2022), though the relative influence of habitat alteration and climate is species-and context-specific (Tourani et al, 2023;Weiskopf et al, 2020). As climate change accelerates and its effects strengthen (Smith et al, 2015), it is incumbent to understand the relative contributions of habitat alteration and climate change to observed biodiversity changes, their interactive effects, and, importantly, the mechanisms through which these factors act.…”

Seasonal activity patterns of a Kalahari mammal community: Trade‐offs between environmental heat load and predation pressure

“…They can partially alleviate this trade-off through the selection of cooler microclimates (Van Beest et al, 2012;Mole et al, 2016) and changes in posture or orientation to reduce the heat load from direct solar radiation (Hetem et al, 2011;Maloney et al, 2005). At the landscape scale, species may even alter their use of habitat types, thereby buffering their exposure to warmer macroclimates (Srinivasan et al, 2019;Tourani et al, 2023). Another strategy includes behavioural changes, such as changes in the timing of activity, which may prevent high metabolic heat production as a result of activity coinciding with high ambient temperatures (Brivio et al, 2024;Hetem et al, 2012).…”