Gray Wolf
Canis lupus
The gray wolf, or timber wolf, is currently one of the largest living carnivores in North America. This animal migrated to North America during the middle-to-late Pleistocene, and it became one of the most widely distributed land mammals in the late Pleistocene (Kurtén and Anderson 1980; Mech 1966, 1970). A recent ancient DNA study (Leonard et al. 2007) has identified genetic differences between the late Pleistocene gray wolves that roamed the continental U.S., including the Midwest, and those that lived in Alaska and northwestern Canada (i.e., eastern Beringia). The Leonard et al. study documented morphological differences between the two groups as well, and determined that the eastern Beringian population was more highly specialized than the main population of North American gray wolves during the Pleistocene. This study also determined that the eastern Beringian population went extinct during the terminal Pleistocene and that modern North American gray wolves are descended from the more generalized population that lived throughout most of North America during the Pleistocene. Unlike the dire wolf, the gray wolf survived the climatic and environmental changes of the late Pleistocene and early Holocene, and this animal continued to enjoy a wide distribution through most of the Holocene. The increase in human population during historical times, however, led to the extirpation of this wolf from most of the U.S. Currently, the gray wolf is found across most of Canada, with patchy distribution in the U.S. along the northern Great Lakes and portions of the Rocky Mountains.
Gray wolf (Canis lupus). Photo Credit: US Fish and Wildlife Service, Gary Kramer.
Length: 1-1.5 m (3.3-4.9 feet)
Weight: 20-80 kg (44.1-176.4lbs)
Physical Description:
Gray wolves resemble domesticated dogs, such as huskies, but typically have longer legs, larger feet and a narrower chest. Unlike dogs, wolves have wide tufts of hair below their ears and most individuals have white fur around their mouths, whereas dogs tend to have black fur. Gray wolves are covered in shaggy coats made up of long, coarse guard hairs and shorter, thicker, softer underfur. The heavy winter coat is shed in late spring, during their annual molt, and replaced by a shorter summer coat. Although their common name implies that they are covered in gray fur, gray wolves actually vary in color from pure white to black. Typically, though, they are light tan or cream mixed with brown, black and white.
Gray wolves are habitat generalists, and have occupied all major habitats in North America at one time or another, including deserts, grasslands, forests and tundra. They require large home ranges, sometimes more than 1000 square km, and travel over large areas within this range to hunt. The size and location of the home range is determined in large part by prey availability and reduced risk of human disturbance (Paquet and Carbyn 2003). Wolves also require suitable sites for denning within their home range, and sometimes multiple dens will be used within a pack's home range. Sites such as underground burrows, hollow logs, caves or crevices, and abandoned beaver lodges may serve as wolf dens.
Gray wolves preferentially hunt large ungulates, such as moose, caribou, bison, sheep or deer, but they will supplement this diet with smaller mammals, such as beavers and rabbits, as well as fish, birds, snakes, lizards, shellfish, eggs and even fruit when necessary (Petersen 1955; Mech 1966). When more than one ungulate species is available, wolves reportedly will concentrate on hunting the smallest or easiest to catch species (Paquet and Carbyn 2003). As with many predators, wolves typically prey on young, old, weak or debilitated individuals, although they will occasionally kill healthy adult animals as well. It has also been found that wolves will change their hunting behaviors in response to snow-induced changes in ungulate prey distribution and mobility (Paquet and Carbyn 2003).
For the most part, gray wolves are extremely social animals who live and hunt in packs with complex social structures. Packs typically consist of the dominate male and his mate (the alpha male and female), their juvenile offspring, and occassionally unrelated adults. Usually, packs include 5-12 members, although packs as large as 20-30 animals have been observed (Mech 2000, Carbyn et al. 1993). Wolves communicate with each other and maintain territories through vocalizations and chemical scent markings. They are well-known for their spine-tingling howl, which is used to communicate with pack members and to send territorial messages to other packs.
During the late Pleistocene, gray wolves occupied all ice-free portions of North America except for the southeastern U.S and the Pacific coastline west of the Sierra Nevada. They were one of the most widely spread land mammals during this time (Kurten and Anderson 1980).
The gray wolf was one of the few large carnivores to survive widespread extinctions at the end of the Pleistocene. The other large, Late Pleistocene wolf, the dire wolf, was less lucky and went extinct at this time. Furthermore, recent genetic and morphological studies have indicated that some uniquely adapted and genetically distinct populations of gray wolf did go extinct at the end of the Pleistocene, possibly due to the loss of the megafauna prey they specialized on (Leonard et al., 2007).
Gray wolf remains have been recovered from late Pleistocene deposits across the Midwest, including Polecat Creek in eastern Illinois.
- Gray wolves are ancestral to domesticated dogs, and they are the largest wild members of the dog family.
- Gray wolves have fascinated people throughout history, and appear in many myths, stories and legends. For instance, in the Pawnee creation story, the gray wolf was the first animal killed, thereby introducing death to the world. In Roman mythology, the founders of Rome, Romulus and Remus, were nursed by the she-wolf, or wolf goddess, Lupa, and in Irish folklore, the High King Cormac mad Airt was carried off by a she-wolf in infancy and reared with her pups.
Carbyn, L., Oosenbrug, S., Anions, D. 1993. Wolves, Bison and the Dynamics Related to the Peace-Athabasca Delta in Canada's Wood Buffalo National Park. Circumpolar Reserach Series No. 4. Canadian Circumpolar Institute, Edmonton, Alberta.
Kurten, B., Anderson, E. 1980. Pleistocene Mammals of North America. Columbia University Press. New York.
Leonard, J., Vila, C., Fox-Dobbs, K., Koch, P., Wayne, R., Van Valkenburgh, B. 2007. Megafaunal Extinctions and the Disappearance of a Specialized Wolf Ecomorph. Current Biology 17: 1146-1150.
Mech, L. D. 1966. The Wolves of Isle Royale. Fauna of the National Parks of the United States. Fauna Series 7. U.S. National Park Service.
Mech, L. D. 1970. The wolf: the ecology and behavior of an endangered species. Natural History Press, Doubleday Publishing Co., New York
Mech, L. D. 2000. A record large wolf, Canis lupus, pack in Minnesota. Canadian Field Naturalist 114:504-505.
Paquet, P., Carbyn, L. 2003. Gray Wolf. In Wild Mammals of North America, edited by Feldhamer, G., Thompson, B., Chapman, J., pp. 482-510. The Johns Hopkins University Press, Baltimore, MD.
Petersen, R. L. 1955. North American Moose. University of Toronto Press, Toronto, Canada.
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