Wolverines are short, compact, and powerful animals weighing 20-40 pounds, with males generally about a third larger than females. Like Canada lynx, their feet are large relative to body size, making them especially suited for snow travel. Like bears, their reproductive rate is low. Breeding commences at 4 years of age or older, occurs only every 2-3 years, and produces litter sizes of just over 1 cub on average. Like wolves, wolverines are highly territorial. Overlap of same-sex individual home ranges averages less than 1%. And like cougars, wolverines are independent and nonsocial for most of the year. But unlike other carnivores, wolverines naturally occur at super low densities. In the Yellowstone ecosystem, estimates suggest over 100 square miles of wildlands are needed to support one wolverine.
Long-term research in the Yellowstone region by the Wildlife Conservation Society (WCS) and others has revealed that just two breeding female and two breeding male wolverines occupy the entire Teton Range, where they prefer high elevation, rugged, and snowy terrain. They scavenge ungulate carcasses in winter, prey on marmots and other small mammals during summer, and den under the mid-winter snowpack in huge tree debris piles created by avalanches. Offspring accompany their mother for about a year before they disperse from the area.
Researchers also discovered that, owing to their low numbers on the landscape, dispersing wolverines must make large movements, sometimes traveling hundreds of miles in search of a mate and breeding territory and crossing low-elevation valleys between mountain ranges in the process. Recently, one radio-marked wolverine moved from just east of Grand Teton National Park to Rocky Mountain National Park in Colorado. These traits point toward a daunting challenge for long-term wolverine conservation, one that will involve coordinating large-scale land management decisions among many competing entities. Indeed, the wolverine may be the perfect poster child for promoting future wildland connectivity in the Rocky Mountains.
Planning for wolverine protection will require knowledge of their distribution and population trends. In an exciting new project, park biologists are collaborating with WCS on testing a noninvasive approach for conducting wolverine inventories. The technique, originally developed in Alaska, involves attracting animals to hanging bait where remote cameras are positioned to photograph individually unique markings and reproductive attributes. This enables researchers to determine sex and reproductive status of individuals. Hairs for DNA sampling are also collected at the site. By locating these stations in a systematic grid across the landscape and creating libraries of individual markings, DNA profiles, and numbers of lactating females, we hope to accurately estimate wolverine numbers and whether or not breeding is occurring in a given region. We believe that developing this technique is a critical step for effective wolverine conservation.
Steve Cain
Senior Wildlife Biologist
Grand Teton National Park
Bob Inman
Director, Greater Yellowstone Wolverine Program
Wildlife Conservation Society
Senior Wildlife Biologist
Grand Teton National Park
Bob Inman
Director, Greater Yellowstone Wolverine Program
Wildlife Conservation Society
