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Canis lupus - Gray Wolf

Skull Pictures:          
Dorsal     Mandible
Lateral    Posterior Mandible

Physical Description:

The gray wolf (Canis lupus) is the largest of the wild canids measuring in length from 53-67 inches.  The gray wolf’s height (measured from base of paws to shoulder) generally ranges from 60 to 90 cm. and can weigh anywhere from 77 lbs to 143 lbs.

The gray wolf’s dorsal color is most times grayish, but can often times be brown or even black; with under parts much lighter.

The gray wolf’s overall body size, narrow chest, large feet, tail that measures 15-19 inches that is straight rather than curving up as in dog species, and their heads that appear more massive due to wide tufts of hair that project down and outward from below their ears are all features that should help distinguish them from both coyotes and domestic dogs. (Kurta, 1995; WI DNR, 1999; Burt, 1957)

Distribution in Wisconsin:

Canis lupus occurred throughout Wisconsin prior to settlement (1832), with estimates of 3000-5000 animals.  These wolves were successful in Wisconsin do to the abundance of game to feed on.  Five species of ungulates were found in Wisconsin during this period: bison, elk, moose, caribou and white-tailed deer were all found prior to settlement.  Between 1870 and 1880 the fur trade was very large and eliminated all large ungulate species in Wisconsin except for the whitetail deer.  These fur traders were not interested in the fur of the gray wolf because it was not that valuable, but negative attitudes towards the gray wolf after the civil war for being a menace to live stock caused state legislature to issue a bounty on the gray wolf in 1865.  This would lead to the eradication of the gray wolf in Wisconsin.  The last Wisconsin wolves were killed in 1958 and 1959.  In 1973 wolves were put under the protection of the federal Endangered Species Act.  In the winter of 1974 a wolf pack was found on the boarder on Minnesota and Wisconsin, and by 1980, there were 5 wolf packs located in Wisconsin, 4 in Douglass County and 1 in Lincoln County. (Thompsom, 1952; WI DNR, 1999)

Due to wolf management plans, there are now between 197-203 wolves in several counties in Wisconsin, with populations steadily Increasing. (WI DNR, 1999)

The history of C. lupus as shown by fossil record, extends far back in the geologic time period.  The phylogeny of the family has been clearly traced to common ancestry with other carnivora in the Miacid family of Creodonts or primitive Carnivora (Lopez, 1945).

Ontogeny and Reproduction:

Breeding between the alpha male and his female partner in a wolf pack occurs between the months of January and April.  Gray wolf pairs will spend most of their time together often times breeding for life.

Canis lupus become sexually mature at 22 months, but generally only the alpha male and female are allowed to breed.  The female wolf goes into estrus once each year for 5 to 14 days with mating occurring at this time.

The gestation period for a gray wolf is between 60-63 days.  Before she gives birth she carefully constructs a den so flooding doesn’t occur.  The gray wolf mother gives birth in mid April to 4-8 pups.  These pups are born blind and deaf, but well furred and weigh about 1.1 lbs.  The pup’s eyes open in approximately 11-12 days after birth.  Pups will remain in the den for the first 3 weeks.  After those 3 weeks the pups will begin to venture out and play.  These pups are kept at the den site for 6-8 weeks until mid June, than are moved to rendezvous sites.  At these rendezvous sites the pups will stay with their mother while other adult wolves hunt.  When the adults return back from hunting they regurgitate food for the mother and pups to eat. These pups will have 2-3 rendezvous sites throughout the summer and by fall when large enough will run with the rest of the pack. (Zgurski, 2002; Kurta, 1995; WI DNR, 1999; A Short Course on Gray Wolves, 1999)

Ecology and Behavior:

Canis lupus is a highly social, pack living animal, which can occupy several diverse habitat types such as tundras, mountains, prairies, and forests.  Each pack is made up of usually 5-9 members.  Wolf packs are composed of alpha male and female, their previous years offspring, and the new born pups of that year.  There might be a non relative that is allowed in by the pack as well.  A wolf pack has an expansive home range, ranging from (80-150 mi squared).  Yearlings of a wolf pack may disperse from that pack between the months of October and January to go out and find a mate of their own and start a new pack in there own territory.  When yearlings disperse it is not uncommon for them to travel 500 or more miles looking for a mate and territory (Thiel, 1988; Kurta, 1995).

In the wolf pack there is a strong  presence of dominant hierarchy.  The alpha male is the pack leader.  All other males in the pack will decide who is next dominant  after the alpha male and so on down the line.  The male wolf that falls second in command is know as the beta male.  Females wolves also have a hierarchy starting with the alpha males mate and then continuing down the line, however all females are subordinate to the males in the pack.   In the event that the alpha male gets to old to run the pack or is injured in some way the beta male may take over the pack forcing the old alpha male to leave the pack or fit somewhere else into the hierarchy of the pack.  Rank in the pack determines which wolves will be allowed to breed and the order of feeding.  Rank is mostly demonstrated by postural cues and facial expressions, such as chin touching, crouching, and rolling over to bear their stomach (Kurta, 1995; WI DNR, 1999).

Gray wolves also are very vocal animals, they depend a great deal on howling to communicate to the other members in the pack.  When they howl they are informing other pack members to come together to hunt, this also lets other packs know the territory of that pack.

Canis lupus often times hunt in packs consisting of the alpha male and female and their yearlings, and there may be an unrelated lone wolf that was allowed into the pack. When hunting, wolves may travel 20 miles each night looking for food.  Wolves main food source in Wisconsin is the whitetail deer.  If a whitetail deer is caught then the wolf who is most dominant will be allowed to eat first and so on down the line.  Wolves are tremendous eaters, just one wolf may put down 4-13 lbs of meat after a kill takes place, although they are capable of eating 20 lbs of food after a kill.  Lone wolfs who have not found a pack or a mate of their won may feed on rabbits, squirrels, and beavers.  Gray wolves in the wild may live thirteen years, though the average lifespan is 5 to 6 years. In captivity they may live to be fifteen years of age (Kurta, 1995; Young and Goldman, 1944; WI DNR, 1999).

Literature Cited:

McManus, J.J.  1970.  Behavior of Captive Opossums, Didelphis marsupialis virginiana.  American Midland Naturalist 84(1): 144-169.

Lyon Jr, M.W.  1936.  Mammals of Indiana.  American Midland Naturalist 17(1):  1-373.

Ladine, T.A. and Kissell Jr, R.E.  1994.  Behavior of Escape Virginia Opossums.  American Midland Naturalist 132(2):  234-238.

Allen, C.H. et al.  1985.  Movement, Habitat Use and Denning of Opossums in the Georgia Piedmont (in Notes and Discussion).  American Midland Naturalist 113(2): 408-412.

Gillette, L.N.  1980.  Movement Patterns of Radio-Tagged Opossums in Wisconsin.  American Midland Naturalist 104(1): 1-12.

Winegarner, M.S.  1982.  Seasonal Changes in the Reproductive Tract of the Male Opossum Didelphis virginiana Kerr in Florida.  American Midland Naturalist 107(2): 258-261.

 Reference written by Michael Hawley, Biol 378: Edited by Chris Yahnke and Jen Callahan.
Page last updated 4-23-04.

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