Carnivore occurrence along an urban-rural gradient: A landscape-level analysis

Human development impacts the landscape by altering the size and shape of natural habitat patches, replacing natural vegetation with other types such as lawns and row crops, or introducing environmental stressors such as increased human activity and pollutants. We investigated the effects of human alterations to the landscape on the distribution of 3 mammalian carnivores (coyote [Cams latrans], raccoon [Procyon lotor], and red fox [Vulpes vulpes]) along an urban-rural gradient in northern Illinois. Distribution of each species was assessed from occurrence at scent stations placed within or along the edges of 47 sites >= 4 ha, representing 7 different natural or anthropogenically altered habitats. We averaged presence or absence scores across several seasonal samples over a year, and used an outlying mean index analysis to compare them to environmental variables gathered for each site, including habitat and landscape metrics presumed to reflect varying degrees of anthropogenic influence across the urban-rural gradient. Coyotes used a variety of habitats within the rural part of the gradient. Red foxes were found in forest interiors or shrubland and old fields near forests where coyotes were least detected. Both canids were detected more often in areas of lower human densities but prey abundance was not a strong determinant of their occurrence. Overall occurrence along the gradient was highest for raccoons, which were positively associated with urban areas with relatively high residential land use.