Large predator competition in an urbanizing world: Cougar and black bear interactions along the wildland-urban gradient of western Washington
Clint Robins, University of Washington
Humans have historically altered ecosystem structure through landscape manipulation, leaving “remnants,” or refuge patches of suitable habitat amidst inhospitable terrain. Large carnivores tend to be especially vulnerable to such habitat alterations because they often occur at low densities, have slow reproductive rates, and wide-ranging behavior necessitated by high food requirements. Multiple wildlife studies, however, have demonstrated large carnivore presence is integral to ecosystem health and function. Although some recent studies have examined carnivore ecology and responses to human activity and land conversion, few studies have focused on the role urbanization plays in driving large predator behavior and, in particular, interactions between predators. Species responses and resiliency to anthropogenic disturbance are not uniform, and not all large carnivores are capable of surviving in urbanizing areas. In order to promote large carnivore conservation in places with human activity, it is important to understand which species exhibit population-level resiliency despite anthropogenic disturbance and potential conflict with humans.
The primary objective of this study was to determine whether human activity and residential development facilitate competition between black bears (Ursus americanus) and cougars (Puma concolor) in western Washington. Data were collected from July-November 2017, with documentation of 83 kill sites, with successful recording of kill site visitation by scavenging species on six occasions using remote sensing cameras. Dr. Brian Kerston of Washington Department of Fish and Wildlife (WDFW) also placed remote sensing cameras on various kill site locations throughout the season. In total (including previous years), the project has accrued 651 kill site locations. Data will be used to determine if the proximity of cougar kills to anthropogenic food resources for bears increases the likelihood that a cougar kill be appropriated by a black bear. We are currently finalizing a WDFW proposal in order to reach a data sharing agreement with the department, which will grant the project access to black bear GPS data. Improving our understanding of how urbanization along an urban-wildland gradient impacts large carnivore competition will not only benefit wildlife management strategies, but will also improve more general predictions on which species and ecosystems will be minimally impacted by environmental change.
Dissemination of project information has been carried out through a guest lecture for the wildlife seminar series at the University of Washington, and through the Doris Duke Conservation Scholars program. Results from the project will be presented at the 25th Annual Conference for The Wildlife Society in October 2018. We currently have one manuscript under review with Ecosphere, and we anticipate three additional publications on cougar-black bear interactions occurring along western Washington’s wildland-urban gradient. ($20,000)