Canis lupus lycaon
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.
The first federal Endangered Species Preservation Act was passed in 1966, and in 1967 gray wolves were classified as endangered and provided limited protection. In 1974, four subspecies of gray wolves in the lower 48 states (Canis lupus irremotus, C. l. lycaon, C. l. bailey, and C. l. monstrabilis) were afforded full protection under the federal Endangered Species Act (ESA) of 1973 (50 CFR 17.11(h)). In 1978, the gray wolf was relisted as endangered at the full species level (C. lupus) throughout the conterminous 48 States and Mexico, except for Minnesota where it was reclassified as threatened (50 CFR 17.11(h)). Under the federal protection provided by the ESA, it was illegal to kill a wolf, except in the defense of a human life. This protection allowed wolves the chance to repopulate portions of the Great Lakes region.
Wolves in Minnesota significantly increased and expanded their range (Fuller et al. 1992; Berg and Benson 1999), which led to the 1978 decision to reclassify them at the threatened level of federal protection. This reclassification allowed the federal government to kill problem wolves in response to livestock depredation. Gray wolves were originally state listed as threatened in Minnesota in 1984, but as wolf numbers continued to increase, they were reclassified as state special concern in 1996. In January 2012, wolves in the western Great Lakes population, including Minnesota, were completely removed from the federal Endangered Species List. On December 19, 2014, a federal judge issued a decision to immediately reinstate federal ESA protections for gray wolves in Minnesota, Wisconsin and Michigan. In Minnesota, this ruling returned the wolf to threatened status under the federal ESA and returned management to the U.S. Fish and Wildlife Service. Learn more about wolf management in Minnesota.
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.
In comparison, coyotes (Canis latrans) are 1.1-1.3 m (3.6-4.4 ft.) long and 40.6-50.8 cm (16-20 in.) high; weigh on average 11-16 kg (25-35 lbs.) in Minnesota; and have gray or reddish brown pelage with rusty legs, feet, and ears and a whitish throat and belly. Additionally, their ears are pointed and relatively long, and they have a petite, pointed muzzle. Coyote tracks average 3.8-6.4 cm (1.5-2.5 in.) long. Several species of dogs also resemble wolves, but coloration, size, body proportion, and behavior can be used to discern the difference.
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).
In the wild, gray wolves generally live to be 6-8 years old, but they have been known to live to 13 in the wild (Mech 1988) and to 16 in captivity (Young and Goldman 1944). Mortality for wild wolf pups is high (40%-60%), but for wolves greater than 5-months old it is approximately 36% (Fuller 1989). Wolf mortality is caused by a variety of factors, both human and non-human related (Fuller 1989). Major non-human related factors include starvation (mostly pups), death from conflicts with other wolves, and diseases such as mange and canine parvovirus (Kreeger 2003). Injuries from prey animals can also be a limiting factor. Human related causes of death include legal depredation control, illegal poaching, and accidental causes. A study of wolves in Minnesota from 1980-1986 indicated that 80% of wolf mortality was human caused (Fuller 1989).
Wolf pack size is highly variable due to the birth of pups, dispersal, and mortality. Gray wolf packs in Minnesota generally contain from 4-8 wolves (Fuller 1989), but in Alaska, Yellowstone National Park, and northwestern Canada, much larger packs have been recorded (20-30 wolves). Packs are usually composed of a breeding adult pair and their offspring from the previous 2-3 litters, however, unrelated wolves have been known to join packs. Wolf territory size is also highly variable. In Minnesota, territory sizes range from about 65-388 square km (25-150 square mi.). Territories in other areas are known to be higher (777-2,590 square km; 300-1,000 square mi.). Wolf territories are separated on the landscape, and territory boundaries are marked with urine and feces and defended. Neighboring wolf packs can share common borders, but territories rarely overlap by more than a mile. Buffer zones are believed to exist between wolf packs (Mech 1977), and wolves have been shown to spend less time along the edge of their territory than in the center (Mech and Harper 2002).
Wolves feed primarily on large, hoofed mammals such as white-tailed deer (Odocoileus virginianus) and moose (Alces alces) in Minnesota. Other medium sized animals, such as beaver (Castor canadensis) and snowshoe hare (Lepus americanus) are important secondary food sources. Wolves will occasionally prey on birds and small mammals.
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.
The range expansion of wolves in Minnesota since the 1950s has increased the number of wolves in agricultural lands (Fuller et al. 1992; Mech 2001) and in areas where road and human densities were formerly believed to be too high to sustain wolf populations without considerable conflict with humans (Berg and Benson 1999; U.S. Fish and Wildlife Service 1978, 1992). Livestock depredations increased as the wolf population expanded its range in Minnesota (Fritts et al. 1992; Paul 2000), however over the last 10 years as the population and distribution of wolves has stabilized, so have the number of livestock depredations. Other factors, such as wolf colonization of new areas within their existing range and learned behavior, may also have contributed to increased depredations (Harper et al. 2005). One of the most critical components of wolf management in Minnesota has been the U.S. Department of Agriculture's wolf depredation management program.
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
The Minnesota DNR (MNDNR) has committed to ensuring the long-term survival of the wolf in Minnesota, and also to resolving conflicts between wolves and humans. In anticipation of the federal delisting of gray wolves, the state legislature passed a wolf management bill in 2000 and the DNR completed a comprehensive wolf management plan in 2001. The plan is designed to protect wolves and monitor their populations while giving owners of livestock and domestic pets more freedoms for preventing wolf depredation. It includes provisions for population monitoring, management and control of problem wolves, management of wolf habitat and prey, enforcement of laws restricting take of wolves, public education, and increased staffing for wolf management and research. The plan splits the state into two management zones with more protective regulations in the northern third, considered the wolf's core range (Minnesota DNR 2001). The DNR has hired staff to implement the 2001 management plan and to monitor wolf populations.
The MNDNR in cooperation with other agencies has carried out wolf population monitoring in the state for several decades, typically at 10-year intervals. To be consistent with federal monitoring guidelines, the survey frequency was increased to 5-year intervals, starting with the winter of 2007/2008. The MNDNR also conducts annual evaluations of moose and deer populations in Minnesota, important prey species for wolves (Minnesota DNR 2001).
Minnesota's wolf management plan establishes a minimum population of 1,600 wolves to ensure long-term survival (Minnesota DNR 2001). The population estimate from the 2007/2008 survey is 2,921 animals, compared to an estimated 3,020 animals in 2003/2004 and 2,445 animals in 1997/1998 (Erb 2008). This indicates that over the last 10 years there has been no significant change in the number or distribution of wolves in Minnesota. Few suitable areas in the state remain unoccupied by wolves indicating a fully recovered gray wolf population in Minnesota.