Gray wolves are the largest wild dog species in the world. They vary in size depending on where they are found, with southern populations being generally smaller than northern populations. Total body length, from tip of the nose to tip of the tail, is from 870 to 1,300 mm. Height (measured from base of paws to shoulder) generally ranges from 60 to 90 cm. Males are, on average, larger than females.
Fur color of gray wolves also varies depending on where they are living. Their color ranges from pure white in Arctic populations, to mixtures of white with gray, brown, cinammon, and black to nearly uniform black in some color phases. Their upperparts are generally darker and they have lighter fur on their undersides, the tail is tipped with black.
Gray wolves have a dense underfur layer, providing them with excellent insulation against cold conditions.
Gray wolves once ranged throughout the Northern hemisphere, from the Arctic south to southern 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.
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.
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. 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 five to fourteen, with the average size being seven pups. Female pups reach maturity at two years of age, while males will not reach full maturity until three years of age.
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.
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.
Gray wolves are very social, pack-living animals. Each pack is made up of two to thirty-six individuals, depending upon their habitat and the abundance of their prey. Most packs are made up of 5 to 9 individuals. Packs are typically made up of an alpha pair and their offspring, including their young from previous years.
There is a strong structure of dominance relationships within each pack. Each pack member has a position in those dominance relationships, called their 'rank'. The pack leader, usually the alpha male, is dominant over all other individuals. The next dominant individual is the alpha female. If the alpha male becomes injured, the next highest ranking male will take his place as alpha male. Rank within the pack determines which animals mate and which eat first.
Each year, gray wolf packs have stationary and nomadic phases. In the spring and summer, while pups are being reared, wolf packs remain in the same area. During the fall and winter wolf packs move around in search of food. Wolf movements are usually at night and may 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.
The territory of a pack ranges from 130 to 13,000 square kilometers, and is defended against intruders.
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.
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 by scent. What wolves eat depends on where they live and what kinds of prey are available. Wolves hunt in packs for large prey such as moose, elk, bison, musk oxen, and reindeer. Wolves help to keep prey populations healthy by hunting the weak, old, and sick animals. A wolf can consume up to 9 kg of meat at one meal. Wolves usually eat almost the entire carcass, including some hair and bones. Smaller animals, such as beavers, rabbits, and other small mammals are usually hunted by lone wolves. Wolves may also eat livestock and garbage when it is available.
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.
As top predators, gray wolves are important in regulating populations of their prey animals.
Gray wolves may sometimes kill livestock. The extent of livestock loss to wolves is often overstated, wolves typically prefer their wild prey.
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.
"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. Unfortunately, people who keep livestock believed that gray wolves posed a terrible threat to their herds and wolf extermination programs became widespread. Populations of gray wolves 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 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.
Except for red wolves, all living North American wolves are considered to be gray wolves. There are 32 different kinds of gray wolves recognized in North America.
Gray wolves are the ancestor of all domestic dog breeds, including wild living dogs such as dingos and New Guinea singing dogs. In domesticating wolves, humans have selected them for particular traits, including size, appearance, aggressiveness, loyalty, and many special skills. The result is an astonishing array of domestic dog breeds that vary in size from diminutive, 1.5 kg chihuahuas to 90 kg giant mastiffs.
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