Wolverine Monitoring in Northwest Montana

Conservation managers devote a considerable amount of time and resources to preserving wildlife populations and balancing other land management values. This is understandable given the complexity of gathering information on complex ecological process or responses of wildlife populations or individuals to management practices. Gathering sufficient information on a rare carnivore such as the wolverine can add greater complexity, because this species exists at low densities and predominately occupy remote, inaccessible habitat.

Over the past six years, wolverine monitoring (in addition to other forest carnivores), has been a focus of the Flathead, Lolo and Helena/Lewis and Clark National Forests. Using a relatively non-invasive detection approach, multi-species bait stations can provide an excellent tool to collect information on wolverine in the winter. This monitoring has been employed by these three forests, in addition to other local and statewide efforts, and has added some interesting pieces to the overall picture of wolverines in Montana.

The North American wolverine (Gulo gulo luscus) is a medium-sized carnivore found across the west-northwestern contiguous United States, Alaska and Canada. A species status assessment by the US Fish and Wildlife Service states that the most recent estimate of wolverine populations in the contiguous United States based on habitat modeling is 318 individuals, with a range from 249 to 949. However, systematic monitoring across the wolverine’s North American range has not been conducted given the difficulty in surveying this highly mobile species and its occupation across large and remote areas. This is certainly true of the occupied landscape in Northwest Montana with its jagged peaks, steep snow-filled avalanche chutes and remote wilderness.

Winter is an opportune time for wolverine monitoring and research. While bears slumber in their dens, bait and other attractants can be placed to lure wolverine for detection through hair snares, remote cameras or even traps for collaring individuals with GPS transmitters. Traditional wildlife research often employing marking individuals with radio-transmitting devices. While incredibly useful, this approach is often costly and can be invasive.

Winter bait stations can provide a non-invasive way to detect an animal’s presence. Remote cameras can provide photographic evidence of species present. Hair snare devices can lend powerful genetic information on individuals visiting the site. Distributing these bait station evenly across a focal area using a grid overlaid on the landscape can give coarse scale information about species distribution and animal movements.

Gathering monitoring data on wolverine with bait stations have proven to spawn an array of different set-ups depending on a project’s particular monitoring objectives. In Alaska, Audrey Magoun and team, demonstrated that H-style bait stations can be used to position wolverine interested in hanging bait so that a photo can be consistently snapped of the unique ventral markings on a wolverine’s chest. This approach makes for individual identification of the wolverine without needed genetics to be amplified at the laboratory.

This style of monitoring has been employed on the Lincoln Ranger District. This work has been successful not only of capturing photos distinguishing unique ventral markings of visiting wolverine but also the photos can identify sex organs and even signs of lactation from females. These are important pieces of information for biologists when piecing evidence together about the presence of reproductive populations.

On the Swan Lake, Seeley Lake and Lincoln Ranger Districts, a special project area denoted by the US Forest Service as the Southwest Crown of the Continent (SWCC), survey efforts have been used to detect wolverine at remote bait stations to attract wolverines and collect hair from visiting individuals. The SWCC monitoring project also included snow track detection surveys where hair or scat along tracks could be sampled to provide genetic information. Between 2013 and 2016, the monitoring effort detected a total of 32 unique wolverines (16 male, 16 female) were identified from genetics.

Last winter, in 2017, Montana Fish, Wildlife and Parks, in partnership with a four-state wolverine survey effort, surveyed a sample of wolverine habitat in state. Using similar bait station techniques, the effort’s statistical analysis found that the Northern Continental Divide Ecosystem, an area comprising the mountains surrounding Glacier National Park, Bob Marshall Wilderness and south to the Blackfoot Valley, had the highest probability of wolverine occupancy in the state. This effort found that a single bait-station placed in a hundred square mile area had a 92 percent chance of detecting a wolverine if it was present.

Monitoring wildlife and wildlife populations is important for both wildlife and habitat management. Information from winter monitoring discussed above gives managers insight into species distribution at both big scales (statewide) and at local scales (Seeley-Swan Valley). Monitoring like this for wolverine can help provide context to the body of scientific work on wolverine ecology, biology and habitat use. Having local monitoring on wolverine is vital. For example, in the SWCC, the wolverine monitoring provides a snapshot of distribution and individuals across the landscape. With repeated monitoring and sampling in the future, this information can help provide an informative look at wolverine response to ongoing work for forest restoration and other forest management.