PS 43-73 - Predictors of mammalian diversity in the New York metropolitan area

Background/Question/Methods

Urbanization can have profound consequences for mammalian biodiversity and is thought to contribute to patterns of species richness and community composition. Large cities can be particularly challenging environments for mammals because these habitats are often impacted by anthropogenic perturbations, including high human population density, fragmented habitats, and extensive human development. In this study, we investigated the impact of six drivers of mammalian community composition in the most densely populated region in the United States: the New York metropolitan area. Specifically, we deployed 138 camera traps from 2015-2019 to investigate the impact of six drivers of mammalian community composition across 31 urban greenspaces: (1) human population density, (2) patch size, (3) habitat type, (4) surrounding land cover, (5) geographical barriers to dispersal, and (6) habitat heterogeneity. To gain better insight into what predicts mammalian diversity across an urban landscape, we modeled three response variables: (1) richness, (2) evenness, and (3) Shannon-Wiener diversity.

Results/Conclusions

In this investigation of predictors of mammalian diversity in the New York metropolitan area, we found ample support for the hypothesis that mammalian diversity is largely driven by anthropogenic factors and geographical barriers. Consistent with our predictions, we found that mammal taxa richness was higher in greenspaces with larger patch sizes and less developed land cover suggesting that species richness is a function of habitat area. Moreover, both Shannon-Wiener diversity and evenness were higher in urban natural habitats than human-altered habitats. In a subset of data that only included carnivores, we found that carnivore Shannon-Wiener diversity was higher in urban natural habitats and in sites with lower human population densities. Finally, we found that biogeographical barriers contributed to both patterns of mammalian diversity and patterns of carnivore diversity: mammal taxa richness, Shannon-Weiner diversity, and evenness were all significantly higher on the continent (Bronx/Westchester) than on Long Island. Collectively, these results provide insights into the drivers of mammalian community composition and are helpful for drawing inferences on what factors contribute to mammalian diversity in urban environments.