The wolverine is one of the rarest mammals in the North America, estimated to number between 250-300 animals in the western continental US. Wolverine habitat in the western continental US is characterized as high elevation alpine and subalpine habitats in mountainous areas. While little information exists on the current distribution of wolverines, they are generally believed to occur within some areas of western Montana, central and northern Idaho, northwestern Wyoming, north-central Washington and northeastern Oregon.
Wolverines occupy large home ranges, with males covering as much as 800 mi2 and female home ranges typically 200-300mi2. Wolverines remain active throughout the winter, traveling extensively across their home ranges in search of carrion that is their primary winter food source. In late February, pregnant female wolverines choose areas with deep snow such as north-facing slopes to dig tunnels down to jumbled talus boulders and fallen logs, creating insulated and safe havens for their 1-3 young, called kits. They maintain these snow-based dens through approximately mid-May, and most wolverine ecologists believe that wolverines exhibit a dependence upon snow for denning and reproduction. The snowpack likely also serves other important functions including preservation of carcasses or cached meat. The loss of wolverine habitat from climate change has been predicted based on the modeled loss of spring (mid-May) snow due to temperature and precipitation changes.
The rugged and remote habitats of the wolverine were naturally inhospitable to people and these areas were historically largely undisturbed by humans in the winter months. In many areas, wolverine habitats are no longer inaccessible to humans for winter activities. The growing popularity of winter backcountry recreation combined with advanced snowmobile technology and availability of other mechanized access options such as tracked vehicles (cat-skiing) and helicopters has resulted in winter recreation expanding across previously undisturbed and unreachable public lands.
The potential effects of winter recreation on wolverine reproduction, behavior, habitat use and populations are unknown but there is concern regarding the effects of winter recreation on wolverine, particularly in areas favored by females for reproductive denning. Currently, there is little scientific foundation for management of winter recreation for wolverine persistence and accounts of wolverine responses to human disturbance are primarily anecdotal and conflicting. Given the potentially vulnerable status of the species, there is the need and interest to develop a scientifically robust understanding of wolverine responses to winter recreation that can provide insights into approaches to management that ensure both winter recreation and wolverine populations may be sustained.
The goal of the Wolverine – Winter Recreation Study is to identify and evaluate wolverine responses to winter recreation. We have developed a research effort that is uniquely collaborative across federal and state agencies, non-government organizations, winter recreationists and local businesses. This collaborative approach to the research is critical not only to the success of data collection efforts but also to build opportunities for collaborative and creative problem solving when research-based management actions are considered.
1) To increase the science-based understanding of the effects of winter recreation on wolverine populations through examining wolverine behaviors, habitat use and reproductive efforts within landscapes supporting a diversity of winter recreation activities;
2) To provide science-based information to guide public land management for the sustainability of both winter recreation and wolverine.
Project Approach: Data are collected on wolverines by live-trapping and fitting Global Positioning System (GPS) collars on animals. Simultaneously, winter recreationists are asked to carry small GPS units that provide the path they have taken. The participation of winter recreationists is voluntary and anonymous, and the overwhelming majority of recreationists approached have participated.
Project Progress: Developing a sound, empirical understanding of the relationship between the wolverine and winter recreation requires considerable effort. Over 6 winter field seasons from 2010-2015, the project collected data across 5 study areas from central Idaho to the western Yellowstone. We successfully collected GPS data that provides movement, habitat use and behavioral data on 19 wolverines, with some individuals monitored for up to 4 years. At the same time, we collected over 4500 gps tracks from winter recreationists including snowmobile and back country ski recreationists in these same landscapes. We are continuing to monitor wolverine presence in some of our study areas through camera and DNA trapping. Over the next several months, we will be analyzing this unprecedented set of data to meet the project goals and objectives, in collaboration with the Rocky Mountain Research Station and the University of Montana.
Please download the reports and progress updates for additional information on the project.