Wildlife in the Columbia Basin

Wildlife Subjects

Mustelids (Weasel Family)

Introduction

The weasel family in the Columbia Basin includes badger, wolverine, mink and river otter, marten, striped skunk, fisher, and, of course, weasel (long-tailed weasel and ermine) . Of these, only the badger has endangered (Red-listed) status. Fisher, the anguinae subspecies of ermine and wolverine are "vulnerable" (Blue-listed) in British Columbia.

Members of the weasel family are carnivores (both meanings: they in the order, Carnivora, and they are all meat-eaters), hunting a variety of prey appropriate to their size and habitat. For example, marten tend to specialize on squirrels and voles, fisher are porcupine specialists, wolverine will eat anything up to the size of a bull caribou, mink prey on fish and aquatic amphibians and mammals (especially muskrats, where present), and otter eat almost exclusively fish. Mustelids of one species or another are nearly ubiquitous in Columbia Basin. Some mustelids also eat a considerable amount of vegetable matter; for example, the marten diet includes berries.

All members of the weasel family have traditionally supported a small trapping industry, usually providing supplemental, seasonal income for rural residents. Most of the land in the Columbia Basin is allocated to licensed trappers as registered traplines. Of the mustelids, marten and river otter provide the steadiest income, because they are ubiquitous in forest and river environments, respectively, both species are easy to trap, and both reproduce rapidly enough to support regular harvest. Because wolverine pelts are valuable, they are vigorously sought by trappers; however, their low numbers throughout the region mean that they rarely contribute more than a fraction of the total value. Wolverines and striped skunks are considered "game," and a few are taken by hunters each year. The fisher is rarely trapped, and a voluntary fisher management program between trappers and the Wildlife Branch limits the number taken accidentally in marten and mink traps. Although long-tailed weasels and ermine are commonly represented in Columbia Basin fur sales, their small size results in low individual and total value. Badgers are not trapped (there is no open season).

Badger

The badger, a grassland species, suffered greatly from eradication efforts of ranchers who historically considered it "vermin," with some justification because of the hazard its holes posed for livestock. Badgers are strong burrowers, excavating dens and holes to dig out ground squirrels, a major prey item. Badgers also died as innocent bystanders when feeding on poison-laced carcasses ranchers left for coyotes. Other population pressures have included hunting, predation (e.g., by cougars and coyotes), highway mortalities, and habitat loss to reservoirs, agriculture, forest encroachment and human habitations. Badgers are currently Red-listed in British Columbia.

The Columbia Basin Fish and Wildlife Compensation Program, with the Invermere Veterinary Hospital and Canada Parks Service, are sponsoring research on badgers in the East Kootenay. Biologists have fitted a dozen badgers with radio transmitters to determine their habitat use, home range size, and sources of mortality.

Wolverine

The wolverine is quintessentially a wilderness species in the popular imagination, and research currently sponsored by the Columbia Basin Fish and Wildlife Compensation Program, Canada Parks Service, Ministry of Forests, B.C. Environment and the Habitat Conservation Trust Fund is confirming this. Researchers follow wolverines by radio tagging and tracking, logging many hundreds of wilderness miles on snowshoes in steep wilderness terrain (Have you tried this? These guys have thighs like tree trunks, and courage to match). They have found that while wolverines are widely distributed, the breeding females locate maternal dens only high up in roadless, undeveloped drainages (Krebs and Lewis, 1997). The management implication is that viability of wolverine populations absolutely depends on substantial areas of wilderness, and is incompatible with even moderate development in denning areas. This information will be used to develop management strategies and integrate wolverine requirements with forestry.

Mink and Otter

Mink and river otter are aquatic mustelids, preying largely on fish - otter, nearly entirely, but mink less so. Otters do live in lakes (and along the coast), but are really river animals.

Mink - about the size of a marten and, when skinned, looking nearly identical - inhabit mainly marshes and small ponds and swampy fringes of lakes where they can find a variety of prey, including fish, waterbird eggs and young, and muskrats, where available.

Evidence of otters occupying an area (besides seeing the animals themselves, a constant source of pleasure to canoeists in the Columbia Basin) include slick logs and rocks where they haul out of the water (often littered with fish bones), slides down steep river banks into the water, and latrine sites where they mark territories. Dens are along the shoreline or in old beaver lodges. In reservoirs, otters can survive fluctuating water levels by denning up tributary streams.

As the top predators of aquatic ecosystems, mink and otters can accumulate heavy metals and organic contaminants, if present. Mink are particularly sensitive, and are known to have poor reproduction in contaminated systems. A study by the Canadian Wildlife Service in the Canadian portion of the Columbia and Kootenay River systems showed that both species accumulated some trace metals and organic contaminants (at low levels, by comparison with more industrialized river systems), and that reproductive organs in the more contaminated male mink were smaller than those of less-contaminated individuals (Harding, et al., 1999). They found no such effects in otters, but previously Henny et al., (1996) found that otters from the highly industrialized portion of the lower Columbia River near Portland, Oregon, had the same sorts of associations between reproductive organ size and organic contaminants that the CWS researchers found in mink on the upper Columbia. The U.S. researchers also found that mink were absent from the industrialized parts of the river. The CWS group also found very high lead levels in the only otter captured from the Columbia River near Trail, a young female. They concluded that reproductive health of otters is uncompromised by contaminants, but contaminants in mink and lead levels in otter in the Trail area warrant further study.

Fisher

The fisher is known to be scarce or absent over much of the Columbia Basin; Banfield (1974) showed it as "extinct" in the Basin, except for the extreme northern portion. They are medium sized carnivores that prey on a wide variety of foods including birds, rabbits, porcupines and carrion. Distribution is likely governed by the availability of food, but the presence of overhead cover may also be an important factor (Strickland et al. 1982). Home range sizes of fisher vary up to 30 square kilometres for adult males. The range of one male will overlap those of more than one female, but home ranges within adult sexes are mutually exclusive (Cannings et al. 1999).

The fisher uses primarily coniferous or mixed-wood habitats. Optimum fisher habitat consists of a diversity of forest types and, therefore, greater prey abundance. Large diameter trees with cavities, especially riparian cottonwoods in British Columbia, are important as natal den sites. Fishers move to larger cavities as the young grow. Dense forest stands in the latter successional stages provide the best quality habitat, particularly in western North America. Weir (1995) regarded fishers in south central British Columbia as a habitat specialist associated with late successional forest (Cannings et al., 1999)

Fewer than 1500 fisher are believed to live in the province; it is vulnerable to habitat loss through forestry, trapping and hydroelectric development. Loss of habitat through the cutting of forests for timber or conversion to other land uses, over-trapping and the widespread use of poisons as a harvest and predator control method have also contributed to the reduction and extirpation of fisher populations. Forest harvesting elsewhere also increases access for trappers, which is a particular concern because fisher are taken in marten sets, and marten trapping is a mainstay of BC's fur industry (Cannings et al. 1999). By agreement with the B.C. Wildlife Branch, trappers voluntarily participate in a fisher management program designed to reduce the fisher harvest and to limit accidental capture of fisher in marten and mink traps.

Marten

Like wolverine and fisher, marten live in forests; unlike wolverine but like fisher, marten are largely arboreal, and often prey on tree-dwelling animals such as red squirrels and birds, as well as terrestrial prey including snowshoe areas and voles. They also eat berries and other vegetation. They are quite common throughout the forested portions of the Columbia Basin. Seemingly nearly tame, they often visit cottages and camp sites scrounging for edibles. At times (when short-hair fur prices are good) marten have been a valuable forest resource. Under intensive trapping pressure their populations are easily depleted, but they can maintain healthy populations under moderate trapping pressure. The CWS study of contaminants in mink and otters, referred to above, found unremarkable levels of trace metals and non-detectable levels of organic contaminants in a small collection of marten from the Revelstoke area.

References and further reading 

Arthur, S. M, W. B. Krohn, and J. R. Gilbert 1989a. Habitat use and diet of Fishers. Journal of Wildlife Management 53: 680-688.

Arthur, S. M, W. B. Krohn, and J. R. Gilbert 1989b. Home range characteristics of adult Fishers. Journal of Wildlife Management 53: 674-679.

Austin, M. 1998. Wolverine winter travel routes and response to transportation corridors in Kicking Horse Pass between Yoho and Banff National Parks. Unpublished thesis. Faculty of Environmental Design, University of Calgary. Calgary, Alberta. 40 p.,

Badry, M. J. 1994. Habitat use by Fishers (Martes pennanti) in the aspen parkland of Alberta. Unpublished M.Sc. thesis. University of Alberta, Dept. of For. Science. Edmonton, Alta. 72 p.

Badry, M. J., G. Proulx, and P. M. Woodard. 1993. Reintroduction of Fisher in the aspen parkland of Alberta. The Edmonton Naturalist 21(1): 23-26.

Banci, V. 1989.  A Fisher management study for British Columbia. B. C. Ministry of Environ., Wildl. Bull. No. B-63. Victoria, B. C. 127 pp.

Banfield, A.W.F. The Mammals of Canada, National Museum of Natural Sciences, University of Toronto Press, 1974.

Cannings, S.G., D.F.Fraser, L.R.Ramsay, and M.Fraker. Rare Amphibians, Reptiles and Mammals of British Columbia. Ministry of Environment, Lands and Parks, Victoria B.C. 1999 (In Press).

Banci, V. 1994. Wolverine. Pp. 99-127 In Ruggiero, L.F., K.B. Aubry, S.W. Buskirk, L.J. Lyon, and W.J. Zielinski, tech. eds., The scientific basis for conserving forest carnivores: American Marten, Fisher, Lynx and Wolverine in the western United States, USDA Forest Serv. Gen. Tech. Rep. RM-254, Fort Collins, Colorado. 184 pp.

Banci, V.A. 1982. The Wolverine in British Columbia: distribution, methods of determining age and status of Gulo gulo vancouverensis. Research, Ministries of Environment and Forests. IWIFR-15. Victoria. 90 pp.

Banfield, A.W.F., 1974. The Mammals of Canada. National Museum of Sciences/Univ. of Toronto Press.

Cannings, S.G., D.F.Fraser, L.R.Ramsay, and M.Fraker. Rare Amphibians, Reptiles and Mammals of British Columbia. Ministry of Environment, Lands and Parks, Victoria B.C. 1999.

Columbia Basin Fish and Wildlife Compensation Program GIS (Newhouse and Ketcheson). 1997. Badger Sightings. Columbia Basin Fish and Wildlife Compensation Program, Nelson.

Harding, L.E., M.L. Harris, C. Stephen and J.E. Elliott , 1999. Reproductive and morphological condition of wild mink (Mustela vison) and river otter (Lutra canadensis) in relation to chlorinated hydrocarbon contamination. Environmental Health Perspectives 107(2): 141-147.

Harding, L.E., M.L. Harris and J.E. Elliott, 1998. Heavy and trace metals in wildl mink (Mustela vison) and river otter (Lutra canadensis) captured on rivers receiving metals discharges. Bull. Environ. Contam. Toxicol. 61: 600-607.

Elliott, J.E., Henny, C.J., Harris, M.L., Wilson, L.K. and Norstrom, R.J. (1998a) Chlorinated hydrocarbons in livers of American mink (Mustela vison) and river otter (Lutra canadensis) from the Columbia and Fraser River basins, 1990-92. Environ. Monitoring and Assessment (in press, 1999).

Henny, C.J., Grove, R.A. and Hedstrom, O.R. (1996) A field evaluation of mink and river otter on the lower Columbia River and the influence of environmental contaminants. Final Report to the Lower Columbia River Bi-State Water Quality Program (Portland, OR) submitted by National Biological Service, Forest and Rangeland Ecosystem Science Center, Corvallis, OR, USA.

Krebs, J. and D. Lewis, 1997. CBFWCP/HCTF Project Proress Report: Kootenay Wolverine 1997/1998.

Lieffers, V.J. and P.M. Woodward. 1997. Silvicultural systems for maintaining marten and fisher in the boreal forest p. 407-418 in G. Proulx, H.N Bryant and P.M. Woodard (eds.) 1997. Martes: taxonomy, ecology, techniques and management. Provincial Museum of Alberta, Edmonton, Alberta.

Mowat, G., Hurlburt, K. and Fear, D. 1998. Estimating Marten Population Size and Distribution Using Hair Capture and DNA Fingerprinting in the Central Selkirk Mountains of British Columbia: PROGRESS REPORT. Ministry of Environment/FRBC report, BC, Canada. (BC Environment, Kootenay Regional Office website).

Nagorsen, D. 1990. The mammals of British Columbia: a taxonomic catalogue. Royal British Columbia Museum, 140pp.

Newhouse, N. 1999. East Kootenay Badger Project: 1998/99 Year-End Summary Report. Forest Renewal British Columbia, BC Environment, Columbia Basin Fish and Wildlife Compensation Program, Canadian Parks Service and East Kootenay Environmental Society report, BC, Canada.

Rahme, A.H., A.S. Harestad, and F.L. Bunnell. 1995. Status of the Badger in British Columbia. Wildlife Working Report WR-72. Ministry of Environment, Lands and Parks. Victoria. 52pp.

Ruggiero, L.F., W.J. Zielinski, K.B. Aubry, S.W. Buskirk, and L.J. Lyon. 1994. A conservation assessment framework for forest carnivores. Pages 1-6 in Ruggiero, L.F., W.J. Zielinski, K.B. Aubry, S.W. Buskirk, and L.J. Lyon (ed's.). The scientific basis for conserving forest carnivores: American marten, fisher, lynx and wolverine in the western United States. General Technical Report RM-254, US Department of Agriculture, Forest Service, Rocky Mountain Forestry and Range Station, Fort Collins, Colorado.

Strickland, M. A., C. W. Douglas, M. Novak and N. P. Hunzinger. 1982. Fisher Martes pennanti. Pages 586-598 in J. A. Chapman and G. A. Feldhamer, eds., Wild Mammals of North America: biology, management and economics. The John Hopkins Univ. Press, Baltimore, Md.

Weir, R.D. 1995. Diet, spatial organization and habitat relationships of fishers in south central British Columbia. M.Sc. Thesis, Simon Fraser University, Burnaby, British Columbia.

Weir, R.D. and A.S. Harestad. 1997. Landscape-level selectivity by fishers in south central British Columbia. pp252-264 in G. Proulx, H.N Bryant and P.M. Woodard (eds.) 1997 . Martes: taxonomy, ecology, techniques and management. Provincial Museum of Alberta, Edmonton, Alberta.

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