Modelling the distribution and intraguild associations of an understudied mesocarnivore across the contiguous United States


Aim: Understanding the range-wide distribution and abundance of species is critical for their conservation and management. Grey foxes (Urocyon cinereoargenteus) are an understudied, low-density mesocarnivore with a broad geographic range. However, the factors that underlie this broad distribution are poorly understood and large-scale analyses of this species' range and ecological niche are lacking. Location: We modelled the probability and intensity of site use for grey foxes at two spatial scales using a coordinated survey of 1485 camera traps across the contiguous United States in 2019. Methods: We used Bayesian occupancy modelling and post hoc species interaction comparisons to evaluate factors hypothesized to affect grey fox site use, including habitat, anthropogenic effects, and intraguild interactions. Results: Our results showed that the presence of bobcats (Lynx rufus) and striped skunks (Mephitis mephitis), as well as forest variables, had positive associations with grey fox site use. Surprisingly, we found no support for negative effects on grey fox space use from dominant competitors (coyotes, Canis latrans, or pumas, Puma concolor), and a complete lack of effects from urbanization metrics and gross primary productivity. We did, however, find a consistent negative association with red foxes (Vulpes vulpes), which is the most ecologically and morphologically similar competitor of grey foxes. Main conclusions: Taken together, these results imply that grey fox distribution is not limited by dominant carnivores or anthropogenic pressure. Rather, this species seems to occupy a unique niche across its broad range by exploiting diverse forest habitats shared with less ecologically similar competitors (striped skunks and raccoons, Procyon lotor), while being somewhat limited by a competitor occupying a similar ecological niche (red foxes). Our study highlights the value of broad-scale approaches for evaluating factors influencing the distribution and abundance of understudied species, as local dynamics might fail to manifest across geographic ranges.

Last updated on 09/29/2023