The grey wolf or gray wolf (Canis lupus), also known as the timber wolf or simply wolf, is a mammal of the order Carnivora. The gray wolf is the largest wild member of the Canidae family and an ice age survivor originating during the Late Pleistocene around 300,000 years ago. DNA sequencing and genetic drift studies indicate that the gray wolf shares a common ancestry with the domestic dog, (Canis lupus familiaris) and might be its ancestor. A number of other gray wolf subspecies have been identified, though the actual number of subspecies is still open to discussion. Gray wolves are typically apex predators in the ecosystems they occupy. Gray wolves are highly adaptable and have thrived in temperate forests, deserts, mountains, tundra, taiga, grasslands and even urban areas.
Though once abundant over much of Eurasia and North America, the gray wolf inhabits a very small portion of its former range because of widespread destruction of its habitat, human encroachment of its habitat, and the resulting human-wolf encounters that sparked broad extirpation. Considered as a whole, however, the gray wolf is regarded as being of least concern for extinction according to the International Union for the Conservation of Nature and Natural Resources. Today, wolves are protected in some areas, hunted for sport in others, or may be subject to extermination as perceived threats to livestock and pets.
In areas where human cultures and wolves are sympatric, wolves frequently feature in the folklore and mythology of those cultures, both positively and negatively.
Gray wolves are built for stamina, possessing features ideal for long-distance travel. Their narrow chests and powerful backs and legs facilitate efficient locomotion. They are capable of covering several miles trotting at about a pace of 10 km/h (6 mph), and have been known to reach speeds approaching 65 km/h (40 mph) during a chase. One female gray wolf was recorded to have made 7 metre bounds when chasing prey.
Gray wolf paws are able to tread easily on a wide variety of terrains, especially snow. There is a slight webbing between each toe, which allows them to move over snow more easily than comparatively hampered prey. Gray wolves are digitigrade, which, with the relative largeness of their feet, helps them to distribute their weight well on snowy surfaces. The front paws are larger than the hind paws, and have a fifth digit, the dewclaw, that is absent on hind paws. Bristled hairs and blunt claws enhance grip on slippery surfaces, and special blood vessels keep paw pads from freezing. Scent glands located between a wolf's toes leave trace chemical markers behind, helping the wolf to effectively navigate over large expanses while concurrently keeping others informed of its whereabouts. Unlike dogs and coyotes, gray wolves lack sweat glands on their paw pads. This trait is also present in Eastern Canadian Coyotes which have been shown to have recent wolf ancestry. Wolves in Israel are unique due to the middle two toes of their paws being fused, a trait originally thought to be unique to the African Wild Dog.
Wolves have bulky coats consisting of two layers. The first layer is made up of tough guard hairs that repel water and dirt. The second is a dense, water-resistant undercoat that insulates. The undercoat is shed in the form of large tufts of fur in late spring or early summer (with yearly variations). A wolf will often rub against objects such as rocks and branches to encourage the loose fur to fall out. The undercoat is usually gray regardless of the outer coat's appearance. Wolves have distinct winter and summer pelages that alternate in spring and autumn. Females tend to keep their winter coats further into the spring than males.
Fur coloration varies greatly, running from gray to gray-brown, all the way through the canine spectrum of white, red, brown, and black. These colors tend to mix in many populations to form predominantly blended individuals, though it is not uncommon for an individual or an entire population to be entirely one color (usually all black or all white). With the exception of Italy, in which black wolves can constitute 20-25% of the entire population, melanistic wolves rarely occur outside the North American continent. A multicolor coat characteristically lacks any clear pattern other than it tends to be lighter on the animal's underside. Fur color sometimes corresponds with a given wolf population's environment; for example, all-white wolves are much more common in areas with perennial snow cover. Aging wolves acquire a grayish tint in their coats. It is often thought that the coloration of the wolf's pelage serves as a functional form of camouflage. This may not be entirely correct, as some scientists have concluded that the blended colors have more to do with emphasizing certain gestures during interaction.
At birth, wolf pups tend to have darker fur and blue irises that will change to a yellow-gold or orange color when the pups are between 8 and 16 weeks old.
Wolves' long, powerful muzzles help distinguish them from other canids, particularly coyotes and golden jackals, which have more narrow, pointed muzzles. In wolves, the anterior incisure of the nasal bones does not have a medial protrusion, unlike jackals. The cingulum on the external edge of the first upper molar is only slightly expressed, while it is broad and distinctly marked in jackals.
Wolves differ from domestic dogs in a more varied nature. Anatomically, wolves have smaller orbital angles than dogs (>53 degrees for dogs compared with <45 degrees for wolves) and a comparatively larger brain capacity. Larger paw size, yellow eyes, longer legs, and bigger teeth further distinguish adult wolves from other canids, especially dogs. Also, precaudal glands at the base of the tail are present in wolves but not in dogs.
Wolves and most larger dogs share identical dentition. The maxilla has six incisors, two canines, eight premolars, and four molars. The mandible has six incisors, two canines, eight premolars, and six molars. The fourth upper premolars and first lower molars constitute the carnassial teeth, which are essential tools for shearing flesh. The long canine teeth are also important, in that they hold and subdue the prey. Capable of delivering up to 10,000 kPa (1450 lbf/in²) of pressure, a wolf's teeth are its main weapons as well as its primary tools. The dentition of grey wolves is better suited to bone crushing than those of other modern canids, though it is not as specialised as that found in hyenas.
Wolf saliva has been shown to reduce bacterial infection in wounds and accelerate tissue regeneration.
Generally, mating occurs between January and April — the higher the latitude, the later it occurs. A pack usually produces a single litter unless the breeding male mates with one or more subordinate females. During the mating season, breeding wolves become very affectionate with one another in anticipation of the female's ovulation cycle. The pack tension rises as each mature wolf feels urged to mate. During this time, the breeding pair may be forced to prevent other wolves from mating with one another. Incest rarely occurs, though Inbreeding depression has been reported to be a problem for wolves in Saskatchewan and Isle Royale. When the breeding female goes into estrus (which occurs once per year and lasts 5–14 days), she and her mate will spend an extended time in seclusion. Pheromones in the female's urine and the swelling of her vulva make known to the male that the female is in heat. The female is unreceptive for the first few days of estrus, during which time she sheds the lining of her uterus; but when she begins ovulating again, the two wolves mate.
The gestation period lasts between 60 and 63 days. The pups, which weigh 0.5 kg (1 lb) at birth, are born blind, deaf, and completely dependent on their mother. The average litter size is 5-6 pups, though litters of 10 can occur . The pups reside in the den and stay there for two months. The den is usually on high ground near an open water source, and has an open chamber at the end of an underground or hillside tunnel that can be up to a few meters long. During this time, the pups will become more independent, and will eventually begin to explore the area immediately outside the den before gradually roaming up to a mile away from it at around 5 weeks of age. Wolf growth rate is slower than that of coyotes and dholes. They begin eating regurgitated foods after 2 weeks of feeding on milk, which in wolves has less fat and more protein and arginine than dog milk. By this time, their milk teeth have emerged — and are fully weaned by 10 weeks. During the first weeks of development, the mother usually stays with her litter alone, but eventually most members of the pack will contribute to the rearing of the pups in some way. After two months, the restless pups will be moved to a rendezvous site, where they can stay safely while most of the adults go out to hunt. One or two adults stay behind to ensure the safety of the pups. After a few more weeks, the pups are permitted to join the adults if they are able, and will receive priority on anything killed, their low ranks notwithstanding. Letting the pups fight for eating privileges results in a secondary ranking being formed among them, and allows them to practice the dominance/submission rituals that will be essential to their future survival in pack life. During hunts, the pups remain ardent observers until they reach about 8 months of age, by which time they are large enough to participate actively.
Wolves typically reach sexual maturity after two or three years, at which point many of them will be compelled to leave their birth packs and seek out mates and territories of their own. Wolves that reach maturity generally live 6 to 10 years in the wild, although in captivity they can live to twice that age. High mortality rates give them a low overall life expectancy. Pups die when food is scarce; they can also fall prey to predators such as bears, tigers, or other wolves. The most significant causes of mortality for grown wolves are hunting and poaching, car accidents, and wounds inflicted while hunting prey. Although adult wolves may occasionally be killed by other predators, rival wolf packs are often their most dangerous non-human enemy.
Wolves in Russia have been recorded to carry over 50 different kinds of harmful parasites, including echinococcus, cysticercosis and coenuri. Wolves are also carriers of Trichinella spiralis. Between 1993-94, 148 wolf carcasses near Fairbanks, Alaska were examined for larvae, 54 (36%) of which were found to be infected. Prevalence of Trichinella spiralis in wolves is significantly related to age.
Despite their habit of carrying harmful diseases, large wolf populations are not heavily regulated by epizootic outbreaks as with other social canids. This is largely due to the habit of infected wolves vacating their packs, thus preventing mass contagion.
Occasionally, single wolves are found in the wild, though packs are more common. Lone wolves are typically old specimens driven from their pack or young adults in search of new territory. Wolf packs tend not to be as compact or unified as those of African wild dogs and spotted hyenas, though they are not as unstable as those of coyotes. Normally, the pack consists of a male, a female and their offspring, essentially making the pack a nuclear family. The size of the pack may change over time and is controlled by several factors, including habitat, personalities of individual wolves within a pack, and food supply. Packs can contain between 2 and 20 wolves, though 8 is a more typical size. An unusually large pack consisting of 36 wolves was reported in 1967 in Alaska. While most breeding pairs are monogamous, there are exceptions. Wolf cubs are very submissive to their parents, though upon reaching sexual maturity, tensions within the pack increase, resulting in expulsions or “revolts” in which on rare occasions daughters kill mothers and sons kill fathers. Usually, the instinct to reproduce drives young wolves away from their birth packs, leading them to seek out mates and territories of their own. Dispersals occur at all times during the year, typically involving wolves that have reached sexual maturity prior to the previous breeding season. It takes two such dispersals from two separate packs for a new breeding pair to be formed, for dispersing wolves from the same maternal pack tend not to mate. Once two dispersing wolves meet and begin traveling together, they immediately begin the process of seeking out territory, preferably in time for the next mating season. Wolves mature after two years, and stay with their parents until that age. Young from the previous season will support their parents in nursing the pups of a later year. When the young reach maturity, they normally leave the territory of their parents to look for a territory for themselves. Parents are invariably dominant over their offspring, therefore hierarchic fights are rare in wild packs. Wolf packs rarely accept strangers, and are ferociously territorial, with one study on wolf mortality in Minnesota and the Denali National Park and Preserve concluding that 14–65% of wolf deaths were due to predation by other wolves. Wolves acting unusually within the pack, such as epileptic pups or thrashing adults crippled by a trap or a gunshot, are usually killed by other members of their own pack.
In literature, wolf packs are commonly portrayed as strongly hierarchic communities, with a dominant breeding "Alpha pair", a group of subordinate "Beta" individuals and the scapegoat "Omega wolf" on the lowest end of the hierarchy. These descriptions are heavily based on research on captive wolves and cannot be extrapolated to wild wolf packs. In captivity, dispersal of mature individuals is impossible, resulting in frequent aggressive hierarchic encounters. According to wolf biologist L. David Mech, "Calling a wolf an alpha is usually no more appropriate than referring to a human parent or a doe deer as an alpha. Any parent is dominant to its young offspring, so alpha adds no information.
Wolves, like other canines, use scent marking to lay claim to anything—from territory to fresh kills. Breeding wolves scent mark the most often, with males doing so more than females. The most widely used scent marker is urine. Male and female breeding wolves urine-mark objects with a raised-leg stance (all other pack members squat) to enforce rank and territory. They also use marks to identify food caches and to claim kills on behalf of the pack. Defecation markers are used for the same purpose as urine marks, and serve as a more visual warning, as well. Defecation markers are particularly useful for navigation, keeping the pack from traversing the same terrain too often and also allowing each wolf to be aware of the whereabouts of its pack members. Above all, though, scent marking is used to inform other wolves and packs that a certain territory is occupied, and that they should therefore tread cautiously.
Wolves have scent glands all over their bodies, including at the base of the tail, between toes, and in the eyes, genitalia, and skin. Pheromones secreted by these glands identify each individual wolf. A dominant wolf will "rub" its body against subordinate wolves to mark such wolves as being members of a particular pack. Wolves may also "paw" dirt to release pheromones instead of urine marking.
Wolves in search of food act upon a series of interlocking instincts and imprinting, thus they will typically avoid a potential prey item which does not conform to what they learned during their long ontogeny. The exploration of a new food source requires a dismantling of what they previously learned, accompanied by a slow re-learning process aided by close observation of the new prey. Generally, the greater the discrepancy of the new prey to what wolves are previously accustomed to, the greater their resistance to exploring it. This is only increased should the new prey act bold, assertive and fearless. Nevertheless, even if there is no food shortage, wolves will explore alternative prey if they continually come in close contact with it and habituate themselves. Wolf packs show little strategic cooperation in hunting unlike lions, though wolf pairs have been shown to strategize when attacking large prey. When hunting large prey, wolves typically attempt to conceal themselves as they approach the selected animal. Often, they will wait for the prey to graze, when it is distracted. Wolves generally do not engage in long chases, and will usually stop a pursuit after a chase of 10-180 metres, though there has been one documented case of a wolf chasing a moose for 36 km. Wolves typically kill large prey by tearing at their haunches and perinium areas, causing massive bleeding. Sometimes, the wolves will bite the throat, severing the windpipe or jugular. A single bite can cause a wound up to 10-15 cm in length. A large deer in optimum health will succumb to three bites at the perinium area after a chase of 150 metres. Once the prey collapses, the wolves will tear open the abdominal cavity and commence feeding on the animal, sometimes whilst it is still alive. On some occasions, wolves will not press an attack, and will wait for their prey to die from their wounds before commencing feeding. Pack status is reinforced during feeding. The breeding pair usually eats first, starting with the heart, liver and lungs. Wolves of intermediate rank will prevent low ranking animals from feeding until the dominant pair finishes eating. The stomach is eaten, though the contents are left untouched. The leg muscles are eaten next, with the hide and bones being the last to be eaten. There are exceptions, with some wolf packs having been reported to show preferences to their prey's fat deposits rather than internal organs.
Though commonly portrayed as targeting solely sick or infirm animals, there is little evidence that they actively limit themselves to such targets. Rather, the evidence shows that wolves will simply target the easiest options available, which as well as sick and infirm animals, can also include young animals and pregnant females. Research from the former Soviet Union for example shows that in some cases, 93% of all killed prey may have no illnesses or infirmities. In the Nenets Autonomous Okrug, wolves were shown to select pregnant female domestic caribou and calves rather than infirm specimens, with some reports showing that wolves bypassed emaciated, sickly animals altogether in favour of well fed ones. However, most healthy, fit individuals will not run from wolves and will instead choose to stand their ground, thus increasing the possibility of injury to the attacking wolves. The wolves are more likely to yield when confronted by bold prey. Wolves are generally inefficient at killing large, assertive prey, with success rates as low as 20% which is due, in part, to the large size and defensive capabilities of their prey. Wolves have on occasion been observed to engage in acts of surplus killing. An example of this was reported by a Conservation Officer for the Minnesota Department of Natural Resources, stating that during a spring snow storm, two wolves killed 21 deer, consuming only two. Surplus killing in the wild peaks in winter months when heavy snow impedes the movements of large hooved prey. Wolves will occasionally attack pregnant ungulates to feed on the fetus(es), whilst leaving the mother uneaten.
Wolves will on occasion supplement their diet with vegetation, with some areas of the former Soviet Union reporting that wolves cause serious damage to watermelon plantations. In certain localities in Eurasia where there is little natural prey, wolves will forage in garbage dumps. There are few cases of wolves in North America relying on garbage for food, though in 2005, a wolf pack in Saskatchewan had been regularly seen in broad daylight at a garbage dump, adjusting their arrival with that of the front-end loader carrying garbage. Wolves which feed regularly in garbage dumps often display bolder behaviour toward humans than those that hunt game.
Cougars are encountered in North America. Wolves are usually hostile toward cougars and will kill cubs if given the opportunity. The wolf's relation to adult cougars is more complex. A pack often takes advantage of cougars, stealing kills and sometimes killing mature adults. Interactions between solitary wolves and cougars are rarer, but the two species have killed each other. National Park Service cougar specialist Kerry Murphy stated that the cougar usually is at an advantage on a one to one basis, considering it can effectively use its claws, as well as its teeth, unlike the wolf which relies solely on its teeth. Yellowstone officials have reported that attacks between cougars and wolves are not uncommon. Multiple incidents of cougars taking wolves and vice versa have been recorded in Yellowstone National Park. However, researchers in Montana have found that wolves regularly kill cougars in the area, though they did not specify whether or not this was a pack situation.
Brown bears are encountered in both Eurasia and North America. The majority of interactions between wolves and brown bears usually amount to nothing more than mutual avoidance. Serious confrontations depend on the circumstances of the interaction, though the most common factor is defence of food and young. Brown bears will use their superior size to intimidate wolves from their kills and when sufficiently hungry, will raid wolf dens. Brown bears usually dominate wolves on kills, though they rarely prevail against wolves defending den sites. Wolves in turn have been observed killing bear cubs, to the extent of even driving off the defending mother bears. Deaths in wolf/bear skirmishes are considered very rare occurrences, the individual power of the bear and the collective strength of the wolf pack usually being sufficient deterrents to both sides. American black bears occur solely in the Americas, and interactions with wolves are much rarer than with brown bears, due to differences in habitat preferences. The majority of black bear encounters with wolves occur in the species' northern range, with no interactions being recorded in Mexico. Wolves have been recorded to kill black bears on numerous occasions without eating them. Unlike brown bears, black bears frequently lose against wolves in disputes over kills.
In areas where wolves and tigers share ranges, such as the Russian Far East, the two species typically display a great deal of dietary overlap, resulting in intense competition. Wolf and tiger interactions are well documented in Sikhote-Alin, which until the beginning of the 20th century, held very few wolves. It is thought by certain experts that wolf numbers increased in the region after tigers were largely eliminated during the Russian colonization in the late 1800s and early 1900s. This is corroborated by native inhabitants of the region claiming that they had no memory of wolves inhabiting Sikohte-Alin until the 1930s, when tiger numbers decreased. Tigers depress wolf numbers, either to the point of localized extinction or to such low numbers as to make them a functionally insignificant component of the ecosystem. Wolves appear capable of escaping competitive exclusion from tigers only when human persecution decreases the latters numbers. Today wolves are considered scarce in tiger inhabited areas, being found in scattered pockets, and usually seen travelling as loners or in small groups. First hand accounts on interactions between the two species indicate that tigers occasionally chase wolves from their kills, while wolves will scavenge from tiger kills. Tigers are not known to prey on wolves, though there are four records of tigers killing wolves without consuming them. This competetive exclusion of wolves by tigers has been used by Russian conservationists to convince hunters in the Far East to tolerate the big cats, as they limit ungulate populations less than wolves, and are effective in controlling the latters numbers.
Wolves may occasionally encounter striped hyenas in the Middle East, Central and Southern Asia, mostly in disputes over carcasses. Though hyenas usually dominate wolves on a one to one basis, wolf packs have been reported to displace lone hyenas from carcasses. Wolf remains have been found in cave hyena den sites, though it is unknown if the wolves were killed or scavenged upon. Unlike cave hyenas, which preferentially preyed on lowland animals such as horses, wolves relyed more on slope-dwelling ibex and roe deer, thus minimising competition. Wolves and cave hyenas seem to display negative abundance relations over time, with wolf populations expanding their ranges as hyenas disappeared.
Wolves can communicate visually through a wide variety of expressions and moods ranging from subtle signals, such as a slight shift in weight, to more obvious ones, such as rolling on their backs to indicate complete submission.
Wolf howls, which can last from 0.5-11 seconds, typically have a frequency of 150-780 Hz. Howling helps pack members keep in touch, allowing them to communicate effectively in thickly forested areas or over great distances. Howling also helps to call pack members to a specific location. Howling can also serve as a declaration of territory, as shown in a dominant wolf's tendency to respond to a human imitation of a "rival" wolf in an area the wolf considers its own. This behavior is stimulated when a pack has something to protect, such as a fresh kill. As a rule of thumb, large packs will more readily draw attention to themselves than will smaller packs. Adjacent packs may respond to each others' howls, which can mean trouble for the smaller of the two. Wolves therefore tend to howl with great care. Wolves will also howl for communal reasons. Some scientists speculate that such group sessions strengthen the wolves' social bonds and camaraderie—similar to community singing among humans. During such choral sessions, wolves will howl at different tones and varying pitches, making it difficult to estimate the number of wolves involved. This confusion of numbers makes a listening rival pack wary of what action to take. For example, confrontation could be disastrous if the rival pack gravely underestimates the howling pack's numbers. A wolf's howl may be heard from up to ten miles (16 km) away, depending on weather conditions. Observations of wolf packs suggest that howling occurs most often during the twilight hours, preceding the adults' departure to the hunt and following their return. Studies also show that wolves howl more frequently during the breeding season and subsequent rearing process. The pups themselves begin howling soon after emerging from their dens and can be provoked into howling sessions easily over the following two months. Such indiscriminate howling usually is intended for communication, and does not harm the wolf so early in its life. Howling becomes less indiscriminate as wolves learn to distinguish howling pack members from rival wolves. The Arabian and Iranian wolf subspecies are unusual as they are not known to howl.
Growling, while teeth are bared, is the most visual warning wolves use. Wolf growls have a distinct, deep, bass-like quality which can range from 250-1,500 Hz. It is often used to threaten rivals, though not necessarily to defend themselves. Wolves also growl at other wolves while being aggressively dominant. Wolves bark when nervous or when allerting other wolves of danger but do so very discreetly and will not generally bark loudly or repeatedly as dogs do. Instead they use a low-key, breathy "whuf" sound which can measure from 320-904 Hz to immediately get attention from other wolves. Wolves also "bark-howl" by adding a brief howl to the end of a bark. Wolves bark-howl for the same reasons they normally bark. Generally, pups bark and bark-howl much more frequently than adults, using these vocalizations to cry for attention, care, or food. A lesser known sound is the rally. Wolves will gather as a group and, amidst much tail-wagging and muzzle licking, emit a high-pitched wailing noise interspersed with something similar to (but not the same as) a bark. Rallying is often a display of submission to an alpha by the other wolves. Wolves also whimper, a sound with a maximum range of 3,500 Hz, usually when submitting to other wolves. Wolf pups whimper when they need a reassurance of security from their parents or other wolves.
With respect to common names, spelling differences result in the alternative spelling grey wolf. As the first-named and most widespread of species termed "wolf", gray wolves are often simply referred to as wolves. It was one of the many species originally described by Carolus Linnaeus in his eighteenth-century work, Systema Naturae, and it still bears its original classification, Canis lupus. The binomial name is derived from the Latin Canis, meaning "dog", and lupus, "wolf". Classifying gray wolf subspecies can be challenging. Although scientists have proposed a host of subspecies, wolf taxonomy at this level remains controversial. Indeed, only a single wolf species may exist. Taxonomic modification will likely continue for years to come.
Current theories propose that the gray wolf first evolved in Eurasia during the early Pleistocene. The rate of changes observed in DNA sequence date the Asiatic lineage to about 800,000 years, as opposed to the American and European lineages which stretch back only 150,000. The gray wolf migrated into North America from the Old World, probably via the Bering land bridge, around 400,000 years ago. However, they did not become widespread until 12,000 years ago, when the native American megafauna began dying out. It is thought by certain experts that the wolf's Eurasian origin could account for it's relative inability to modify it's behaviour in light of human encroachment, compared to native American predators like black bears, cougars and coyotes which were under greater predation pressure from larger, now extinct predators. The gray wolf then coexisted with the Dire Wolf (Canis dirus). Although more heavily built and possessing a stronger bite, the dire wolf's dentition was less adept at crushing bones as the grey wolf was. The Dire Wolf ranged from southern Canada to South America until about 8,000 years ago when climate changes are thought to have caused it to become extinct. After that the gray wolf is thought to have become the prime canine predator in North America.
Much debate has centered on the relationship between the wolf and the domestic dog, though most authorities see the wolf as the dog's direct ancestor. Because the canids have evolved recently and different canids interbreed readily, untangling the relationships has been difficult. However, molecular systematics now indicate very strongly that domestic dogs and wolves are closely related, and the domestic dog is now normally classified as a subspecies of the wolf: Canis lupus familiaris. All skeletal dog remains found from the upper Paleolithic and Mesolithic periods are from relatively small specimens, therefore pointing to either the Arabian or Iranian wolf as the most likely progenitor. North American domestic dogs are believed to have originated from Old World wolves. No known dog breed is derived from wolves indigenous to North America. The first people to colonize North America 12,000 to 14,000 years ago brought their dogs with them from Asia, and apparently did not separately domesticate the wolves they found in the New World (that is, in the Americas).
The domestication of wolves may have occurred as a side effect when primitive humans disposed of waste in landfills close to their settlements, attracting wolves to easy meals. Natural selection favoured wolves which were less prone to fleeing upon seeing approaching humans; physical changes quickly appeared in subsequent generations, namely a reduction in head and tooth size, as the abundance of easily acquired food made the hunting of large game unnecessary.
Compared to equally sized wolves, dogs tend to have 20% smaller skulls and 10% smaller brains, as well as proportionately smaller teeth than other canid species. The premolars and molars of dogs are much more crowded. Dog's teeth also have less complex cusp patterns, and their tympanic bulla is much smaller than in wolves. Dogs require fewer calories to function than wolves. The dog's diet of human refuse in antiquity made the large brains and jaw muscles needed for hunting unnecessary. It is thought by certain experts that the dog's limp ears are a result of atrophy of the jaw muscles. The paws of a dog are half the size of those of a wolf, and their tails tend to curl upwards, another trait not found in wolves. Dogs are not monogamous, and breeding in feral packs is not restricted to a dominant breeding pair. Male dogs differ from male wolves by the fact that they play no role in raising their puppies, and do not kill the young of other females to increase their own reproductive success. Dogs differ also from wolves by the fact that they do not regurgitate food for their young, nor the young of other dogs in the same territory.
Wolves can interbreed with domestic dogs and produce fertile offspring. Wolf-dog hybrids are generally said to be naturally healthy animals, and are affected by less inherited diseases than most breeds of dog. Wolfdogs are usually healthier than either parent due to heterosis. According to the National Wolfdog Alliance, 40 U.S. states effectively forbid the ownership, breeding and importation of wolfdogs, while others impose some form of regulation upon ownership. Most European nations, as well as many U.S. counties and municipalities, also either outlaw the animal entirely or put restrictions on ownership.. Although wolves in the wild will usually kill dogs, matings of dogs and wild wolves has been confirmed in some populations through genetic testing. As the survival of most Continental wolf packs is severely threatened, scientists fear that the creation of wolf-dog hybrid populations in the wild is a threat to the continued existence of some isolated wolf populations. Hybridization in the wild usually occurs near human habitations where wolf density is low and dogs are common. However, extensive wolf-dog hybridization is not supported by morphological evidence, and analyses of mtDNA sequences have revealed that such matings are rare. In some cases, the presence of dewclaws is considered a useful, but not absolute indicator of dog gene contamination in wild wolves. Dewclaws are the vestigial fifth toes of the hind legs common in domestic dogs but thought absent from pure wolves, which only have four hind toes. Observations on wild wolf hybrids in the former Soviet Union indicate that wolf hybrids in a wild state may form larger packs than pure wolves, and have greater endurance when chasing prey.
Wolves and coyotes can interbreed and produce fertile offspring, a fact which calls into question their status as two separate species. The offspring, known as a coywolf, is generally intermediate in size to both parents, being larger than a pure coyote, but smaller than a pure wolf. A study showed that of 100 coyotes collected in Maine, 22 had half or more wolf ancestry, and one was 89 percent wolf. A theory has been proposed that the large eastern coyotes in Canada are actually hybrids of the smaller western coyotes and wolves that met and mated decades ago as the coyotes moved toward New England from their earlier western ranges. The Red Wolf is thought by certain scientists to be in fact a wolf/coyote hybrid rather than a unique species. Strong evidence for hybridization was found through genetic testing which showed that red wolves have only 5% of their alleles unique from either grey wolves or coyotes. Genetic distance calculations have indicated that red wolves are intermediate between coyotes and grey wolves, and that they bear great similarity to wolf/coyote hybrids in southern Quebec and Minnesota. Analyses of mitochondrial DNA showed that existing Red Wolf populations are predominantly coyote in origin.
Though once abundant over much of North America and Eurasia, the gray wolf inhabits a very small portion of its former range because of widespread destruction of its habitat, human encroachment of its habitat, and the resulting human-wolf encounters that sparked broad extirpation. Considered as a whole, however, the gray wolf is regarded as being of least concern for extinction according to the International Union for the Conservation of Nature and Natural Resources. Today, wolves are protected in some areas, hunted for sport in others, or may be subject to extermination as perceived threats to livestock and pets.
Wolves tend to have difficulty adapting to change, and are often referred to as an indicator species; a species delineating an ecoregion or indicating an environmental condition such as a disease outbreak, pollution, species competition or climate change. Wolves do not seem to be able to adapt as readily to expanding civilisation the way coyotes do. While human expansion has seen an increase in the latters numbers, it has caused a drop in those of the former.
Humans historically have had a complex relationship with wolves. In many parts of the world, wolves were respected and revered, while in others they were feared and held in distaste. The latter viewpoint was notably accentuated in European folklore beginning in the Christian era, though wolves did feature as heraldic animals on the Arms and crests of numerous noble families. Many languages have names meaning "wolf", examples including: Scandinavian Ulf, Albanian "Ujk", Hebrew Ze'ev, Hungarian Farkas, Serbian Vuk, Ukrainian Vovk, Romanian Lupu, Lupescu/Lupulescu and Bulgarian Vǎlko. Wolves also figure prominently in proverbs. Many Chinese proverbs use wolves as a description towards any ill-willed person with a hidden agenda like Wolf hearted (狼子野心) which could also connote to the impossibility of taming bad people, while Wolf heart; dog lungs (狼心狗肺) refers to an ungrateful person who later betrays someone who previously helped them. The Kazakh language has up to 20 proverbs referring to wolves, while the Russian language has 253.
In Altaic mythology of the Turkic and Mongolian peoples, the wolf is a revered animal (in Turkish Börü or Kurt). The shamanic Turkic peoples even believed they were descendants of wolves in Turkic legends. The legend of Asena is an old Turkic myth that tells of how the Turkic people were created. In Northern China a small Turkic village was raided by Chinese soldiers, but one small baby was left behind. An old she-wolf with a sky-blue mane named Asena found the baby and nursed him, then the she-wolf gave birth to half wolf, half human cubs therefore the Turkic people were born. Also in Turkic mythology it is believed that a gray wolf showed the Turks the way out of their legendary homeland Ergenekon, which allowed them to spread and conquer their neighbours. In modern Turkey this myth inspired extreme-right nationalist groups known as "Grey Wolves".
The genesis story of the Turks and Mongols is paralleled in the Roman myth of Romulus and Remus, the traditional founders of Rome. The twin babies were ordered to be killed by their great uncle Amulius. The servant ordered to kill them, however, relented and placed the two on the banks of the Tiber river. The river, which was in flood, rose and gently carried the cradle and the twins downstream, where under the protection of the river deity Tiberinus, they would be adopted by a she-wolf known as Lupa in Latin, an animal sacred to Mars.
In Norse mythology, Fenrir or Fenrisulfr is a gigantic wolf, the son of Loki and the giantess Angrboða. Fenrir is bound by the gods, but is ultimately destined to grow too large for his bonds and devour Odin during the course of Ragnarök. At that time he will have grown so large that his upper jaw touches the sky while his lower touches the earth when he gapes. He will be slain by Odin's son, Viðarr, who will either stab him in the heart or rip his jaws asunder according to different accounts.
The Bible contains 13 references to wolves, usually as metaphors for greed and destructiveness. In the New Testament, Jesus is quoted to have used wolves as illustrations to the dangers His followers would have faced should they follow him (Matthew 10:16, Acts 10:29, Matthew 7:15)
In the medieval Russian folktale Ivan Tsarevich and the Grey Wolf (also known as Ivan Tsarevich and the Firebird or The Firebird), the grey wolf is a benevolent character who assists Ivan on his quest, using his knowledge and magical powers.
In Japan, grain farmers once worshiped wolves at shrines and left food offerings near their dens, beseeching them to protect their crops from wild boars and deer. Talismans and charms adorned with images of wolves protected against fire, disease, and other calamities and brought fertility to agrarian communities and to couples hoping to have children. The Ainu people believed that they were born from the union of a wolflike creature and a goddess.
Wolves also figure prominently in the folklore and mythology of some Native American tribes. In the Cardinal directions of the Plains Indians, the wolf represented the west, while for the Pawnee, it represented the southeast. According to the Pawnee creation myth, the wolf was the first creature to experience death. The Wolf Star (Sirius), enraged at not having been invited to attend a council on how the Earth should be made, sent a wolf to steal the whirlwind bag of The Storm that Comes out of the West, which contained the first humans. Upon being freed from the bag, the humans killed the wolf, thus bringing death into the world. The Pawnee, being both an agricultural and hunting people, associated the wolf with both corn and the bison; the "birth" and "death" of the Wolf Star was to them a reflection of the wolf's coming and going down the path of the Milky Way known as Wolf Road. Wolves however were not always portrayed positively in Native American cultures. The Netsilik Inuit and Takanaluk-arnaluk believed that the sea-woman Nuliayuk's home was guarded by wolves. The Naskapi's believed that the caribou afterlife is guarded by giant wolves which kill careless hunters venturing too near. The Navajo people feared witches in wolf's clothing called "Mai-cob".
Wild wolves are generally timid around humans, though overall, how they react to people generally depends on prior experiences with humans rather than inherent behaviour. When they have sufficient habitat, food, and are occasionally hunted, wolves will usually try to avoid contact with people, to the point of even abandoning their kills when an approaching human is detected, though there are several reported circumstances (provocation, habituation, rabies, mistaken identity, teaching cubs how to hunt, hybridization with dogs and seasonal prey scarcity), in which wolves have been recorded to act aggressively toward humans. However, compared to other carnivorous mammals known to attack humans, the frequency with which wolves have been recorded to kill people is rather low, indicating that though potentially dangerous, wolves are among the least threatening for their size and predatory potential. Wolf attacks were an occasional but widespread feature of life in pre-20th century Europe. The case of the Beast of Gévaudan is considered by some historians to be among the most well documented incidents of European wolf attacks. There are numerous documented accounts of wolf attacks in the Asian continent, with three Indian states reporting a large number of non-rabid attacks in recent decades. These attacks were well documented by trained biologists. North America has fewer cases of wolf attacks than Europe and Asia, though more aggressive encounters have been recorded as humans begin to encroach on wolf habitat more. Retired wolf biologist Mark McNay compiled 80 events in Alaska and Canada where wolves closely approached or attacked people, finding 39 cases of aggression by apparently healthy wolves, and 29 cases of fearless behavior by nonaggressive wolves.
Wolf depredations on livestock tend to increase in September and October when females teach their cubs how to hunt. Wolves usually attack livestock when they are grazing, though it is not uncommon for some wolves to break into fenced enclosures. Sheep are the most frequently recorded victims in Europe, in India it is goats, in Mongolia it is horses, while North American records show wolves having a greater tendency to attack cattle and turkeys. Wolves usually disregard size or age on medium sized prey such as sheep and goats. According to Theodore Roosevelt, the small wolves of the Southern Plains rarely attack full grown cattle or steers, preferring instead young or sick animals, while the large wolves of the northern Rockies can kill fully grown steers unaided. Injuries may include a crushed skull, severed spine, disembowelment and massive tissue damage. Wolves will also kill sheep by attacking the throat, similar to the manner in which coyotes kill sheep. Wolf kills can be distinguished from coyote kills by the far greater damage to the underlying tissue. Surplus killing often occurs when within the confines of human made livestock shelters. One specimen known as the "Aquila Wolf" in Arizona was known to have killed 65 sheep in one night and 40 at another time. Sometimes, the animals survive, but are left with severe mutilations, sometimes warranting euthanasia. Livestock with prior experience of a wolf attack may develop behavioural problems, with some animals having been reported to run through barbed wire fences upon hearing wolves, or refusing to go out into pastures, causing severe weight loss. Animals severely injured by wolves often appear dazed and are reluctant to move due to the deep pain. It is often difficult to confirm kills, seeing as wolves often eat all of the animal they have killed if it is below the size of a calf. Some non- or less-lethal methods of protecting livestock from wolves have been under development for the past decade. Such methods include rubber ammunition and use of guard animals. Recorded wolf howls have also been shown to be effective in at least one incident.
The extent of livestock losses to wolves vary regionally; from being statistically insignificant, to having critical effects on local economies. In North America, loss of livestock by wolves makes up only a small percentage of total losses. In the United States, wolf predation is low compared to other human or animal sources of livestock loss. Since the state of Montana began recording livestock losses due to wolves back in 1987, only 1,200 sheep and cattle have been killed. 1,200 killings in twenty years is not very significant when in the greater Yellowstone region 8,300 cattle and 13,000 sheep die from natural causes. According to the International Wolf Center, a Minnesota-based organization: Furthermore, Jim Dutcher, a film maker who raised a captive wolf pack observed that wolves are very reluctant to try meat that they have not eaten or seen another wolf eat before possibly explaining why livestock depredation is unlikely except in cases of desperation. The results however differ in Eurasia. Greece for example reports that between April 1989 and June 1991, 21000 sheep and goats plus 2729 cattle were killed. In 1998 it was 5894 sheep and goats, 880 cattle and very few horses. A study on livestock predation taken in Tibet showed that the wolf was the most prominent predator, accounting for 60% of the total livestock losses, followed by the snow leopard (38%) and lynx (2%). Goats were the most frequent victims (32%), followed by sheep (30%), yak (15%), and horses (13%). Wolves killed horses significantly more and goats less than would be expected from their relative abundance. In 1987, Kazakhstan reported over 150,000 domestic livestock losses to wolves, with 200,000 being reported a year later.
In some areas, dogs are a major food source for wolves. Reports from Croatia indicate that dogs are killed more frequently than sheep. Wolves in Russia apparently limit feral dog populations. In Wisconsin, more compensation has been paid for dog losses than livestock. Some wolf pairs have been reported to predate on dogs by having one wolf lure the dog out into heavy brush where the second animal waits in ambush. In some instances, wolves have displayed an uncharacteristic fearlessness of humans and buildings when attacking dogs, to an extent where they have to be beaten off or killed. Specially bred Livestock guardian dogs have been used to repell wolves from pastures, though their primary function has more to do with intimidating the wolves rather than fighting them.
Wolves are usually hunted for sport, for their skins, to protect livestock, and in some rare cases to protect humans. Historically, the hunting of wolves was a huge, capital and manpower intensive operation, requiring miles of netting, specialized net-carts and big drying sheds for storing and drying nets. The threat wolves posed to both livestock and people was significant enough to warrant the conscription of whole villages under threat of punishment, despite the disruption of economic activities and reduced taxes. Some cultures, such as the Apache, would hunt wolves as a rite of passage. Wolves are usually hunted in heavy brush and are considered especially challenging to hunt, due to their elusive nature and sharp senses. Wolves are notoriously shy and difficult to kill, having been stated to be almost as hard to still hunt as cougars, and being far more problematic to dispatch with poison, traps or hounds. Wolves though generally do not defend themselves as effectively as cougars or bears. Some wolves will evade capture for very long periods of time and display great cunning. One specimen nicknamed "Three Toes of Harding County" in South Dakota eluded its pursuers for 13 years before finally being caught. Another wolf nicknamed "Rags the digger" near Meeker, Colorado would deliberately ruin trap lines by digging up traps without tripping them. In Sport hunting, wolves are usually taken in late Autumn and early Winter, when their pelts are of the highest quality and because the heavy snow makes it easier for the wolves to be tracked. Wolves have occasionally been hunted for food, the meat having been variously described as being tough and tasting like chicken.
The hunting of grey wolves, while originally actively endorsed in many countries, has become a controversial issue in some nations. Opponents see it as cruel, unnecessary and based on misconceptions, while proponents argue that it is vital for the conservation of game herds and as pest control.
In North America, debate about wolf reintroduction is ongoing and often heated, both where reintroduction is being considered and where it has already occurred. Where wolves have been successfully reintroduced, as in the greater Yellowstone area and Idaho, reintroduction opponents continue to cite livestock predation, surplus killing, and economic hardships caused by wolves. Opponents in prospective areas echo these same concerns. These reintroductions were the culmination of over two decades of research and debate. Ultimately, the economic concerns of the local ranching industry were dealt with when Defenders of Wildlife decided to establish a fund that would compensate ranchers for livestock lost to wolves, shifting the economic burden from industry to the wolf proponents themselves. As of 2005, there are over 450 Mackenzie Valley wolves in the Greater Yellowstone Ecosystem and over 1,000 in Idaho. Both populations have long since met their recovery goals. Lessons learned from this ordeal may yet prove useful where wolf reintroduction continues to create a sharp divide between industry and environmental interests, as it has in Arizona (where the Mexican Wolf was released beginning in 1998).
Proponents claim that the food chain within the Yellowstone ecosystem has been re-ordered to deliver a banquet that favors a more varied array of species. Prior to wolf reintroduction, high numbers of elk were believed to be linked to reductions in aspen and willow communities, which negatively affected beaver and moose. Pre-wolf coyote numbers were much larger, affecting small rodent populations, foxes, and the production of pronghorn antelope. Scavengers had slimmer pickings. Today, with wolves taking elk, reducing their numbers, and leaving more carcasses on the landscape, grizzlies and wolverines have easier access to more meat, meaning a better chance for larger litters of cubs and pups. Coyote numbers have been significantly reduced, meaning more mice and pocket gophers for foxes and avian predators like hawks and eagles.
Opponents argue that the Yellowstone reintroductions were unnecessary, as American wolves were never in danger of biological extinction. Opponents have stated that wolves are of little commercial benefit, as cost estimates on wolf recovery are from $200,000 to $1 million per wolf. Tourism based on wolves is problematic, as wolves are elusive and very hard to spot; In 1996, less than 0.5% of visitors to Yellowstone ever saw a wolf. Hunters have also cited the possibility of large ungulate population drops in within the park due to wolf predation. National Park Service Biologist Wayne Brewster informed guides and outfitters living north of Yellowstone National Park, to expect a fifty percent (50%) drop in harvestable game when wolves were reintroduced to Yellowstone National Park. This was confirmed when in 2006, the Yellowstone elk herd had in fact shrunk to 50% since the mid 1990s. Two thirty day periods of tracking radio collared wolves showed that 77-97% of prey species documented by wolves in the park were elk. Outside the park, numerous hunting outfitters have been run out of business due to elk hunting opportunities being reduced by 90%. Although Defenders of Wildlife have established a $100,000 compensation program to reimburse ranchers in Wyoming, Idaho, Montana, New Mexico and Arizona for losses caused by wolves, reintroduction opponents have argued that the program is nothing more than a publicity tool and is inadequate for addressing the problem of livestock loss to wolves, due to the fact that the programme has apparently unrealistic criteria in confirming wolf kills. This can be problematic, as wolves often leave little physical evidence of kills the size of lambs and small calves.
Native American attitudes toward wolf reintroductions varied. Although the Nez Perce welcomed the reintroduction of wolves in Idaho, the Apaches of the southwestern US and Kalispells of Washington opposed any reintroduction, as wolves held little spiritual significance in their cultures.
Captive wolf pups are usually taken from their mother at two weeks of age. Pups will typically develop behavioural problems if raised without another member of their own kind. Due to their wild nature, wolf cubs require more socialisation than dog puppies. Socialising cubs solely with humans runs the risk of the cubs devoting their attention to people rather than their own kind. Wolf pups typically stop responding to socialization at the age of 19 days, as opposed to dogs which can still be socialised at the age of 10 weeks. Due to the fact that wolf milk contains more arginine than can be found in puppy milk substitutes, an arginine supplement is needed when feeding pups below the weaning age. Failure to do so can result in the pups developing cataracts. As adults, wolves have been shown, most of the time, to be largely untrainable and unpredictable, and will sometimes display aggressive behaviour toward small animals and children. Captive wolves are generally shy and avoid eye contact with humans other than their owner, as well as not listening to any commands made by any other humans. They usually vacate rooms or hide when a new person enters the establishment. Ordinary pet food is inadequate, seeing as an adult wolf needs 1-2.5 kg (2-5 lbs) of quality meat daily along with bones, skin and fur to meet its nutritional requirements. The exercise needs of a wolf exceed the average dog's demand. Because of this, captive wolves typically do not cope well in urban areas. Due to their talent at observational learning, adult captive wolves can quickly work out how to escape confinement, and need constant reminding that they are not the leader of their owner/caretaker, which makes raising wolves difficult for people who raise their pets in an even, rather than subordinate, environment. They will instinctively challenge their owner for pack status after reaching adult age. Some wildlife centres housing captive wolves prohibit handlers from entering wolf enclosures if they happen to have a cold or other vulnerability which the wolves can detect. According to the American Zoological Association, the minimum housing recommended for a large canid is an enclosure of 4m x 4m (12 x 12 ft), increased by 50% for each additional canid. To prevent the wolf jumping over the enclosure, fences are specified to be necessarily at least 2m (6 ft) high and needing an overhang at the top. An inside skirt buried below ground is also required to prevent tunnelling. Some pet wolves are euthanised or might be released into the wild where they are likely to starve or be killed by resident wolf packs in regions where they are still present. Abandoned or escaped captive wolves can be more destructive and pose a greater danger to humans and livestock than wild wolves, seeing as their habituation to humans causes them to lose their natural shyness. The Wolf of Gysinge is thought to have been one such animal.
Captive wolves have also been shown to be unsuitable for working as dogs do. German wolf biologist Erik Zimen once attempted to form a dog sled team composed entirely of pure wolves. The attempt proved to be a complete failure, as the wolves were far more prone to fighting than sled dogs and ignored most commands. North American wolves and wolf hybrids were used as experimental attack dogs by the South African Defence Force in Apartheid South Africa in an attempt to breed animals capable of tracking guerillas. However, the experiment proved a failure and was discontinued due to the wolves' inability to follow even basic commands.