Gray Wolf
Canis lupus
Summary 2
The wolf (Canis lupus),[a] also known as the grey/gray wolf or timber wolf,[4][5] is a canine native to the wilderness and remote areas of Eurasia and North America. 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).[6] It is distinguished from other Canis species by its larger size and less pointed features, particularly on the ears and muzzle.[7] Its winter fur is long and bushy and predominantly a mottled gray in color, although nearly pure white, red and brown to black also occur.[5] Mammal Species of the World (3rd ed., 2005), a standard reference work in zoology, recognises 38 subspecies of C. lupus.[8]
The gray wolf is the second most specialized member of the genus Canis, after the Ethiopian wolf, as demonstrated by its morphological adaptations to hunting large prey, its more gregarious nature,[9] and its highly advanced expressive behavior.[10][11] It is nonetheless closely related enough to smaller Canis species, such as the coyote,[12] and golden jackal,[13][14] to produce fertile hybrids. It is the only species of Canis to have a range encompassing both Eurasia and North America,[15] and originated in Eurasia during the Pleistocene, colonizing North America on at least three separate occasions during the Rancholabrean.[15] It is a social animal, travelling in nuclear families consisting of a mated pair, accompanied by the pair's adult offspring.[16] The gray wolf is typically an apex predator throughout its range, with only humans and tigers[9][17][18][19] posing a serious threat to it. It feeds primarily on large ungulates, though it also eats smaller animals, livestock, carrion, and garbage.[5] A seven-year-old wolf is considered to be relatively old, and the maximum lifespan is about 16 years.[20]
The global gray wolf population is estimated to be 300,000.[21] The gray wolf is one of the world's best-known and most-researched animals, with probably more books written about it than any other wildlife species.[22] It has a long history of association with humans, having been despised and hunted in most pastoral communities because of its attacks on livestock, while conversely being respected in some agrarian and hunter-gatherer societies.[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 rare, as wolves are relatively few, live away from people, and have developed a fear of humans from hunters and shepherds.[24]
In 2013, a genetic study found that the wolf population in Europe was divided along a north-south axis and formed five major clusters. Three clusters were identified occupying southern and central Europe in Italy, the Dinaric-Balkans, the Carpathians. Another two clusters were identified occupying north-central Europe and the Ukrainian steppe. The Italian wolf consisted of an isolated population with low genetic diversity. Wolves from Croatia, Bulgaria, and Greece formed the Dinaric-Balkans cluster. Wolves from Finland, Latvia, Belarus, Poland and Russia formed the north-central Europe cluster, with wolves from the Carpathians cluster coming from a mixture of wolves from the north-central cluster and the Dinaric-Balkans cluster. The wolves from the Carpathians were more similar to the wolves from the Pontic-Caspian Steppe than they were to wolves from north-central Europe. These clusters may have been the result of expansion from glacial refugia, an adaptation to local environments, and landscape fragmentation and the killing of wolves in some areas by humans.[38]
In 2016, two genetic studies of North American gray wolves found that they formed six ecotypes – genetically and ecologically distinct populations separated from other populations by their different type of habitat. These six wolf ecotypes were named West Forest, Boreal Forest, Arctic, High Arctic, Baffin, and British Columbia. The studies found that precipitation and mean diurnal temperature range were the most influential variables.[28][39] These findings were in accord with previous studies that precipitation influenced morphology and that vegetation and habitat type influenced wolf differences.[39] The local adaptation of a wolf ecotype most likely reflects a wolf's preference to remain in the type of habitat that it was born into.[28]
The gray wolf is a social animal, whose basic social unit consists of a mated pair, accompanied by the pair's adult offspring.[b] The average pack consists of a family of 5–11 animals (1–2 adults, 3–6 juveniles and 1–3 yearlings),[9] or sometimes two or three such families,[4] with exceptionally large packs consisting of up to 42 wolves being known.[74] In ideal conditions, the mated pair produces pups every year, with such offspring typically staying in the pack for 10–54 months before dispersing.[16] Triggers for dispersal include the onset of sexual maturity and competition within the pack for food.[75] The distance travelled by dispersing wolves varies widely; some stay in the vicinity of the parental group, while other individuals may travel great distances of 206 km (128 mi), 390 km (240 mi), and 670 km (420 mi) from their natal packs.[61] A new pack is usually founded by an unrelated dispersing male and female, travelling together in search of an area devoid of other hostile packs.[76] Wolf packs rarely adopt other wolves into their fold, and typically kill them. In the rare cases where other wolves are adopted, the adoptee is almost invariably an immature animal (1–3 years of age) unlikely to compete for breeding rights with the mated pair. In some cases, a lone wolf is adopted into a pack to replace a deceased breeder.[74] During times of ungulate abundance (migration, calving etc.), different wolf packs may temporarily join forces.[9] Studies of wolves' cortisol levels show that they rise significantly when a pack member dies, indicating the presence of stress.[77]
Wolves are highly territorial animals, and generally establish territories far larger than they require to survive in order to assure a steady supply of prey. Territory size depends largely on the amount of prey available and the age of the pack's pups, tending to increase in size in areas with low prey populations[78] or when the pups reach the age of 6 months, thus having the same nutritional needs as adults.[79] Wolf packs travel constantly in search of prey, covering roughly 9% of their territory per day (average 25 km/d (16 mi/d)). The core of their territory is on average 35 km2 (14 sq mi), in which they spend 50% of their time.[78] Prey density tends to be much higher in the territory's surrounding areas, though wolves tend to avoid hunting in the fringes of their range unless desperate, because of the possibility of fatal encounters with neighboring packs.[80] The smallest territory on record was held by a pack of six wolves in northeastern Minnesota, which occupied an estimated 33 km2 (13 sq mi), while the largest was held by an Alaskan pack of ten wolves encompassing a 6,272 km2 (2,422 sq mi) area.[79] Wolf packs are typically settled, and usually only leave their accustomed ranges during severe food shortages.[9]
Wolves defend their territories from other packs through a combination of scent marking, direct attacks and howling (see Communication). Scent marking is used for territorial advertisement, and involves urination, defecation and ground scratching.[81][82][83][84][85] Scent marks are generally left every 240 m (260 yd) throughout the territory on regular travelways and junctions. Such markers can last for 2–3 weeks,[79] and are typically placed near rocks, boulders, trees, or the skeletons of large animals.[9] Territorial fights are among the principal causes of wolf mortality, with one study concluding that 14–65% of wolf deaths in Minnesota and the Denali National Park and Preserve were due to predation by other wolves.[86]
Gray wolves howl to assemble the pack (usually before and after hunts), to pass on an alarm (particularly at a den site), to locate each other during a storm or unfamiliar territory and to communicate across great distances.[119] Wolf howls can under certain conditions be heard over areas of up to 130 km2 (50 sq mi).[4] Wolf howls are generally indistinguishable from those of large dogs.[120] Male wolves give voice through an octave, passing to a deep bass with a stress on "O", while females produce a modulated nasal baritone with stress on "U". Pups almost never howl, while yearling wolves produce howls ending in a series of dog-like yelps.[9] Howling consists of a fundamental frequency that may lie between 150 and 780 Hz, and consists of up to 12 harmonically related overtones. The pitch usually remains constant or varies smoothly, and may change direction as many as four or five times.[48] Howls used for calling pack mates to a kill are long, smooth sounds similar to the beginning of the cry of a great horned owl. When pursuing prey, they emit a higher pitched howl, vibrating on two notes. When closing in on their prey, they emit a combination of a short bark and a howl.[120] When howling together, wolves harmonize rather than chorus on the same note, thus creating the illusion of there being more wolves than there actually are.[119] Lone wolves typically avoid howling in areas where other packs are present.[121] Wolves from different geographic locations may howl in different fashions: the howls of European wolves are much more protracted and melodious than those of North American wolves, whose howls are louder and have a stronger emphasis on the first syllable. The two are however mutually intelligible, as North American wolves have been recorded to respond to European-style howls made by biologists.[122]
Other vocalisations of wolves are usually divided into three categories: growls, barks and whines.[123] Barking has a fundamental frequency between 320–904 Hz,[48] and is usually emitted by startled wolves. Wolves do not bark as loudly or continuously as dogs do, but bark a few times and retreat from perceived danger.[123] Growling has a fundamental frequency of 380–450 Hz,[48] and is usually emitted during food challenges. Pups commonly growl when playing. One variation of the howl is accompanied by a high pitched whine, which precedes a lunging attack.[119] Whining is associated with situations of anxiety, curiosity, inquiry and intimacy such as greeting, feeding pups and playing.[123]
Sources and Credits
- (c) Matt, some rights reserved (CC BY-NC-SA), https://www.flickr.com/photos/furlined/5964580975/
- Adapted by calgaryzoo from a work by (c) Wikipedia, some rights reserved (CC BY-SA), https://en.wikipedia.org/wiki/Canis_lupus
