Canis lupus Linnaeus, 1758
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Basis for Listing
Prior to European settlement, the gray wolf, sometimes called the timber wolf, inhabited most of North America south to at least 20° latitude (Mech 1995). Human persecution, habitat deterioration, and the reduction of prey populations led to the decline of wolves. Wolves were almost completely eliminated from the western United States by the 1930s. In Wisconsin and Michigan, wolves were eliminated by the mid-1960s. At that time, only a small number of wolves survived in northeastern Minnesota and on Isle Royale in Michigan, although large populations remained in Canada and Alaska.
Adult female gray wolves in Minnesota weigh 22.7-38.6 kg (50-85 lbs.) and average 1.4-1.8 m (4.5-6 ft.) long. Adult males weigh 31.8-49.9 kg (70-110 lbs.) and average 1.5-2.0 m (5-6.5 ft.) long. Average height at the shoulder in both sexes is 66-81 cm (26-32 in.). Their pelage is gray, black and/or buff with reddish coloring, but they can also be all black. Wolves have rounded and relatively short ears, and a large, blocky muzzle. The size of wolf tracks is dependent on the age and size of the wolf, and whether it is a front or rear paw, but the average size of an adult wolf track is 11.4 cm (4.5 in.) long and 8.9 cm (3.5 in.) wide.
Gray wolves are habitat generalists and populations can thrive in any type of habitat in the Northern Hemisphere (forests, prairies, swamps, mountains, deserts, tundra, and barren lands) from about 20° latitude to the polar ice pack, as long as there is abundant prey and controlled human-caused mortality (Young and Goldman 1944). They were once considered a wilderness animal, but have expanded into areas previously considered uninhabitable by wolves (U.S. Fish and Wildlife Service 1978, 1992; Berg and Benson 1999). In the early 1950s, Minnesota's primary wolf range encompassed a 31,080 square km (12,000 square mi.) area in northern Minnesota. Since the winter of 1997-98, regularly-occupied wolf range in Minnesota has been estimated at 88,325 square km (34,102 square mi.) in the forested portions of central and northern Minnesota. However, dispersing individuals have been documented in southern Minnesota.
Biology / Life History
Female gray wolves reach sexual maturity at 22 months of age, or older, but social standing influences breeding status (Mech 1970). Generally, only the alpha (top ranking) pair in a wolf pack breeds. However, in areas of high prey numbers, there can be multiple litters in a pack. Wolves breed from February to March in Minnesota, but breeding period varies among regions. Gestation period is usually around 63 days, with 4-7 pups born in April and May. Pups are born in a den and will live there until they are 6-8 weeks old. At this time, the pups are moved to rendezvous sites. Various rendezvous sites may be used by a pack throughout the course of the summer. Pups remain at or near these sites while the adults hunt and bring back food. The pups join the pack by September or October, and the rendezvous sites are abandoned. Gray wolves generally disperse from their pack at 1-2 years old (Fuller 1989), and commonly disperse 80.5-161 km (50-100 mi.) from their natal pack (Fritts and Mech 1981; Fuller 1989). However, wolves have been known to disperse up to 885 km (550 mi.) (Fritts 1983).
Conservation / Management
The greatest long-term threat to wolf conservation is habitat reduction and destruction (Boitani 2003). Human population growth and subsequent increases in human dispersion on the land are contributing to the decrease of available habitat for large ungulates, and hence wolves. This growth also increases the chance of human-wolf encounters, which usually end poorly for wolves. Depletion of prey, however, has not currently seriously threatened any wolf populations (Boitani 2003). Gray wolves have a demonstrated ability to adapt to human pressures, and human intolerance of their presence may be the limiting factor for wolves in Minnesota.
Conservation Efforts in Minnesota
There has been extensive research on wolves in Minnesota, resulting in a wealth of information on the ecology of wolves. Sigurd Olson's field studies of wolves in the 1930s were some of the first in Minnesota. Milt Stenlund studied wolves in the Superior National Forest during the late 1940s and early 1950s. In the mid-to-late 1960s, L. David Mech began his studies in the Superior National Forest, research that continues today (Mech 2000). Wolves have also been studied in several other regions of northern and north-central Minnesota
Berg, W., and S. Benson. 1999. Updated Wolf population estimate for Minnesota, 1997-1998. Minnesota Department of Natural Resources, Grand Rapids, Minnesota.
Boitani, L. 2003. Wolf conservation and recovery. Pages 317- 340 in L. D. Mech and L. Boitani, editors. Wolves: behavior, ecology, and conservation. University of Chicago Press, Chicago, Illinois.
Erb, J. 2008. Distribution and abundance of Wolves in Minnesota, 2007-08. Minnesota Department of Natural Resources, Grand Rapids, Minnesota. 11 pp.
Fritts, S. H. 1983. Record dispersal by a Wolf from Minnesota. Journal of Mammalogy 64:166-167.
Fritts, S. H., and L. D. Mech. 1981. Dynamics, movements, and feeding ecology of a newly protected Wolf population in northwestern Minnesota. Wildlife Monograph No. 80. 79 pp.
Fritts, S. H., W. J. Paul, L. D. Mech, and D. P. Scott. 1992. Trends and management of wolf-livestock conflicts in Minnesota. United States Fish and Wildlife Service Resource Publication 181, Washington, D.C. 27 pp.
Fuller, T. K. 1989. Population dynamics of wolves in north-central Minnesota. The Wildlife Society Wildlife Monographs No. 105. 41 pp.
Fuller, T. K., W. E. Berg, G. L. Radde, M. S. Lenarz, and G. B. Joselyn. 1992. A history and current estimate of Wolf distribution and numbers in Minnesota. Wildlife Society Bulletin 20:42-55.
Harper, E. K., W. J. Paul, and L. D. Mech. 2005. Causes of Wolf depredation increase in Minnesota from 1979-1998. Wildlife Society Bulletin 33(3):888-896.
Kreeger, K. J. 2003. The Internal Wolf: Physiology, Pathology, and Pharmacology. Pages 192 - 217 in L. D. Mech and L. Boitani, editors. Wolves: behavior, ecology, and conservation. University of Chicago Press, Chicago, Illinois.
Mech, L. D. 1970. The Wolf: the ecology and behavior of an endangered species. Natural History Press, Garden City, New York. 389 pp.
Mech, L. D. 1974. Canis lupus. American Society of Mammalogists, Mammalian Species No. 37. 6 pp.
Mech, L. D. 1977. Wolf-pack buffer zones as prey reservoirs. Science 198:320-321.
Mech, L. D. 1988. Longevity in wild wolves. Journal of Mammalogy 69(1):197-198.
Mech, L. D. 1995. The challenge and opportunity of recovering Wolf populations. Conservation Biology 9:270-278.
Mech, L. D. 2000. Wolf research in Minnesota. Pages 37-49 in L. D. Mech, editor. The wolves of Minnesota: howl in the heartland. Voyageur Press, Stillwater, Minnesota.
Mech, L. D. 2001. Managing Minnesota's recovered wolves. Wildlife Society Bulletin 29:70-77.
Mech, L. D., and E. K. Harper. 2002. Differential use of Wolf, Canis lupus, pack territory edge and core. Canadian Field Naturalist 116:315-316.
Mech, L. D., E. K. Harper, T. J. Meier, and W. J. Paul. 2000. Assessing factors that may predispose Minnesota farms to Wolf depredations on cattle. Wildlife Society Bulletin 28:623-629.
Minnesota Department of Natural Resources. 2001. Minnesota Wolf management plan. Division of Wildlife, Minnesota Department of Natural Resources, St. Paul, Minnesota. 36 pp. + appendices.
Paul, W. J. 2000. Wolf depredation on livestock in Minnesota annual update of statistics 1999. United States Department of Agriculture, Grand Rapids, Minnesota.
Treves, A., L. Naughton-Treves, E. Harper, D. J. Mladenoff, R. A. Rose, T. A. Sickley, and A. P. Wydeven. 2004. Predicting human-carnivore conflict: a spatial model derived from 25 years of data on Wolf predation on livestock. Conservation Biology 18:114-125.
United States Fish and Wildlife Service. 2003. Gray Wolf eastern distinct population segment. United States Fish and Wildlife Service, Twin Cities, Minnesota.
U.S. Fish and Wildlife Service. 1978. Recovery plan for the Eastern Timber Wolf. United States Fish and Wildlife Service, Washington, D.C.
U.S. Fish and Wildlife Service. 1992. Recovery plan for the Eastern Timber Wolf. United States Fish and Wildlife Service, Twin Cities, Minnesota. 73 pp.
U.S. Fish and Wildlife Service. 2008. Post-delisting monitoring plan for the Western Great Lakes Distinct Population Segment of the Gray Wolf. U.S. Fish and WIldlife Service, Twin Cities Field Office and Midwest Region. Bloomington, MN and Ft. Snelling, MN. 13 pp.
Young, S. P., and E. A. Goldman. 1944. The wolves of North America. The American Wildlife Institute, Washington, D.C. 636 pp.