The Impacts of Winter Recreation and Snowmobiles on Wolverines

Recently the U.S. Fish and Wildlife Service found wolverines (Gulo gulo) to be warranted (but precluded) for endangered species protection because of their low numbers and disappearing habitat. Indeed, these elusive creatures are emblematic of the backcountry and make their home in remote mountainous terrain. The largest member of the Mustelidae (weasel) family, wolverines’ large home range, alpine habitat, and aversion to humans makes them difficult to study. And while little research has been done on the effects of human presence and activity on wolverines, these animals possess many characteristics that make them particularly vulnerable to recreation related disturbances. These characteristics include low population densities, low reproductive rates, large home ranges, elusive behavior, and avoidance of humans (Olliff et al. 1999). Wolverines’ low dispersal and colonization rates also make them sensitive to human impacts (Claar et al. 1999). While backcountry winter recreation has gained popularity in recent years, little research has examined its impacts on wolverine. This paper reviews some specific impacts of winter recreation and points to management strategies that could mitigate these impacts.

Impacts of Winter Recreation

Winter recreation activities such as snowmobiling, cross-country and backcountry skiing, and snowshoeing can have harmful effects on wolverine populations (Hornocker and Hash 1981, Copeland 1996, Olliff et al. 1999). Backcountry snowmobiling and skiing are most popular in the late winter and early spring, during wolverines’ most sensitive time of year - the denning season. Disturbance from snowmobile noise or even the presence of humans during this time can be of particular concern. Additionally, advances in snowmobile technology now allow the vehicles to travel farther, climb steeper slopes and cover more rugged terrain, making it easier to reach remote wolverine natal den habitats and thereby further increasing risks to wolverine (Heinemyer and Copeland 1999; Heinemeyer et al. 2001).

Human disturbance can lead to direct loss of habitat, increased habitat fragmentation, and the indirect effect of avoidance behavior in wildlife (Johnson et al. 2005). Allowing snowmobile access can also increase trapping mortality (Weaver 1993), and in rare cases wolverines may experience mortality due directly to recreational uses, such as an accidental collision with a snowmobile. Other indirect impacts of snowmobiling may include avoidance or displacement due to noise or human presence (Olliff et al. 1999). When wolverines opt to avoid an area due to human presence, they may be forgoing access to resources that area provided (Claar et al. 1999, May et al. 2006). For example, should snowmobile use cause wolverines to avoid an area rich in ungulate carrion, they may seek out areas that provide lesser food sources and as a result, experience poor nutrition.

Snowmobile and other recreational trails may cause a change in the species composition of an area by facilitating the movement of species that would otherwise be excluded due to snow depth. Species such as wolves, coyotes, or bobcats that move into wolverine habitat via human-created trails could alter predator-prey relationships in the area by either directly preying on wolverines or increasing competition for carrion (Claar et al. 1999). In addition, snowmobile use near natal dens may cause wolverines to seek out other, less secure den sites, which in turn could impact kit and adult female mortality (Olliff et al. 1999).

Management Implications

Considering that “the essential component of wolverine habitat may be isolation and the total absence of disturbance by humans,” land  use, recreation, and wildlife management plans must account for the negative impacts humans can have on wolverines (Lyon et al. 1994: 130). Furthermore, due to a general lack of knowledge about wolverines, land managers need to practice “adaptive management” and use “professional judgment” and “common sense” when land use planning in wolverine habitat areas (Olliff et al. 1999: 69). Other general considerations include raising awareness of the impact snowmobile and ski trails may have on wolverines, and carefully monitoring wolverine activity and human use in areas recognized as potential wolverine habitat (Austin 1998).

In some instances, human presence and activity should be limited in wolverine habitat. Strategic trail closures and limits on the type and level of human use may mitigate the negative impact of humans on wolverines (Austin 1998). The use of existing winter trails, as well as the development of new trails, should be considered likely to create negative impacts on wolverines. Others have proposed management guidelines such as excluding recreational activities from denning and foraging areas in the winter, as well as managing for minimal recreational impacts through the use of quotas or weekend closures, and establishing five mile buffer zones around predicted denning habitat (Olliff et al. 1999).

Banci (1994:109) notes that “refugia may be the best means of ensuring persistence of wolverine populations.” Refuge areas must be large enough to accommodate the wide home range of wolverines and include travel corridors that allow for dispersal. Land managers should plan at multiple scales when managing wolverine habitat. Planning at the “stand” or small scale should account for food and denning requirements, while planning at the landscape scale should address wolverines’ large home range, travel, and dispersal (Banci 1994).

Conclusion

Wolverines are sensitive animals that avoid contact with humans. And while this iconic species represents wildness in its purest form, their long-term survival will require deliberate choices on our part to limit the impacts of our own enjoyment of wild country. By managing for conservative recreational use and habitat protection land managers can ensure that this rare species will thrive in the remote alpine environments it inhabits.

—Laura Goldberg is a University of Montana Environmental Studies graduate student.

Literature Cited

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