Spatiotemporal partitioning between the endangered San Joaquin kit fox and a novel mesocarnivore community in the urban environment as revealed by camera traps

Abstract

Urbanization has led to the rapid formation of novel biotic communities, which via interspecific interactions, may affect niche partitioning dynamics of native, sensitive species. The endangered San Joaquin kit fox (Vulpes macrotis mutica; hereafter ‘kit fox’) is a small mesocarnivore inhabiting urban areas of the southern Central Valley of California alongside other urban mesocarnivores. These other species may pose challenges for kit foxes due to a potential lack of evolved mechanisms of defense or avoidance. To address this notion, we evaluated evidence of temporal and spatial partitioning between the kit fox and its potential predators and competitors in an urban environment. We predicted that spatial and temporal overlap would be lower between kit foxes and their predators than with their competitors. We used camera traps with scent lures at high school and college campuses across the southern San Joaquin Valley to monitor the visitation patterns of urban mesocarnivores from 2020 to 2022. We used generalized linear mixed models and AIC model selection to evaluate spatial relationships between kit foxes and other mesocarnivores and we used temporal overlap coefficients and peak activity analysis to evaluate temporal overlap. Kit foxes exhibited low spatial overlap (negative association) with Virginia opossums (Didelphis virginiana) and high spatial overlap (positive association) with domestic cats (Felis catus), domestic dogs (Canis lupus familiaris), northern raccoons (Procyon lotor), and striped skunks (Mephitis mephitis). Kit foxes exhibited low to moderate levels of temporal overlap with other species, the least of which occurring with potential predators (i.e., coyotes (C. latrans), domestic dogs). Our findings support the temporal partitioning and partially support the spatial partitioning hypothesis as potential mechanisms to promote coexistence among mesocarnivores in an urban environment.