Gray Wolf

Canis lupus

Description

In physical appearance the gray wolf, Canis lupus, resembles a large domestic dog, such as the Alaskan malamute. It is larger than the endangered red wolf. Adult males average about 95 lb (43 kg), and can weigh as much as 175 lb (80 kg). Females are smaller, averaging about 80 lb (36 kg), but can get as large as 125 lb (57 kg). The gray wolf's markings vary with both habitat and season; it is usually gray with black speckles and a yellowish underbelly and stockings. Entirely black or white wolves occur in northern Canada and Alaska.

There are numerous races and subspecies of wolves, including the Mexican wolf (Canis lupus baileyi ), the Japanese wolf (C. lupus hodophylax ), and the Indian wolf (C. lupus pallipes ). Overall there are more than 20 North American subspecies and more than 15 subspecies in other parts of the world, most of them subspecies of C. lupus. The gray wolf is also known as the timber wolf.

Behavior

The gray wolf is strongly social and territorial. It typically hunts a territory in a pack consisting of several or as many as 20 members, depending on the abundance of prey species. A pack can range as far as 100 mi (160 km) in search of prey. When on the hunt, wolves shelter for sleep in rocky crevices or in thick underbrush; in open country they may dig protective holes.

Life within a wolf pack is highly regulated. A strict social hierarchy, with distinct dominance and subordinance, governs each animal's behavior. Hunting, breeding, and pup rearing require a high degree of group cooperation, but males compete vigorously for rank within each pack. Each pack is led by a pair of co-dominant wolves, the alpha-male and alpha-female. Leadership in hunting, feeding, and reproduction is assumed by the alpha pair, which mates for life. Usually the alpha pair is the only pair in the pack to mate and reproduce. Subordinate wolves are harassed and discouraged from mating by the dominant pair. Subordinate males who challenge the alpha-male are often driven out of the pack. This ejected male or "lone wolf" might encounter a solitary young female and start a new pack in an uncontested area. Sometimes, competition within a pack or a lack of prey causes a pack to split into smaller packs.

The gray wolf is a fierce carnivore. It is the primary predator on large, hoofed mammals, such as moose, elk, or deer. Wolves can bring down these large animals because the disciplined pack is able to coordinate and sustain its attack, often wearing down the prey animal. Wolves can run for hours at a time, sometimes at speeds of 20-25 mph (32-40 kph).

Yet wolves do not kill indiscriminately. When stalking a herd of moose or elk, they identify weaker members of the herd—usually young, aged, or sick animals—separate one of them from the herd, then encircle and kill it. If a pursued animal fights back with any spirit, the pack will often abandon its attack and seek a more acquiescent prey. Hunting packs have been observed to make over a dozen forays at different herds before finally making a kill.

When another species of prey—deer, for example—is more plentiful in the territory than moose or elk, a wolf pack will generally kill a higher proportion of deer, leaving much of the carcass uneaten, allowing other animals to feed on the carcass.

Hunting behaviors such as these are considered by some biologists to be beneficial to prey populations, since the weeding out of weak animals maintains herd vigor and controls explosive population growth.

When larger prey is unavailable, gray wolves will feed on smaller animals, such as beavers, rodents, domestic animals, or even carrion. Overall, the size of the wolf population of any area is tied closely to the availability of prey. Wolves would not completely eliminate a caribou herd into extinction, as some have suggested, but would switch to other prey species, split up the pack, or otherwise limit the number of animals in the territory.

The breeding season of the wolf is from January to March. After a gestation period of about 60 days, the alpha-female bears a litter that averages seven pups. The female prepares a den for whelping and suckles the pups, which are born blind and helpless. The pups' eyes open after about a week. After about ten weeks, the mother returns to hunt with the pack, leaving her playful pups with another, usually younger, female.

During the summer, after pups are weaned and while they are still too young to join the hunting pack, they remain at a series of "rendezvous sites." The mother returns regularly to regurgitate food for them. A number of these sites are used by the pack until the fall when the pups are mature enough to travel with the adults. Young wolves become fully mature in two to three years and learn to hunt from both parents. Wolves can live as long as ten years in the wild and slightly longer in captivity.

Some naturalists cite the wolf's cooperative group behavior and its territoriality as evidence that it is the ancestor of the domestic dog. The dog shares similar behaviors, and there has certainly been scattered interbreeding between wolves and dogs in the past. The wolf, however, is not suited for domestication because when brought into captivity it treats humans as packmates and will fight them for social rank and dominance. It is suspected that this is the reason wolves raised by humans will sometimes attack their owners unprovoked.

Habitat

The gray wolf has occupied nearly all habitats in the Northern Hemisphere except deserts. Its primary habitat requirements are adequate numbers of large, hooved mammals for prey and seclusion.

Distribution

The gray wolf was once widespread in the wilder areas of northern Europe, Asia, and throughout most of North America. Humans have been the overwhelming cause of the decline of the gray wolf. The wolf was exterminated from England as early as the fifteenth century and has become increasingly rare in those parts of the world where large tracts of wilderness have been diminished by human settlements.

Because wolves attack domestic animals, North American ranchers and farmers made concerted efforts to exterminate them. In the nineteenth century wolves were hunted and trapped extensively and almost eliminated from the eastern United States. In the twentieth century, the use of strychnine as a poison made it possible to exterminate wolves throughout the United States. By 1930, a government-sponsored wolf control program had virtually eliminated the gray wolf from the western United States. As recently as the 1960s, some states in the wolf's remnant range paid bounties to wolf hunters in an effort to control predation on domestic livestock.

While the total population is unknown, the gray wolf is still relatively abundant in northern North America. There are thought to be about 10,000 in Alaska, and about 15,000 in Canada (British Columbia, Alberta, and Manitoba). These populations are not protected by the Endangered Species Act, although Canadian wolves are protected in Canadian National Parks.

In the U. S. midwest, by 1990 a viable population of about 1,200 gray wolves inhabited northeastern Minnesota, within the Superior National Forest, Voyageurs National Park, and a number of state forests.

From 1960 to 1975, Wisconsin apparently had no breeding population of gray wolves. But shortly after federal protection was extended to the eastern timber wolf in Minnesota in 1974, wolves began reestablishing themselves in Wisconsin. The Wisconsin Department of Natural Resources, with assistance from the U. S. Fish and Wildlife Service (FWS), began a monitoring program in 1979, a time when the State had about 25 wolves in five packs. Wisconsin's wolf population has increased steadily since the 1985-87 winter surveys; wolf surveys from the winter of 1996-97 documented about 150 wolves in Wisconsin, up a third from the winter 1995-96 estimates of 100 wolves.

In Michigan, the 1996-97 winter wolf survey confirmed the presence of 112 wolves in at least 16 packs across the Upper Peninsula of Michigan, a number down from the previous year's survey count of 116 wolves, but still a substantial increase from the recorded 80 wolves in 12 packs in 1995. The 1997 decrease may have been due to the impact of a harsh winter on the deer population, decreasing the available food source for the wolves. There are no wolves in the Lower Peninsula of Michigan. The wolf increase in the Upper Peninsula from near extinction in the 1970s is due to both natural immigration and the production of pups.

Canadian wolves in Alberta have periodically expanded south into Montana. During the winter of 1985-86, the FWS estimated that 15-20 wolves inhabited areas in and near Glacier National Park, Montana.

Though the wolves had been extirpated from the Yellowstone Park region, wolf reintroduction programs begun in 1995 have released more than 50 wolves into the park, central Idaho and northwestern Montana. Wolf pack activity is again alive in those areas, and the packs are breeding effectively. Prior to the reintroductions, there had been continuing credible reports during the 1970s and 1980s of wolves in central Idaho and within and around Yellowstone National Park, but no sustained pack activity had been evident.

Threats

All subspecies of North American wolves, including the gray wolf, have declined or become extinct as a result of human predation. Ranchers and farmers systematically extirpated wolves from their lands through hunting, trapping, and poisoning. Although human predation is now controlled through federal and state laws, the gray wolf is threatened by segmented populations, which affects breeding and genetic viability, and by loss of wilderness habitat.

Conservation and Recovery

When the wolf was first recognized as being threatened with extinction in the lower 48 states, proposals for protecting the animal were met with widespread hostility by livestock interests. Therefore, one of the main goals of the recovery effort has been to educate the public about wolf behavior and to manage wolf populations to minimize the contact with livestock.

In Minnesota, where the wolf is federally listed as a Threatened species, federal agents each year have killed several dozen wolves that have preyed on livestock. The state also has a program to compensate ranchers for livestock lost to wolves. An effort in the early 1980s by the FWS to return management to the state of Minnesota would have allowed a limited wolf hunting and trapping season. Although championed by state wildlife officials as a way to control wolf populations and increase public acceptance of wolves, the attempt was blocked by a federal court after a coalition of conservation groups filed suit.

Beginning in January, 1995, the FWS has reintroduced small numbers of gray wolves captured in western-central Alberta, Canada, into Yellowstone National Park. With the assistance of the Nez Perce Tribe, wolves have also been introduced into national forests in central Idaho. Wolves had been extirpated from those two areas for more than 60 years. Wolves reintroduced in the first releases were designated "non-essential, experimental" under the Endangered Species Act, allowing federal, state and tribal resource managers and private citizens more flexibility in managing the introduced animals. The release program, expected to last three to five years, has the goal of restoring the gray wolf by establishing ten breeding pairs in each of the three designated recovery areas (Yellowstone National Park, central Idaho, and northwestern Montana) by 2002, at which point the species would be considered for removal from the protection of the Endangered Species Act. Wolves are placed in temporary holding pens before their release to acclimate them to the new environment; following their release the wolves are tracked with radio collars, so biologists can study their movements and breeding patterns. Initial results from the Yellowstone area show that the wolves have managed to breed there. Their predation is reducing the over-abundant numbers of elk, allowing better regeneration of aspen, and resulting in improved ecological health of the Greater Yellowstone Ecosystem.

A crucial aspect of the reintroduction program is dealing with the public and gaining the acceptance and cooperation of landowners and other interested parties. The progress being made in this recovery effort is due in part to an intensive outreach campaign in Idaho to work directly with different segments of the public in addressing issues surrounding the introduction. Fears that had to be overcome have included concerns that the presence of the wolves would cause land-use restrictions, that the presence of these predators would endanger livestock, and that the wolves might even kill people (this has never been known to happen). Overall, public acceptance of the wolf reintroductions has been high: surveys found that 72% of Idahoans supported wolf recovery efforts in their state.

Progress in the effort to recover the gray wolf in the Rocky Mountains continues at a pace far better than biologists and managers had expected. It is likely that this could soon result in sufficiently large numbers of these predators to allow their delisting in the regions where the reintroductions have taken place.

Since November of 1996, five young pairs of Mexican wolves (Canis lupus baileyi ) have been held in the FWS captive management facility at Sevilleta National Wildlife Refuge in New Mexico. Two pairs produced pups in May 1997 and three pairs were released in the Blue Range Recovery Area in Arizona in 1998.

A great boost to the wolf recovery effort has been given by the private conservation organization, Defenders of Wildlife. This organization has worked to persuade stockmen to support the reintroduction program, and brought Wyoming ranchers to Minnesota to learn from ranchers there about the effects of a local wolf population. The organization has also established a private fund to compensate Wyoming ranchers for stock losses caused by wolves.

Contacts

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Complex
911 N. E. 11th Ave.
Portland, Oregon 97232-4181
Telephone: (503) 231-6121
http://pacific.fws.gov/

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
1 Federal Drive
BHW Federal Building
Fort Snelling, Minnesota 55111
Telephone: (612) 713-5360
http://midwest.fws.gov/

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
P. O. Box 25486
Denver Federal Center
Denver, Colorado 80225
http://www.r6.fws.gov/

References

Clarkson, E. 1975. Wolf Country. E. P. Dutton, New York.

Lopez, B. 1978. Of Wolves and Men. Charles Scribners Sons, New York.

Mech, L. D. 1970. The Wolf: The Ecology and Behavior of an Endangered Species. Natural History Press, New York.

Peterson, R. O. 1986. "Gray Wolf." Audubon Wildlife Report 1986. Academic Press, San Diego.

U. S. Fish and Wildlife Service. 1987. "Northern Rocky Mountain Wolf Recovery Plan." U. S. Fish and Wildlife Service, Denver.

U. S. Fish and Wildlife Service. 1978. "Eastern Timber Wolf Recovery Plan." U. S. Fish and Wildlife Service, Twin Cities.

Zimen, E. 1981. The Wolf: A Species in Danger. Dela-court Press, New York.