Gentrification drives patterns of alpha and beta diversity in cities.

While there is increasing recognition that social processes in cities like gentrification have ecological consequences, we lack nuanced understanding of the ways gentrification affects urban biodiversity. We analyzed a large camera trap dataset of mammals (>500 g) to evaluate how gentrification impacts species richness and community composition across 23 US cities. After controlling for the negative effect of impervious cover, gentrified parts of cities had the highest mammal species richness. Change in community composition was associated with gentrification in a few cities, which were mostly located along the West Coast. At the species level, roughly half (11 of 21 mammals) had higher occupancy in gentrified parts of a city, especially when impervious cover was low. Our results indicate that the impacts of gentrification extend to nonhuman animals, which provides further evidence that some aspects of nature in cities, such as wildlife, are chronically inaccessible to marginalized human populations.

Effects of urbanization on resource use and individual specialization in coyotes (Canis latrans) in southern California.

Urban environments are unique because fragments of natural or semi-natural habitat are embedded within a potentially permeable matrix of human-dominated areas, creating increased landscape and, potentially, habitat heterogeneity. In addition, urban areas can provide diet subsidies for wildlife species in the form of fruiting ornamental plants, trash, and domestic animals. Ecological opportunity in the forms of habitat and food heterogeneity are thought to be important mechanisms in maintaining individual specialization. Identifying which contexts, traits, and mechanisms determine the success or failure of individuals within an urban wildlife population could potentially provide predictions about which populations may succeed in human-dominated landscapes and which may experience local extinction. We used both scat and stable isotope analysis of whiskers to investigate the degree to which coyotes (Canis latrans) utilized anthropogenic subsidies and exhibited individual diet specialization across the urban-rural gradient in southern California. Land use surrounding scat and isotope sample locations was also evaluated to determine the effect of land cover on diet. Human food constituted a significant portion of urban coyote diet (22% of scats, 38% of diet estimated by stable isotope analysis). Domestic cats (Felis catus) and ornamental fruit and seeds were also important 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. The amount of altered open space (areas such as golf courses, cemeteries, and landscaped parks) nearby had a negative effect on the consumption of anthropogenic items in both urban and suburban areas. Contrary to our hypothesis, urban coyotes displayed reduced between-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.