The wolverine (Gulo gulo), a rare and elusive, thick-furred predator renowned for its strength was recently documented west of the Cascade Crest in Mount Baker-Snoqualmie National Forest. Roger Christophersen, wildlife biologist with North Cascades National Park Complex, set up a run-pole camera station to photograph the wolverine after visitors reported seeing a wolverine chasing a marmot in an area north of the Skagit River.
Christophersen and volunteers Steven Borrego and Azzurra Valerio built the camera station by attaching a small diameter log (or run-pole) at a 90° angle from a tree trunk. The run-pole provides a small platform for a wolverine to run up a tree and attempt to grab bait hanging from a branch above the run-pole.
Christophersen drilled holes through the bones and inserted a wire to hang the food from the branch, just as campers hang their food to keep them away from bears. In this case, the bait was four chicken legs. Two cameras were installed on nearby trees and focused on the run-pole station. Biologists aimed the cameras to capture the wolverine's unique throat and chest blazes as it looks up to investigate the bait. Finally, a special scent lure was smeared on branches around the run-pole station to attract the wolverine to the bait.
The run-pole was designed to be checked about once a month. In that time, wolverines travel over their territory in a figure eight pattern. To everyone's surprise, the run-pole station captured photos of a previously undocumented wolverine within five days. Additional monitoring is needed to discover if the wolverine is resident or if there is more than one individual in the area.
Wolverines weigh between 17 and 40 pounds and are members of the weasel (or mustelid) family. They travel over mountainous terrain to hunt for carrion, hares, marmots, and smaller rodents. Wolverines depend on heavy snow each winter to den and give birth to their young, or kits. Almost all verified wolverine dens are under three to twenty-five feet of snow and their snow tunnels may last until mid-May.
Wolverines are a candidate for listing under the Endangered Species Act due to declining populations across North America. Historically, declines have resulted from trapping, but warming climates and lower snowpacks present future threats to the species. With decreasing snowpacks, suitable den sites may be threatened.