Canis lupus Linnaeus, 1758
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Basis for Former 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.
Basis for Delisting
The current density of the gray wolf is approximately 1 per 10 square miles. Alaska is the only U. S. state with a higher population of gray wolves than Minnesota. Minnesota's gray wolf range has expanded from a 12,000 square mile area in the 1950's to over 27,000 square miles. As of 2013, the population is estimated at 2,200, which exceeds the federal delisting goal of 1,250-1,400. Minnesota's gray wolf population has remained stable over the last 10 years, with most areas of suitable habitat in the state now occupied. These data suggest that the population has fully recovered and special concern status is no longer necessary. The gray wolf was removed from Minnesota special concern status in 2013.
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.
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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.
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