Northern Prairie Wildlife Research Center
Wolves live in packs or family groups that, in Minnesota in midwinter, average from three to eight individuals and occupy territories of 110 to 260 km2 (Mech 1973, 1986; Van Ballenberghe et al. 1975; Fritts and Mech 1981; Berg and Kuehn 1982; Fuller 1989). Packs typically consist of an adult male, adult female, and their offspring from one or more generations. A dominance hierarchy exists within packs, with breeding animals usually being the dominant members. The dominant male and female guide almost all the pack's activities. In Minnesota, except for rare occurrences, only one female within each pack breeds; litters of 5-6 pups are born in early April to early May. Pups are adult-sized by winter, but usually stay with their packs until they are 1-2 years old or older. Some wolves disperse from their packs to become lone wolves that search for a mate and an area for establishing their own packs. Large ungulates are the main prey of wolves wherever they have been studied in North America (Mech 1970; Carbyn 1987).
In the contiguous United States, the wolf is found mainly in northern Minnesota where the population numbers about 1,200 (USFWS 1978; Berg and Kuehn 1982). The animal is listed by the U.S. Fish and Wildlife Service (Service) as threatened in Minnesota (43 Federal Register 9612, 9 March 1978) and endangered elsewhere. The wolf presently shows some natural range expansion into other states, recolonizing northern Wisconsin (Mech and Nowak 1981; Thiel and Welch 1981); Michigan (Robinson and Smith 1977; Thiel 1988; Thiel and Hammill 1988), extreme northwestern Montana (Boyd 1982; Ream and Mattson 1982; Ream et al. 1985; Ream et al. 1991), and possibly Idaho (Kaminski and Boss 1981; Kaminski and Hansen 1984). Some recent activity is suspected in the Cascades Range of Washington (Laufer and Jenkins 1989). However, only in Minnesota has substantial experience been obtained in managing wolf-human conflicts during recent times and under the Endangered Species Act of 1973.
Wolves kill livestock and other domestic animals in northern Minnesota (Fritts and Mech 1981; Fritts 1982; Mech et al. 1988b; Fritts and Paul 1989). These depredations are of concern not only to the Service, but to the Minnesota Departments of Natural Resources (MDNR) and Agriculture (MDA), and to the U.S. Department of Agriculture (USDA), to which animal damage control responsibility was transferred in March 1986. Moreover, the nature and extent of wolf-livestock conflicts in Minnesota is closely monitored by advocates and opponents of wolf recovery in other parts of the United States, particularly the northern Rocky Mountains and the Southwest. Several types of livestock are available to wolves in Minnesota. Our experience with active depredations in the state may lend insight into problems and solutions that may occur where wolves become established naturally or by reintroduction, and can provide background for developing effective control programs in those areas.
Programs for controlling wolf depredations in Minnesota have been described and the results provided (Fritts 1982; Fritts et al. 1984). Since 1978, the threatened status of the wolf in Minnesota has allowed state and federal authorities to kill wolves proven to have committed depredations on domestic animals, except in Wolf Management Zone 1 in extreme northeastern Minnesota, an established sanctuary (USFWS 1978; Fig. 1a).
The primary source of information about wolf depredations in Minnesota, including a program description for dealing with the problem (Fritts 1982), is based on data obtained from 1975 through 1980, but focused on information from 1979 and 1980. With more recent data obtained we are able to (1) describe the wolf depredation problem in Minnesota more thoroughly than was previously possible, (2) evaluate the effectiveness of control methods used, and (3) reevaluate the conclusions of the earlier report (Fritts 1982). For the present report we analyzed data from 1975 through 1986, the years from the listing of the wolf as threatened in Minnesota and the initiation of a federal control program to the transfer of the depredation control program from the Service to the USDA in 1986. The Epilogue contains an update for 1987-89.
Fig. 1.a.Wolf Management Zones in Minnesota. Two counties where depredations were relatively high in Zone 5 are also shown. Zones 1, 2, and 3 are critical habitat. b. Occupied and potential wolf range in Minnesota. A = primary, B = Roseau peripheral, C = northwest nonoccupied, D = Marshall peripheral, E = Hubbard disjunct, F = central nonoccupied, G = Crow Wing disjunct, H = main peripheral, I = Nemadji disjunct. Blank areas indicate intensively farmed or developed areas devoid of resident wolves (Mech et al. 1988a).