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COSEWIC assessment and update status report on the wolverine Gulo gulo in Canada

Summary of Status Report

Wolverine range has been reduced over much of southern and eastern Canada since the mid-19th century. Although the exact range limits of viable wolverine populations pre-European settlement are unknown, the wolverine range has receded north in the Prairie Provinces and Ontario, is extirpated from New Brunswick, and may possibly be extirpated from Quebec and Labrador.

The western population is relatively healthy but is not a source for the natural repopulation of the eastern wolverine in Quebec and Labrador. Harvest restrictions and naturally increasing caribou herds were not sufficient to prevent the extirpation of the eastern population. There is a draft recovery plan in place for wolverines in Quebec and Labrador.

There is evidence of restricted gene flow to at least two areas within the range of the western population: the Revelstoke population of British Columbia, and the sub-populations of northwestern Ontario and Manitoba (Kyle and Strobeck 2002). The Southern Mountain sub-population of British Columbia and Alberta is more vulnerable to land use practices which may fragment and destabilize the population in the future. The status of other isolated populations, namely those of the Pacific islands (Vancouver and Pitt), and the arctic islands, is unknown. The Vancouver Island wolverine population may be extirpated.

Biological factors that contribute to the wolverine’s vulnerability to population decline and ability to recolonize include large spatial requirements, low densities, low reproductive rates, and poor juvenile survival. Despite these factors, given time, wolverines are able to rebuild their populations and reclaim former ranges. Threats to the populations have included habitat losses, trapping and hunting, poisoning (during wolf control programs), and disruptions to important ecosystem components such as ungulates (as a primary winter food source) and wolves (a carrion provider). The disturbance of denning females is a growing problem in the mountains of western Canada, where winter recreational use is growing rapidly. Parks and protected areas are susceptible to recreational impacts, transportation corridor impacts and, in some cases, trapping.

Habitat losses are not as significant today as they were during earlier periods of human settlement. More important effects on habitats are fragmentation and indirect effects on the prey base, most notably mountain caribou populations in western Canada.

The reversal of several factors which have reduced either the range of wolverines or their populations in local areas has resulted in apparent (based on harvests and sightings) population and range recoveries. Government subsidized poisoning of wolves in most of western Canada has been terminated. Several large caribou herds in Manitoba, Ontario, Quebec and Labrador have increased naturally. Trapping is now only permitted in the 4 western provinces and the 3 territories. Wolverine harvest management systems used by both governments and trappers are improving. Local wolverine population recoveries have been noted in northwestern Ontario and northern Manitoba. Populations in the 3 northern territories and northern British Columbia are healthy and stable, although local concerns exist. Possible declines have been noted in Alberta. The western wolverine population remains vulnerable on several fronts.

Some local and traditional knowledge was used in this report (such as trapper and harvest surveys, and observations of wolverine in Quebec and Labrador); however, other relevant Aboriginal traditional knowledge (ATK) is not well documented or available for use. A pilot project on wolverine ATK in northern Canadian communities is being conducted to investigate how ATK can be documented, described and utilized in the species assessment process (Cardinal, pers. com., 2003). The project will not gather all ATK, but will use information from the 3 territories and existing studies in Labrador.