Skokomish Tribe Tracks Cougars to Study Deer, Elk Populations

Crashing through the forest just outside of Matlock, Skokomish Tribe wildlife biologist Bethany Tropp glances at her GPS unit while surveying the surrounding understory, looking for any sign of a cougar’s kill site.

“Finding out where, what and how much the cougars are eating helps determine how they are affecting elk and deer population,” Tropp said. It is generally thought that cougars are hard on elk herds, she said, and the tribe wants to research that further.

“So far, this cat seems to like beaver and deer,” Tropp said.

WDFW biologist Scott Harris and Skokomish Tribe biologist Bethany Tropp look over the remains of a deer after it was preyed on by a cougar. Click the photo for more pictures of the field work. 

The tribe put a radio collar on a young 100-pound female cougar in March. The GPS in the collar records the cat’s location every three hours. Tropp downloads the information with a handheld computer in the field and analyzes the locations to determine a potential kill site. If the cat stays in one place for an unusually long time, which could be from several hours to several days, the location is likely a site where the animal has fed.

With the help of wildlife biologists from Washington Department of Fish and Wildlife, Tropp seeks out kill sites weekly. Besides using the GPS coordinates, hints to finding a site include scouting the “eco-edge,” where wetlands and forests meet and looking for paw prints and freshly torn-up brush. Tropp also sniffs around possible kill sites for odors of a rotting carcass.

If the kill site remains of a deer or elk are still intact, Tropp notes the animal’s gender and age, and also gathers a femur (leg) bone to determine the animal’s health.

“Looking at the bone marrow in the long bones, like the femur, lets us assess the nutritional status of the animal,” she said. “If the marrow is white and chalky, it was a pretty healthy animal; if it’s pink and gelatinous, the animal was malnourished. These observations give us more information about the health of the population.”