Thesis

Urbanization and its effects on resource use and individual specialization in coyotes (Canis latrans) in a southern California urban landscape

Ecological opportunity in the form of habitat and food heterogeneity are thought to be important mechanisms in maintaining individual specialization. Urban environments are unique because fragments of natural or semi-natural habitat are embedded within a permeable matrix of human-dominated areas, creating increased habitat heterogeneity compared to the surrounding landscape. In addition, urban areas can provide diet subsidies in the form of human trash and domestic animals, which also increases ecological opportunities. I investigated the degree to which coyotes (Canis latrans) utilized anthropogenic subsidies and exhibited individual specialization across the urban-rural gradient in Los Angeles and Ventura Counties, California. I used scat analysis to analyze population-level differences in diet combined with stable isotope analysis to understand diet variation on an individual level. Land use surrounding scat and isotope sample collection sites was also evaluated to determine the effect of urban land cover on diet. Human food constituted a significant portion of urban coyote diet (22% of scats, 38% of diet as estimated by stable isotope analysis). Domestic cats (Felis catus) and non-native fruit and seeds were also important prey items in urban coyote diets. Consumption of anthropogenic items decreased with decreasing urbanization. In suburban areas, seasonality influenced the frequency of occurrence of anthropogenic subsidies with increased consumption in the dry season. Seasonal effects were not seen in urban areas. The amount of altered open space (defined as golf courses, cemeteries, and mowed parks) in a coyote's home range had a negative effect on the consumption of anthropogenic items. Urban coyotes displayed reduced among-individual variation compared to suburban and rural coyotes. It is possible that the core urban areas of cities are so densely developed and subsidized that wildlife inhabiting these areas actually have reduced ecological opportunity. Suburban animals had the broadest isotopic niches and maintained similar individual specialization to rural coyotes. Wildlife in suburban areas still have access to relatively undisturbed natural areas while being able to take advantage of anthropogenic subsidies in neighboring residential areas. Therefore, areas with intermediate urban development may be associated with increased ecological opportunity and specialization.

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