Characteristics of Winter Wolf Kill Sites in the Southern Yellowstone Ecosystem

Understanding the spatial use of wolves and how that might relate to prey species may help predict areas with increased likelihood of wolf–prey interactions, areas where wolves may have a higher impact on prey populations, or areas of wolf–livestock conflict. After reintroduction into Yellowstone National Park in 1995, wolves Canis lupus expanded south and recolonized areas in and around Grand Teton National Park in the southern Yellowstone ecosystem in Wyoming, USA. Elk Cervus elaphus in this area are supplementally fed at three feedgrounds artificially increasing elk density. We tracked radio-collared and uncollared wolves annually in winter (December–March) from 2000 to 2008 to investigate kill sites. Our objective was to investigate potential differences in habitat variables (e.g., canopy cover, elevation) between kill sites (n = 295) and available (random; n = 2,360) locations and investigate whether factors influencing winter wolf kill sites differed in a natural setting (i.e., native winter range) vs. an artificial setting (i.e., near or on feedgrounds). Wolf kills occurred at sites with lower elevation, canopy cover, and terrain roughness compared with random locations. Wolf kills were also slightly farther from packed surfaces (i.e., roads or groomed snowmobile trails) and elk feedgrounds, although still in areas of higher intensity of use by elk compared with random locations. Kill sites on native winter range were considerably more rough (odds ratio = 4.47) than those on feedgrounds. Our results suggest wolves hunt where the likelihood of encountering prey is high, although in areas where prey distribution is more sparse (i.e., native winter range), wolves may need to rely on rougher terrain for successful hunts. The relationship between areas of high prey use and increased wolf activity has important implications for both wildlife managers and livestock producers. In the future, managers will continue to face the issue of having high concentrations of ungulates, either wild or domestic, and the obvious attraction this has for wolves.