Gray wolf

Name and taxonomy

The English word wolf comes from the Old English wulf and, further back, from the same root as the Latin lupus. Anglo-Saxons put it in their names: Wulfstan, Cynewulf and Aethelwulf all mean a kind of wolf. Carl Linnaeus named the wolf Canis lupus in 1758, and in the same book he named the dog Canis familiaris. He kept them apart because the dog carries its tail curled up, which no wild canid does.

Mammal Species of the World listed 36 wild subspecies in 2005 and added the dog and the dingo as two more. The nominate form is the Eurasian wolf, C. l. lupus. In 2019 the IUCN Canid Specialist Group decided the dingo and the New Guinea singing dog are feral dogs, not wolves. Wolves can still breed with coyotes and golden jackals, and the young are fertile.

Evolution and relatives

The wolf descends from Canis mosbachensis, which first appeared about 1.4 million years ago, and before that from Canis etruscus. One of the oldest fossils of the modern wolf, from Ponte Galeria in Italy, is about 406,500 years old. Late Pleistocene wolves had heavier skulls and teeth than today's, and broke their teeth as often as the dire wolf did.

The Himalayan and Indian plains wolves split from all other wolves about 200,000 years ago. The rest share most of their ancestry from within the last 23,000 years, spreading out from Siberia or Beringia. Old World and New World wolves parted around 12,500 years ago. The dog line left other Old World wolves about 11,100 to 12,300 years ago, though the wolf that was tamed is now extinct. Black wolves in North America got their colour from dogs that crossed the Bering land bridge 12,000 to 14,000 years ago.

Appearance

The wolf looks like a large, long-legged German shepherd with a broader snout, shorter ears and bigger feet. Head and body measure 105 to 160 centimetres, the tail 29 to 50 cm, and the shoulder stands 80 to 85 cm high. Adults weigh 23 to 80 kilograms. The mean is about 40 kg, and the heaviest wolf on record weighed 79.4 kg. European wolves average 38.5 kg, North American ones 36 kg, and Indian and Arabian wolves only 25 kg.

The body is slim but powerful, with a deep chest, a back that slopes and a thick muscular neck. The legs are longer than in other canids, which helps in deep snow. The head is big, the forehead wide and the muzzle long and blunt, and the teeth are built to crush bone. A wolf has 42 teeth. Females have narrower muzzles, thinner necks and lighter shoulders than males, and weigh 2.3 to 4.5 kg less.

The winter coat is dense: a short undercoat under long coarse guard hairs that reach 110 to 130 millimetres on the shoulders. It insulates so well that a wolf can sleep in the open at minus 40 degrees with its nose tucked under its tail. The guard hairs give the colour: ochre, grey and rust, a black stripe down the back, and white on the throat and belly. Arctic wolves are white, and many wolves in the Rockies of western Canada are black.

Habitat and range

The wolf once lived across the whole Northern Hemisphere, south to Mexico, North Africa and southern Asia. Persecution has cut that range to about one-third. It is gone from the British Isles, Ireland and Japan, and from much of Western Europe, the United States and Mexico. Canada and Alaska hold the strongest populations, and Russia holds up to 45,000.

The wolf uses forests, wetlands, shrubland, grassland, tundra, pasture, desert and rocky mountain peaks. It is found from sea level to 3,000 metres. What matters is prey, snow, the density of livestock and roads, and how many people are about.

A pack's territory runs from 75 to 2,500 square kilometres depending on prey. The smallest on record was 33 square kilometres in Minnesota, and the largest 6,272 in Alaska. GBIF lists records from 211 countries, but that count includes domestic dogs, which GBIF files under the same species.

Diet and hunting

The wolf is a carnivore that lives mainly on hooved mammals, from roe deer of 23 kilograms up to moose and bison of 650 kg. In North America wolves live mainly on elk, moose, caribou and two kinds of deer. Across Eurasia the main prey are moose, red and roe deer and wild boar, plus livestock where wild prey is scarce. Beavers, hares, rodents, waterfowl and eggs fill in, and wolves eat fish, berries, apples and grass as well. In hard times they take carrion, garbage and even dead pack members.

Wolves hunt mostly at night in winter, setting out at dusk and covering tens of kilometres before dawn. In summer they often hunt alone and ambush prey rather than chase it. A pack tries to cut one animal out of the herd, usually one that is old, young or sick. Chases run from 100 metres to more than 5 kilometres. Single wolves and pairs succeed more often than big packs, and one wolf can kill a moose alone.

Wolves bite large prey on the rump and flanks and wear it down, sometimes resting for hours while it weakens from blood loss. Medium prey such as roe deer or sheep dies from a throat bite within a minute. Once the animal is down the pack eats fast, starting with the heart, liver, lungs and stomach lining. A wolf can eat 15% to 19% of its own weight in one sitting, and it needs about 2.5 to 6.3 kg a day.

Behaviour and social life

The pack is a family, built around a mated pair and their offspring. A North American pack averages eight wolves and a European one 5.5, though packs of up to 42 have been recorded. The old idea of an alpha that fights its way to the top probably comes from captive wolves, not wild packs. The parents lead because they are the parents, and rank shows in posture rather than in fights.

Young wolves stay 10 to 54 months, then leave to find a mate and empty ground. Some settle next door, and others travel 206, 390 or even 670 kilometres from their birth pack. A lone wolf is almost always a young animal in transit, not an outcast. Packs rarely accept a stranger and usually kill one, though a young wolf of one to three years is sometimes adopted. Territorial fights are a leading cause of death: 14% to 65% of wolf deaths in Minnesota and Denali came from other wolves.

A pack is on the move most of the time, covering about 9% of its territory and roughly 25 kilometres a day. Wolves trot at about 8 kilometres per hour and can run at 55 to 70 km/h. Brown bears usually win over a carcass, but a pack wins at its den, and in the Russian Far East tigers push wolves out.

Communication and senses

The howl gathers the pack before and after a hunt, raises the alarm at a den, finds lost members and warns other packs. Under good conditions a howl can be heard across 130 square kilometres. Wolves do not howl at the moon, and its phases have no effect on their calls. Growls, barks and whines cover shorter distances, and a wolf barks a few times and retreats rather than barking on like a dog.

Posture says a great deal. A confident wolf moves slowly with its body high and hackles up, and a submissive one crouches with ears and tail down. Scent does the real work of marking territory. Wolves leave urine, droppings and gland scent about every 240 metres along their trails, and each mark lasts two to three weeks. Raised-leg urination makes up 60% to 80% of all marks, and a newly bonded pair marks most of all. Like other dogs, the wolf finds most prey by scent rather than sight.

Reproduction and life cycle

Wolves are monogamous, and a pair usually stays together for life. The female chooses her mate, and she comes into heat once a year for 5 to 14 days, in the second half of winter. Only the breeding pair produces pups, and other females in the pack are held back unless food is plentiful.

The den is a rock crevice, an overhang, a hole under thick cover, or an enlarged fox, badger or marmot burrow. It usually sits within 500 metres of water, faces south and lies well inside the territory, away from rival packs. Gestation lasts about 63 days. A young female bears four or five pups, an older one six to eight, and up to 14 have been recorded. Pups weigh 300 to 500 grams at birth and are blind and deaf.

The eyes open at 9 to 12 days, and the pups first leave the den at about three weeks. The mother stays with them for the first weeks while the father brings food. Every pack member feeds the pups regurgitated meat until they are about 45 days old. A pup's weight rises nearly 30 times in its first four months, and by autumn it hunts with the adults. Pup mortality runs at 60% to 80%. A wild wolf can reach 13 years, though most die at five or six, and the captive record is 20.6.

Predators and threats

Adult wolves have no regular predator. Other wolves are the main danger, and packs kill pups they find in a rival's den. Brown bears kill young wolves, cougars kill lone wolves in a one-to-one meeting, and tigers kill wolves in the Russian Far East.

Disease takes a toll. Rabies incubates for 8 to 21 days, then sends a wolf away from its pack, travelling up to 80 kilometres a day and biting. Distemper, parvovirus, Lyme disease, mange mites, tapeworms and more than 30 kinds of roundworm also infect wolves.

People remain the greatest threat. Herders shoot, trap and poison wolves for killing sheep, reindeer, goats, horses and cattle. Canada allows a harvest of up to 4,000 a year and Alaska about 1,200. Russia pays bounties and kills 20% to 30% of its wolves each year. Roads, farms and towns break up habitat, and even snowmobiles near a territory raise a wolf's stress hormones.

Population and conservation

The IUCN Red List rates the wolf Least Concern, because its range is wide and its numbers are stable. The wild population was about 300,000 in 2003 and stands at 200,000 to 250,000 as of 2026. Declines were halted in the 1970s, and legal protection, land-use change and rural depopulation have let wolves return to old ground. CITES lists the wolf on Appendix II, and the populations of Bhutan, India, Nepal and Pakistan on Appendix I.

Canada holds 50,000 to 60,000 wolves across 80% of its historic range, and Alaska 7,000 to 11,000. In the lower 48 states, settlement and the loss of bison nearly wiped wolves out, until the Endangered Species Act of 1973 protected them. Reintroductions in Yellowstone and Idaho and natural recolonisation brought them back: over 4,000 in the Great Lakes states and over 3,000 in the northern Rockies. The Mexican wolf was taken into captivity in the late 1970s, and the reintroduced population now numbers over 300.

Britain lost its wolves by 1684, Ireland by 1770, Central Europe by 1899 and France by the 1930s. Since 1980 wolves have spread back across Europe, and the European Union now holds about 20,300 in 23 countries. Russia holds up to 45,000, Kazakhstan 20,000 and Mongolia 10,000 to 20,000.

Relationship with humans

Herding peoples have hated and hunted the wolf for as long as they have kept sheep. Hunter-gatherers took a different view, and admired wolves as parents, mates and hunters. Livestock losses are the main reason wolves are still killed, and no method short of extermination stops them fully. Some countries pay compensation, and guard dogs that confuse a wolf with barking or play cut losses a great deal.

Wolves are not natural predators of people, and most avoid us. Most recorded attacks come from rabid wolves, and a rabid wolf's bite is 15 times more dangerous than a rabid dog's. Between 1952 and 2002, Europe and Russia recorded eight deaths from wolves, and southern Asia more than two hundred. Predatory attacks follow a period in which wolves lose their fear of people, and the victims are mostly children. In North America such attacks are close to unknown.

People have hunted wolves with hounds, poison, traps, aircraft and, in Kazakhstan and Mongolia, with eagles. Wolf fur once kept people warm, and wolf-watching now earns parks real money. Some people keep wolves and wolf-dogs, but they obey badly and bite more. A pet wolf is likelier to kill its owner than a dog is.

In culture and myth

The Greeks linked the wolf to Apollo, and the Romans to Mars. Roman legend says a she-wolf suckled Romulus and Remus, the founders of Rome. In Norse myth the giant wolf Fenrir is feared, while Geri and Freki are Odin's loyal companions. Chinese astronomy makes the wolf the star Sirius, guardian of the heavenly gate, but Chinese sayings tie it to greed and cruelty.

In the Pawnee creation story the wolf was the first animal on Earth, and its killing cost people their immortality. To the Pawnee and the Blackfoot the Milky Way is a wolf trail, and Sirius is the wolf star. The wolf is a clan crest among Pacific Northwest peoples such as the Kwakwaka'wakw. The Dena'ina saw wolves as former men and called them brothers, while the Navajo feared witches who wore wolf skins. Werewolf stories run through European folklore, and Zeus turned King Lycaon into a wolf.

Aesop's boy who cried wolf gave English its idiom for a false alarm. Charles Perrault's Little Red Riding Hood of 1697 fixed the Big Bad Wolf in Western minds, and the Three Little Pigs followed. Kipling's Jungle Book wolves live in loving families, which biologists later praised as closer to the truth. Farley Mowat's Never Cry Wolf of 1963 changed public feeling toward wolves, though much of it was invented.