The gray wolf, Canis lupus, also known as "timber wolf", originally occurred across North America, Europe and Asia (Nowak 1995). Coyotes, Canis latrans, are sometimes called "brush wolves" but are not true wolves.
Wisconsin's wolves were formerly classified as the subspecies, Canis lupus lycaon (Eastern timber wolf) when the 1989 Timber Wolf Recovery Plan was approved (WDNR 1989). Recently the number of subspecies of the gray wolf has been reduced from 24 to 5 (Nowak 1995). The revised classification places all wolves in the Great Lakes Region west of Sault Ste. Marie, Michigan with the subspecies Canis lupus nubilis (Great Plains Wolf). For the purpose of this management plan, we will refer only to the species, Canis lupus.
Physical Characteristics: Gray wolves resemble large dogs but usually have longer legs, larger feet, and a narrower chest (Banfield 1974). Their tail is straight rather than curving upward, and their head appears more massive due to wide tufts of hair that project down and outward from below the ears (Mech 1970). Adult males captured in Wisconsin averaged 77 pounds (57-102 pounds) and adult females averaged 62 pounds (46-75 pounds)(Wydeven et al 1995). They are 4.5 to 6.5 feet long from tail tip to nose tip and stand 28-34 inches at the shoulder. Pelt color seldom varies from a grizzled gray/brown, but at least 2 black individuals have been recently observed in Wisconsin.
Social System: Wolves live in family groups called "packs" that consist of a dominant breeding pair ("alphas"), and generally surviving offspring from the previous year, and the current year's pups (Mech 1970). Occasionally older offspring remain with the pack or an unrelated adult wolf may be a member. Pack size in Wisconsin ranges from 2-10 wolves and averaged 4.3 wolves during the 1996-97 winter (Wydeven and Cervantes 1997). Each family group occupies an exclusive territory of 20-160 square miles, averaging 70 square miles in Wisconsin (Wydeven et al. 1995). Territories rarely overlap and are defended against other wolves (Peters and Mech 1975).
Yearling wolves normally disperse from their natal packs, usually during October-January, to seek a mate and their own territory. Adult dispersal has also been noted (Fritts and Mech 1981). Dispersers may travel up to 500 miles in less than 10 months (Fritts 1983). Wisconsin wolves dispersed an average of 71 miles from natal territories and have traveled 300 miles (Figure 5) (Wydeven et al. 1995).
Reproduction: Wolves are sexually mature at 22 months but generally only the alpha male and female breed (Mech 1970). The alpha pair normally inhibit sexual contact between other mature members (Packard et al. 1983). Breeding takes place between late January to early March, and gestation is 60-63 days. Pups (4-8) are born in early to mid April (Fuller 1989). The pups are kept at a den site for 6 to 8 weeks. By mid June the pups are moved to rendezvous sites where they stay while adult search for food. Throughout summer wolves utilize 2-3 rendezvous sites (Fuller 1995). In September and October, when the pups become large enough to travel with the adults, rendezvous sites are vacated and the pack moves as a single unit throughout its territory.
Mortality: Keith (1983) found that wolf populations declined when annual mortality rates of wolves greater than 6 months exceeded 30-40%. Wydeven et al. (1995) reported that average annual mortality rates for Wisconsin wolves greater than one year old decreased from 39% during 1979-85 to 18% during 1986-92.
Wolves are susceptible to diseases, predation, human persecution, starvation, and accidents. Human-caused deaths declined from 72% in 1979-85 to 22% in 1986-92. In recent years (1993-1996) 50% of wolf mortality was caused by humans, and over 25% of mortality was caused by vehicle collisions (WDNR files). Mortality rates for wolves 1 year old or older continues to be less than 20% annually.
Diseases such as canine distemper, canine parvovirus, Lyme disease, and blastomycosis have been observed in Wisconsin wolves. Wydeven et al. (1995) felt that canine parvovirus negatively impacted Wisconsin's wolf population during 1982-86. Parasites observed in Wisconsin wolves include protozoans and intestinal worms, ticks, mites, lice, and heartworm (Mech et al. 1985, Archer et al. 1986, Thiel, unpubl. data). Mange has been observed frequently in Wisconsin wolves since 1992, and has been diagnosed as the primary cause of death for at least nine wolves in the past 5-6 years. In 1992 and 1993, 58% of wolves handled by WDNR had signs of mange, but this has declined to 15% in recent years (WDNR files).
Food Habits: In the 1940's, deer occurred in 97% of 435 wolf scats found in Wisconsin, at a time when deer populations were very high and beaver numbers were low (Thompson 1952). Deer comprised 55% of scats collected between 1980 and 1982 and analyzed by Mandernack (1983). Beaver comprised 16% and snowshoe hare 10% in his analysis. Miscellaneous items accounted for the remainder. Some wolves have also killed domestic animals in Wisconsin in recent years (Appendix A).
Habitat Requirements: Wolves are adaptable and can survive on large landscapes with adequate prey populations and low rates of human persecution (Fuller 1995). Pack territories are typically 70 square miles (average pack territory size) and contain low human densities, limited public accessibility, and minimal livestock production (Thiel 1985, Mech 1986, Fuller 1995). Fuller (1995) suggested that clusters of 2-3 packs (areas of 200 square miles) represents the minimal number of packs necessary to support a viable population. The large land requirements of wolves can conflict with human use of those lands. Examples of direct conflict over land use by humans include livestock production, urban areas, and intensive recreational activities. Conflicts may also arise anywhere people have the opportunity to encounter wolves either accidentally or intentionally.
Keith (1983) and Fuller (1989) found that over 90% of the variation in wolf densities could be accounted for by variation in prey populations. In northeast Minnesota, Mech (1986) and Nelson and Mech (1986) reported a density of 1 wolf per 17 square miles in an area with deer densities of about one deer per square mile, but moose and beaver also occurred in this area. In north-central Minnesota, wolf densities of 1 wolf per 10-13 square miles were found in an area supporting 10-26 deer per square mile (Fuller 1989, Fuller 1990). Average deer density in deer management units comprising Wisconsin's Northern Forest, which includes most of Wisconsin's wolf range, was 22 deer per square mile during the 1996-97 winter and density of wolves in 2,200 square miles of wolf range was 1 wolf per 15 square miles (Wydeven and Cervantes 1997). Prey abundance should not be a limiting factor in Wisconsin.
Mladenoff et al. (1995) estimated that approximately 5,700 square miles of suitable wolf habitat exists in Northern Wisconsin and that it is highly fragmented. They suggested that human-caused mortalities and continued habitat loss due to human development could reverse wolf population trends in a fragmented region such as Wisconsin. An update of this analysis shows 5,812 mi2 of primary wolf habitat , 5,015 mi2 of secondary habitat, and 45,252 mi2 of unsuitable habitat on a statewide basis (Figure 6).