Effects of Canopy Cover and Impervious Surface Cover on Occurrence of Coyotes (Canis latrans) and Gray Foxes (Urocyon cinereoargenteus) throughout the United States
Date
2023-12
Authors
Gay, Danielle
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Abstract
Coyotes (Canis latrans) and gray foxes (Urocyon cinereoargenteus) are habitat generalist species that occupy similar ecological niches and compete for the same food resources. Urbanization may disrupt habitat resources and intensify interspecific competition. Therefore, there is a need to determine the extent to which coyotes and gray foxes require certain habitat elements, particularly in anthropogenic landscapes. A consensus on the habitat associations of each species has yet to be reached, as studies on occupancy and abundance of coyotes and gray foxes have found that each species' response to urbanization varies by region and spatial scales. My study examined the effect of canopy cover, presumably an important component of natural habitat, and impervious surface cover as an indicator of urbanization, on the occurrence of coyotes and gray foxes. Additionally, I determined whether associations with canopy cover and impervious surface cover differed between these species. I obtained data from 9,010 camera trap locations grouped into two spatial scales. At the local level, I had 3,920 groups, and at the landscape level, I had 280 groups. I obtained percent canopy cover and impervious surface cover data from the National Land Cover Database. In ArcGIS, I calculated mean percent canopy cover, mean percent impervious surface, and standard deviation of percent canopy cover within buffers placed around each camera trap group at the local and landscape scales. Furthermore, covariates such as mean geographic location, number of cameras in a group, and number of trap nights per group were included in the analysis as these could affect coyote and gray fox detection. I constructed logistic multiple regression models to examine the effect of canopy cover and impervious surface on coyote and gray fox occurrence at the local and landscape levels. Coyotes and gray foxes occurred at localities and in landscapes with a wide range of canopy cover and impervious surface. However, for both species, probability of species occurrence was highest at localities and in landscapes with an intermediate percentage of canopy cover and a low percentage of impervious surface. At the landscape level, gray fox occurrence sharply declined as heterogeneity of canopy cover increased, indicating that the connectivity of canopy cover may be an important habitat variable for gray foxes. Understanding the habitat associations and avoidances of coyotes and gray foxes provides insight into their spatial distributions and possibly can advise better management strategies.
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Keywords
occurrence, coyote, gray fox, canopy cover, impervious surface
Citation
Gay, D. (2023). Effects of canopy cover and impervious surface cover on occurrence of coyotes (Canis latrans) and gray foxes (Urocyon cinereoargenteus) throughout the United States (Unpublished thesis). Texas State University, San Marcos, Texas.