Carnivore responses to urbanization and human presence along an urban-wildland gradient in western Washington

Abstract

Urbanization and human activity are primary drivers of wildlife habitat loss and degradation, but few studies to date have explored their impacts simultaneously. I investigated how anthropogenic infrastructure and the presence of humans affected habitat use of six carnivore species along an urban-wildland gradient of human development in western Washington, USA. Specifically, I deployed camera traps at 175 locations to quantify habitat use by American black bears (Ursus americanus), bobcats (Lynx rufus), cougars (Puma concolor), coyotes (Canis latrans), Virginia opossums (Didelphis virginiana), and raccoons (Procyon lotor). I then used single-species, single-season occupancy models to characterize their respective patterns of habitat use. No covariate was significant for all six species, and I only detected significant relationships with any of the covariates for four of the species. Two species had significant relationships with distance to road but different responses; cougar occupancy increased while coyote occupancy probability decreased as the distance to road increased. Black bear occupancy was positively associated with increasing canopy cover and the probability of occupancy for opossums decreased withincreasing elevation. Cougars were not detected at any sites ≤ 250 m from any buildings, suggesting that cougars may avoid using habitat in close proximity to these structures. I detected no significant response to the presence of humans by any of the species. My results reveal that carnivore spatial responses to human infrastructure and presence are species-specific and can be limited, highlighting the need for efforts to identify key drivers of species differences as well as tailored conservation and management approaches.