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Canis lupusgray wolf

By Tanya Dewey and Julia Smith

Geographic Range

The original range of Canis lupus consisted of the majority of the Northern hemisphere -- from the Arctic continuing south to a latitude of 20° S, which runs through southern Central Mexico, northern Africa, and southern Asia. However, due to habitat destruction, environmental change, persecution by humans, and other barriers to population growth, gray wolf populations are now found only in a few areas of the contiguous United States, Alaska, Canada, Mexico (a small population), and Eurasia.

Habitat

Gray wolves are one of the most wide ranging land animals. They occupy a wide variety of habitats, from arctic tundra to forest, prairie, and arid landscapes.

Physical Description

The largest of approximately 41 wild species of canids, gray wolves vary in size based primarily on geographic locality, with southern populations generally smaller than northern populations. Total body length, from tip of the nose to tip of the tail, is from 1000 to 1300 mm in males, and 870 to 1170 mm in females. Tail length ranges between 350 to 520 mm. Males can weigh from 30 to 80 kg, with an average of 55 kg, females can weigh from 23 to 55 kg, with an average of 45 kg. Height (measured from base of paws to shoulder) generally ranges from 60 to 90 cm. Distance between the canines is around 4 cm.

Fur color of gray wolves also varies geographically, ranging from pure white in Arctic populations, to mixtures of white with gray, brown, cinammon, and black to nearly uniform black in some color phases.

North American populations have three distinct color phases. The normal phase is characterized by varying mixtures of white with shades of black, gray, cinnamon, and brown on the upper parts of the animal. The back is usually more profoundly black, and the muzzle, ears, and limbs have cinammon coloration as well. Under parts are whitish and the tail is conspicuously black over the tail gland, and paler below to the tip, which is nearly pure black. The black phase of North American populations is characterized by the upper parts varying from brown to black, with specks of white; the underparts are paler in tone, and there is often a pure white medial pectoral spot. The third color phase occurs during the first pelage of young wolves. The upper parts are drab-gray, overlaid with brownish-black. The underparts are paler as well, and the ears vary from black to buffy, depending on the subspecies (Young 1944).

Gray wolves have a dense underfur layer, providing them with excellent insulation against cold conditions.

Gray wolves can be distinguished from red wolves (Canis rufus) by their larger size, broader snout, and shorter ears. They are distinguished from coyotes (Canis latrans) by being 50 to 100% larger and having a broader snout and larger feet.

  • Sexual Dimorphism
  • male larger
  • Range mass
    23.0 to 80 kg
    50.66 to 176.21 lb
  • Range length
    870 to 1300 mm
    34.25 to 51.18 in

Reproduction

The dominant pair in a grey wolf pack are the only members that breed. This pair is monogamous although, with the death of an alpha individual, a new alpha male or female will emerge and take over as the mate.

Breeding occurs between the months of January and April, with northern populations breeding later in the season than southern populations. Female gray wolves choose their mates and often form a life-long pair bond. Gray wolf pairs spend a great deal of time together. Female gray wolves come into estrus once each year and lasts 5 to 14 days, mating occurs during this time. After mating occurs, the female digs a den in which to raise her young. The den is often dug with an entrance that slopes down and then up again to a higher area to avoid flooding. Pups are born in the den and will remain there for several weeks after birth. Other dens are under cliffs, under fallen trees, and in caves. The gestation period lasts between 60 and 63 days, litter size ranges from one to fourteen, with the average size being six or seven pups. Pups remain in the den until they are 8 to 10 weeks old. Females stay with their pups almost exclusively for the first 3 weeks. Pups are cared for by all members of the pack. Until they are 45 days old the pups are fed regurgitated food by all pack members. They are fed meat provided by pack members after that age. Female pups reach maturity at two years of age, while males will not reach full maturity until three years of age. Most young gray wolves disperse from their natal pack when they are between 1 and 3 years old.

  • Breeding interval
    Gray wolves breed once each year.
  • Breeding season
    Gray wolves breed between January and March, depending on where they are living.
  • Range number of offspring
    5.0 to 14.0
  • Average number of offspring
    7.0
  • Average number of offspring
    6
    AnAge
  • Range gestation period
    63.0 (high) days
  • Average weaning age
    45.0 days
  • Range age at sexual or reproductive maturity (female)
    2.0 to 3.0 years
  • Range age at sexual or reproductive maturity (male)
    2.0 to 3.0 years

Gray wolf pups are born blind and deaf. They weigh approximately 0.5 kg and depend on the mother for warmth. At ten to fifteen days of age, the pups' blue eyes open, but they only have control over their front legs, thus crawling is their only mode of mobility. Five to ten days later, the young are able to stand, walk, and vocalize. Pups are cared for by all members of the pack. Until they are 45 days old the pups are fed regurgitated food by all pack members. They are fed meat provided by pack members after that age. During the 20th to 77th day, the pups leave the den for the first time and learn to play fight. Interactions at this time, as well as the dominance status of the mother, ultimately determines their position in the pack hierarchy. Wolf pups develop rapidly, they must be large and accomplished enough to hunt with the pack with the onset of winter. At approximately ten months old, the young begin to hunt with the pack.

  • Parental Investment
  • no parental involvement
  • altricial
  • pre-fertilization
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • pre-independence
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • post-independence association with parents
  • extended period of juvenile learning
  • maternal position in the dominance hierarchy affects status of young

Lifespan/Longevity

Gray wolves may live thirteen years in the wild, though average lifespan is 5 to 6 years. As adults they usually die from old age or from injuries received while hunting or fighting with other wolves. In captivity they may live to be fifteen years of age.

Behavior

Gray wolves are highly social, pack-living animals. Each pack comprises two to thirty-six individuals, depending upon habitat and abundance of prey. Most packs are made up of 5 to 9 individuals. Packs are typically composed of an alpha pair and their offspring, including young of previous years. Unrelated immigrants may also become members of packs.

There is a strong dominance hierarchy within each pack. The pack leader, usually the alpha male, is dominant over all other individuals. The next dominant individual is the alpha female, who is subordinate only to the alpha male. In the event that the alpha male becomes injured or is otherwise unable to maintain his dominance, the beta male will take his place in the hierarchy. Alpha males typically leave the pack if this occurs, but this is not always the case. Rank within the pack hierarchy determines which animals mate and which eat first. Rank is demonstrated by postural cues and facial expressions, such as crouching, chin touching, and rolling over to show the stomach.

Each year, gray wolf packs have a stationary and nomadic phase. Stationary phases occur during the spring and summer, while pups are being reared. Nomadic phases occur during the fall and winter. Wolf movements are usually at night and cover long distances. Daily distance traveled can be up to 200 km, the usual pace is 8 km/hr. Wolves can run at speeds up to 55 to 70 km/hr.

Home Range

The territory of a pack ranges from 130 to 13,000 square kilometers, and is defended against intruders.

Communication and Perception

Rank is communicated among wolves by body language and facial expressions, such as crouching, chin touching, and rolling over to show their stomach.

Vocalizations, such as howling allows pack members to communicate with each other about where they are, when they should assemble for group hunts, and to communicate with other packs about where the boundaries of their territories are. Scent marking is ordinarily only done by the alpha male, and is used for communication with other packs.

Food Habits

Gray wolves are carnivores. They hunt prey on their own, in packs, steal the prey of other predators, or scavenge carrion. Prey is located by chance or scent. Animals included in the diet of gray wolves varies geographically and depends on prey availability. Wolves primarily hunt in packs for large prey such as moose, elk, bison, musk oxen, and reindeer. Once these large ungulates are taken down, the wolves attack their rump, flank, and shoulder areas. Wolves control prey populations by hunting the weak, old, and immature. A wolf can consume up to 9 kg of meat at one meal. Wolves usually utilize the entire carcass, including some hair and bones. Smaller prey such as beavers, rabbits, and other small mammals are usually hunted by lone wolves, and they are a substantial part of their diet. Wolves may also eat livestock and garbage when it is available.

  • Primary Diet
  • carnivore
    • eats terrestrial vertebrates

Predation

Few animals prey on gray wolves. Wolves and coyotes are highly territorial animals so wolves from other packs and coyotes will attack wolves that are alone or young. They will kill pups if they find them.

  • Known Predators

Ecosystem Roles

As top predators, gray wolves are important in regulating populations of their prey animals.

Economic Importance for Humans: Positive

Historically, the fur of grey wolves was used for warmth. As top predators in many ecosystems, wolves are important in controlling populations of their prey.

Wolves are important in our culture, many people believe they symbolize the spirit of wilderness. Wolf products, including posters, books, and t-shirts are very popular. Wolf ecotourism is a major source of revenue for parks and reserves.

  • Positive Impacts
  • body parts are source of valuable material
  • ecotourism

Economic Importance for Humans: Negative

Gray wolves may sometimes kill livestock. The extent of livestock loss to wolves is often overstated, wolves typically prefer their wild prey.

Conservation Status

"Few animals have ever haunted our dreams or fired our imaginations more than the wolf. Unfortunately, by the early part of this century, man had almost exterminated the wolf from the lower 48 states. The recovery of the wolf is becoming an impressive conservation success story and a gift to future generations" (Bruce Babbitt, Secretary of the Interior).

Wolves play an important role in the ecosystem by controlling natural prey populations and removing weak individuals. As settlement increased, the belief that livestock was endangered by wolf populations also increased. As such, the frequency of hunting the gray wolf exploded. The populations were nearly eradicated. Currently in the lower 48 United States, about 2,600 gray wolves exist, with nearly 2,000 in Minnesota (compared to the few hundred living there in the mid-20th century). Successful recovery plans have been developed throughout the country. These plans evaluate the populations to determine distribution, abundance, and status. The main cause of population declines has been habitat destruction and persecution by humans. But the reintroduction of gray wolves into protected lands has greatly increased the likelihood of their survival in North America. Populations in Alaska and Canada have remained steady and are fairly numerous. Currently the State of Alaska manages 6,000 to 8,000 gray wolves and Canada's populations are estimated at about 50,000. The wolves in Canada are managed by provincial governments and are not currently threatened.

In western Eurasia gray wolf populations have been reduced to isolated remnants in Poland, Scandinavia, Russia, Portugal, Spain, and Italy. Wolves were exterminated from the British Isles in the 1700's and nearly disappeared from Japan and Greenland in the 20th century. Greenland's wolf populations seem to have made a full recovery. The status of wolf populations throughout much of eastern Eurasia is poorly known, but in many areas populations are probably stable.

Gray wolves are listed were until recently listed as endangered by the U.S. Fish and Wildlife Service and as threatened by the state of Michigan DNR. Most U.S. populations of gray wolves have now been delisted, except for experimental populations of Mexican gray wolves in the southwest. They are in CITES Appendix II, except for populations in Bhutan, India, Nepal and Pakistan, which are in Appendix I.

Other Comments

Except for red wolves (Canis rufus), all living North American wolves are considered to be Canis lupus -- a total (as of 1997) of 32 recognized subspecies.

Gray wolves are widely recognized to be the ancestor of all domestic dog breeds (Canis lupus familiaris), including feral forms such as dingos (Canis lupus dingo) and New Guinea singing dogs (Canis lupus halstromi). Genetic evidence suggests that gray wolves were domesticated at least twice, and perhaps as many as 5 times, by humans. Artificial selection by humans for particular traits, including size, appearance, aggressiveness, loyalty, and many desirable, specialized skills, has resulted in an astonishing array of domestic dog morphologies. Domestic dogs vary in size from diminutive, 1.5 kg chihuahuas to 90 kg giant mastiffs.

Contributors

Tanya Dewey (author, editor), Animal Diversity Web.

Julia Smith (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

carrion

flesh of dead animals.

chaparral

Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.

chemical

uses smells or other chemicals to communicate

cooperative breeder

helpers provide assistance in raising young that are not their own

diurnal
  1. active during the day, 2. lasting for one day.
dominance hierarchies

ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates

ecotourism

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

holarctic

a distribution that more or less circles the Arctic, so occurring in both the Nearctic and Palearctic biogeographic regions.

World Map

Found in northern North America and northern Europe or Asia.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

nomadic

generally wanders from place to place, usually within a well-defined range.

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

taiga

Coniferous or boreal forest, located in a band across northern North America, Europe, and Asia. This terrestrial biome also occurs at high elevations. Long, cold winters and short, wet summers. Few species of trees are present; these are primarily conifers that grow in dense stands with little undergrowth. Some deciduous trees also may be present.

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tundra

A terrestrial biome with low, shrubby or mat-like vegetation found at extremely high latitudes or elevations, near the limit of plant growth. Soils usually subject to permafrost. Plant diversity is typically low and the growing season is short.

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

"A Short Course on Gray Wolves" (On-line). Accessed December 9, 1999 at http://www.boomerwolf.com/graycors.htm.

July 1998. "Gray Wolf (Canis lupus)" (On-line). Accessed December 9, 1999 at http://www.fws.gov/r3pao/wolf/wolfindx.html.

January 16, 1997. "Gray Wolf" (On-line). Accessed December 9, 1999 at http://www.kats-korner.com/graywolf.html.

Dog Breed Info Center, 2000. "Dog Breeds in Alphabetical Order" (On-line). Accessed February 16, 2002 at http://www.dogbreedinfo.com/abc.htm.

Kinder, A. 1995. "Animal Diversity Web, Canis lupus dingo (Dingo)" (On-line). Accessed February 19, 2002 at http://animaldiversity.ummz.umich.edu/accounts/canis/c._lupus_dingo$narrative.html.

McIntyre, R. 1993. A Society of Wolves: National Parks and the Battle Over the Wolf. Stillwater, MN: Voyageur Press.

Mech, L. 1999. Gray Wolf. Pp. 141-143 in D Wilson, S Ruff, eds. The Smithsonian Book of North American Mammals. Washington and London: Smithsonian Institution Press.

Shetal, B. 1995. "Animal Diversity Web, Canis lupus familiaris (Dog)" (On-line). Accessed February 19, 2002 at http://animaldiversity.ummz.umich.edu/accounts/canis/c._lupus_familiaris$narrative.html.

Strauber, J. June 12, 1997. "The Gray Wolf" (On-line). Accessed December 9, 1999 at http://www.hillsborough.k12.nj.us/hhs/endspeci/canislupus.html.

Young, S., E. Goldman. 1944. The Wolves of North America. Washington D.C.: The American Wildlife Institute.

Zgurski, J. 2002. "The Behavior and Ecology of Wolves" (On-line). Accessed February 16, 2002 at http://www.ualberta.ca/~jzgurski/.

Zgurski, J. 2002. "The Origin of the Domestic Dog" (On-line). Accessed February 16, 2002 at http://www.ualberta.ca/~jzgurski/dog.htm.

Zgurski, J. 2002. "Wolf Taxonomy" (On-line). Accessed February 16, 2002 at http://www.ualberta.ca/~jzgurski/taxa.html.

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