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Wolverine

Limiting Factors

The naturally low population Wolverines, coupled with a low reproductive potential, makes the species susceptible to population declines resulting from human activities. Such activities can be grouped into two Major classes of human impact: direct and indirect. Direct impacts include trapping, hunting, and rabies-control programs. Indirect impacts include habitat loss and reductions in ungulate populations.

Wolverines are trapped in many parts of their range, and this activity has no doubt had an impact on population size in the same areas. Intuitively, the impacts of trapping should be greatest when fur prices are high (as high as $254.00 in 1995-1996). However this wolverine population is so small and dispersed that the species is rarely the target of specific trapping efforts. More likely, Wolverine harvest increases when the price of more common furbearers, which require the same size of the traps, is high. Trapping may also impact reproductive success by causing the shortage of male Wolverines. In this species, males have much larger home ranges than females, and several females may occur within a range of a single male. Because males travel greater distances than females, they may be more prone to encountering traps. Thus, the loss of a single male may impact reproductive success of several females in the area. In the 1950s, a rabies-control program in Alberta may have caused a reduction in provincial population. Given the low reproductive output of Wolverines, recovery from substantial reduction in numbers, if it occurred, may have taken decades. In the absence of accurate information on the density of Wolverines in Alberta, the impacts of trapping and predator control programs remain difficult to assess.

Research has shown that habitat loss is also an important factor currently affecting Wolverine numbers. Wolverines seem to have been most affected by activities that fragment and supplant habitat, such as human settlement, extensive logging, oil and gas development, mining, recreational developments and the accompanying access. More generally, other researchers conclude that Wolverines avoid human contact and therefore human settlement has contributed to reducing the range of Wolverines. Large reductions in the ungulate prey base by humans before the turn of the century are thought to have aided in the reduction of the Wolverines' range. Large declines in Caribou populations in Quebec and Labrador have been correlated with declines in Wolverine pelt harvests.  The extent to which habitat loss and changes in ungulate populations limit Wolverine populations in Alberta is unknown. It is certainly likely that these two factors played an important role in the extirpation of this species on the prairies following human settlement. The impacts of more recent land-use changes such as agriculture, forest harvest, oil and gas development on Wolverine populations in the foothills and in northern areas of the province remains to be seen. However, it is clear that contact with humans has eroded the edge of the species' range on a provincial and global scale. With an ever expanding human population, there may be a time when most Wolverine populations will be restricted to large protected areas like the proposed carnivore conservation areas, or to areas included in the Yellowstone to Yukon project. These proposals are aimed at setting aside areas large enough to protect viable populations of species, like Wolverines, which require large areas of wilderness. 

Reprinted from Alberta Wildlife Status Report No. 2 (1997), with permission from Alberta Sustainable Resource Development.

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