he gray wolf has very dense and fluffy winter fur, with short underfur and long, coarse guard hairs. Most of the underfur and some of the guard hairs are shed in the spring and grow back in the autumn period. The longest hairs occur on the back, particularly on the front quarters and neck. Especially long hairs are found on the shoulders, and almost form a crest on the upper part of the neck. The hairs on the cheeks are elongated and form tufts. The ears are covered in short hairs which strongly project from the fur. Short, elastic and closely adjacent hairs are present on the limbs from the elbows down to the calcaneal tendons. The winter fur is highly resistant to cold; wolves in northern climates can rest comfortably in open areas at −40° by placing their muzzles between the rear legs and covering their faces with their tail. Wolf fur provides better insulation than dog fur, and does not collect ice when warm breath is condensed against it. In warm climates, the fur is coarser and scarcer than in northern wolves. Female wolves tend to have smoother furred limbs than males, and generally develop the smoothest overall coats as they age. Older wolves generally have more white hairs in the tip of the tail, along the nose and on the forehead. The winter fur is retained longest in lactating females, though with some hair loss around their nipples. Hair length on the middle of the back is 60–70 mm. Hair length of the guard hairs on the shoulders generally does not exceed 90 mm, but can reach 110–130 mm.
Coat color ranges from almost pure white through various shades of blond, cream, and ochre to grays, browns, and blacks, with variation in fur color tending to increase in higher latitudes. Differences in coat colour between sexes are largely absent, though females may have redder tones. Black coloured wolves (which occur through wolf-dog hybridisation) rarely occur in Eurasia, where interactions with domestic dogs have been reduced over the past thousand years due to the depletion of wild wolf populations. Black specimens are more common in North America, with about half the wolves in Yellowstone National Park being black.
Compared to its closest cousins (the coyote and golden jackal), the gray wolf is larger and heavier, with a broader snout, shorter ears, a shorter torso and longer tail. It is a slender, powerfully built animal with a large, deeply descending ribcage, a sloping back and a heavily muscled neck. The wolf's legs are moderately longer than those of other canids, which enables the animal to move swiftly, and allows it to overcome the deep snow that covers most of its geographical range. Females tend to have narrower muzzles and foreheads, thinner necks, slightly shorter legs and less massive shoulders than males. The gray wolf's head is large and heavy, with a wide forehead, strong jaws and a long, blunt muzzle. The ears are relatively small and triangular. The teeth are heavy and large, being better suited to crushing bone than those of other extant canids, though not as specialised as those found in hyenas. Its molars have a flat chewing surface, but not to the same extent as the coyote, whose diet contains more vegetable matter. The gray wolf's jaws can exert a crushing pressure of perhaps 10,340 kPa (1,500 psi) compared to 5,200 kPa (750 psi) for a German shepherd. This force is sufficient to break open most bones. The gray wolf usually carries its head at the same level as the back, raising it only when alert. It usually travels at a loping pace, placing its paws one directly in front of the other. This gait can be maintained for hours at a rate of 8–9 km/h, and allows the wolf to cover great distances. On bare paths, a wolf can quickly achieve speeds of 50–60 km/h. The gray wolf has a running gait of 55 to 70 km/h, can leap 5 metres horizontally in a single bound, and can maintain rapid pursuit for at least 20 minutes.
Gray wolf and golden jackal exhibit at The Museum of Zoology, St. Petersburg. Note the wolf's larger size and broader muzzle.
The gray wolf is the largest extant member of the Canidae, excepting certain large breeds of domestic dog. Gray wolf weight and size can vary greatly worldwide, tending to increase proportionally with latitude as predicted by Bergmann's Rule, with the large wolves of Alaska and Canada sometimes weighing 3–6 times more than their Middle Eastern and South Asian cousins. On average, adult wolves measure 105–160 cm (41–63 in) in length and 80–85 cm (32–34 in) in shoulder height. The tail measures 29–50 cm (11–20 in) in length. The ears are 90–110 millimetres (3.5–4.3 in) in height, and the hind feet are 220–250 mm.
The skull averages 9–11 inches in length, and 5–6 inches wide. Gray wolf weight varies geographically; on average, European wolves may weigh 38.5 kilograms (85 lb), North American wolves 36 kilograms (79 lb) and Indian and Arabian wolves 25 kilograms (55 lb). Females in any given wolf population typically weigh 5–10 lbs less than males. Wolves weighing over 54 kg (120 lbs) are uncommon, though exceptionally large individuals have been recorded in Alaska, Canada, and the former Soviet Union. The heaviest recorded gray wolf in North America was killed on 70 Mile River in east-central Alaska on July 12, 1939 and weighed 79.4 kilograms (175 lb), while the heaviest recorded wolf in Eurasia was killed after World War II in Ukraine's Poltavskij Region, and weighed 86 kilograms (190 lb).
Although dogs and gray wolves are genetically very close, and have shared vast portions of their ranges for millennia, the two generally do not voluntarily interbreed in the wild, though they can produce viable offspring, with all subsequent generations being fertile. In North America, black colored wolves acquired their coloration from wolf-dog hybridization, which occurred 10,000–15,000 years ago. Although wolf-dog hybridization in Europe has raised concern among conservation groups fearing for the gray wolf's purity, genetic tests show that introgression of dog genes into European gray wolf populations does not pose a significant threat. Also, as wolf and dog mating seasons do not fully coincide, the likelihood of wild wolves and dogs mating and producing surviving offspring is small. Like pure wolves, hybrids breed once annually, though their mating season occurs three months earlier, with pups mostly being born in the winter period, thus lessening their chances of survival. However, one genetic study undertaken in the Caucasus Mountains showed that as many as 10% of dogs in the area, including livestock guardian dogs, are first generation hybrids. The captive breeding of wolf-dog hybrids has proliferated in the USA, with 300,000 such animals being present there.
F1 hybrid coyote-gray wolf hybrid, conceived in captivity
The gray wolf has interbred extensively with the eastern wolf across northern Ontario, into Manitoba and Quebec, as well as into the western Great Lakes states of Minnesota, Wisconsin, and Michigan, producing a hybrid population termed Great Lakes boreal wolves. The boreal wolf is 25% larger than a pure eastern wolf, and typically has a similarly colored gray-fawn coat but, unlike the eastern wolf, can also be black, cream, or white. It also specalises on larger prey such as moose and caribou rather than white-tailed deer. Unlike pure eastern wolves, Great Lakes boreal wolves primarily inhabit boreal rather than deciduous forests.
Unlike the red and eastern wolf, the gray wolf does not readily interbreed with coyotes. Nevertheless, coyote genetic markers have been found in some wild isolated gray wolf populations in the southern United States. Gray wolf Y-chromosomes have also been found in Texan coyote haplotypes. In tests performed on a putative chupacabra carcass, mtDNA analysis showed that it was a coyote, though subsequent tests revealed that it was a coyote–gray wolf hybrid sired by a male Mexican gray wolf. In 2013, a captive breeding experiment in Utah between gray wolves and western coyotes produced six hybrids through artificial insemination, making this the very first hybridization case between pure coyotes and northwestern gray wolves. At six months of age, the hybrids were closely monitored and were shown to display both physical and behaviourial characteristics from both species.
Although hybridization between wolves and golden jackals has never been observed, evidence of such occurrences was discovered through mtDNA analysis on jackals in Senegal and Bulgaria. Although there is no genetic evidence of gray wolf-jackal hybridization in the Caucasus Mountains, there have been cases where otherwise genetically pure golden jackals have displayed remarkably gray wolf-like phenotypes, to the point of being mistaken for wolves by trained biologists.
The gray wolf was the first animal and only large carnivore to be domesticated by humans. The origin of the domestic dog has been controversial, and subject to numerous studies, with genetic data and paleontological evidence contradicting each other on the date and location of the first domestication event. Proposed centers of dog origins from genetic data have included the Middle East and East Asia 32,000 years ago, though this is inconsistent with the paleontological record, as the oldest dog remains in those areas are no older than 13,000 years. Much older remains were discovered in Europe and Russia, with one specimen discovered in Goyet, Belgium having been estimated to be 31,700 years old, and another found in the Altai Mountains being dated to be 33,000 years old.
Several studies on gray wolf and dog mitochondrial genomes in 2013-14 showed that modern dog genomes don't match those of extant gray wolf populations, and likely arose from a now extinct lineage of prehistoric gray wolves in Europe, with any similarity with modern wolf populations reflecting historical admixture rather than recent divergence. The genetic data is consistent with the paleontological record, which shows that the oldest dog remains in Europe are 18,800 to 32,100 years old. The domestication event may have begun during the Last Glacial Maximum, prior to the Neolithic Revolution, when hunter-gatherers actively hunted Pleistocene megafauna. The morphology and DNA of the Goyet and Altai specimens didn't match those of modern dogs, thus indicating that they were the result of separate, ultimately aborted domestication episodes. Further studies indicate that prehistoric Eurasian gray wolves underwent a threefoldpopulation bottleneck approximately 15,000-20,000 years ago, thus indicating that these gray wolves had substantially more genetic diversity for selection to act on than what is observed in modern wolf populations.
Although the genetic divergence between gray wolves and dogs is only 1.8%, as opposed to over 4% between gray wolves, Ethiopian wolves and coyotes, there are a number of diagnostic features to distinguish the two. The tympanic bullae are large, convex and almost spherical in gray wolves, while the bullae of dogs are smaller, compressed and slightly crumpled. The teeth of gray wolves are also proportionately larger than those of dogs; the premolars and molars of wolves are much less crowded, and have more complex cusp patterns. Dogs lack a functioning pre-caudal gland, and most enter estrus twice yearly, unlike gray wolves which only do so once a year.
Ancestry
The species' most likely ancestral candidate is Canis lepophagus, a small, narrow skulled North American canid of the Miocene era, which may have also given rise to C. latrans. After the extinction of the large bodied Borophaginae family, C. lepophagus developed into a larger, broader-skulled animal. Fossils of this larger form of C. lepophagus found in northern Texas may represent the ancestral stock from which C. lupus derives. The first true wolves began to appear at the end of the Blancan North American Stage and the onset of the early Irvingtonian. Among them was C. priscolatrans, a small species closely resembling modern-day C. rufus, which colonized Eurasia by crossing the Bering land bridge. The new Eurasian C. priscolatrans population gradually evolved into C. mosbachensis, which subsequently developed in the direction of C. lupus. The earliest identifiable C. lupus remains date back to the Middle Pleistocene, and occur in Beringia.
Subspeciation
MtDNA studies have shown that there are at least four extant C. lupus lineages; the most ancient is that of C. l. lupaster (native to North, West, and East Africa), which is thought to have originated as early as the Middle to Late Pleistocene. All other lineages occur together in the Indian Subcontinent, the oldest of which is the Himalayan wolf (native to the Himalayan region of eastern Kashmir, Himachal Pradesh, parts of Tibet and eastern Nepal), which is thought to have originated 800,000 years ago, when the Himalayan region was going through major geologic and climatic upheaval. C. l. pallipes, likely diverged from the Himalayan wolf 400,000 years ago. The youngest C. lupus lineage in India is represented by C. l. chanco (native to the northwestern Himalayan region of Kashmir), which originated 150,000 years ago. This last lineage, known as the Holarctic clade, expanded into Europe and North America, as shown by it sharing genetic markers with domestic dogs, European and North American wolves.
The now extinct Japanese wolves were descended from large Siberian wolves which colonised the Korean Peninsula and Japan, before it separated from mainland Asia, 20,000 years ago during the Pleistocene. During the Holocene, the Tsugaru Strait widened and isolated Honshu from Hokkaidō, thus causing climatic changes leading to the extinction of most large bodied ungulates inhabiting the archipelago. Japanese wolves likely underwent a process of island dwarfism 7,000–13,000 years ago in response to these climatological and ecological pressures. C. l. hattai (formerly native to Hokkaidō) was significantly larger than its southern cousin C. l. hodophilax, as it inhabited higher elevations and had access to larger prey, as well as a continuing genetic interaction with dispersing wolves from Siberia.
C. lupus colonized North America during the late Rancholabrean era through the Bering land bridge in at least three separate invasions, with each wave being represented by one or more different Eurasian gray wolf clades. Among the first to enter was a broad-skulled, hypercarnivorous ecomorph which never expanded its range below the Wisconsin ice sheet, likely due to competitive exclusion by C. dirus populations in the south, with both dying out during the Quaternary extinction event without leaving any modern descendants. The first gray wolves to permanently enter North America were the ancestors of C. l. baileyi, though these were followed and displaced by C. l. nubilus and pushed southwards. C. l. nubilus was in turn displaced from its northern range by C. l. occidentalis, likely during the Holocene, a process which may have continued into historic times.
The gray wolf[a] (Canis lupus[b]), also known as the timber wolf, true wolf or western wolf[c] is a canid native to the wilderness and remote areas of North America, Eurasia, and North Africa. It is the largest extant member of its family, with males averaging 43–45 kg (95–99 lb), and females 36–38.5 kg (79–85 lb). Like the red wolf, it is distinguished from other Canis species by its larger size and less pointed features, particularly on the ears and muzzle. Its winter fur is long and bushy, and predominantly a mottled gray in color, although nearly pure white, red, or brown to black also occur.
The gray wolf is the most specialised member of the genus Canis, as demonstrated by its morphological adaptations to hunting large prey, its more gregarious nature, and its highly advanced expressive behavior. It is nonetheless closely related enough to smaller Canis species, such as the eastern wolf, coyote and golden jackal to produce fertile hybrids. It is the only species of Canis to have a range encompassing both the Old and New Worlds, and originated in Eurasia during the Pleistocene, colonizing North America on at least three separate occasions during the Rancholabrean. It is a social animal, travelling in nuclear families consisting of a mated pair, accompanied by the pair's adult offspring. The gray wolf is typically an apex predator throughout its range, with only humans and tigers posing a serious threat to it. It feeds primarily on large ungulates, though it also eats smaller animals, livestock, carrion, and garbage.
The gray wolf is one of the world's best known and well researched animals, with probably more books written about it than any other wildlife species. It has a long history of association with humans, having been despised and hunted in most pastoral communities due to its attacks on livestock, while conversely being respected in some agrarian and hunter-gatherer societies.[22] It is the sole ancestor of the dog, which genetic and paleontological records indicate was first domesticated in Europe 18,800-32,100 years ago by hunter-gatherers.[23] Although the fear of wolves is pervasive in many human societies, the majority of recorded attacks on people have been attributed to animals suffering from rabies. Non-rabid wolves have attacked and killed people, mainly children, but this is unusual, as wolves are relatively few, live away from people, and have been taught to fear humans by hunters and shepherds.[24]
The gray wolf was once one of the world's most widely distributed mammals, living throughout the northern hemisphere north of 15°N latitude in North America and 12°N in India. However, deliberate human persecution has reduced the species' range to about one third, due to livestock predation and fear over attacks on humans. The species is now extinct in much of Western Europe, in Mexico and much of the USA. In modern times, the gray wolf occurs mostly in wilderness and remote areas, particularly in Canada, Alaska and northern USA, Europe, and Asia from about 75°N to 12°N. Wolf population declines have been arrested since the 1970s, and have fostered recolonization and reintroduction in parts of its former range, due to legal protection, changes in land-use and rural human population shifts to cities. Competition with humans for livestock and game species, concerns over the danger posed by wolves to people, and habitat fragmentation pose a continued threat to the species. Despite these threats, because of the gray wolf's relatively widespread range and stable population, it is classified as Least Concern by the IUCN.
