Patterns of mammalian diversity and the detection of coyotes and free-ranging cats along the highly urbanized Bronx River

Abstract Urban watersheds are vital habitats for many mammalian taxa. Freshwater rivers situated in urban areas provide mammals with food and water resources as well as habitat space for raising their young. In New York City and adjacent Westchester County, the Bronx River and its surrounding greenspaces are thought to be important habitats for sustaining mammalian species diversity. Despite the presumed importance of urban watersheds, very little is known about mammalian taxa distribution along the Bronx River, New York City’s only freshwater river. To address this gap, we used motion-activated cameras to survey mammals along the 36-km transect of the Bronx River. We also measured eastern coyote (Canis latrans) and free-ranging cat (Felis catus) occupancy and detection probability and investigated anthropogenic and ecological factors thought to impact patterns of biodiversity. We detected a total of 16 mammalian taxa, excluding humans and domestic dogs. None of the anthropogenic or ecological features that we measured—human population density, percentage greenspace, or habitat heterogeneity—were predictive of mammal diversity along the Bronx River. However, free-ranging cat detection probability was negatively associated with coyote relative abundance, rodent relative abundance, and habitat heterogeneity, and positively associated with human population density. Moreover, the daily detection rate of free-ranging cats was significantly lower in habitats where coyotes were present. Finally, the daily detection rate of coyotes was positively associated with percentage greenspace. These results suggest that the Bronx River is an essential wildlife corridor for many mammalian taxa and emphasize the need to conserve urban riparian habitats.