Wolf

All you need to know about the Wolves

The wolf (Canis lupus), also known as the gray wolf or grey wolf, is a large canine native to Eurasia and North America. It is the largest extant member of Canidae, males averaging 40 kg (88 lb) and females 37 kg (82 lb).

On average, wolves measure 105–160 cm (41–63 in) in length and 80–85 cm (31–33 in) at shoulder height. The wolf is also distinguished from other Canis species by its less pointed ears and muzzle, as well as a shorter torso and a longer tail.

The wolf is nonetheless related closely enough to smaller Canis species, such as the coyote and the golden jackal, to produce fertile hybrids with them.

The banded fur of a wolf is usually mottled white, brown, gray, and black. Up to 38 subspecies of wolf have been recognized including the domestic dog.

Of all members of the genus Canis, the wolf is most specialized for cooperative game hunting as demonstrated by its physical adaptations to tackling large prey, its more social nature, and its highly advanced expressive behaviour.

It travels in nuclear families consisting of a mated pair accompanied by their offspring. Offspring may leave to form their packs on the onset of sexual maturity and in response to competition for food within the pack. Wolves are also territorial and fights over territory are among the principal causes of wolf mortality. The wolf is mainly a carnivore and feeds primarily on large wild hooved mammals, though it also eats smaller animals, livestock, carrion, and garbage.

Single wolves or mated pairs typically have higher success rates in hunting than do large packs. Pathogens and parasites, notably rabies, may infect wolves.

The global wolf population was estimated to be 300,000 in 2003 and is considered to be of Least Concern by the International Union for Conservation of Nature (IUCN).

Wolves have a long history of interactions 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.

Although the fear of wolves exists in many human societies, the majority of recorded attacks on people have been attributed to animals suffering from rabies.

Wolf attacks on humans are rare because wolves are relatively few, live away from people, and have developed a fear of humans because of their experiences with hunters, ranchers, and shepherds.

Wolves Documentary Film

Evolution

The phylogenetic descent of the extant wolf C. lupus from C. etruscus through C. mosbachensis is widely accepted.

The earliest fossils of C. lupus were found in what was once eastern Beringia at Old Crow, Yukon, Canada, and at Cripple Creek Sump, Fairbanks, Alaska.

The age is not agreed upon but could date to one million years ago. Considerable morphological diversity existed among wolves by the Late Pleistocene.

They had more robust skulls and teeth than modern wolves, often with a shortened snout, a pronounced development of the temporalis muscle, and robust premolars. It is proposed that these features were specialized adaptations for the processing of carcass and bone associated with the hunting and scavenging of Pleistocene megafauna.

Compared with modern wolves, some Pleistocene wolves showed an increase in tooth breakage that is similar to that seen in the extinct dire wolf.

This suggests that they either often processed carcasses, or that they competed with other carnivores and needed to consume their prey quickly. Compared with those found in the modern spotted hyena, the frequency and location of tooth fractures found in these wolves indicates that they were habitual bone crackers.

Genomic studies suggest that modern wolves and dogs descend from a common ancestral wolf population that existed 20,000 years ago.

Studies in 2017 and 2018 found that the Himalayan wolf is part of a lineage that is basal to other wolves and split from them 691,000–740,000 years ago.

Other wolves appear to have originated in Beringia in an expansion that was driven by the huge ecological changes that occurred during the close of the Late Pleistocene.

A study in 2016 indicates that a population bottleneck was followed by a rapid radiation from an ancestral population at a time during, or just after, the Last Glacial Maximum.

This implies that the original morphologically diverse wolf populations were out-competed and replaced by more modern wolves.

A 2016 genomic study suggests that Old World and New World wolves split around 12,500 years ago followed by the divergence of the lineage that led to dogs from other Old World wolves around 11,100–12,300 years ago.

An extinct Late Pleistocene wolf may have been the ancestor of the dog, with the dog's similarity to the extant wolf being the result of genetic admixture between the two.

The dingo, Basenji, Tibetan Mastiff and Chinese indigenous breeds are basal members of the domestic dog clade. The divergence time for wolves in Europe, the Middle East and Asia is estimated to be fairly recent at around 1,600 years ago.

Among New World wolves, the Mexican wolf diverged around 5,400 years ago.

Distribution and Habitat

Wolves occurred originally across Eurasia and North America. Deliberate human persecution because of livestock predation and fear of attacks on humans has reduced the wolf's range to about one-third of what it once was.

The wolf is now extirpated (locally extinct) in much of Western Europe, the United States and Mexico, and in Japan. In modern times, the wolf occurs mostly in wilderness and remote areas. The wolf can be found between sea level and 3,000 m (9,800 ft).

It lives in forests, inland wetlands, shrublands, grasslands (including Arctic tundra), pastures, deserts, and rocky peaks on mountains.

Habitat use by wolves depends on the abundance of prey, snow conditions, livestock densities, road densities, human presence and topography.

Behaviour and Ecology

The wolf is a social animal.

Its populations consist of packs and lone wolves, most lone wolves being temporarily alone while they disperse from packs to form their own or join another one.

The wolf's basic social unit is the nuclear family consisting of a mated pair accompanied by their offspring.

The average pack size in North America is eight wolves and in Europe five to six wolves.

The average pack across Eurasia consists of a family of five to 11 wolves (two adults, three to six juveniles, and one to three yearlings), or sometimes two or three such families, with examples of exceptionally large packs consisting of up to 42 wolves being known.

Cortisol levels in wolves rise significantly when a pack member dies, indicating the presence of stress. During times of prey abundance caused by calving or migration, different wolf packs may join together temporarily.

Offspring typically stay in the pack for 10–54 months before dispersing.

Triggers for dispersal include the onset of sexual maturity and competition within the pack for food.

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 upwards of 206 km (128 mi), 390 km (240 mi), and 670 km (420 mi) from their natal (birth) packs.

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.

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 of one to three years old, and unlikely to compete for breeding rights with the mated pair.

This usually occurs between the months of February and May. Adoptee males may mate with an available pack female and then form their own pack. In some cases, a lone wolf is adopted into a pack to replace a deceased breeder.

Wolves are territorial and generally establish territories far larger than they require to survive assuring a steady supply of prey.

Territory size depends largely on the amount of prey available and the age of the pack's pups. They tend to increase in size in areas with low prey populations, or when the pups reach the age of six months when they have the same nutritional needs as adults.

Wolf packs travel constantly in search of prey, covering roughly 9% of their territory per day, on average 25 km/d (16 mi/d). The core of their territory is on average 35 km2 (14 sq mi) where they spend 50% of their time.

Prey density tends to be much higher on the territory's periphery. Except out of desperation, wolves tend to avoid hunting on the fringes of their range to avoid fatal confrontations with neighbouring packs.

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 6,272 km2 (2,422 sq mi).

Wolf packs are typically settled, and usually only leave their accustomed ranges during severe food shortages.

Wolves advertise their territories to other packs through howling and scent marking. Scent marking involves urine, feces, and anal gland scents.

This is more effective at advertising territory than howling and is often used in combination with scratch marks. Wolves increase their rate of scent marking when they encounter the marks of wolves from other packs.

Lone wolves will rarely mark, but newly bonded pairs will scent mark the most.

These marks are generally left every 240 m (260 yd) throughout the territory on regular travelways and junctions. Such markers can last for two to three weeks, and are typically placed near rocks, boulders, trees, or the skeletons of large animals.

Territorial fights are among the principal causes of wolf mortality, one study concluding that 14–65% of wolf deaths in Minnesota and the Denali National Park and Preserve were due to other wolves.

Wolves communicate to anticipate what their pack mates or other wolves might do next.

This includes the use of vocalization, body posture, scent, touch, and taste.

The phases of the moon have no effect on wolf vocalization, and despite popular belief, wolves do not howl at the moon.

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, while crossing unfamiliar territory, and to communicate across great distances.

Wolf howls can under certain conditions be heard over areas of up to 130 km2 (50 sq mi).

Other vocalizations include growls, barks and whines. Wolves do not bark as loudly or continuously as dogs do in confrontations, rather barking a few times and then retreating from a perceived danger.

Aggressive or self-assertive wolves are characterized by their slow and deliberate movements, high body posture and raised hackles, while submissive ones carry their bodies low, flatten their fur, and lower their ears and tail.

Raised leg urination is considered to be one of the most important forms of scent communication in the wolf, making up 60–80% of all scent marks observed.

Diet

Like all land mammals that are pack hunters, the wolf feeds predominantly on wild herbivorous hoofed mammals that can be divided into large size 240–650 kg (530–1,430 lb) and medium size 23–130 kg (51–287 lb), and have a body mass similar to that of the combined mass of the pack members.

The wolf specializes in preying on the vulnerable individuals of large prey, with a pack of 15 able to bring down an adult moose.

The variation in diet between wolves living on different continents is based on the different varieties of hoofed mammals and of smaller and domestic prey that are available.

In North America, the wolf's diet is dominated by wild large hoofed mammals and medium-sized mammals.

In Asia and Europe, their diet is dominated by wild medium-sized hoofed mammals and domestic species. The wolf depends on wild species, and if these are not readily available, as in Asia, the wolf is more reliant on domestic species.

Across Eurasia, wolves prey mostly on moose, red deer, roe deer and wild boar.

In North America, important range-wide prey are elk, moose, caribou, white-tailed deer and mule deer.

Wolves can digest their meal in a few hours and can feed several times in one day, making quick use of large quantities of meat.

A well-fed wolf stores fat under the skin, around the heart, intestines, kidneys, and bone marrow, particularly during the autumn and winter.

Nonetheless, wolves are not fussy eaters. Smaller-sized animals that may supplement their diet include rodents, hares, insectivores and smaller carnivores. They frequently eat waterfowl and their eggs.

When such foods are insufficient, they prey on lizards, snakes, frogs, and large insects when available.

Wolves in northern Minnesota prey on northern pike in freshwater streams.

The diet of coastal wolves in Alaska includes 20% salmon, while those of coastal wolves in British Columbia includes 25% marine sources, and those on the nearby islands 75%.

In Europe, wolves eat apples, pears, figs, melons, berries and cherries. In North America, wolves eat blueberries and raspberries. Wolves also eat grass, which may provide some vitamins.

They are known to eat the berries of mountain-ash, lily of the valley, bilberries, cowberries, European black nightshade, grain crops, and the shoots of reeds.

In times of scarcity, wolves will readily eat carrion.

In Eurasian areas with dense human activity, many wolf populations are forced to subsist largely on livestock and garbage.

Prey in North America continue to occupy suitable habitats with low human density, the wolves eating livestock and garbage only in dire circumstances.

Cannibalism is not uncommon in wolves during harsh winters, when packs often attack weak or injured wolves, and may eat the bodies of dead pack members.

Hunting

Single wolves or mated pairs typically have higher success rates in hunting than do large packs; single wolves have occasionally been observed to kill large prey such as moose, bison and muskoxen unaided.

This contrasts with the commonly held belief that larger packs benefit from cooperative hunting to bring down large game.

The size of a wolf hunting pack is related to the number of pups that survived the previous winter, adult survival, and the rate of dispersing wolves leaving the pack. The optimal pack size for hunting elk is four wolves, and for bison a large pack size is more successful.

As well as their physical adaptations for hunting hoofed mammals, wolves possess certain behavioural, cognitive, and psychological adaptations to assist with their hunting lifestyle. Wolves are excellent learners that match or outperform domestic dogs.

They can use gaze to focus attention on where other wolves are looking. This is important because wolves do not use vocalization when hunting. In laboratory tests they appear to exhibit insight, foresight, understanding, and the ability to plan.

To survive, wolves must be able to solve two problems—finding a prey animal, then confronting it.

Tracking

Wolves move around their territory when hunting, using the same trails for extended periods.

After snowfalls, wolves find their old trails and continue using them. These follow the banks of rivers, the shorelines of lakes, through ravines overgrown with shrubs, through plantations, or roads and human paths.

Wolves are nocturnal predators. During the winter, a pack will commence hunting in the twilight of early evening and will hunt all night, traveling tens of kilometers. Sometimes hunting large prey occurs during the day. During the summer, wolves generally tend to hunt individually, ambushing their prey and rarely giving pursuit.

The wolf usually travels at a loping pace, placing one of its paws directly in front of the other. This gait can be maintained for hours at a rate of 8–9 km/h (5.0–5.6 mph).

On bare paths, a wolf can quickly achieve speeds of 50–60 km/h (31–37 mph). The wolf has a running gait of 55–70 km/h (34–43 mph), can leap 5 m (16 ft) horizontally in a single bound, and can maintain rapid pursuit for at least 20 minutes.

A wolf's foot is large and flexible, which allows it to tread on a wide variety of terrain. A wolf's legs are long compared to their body size allowing them to travel up to 76 km (47 mi) in 12 hours.

This adaptation allows wolves to locate prey within hours, but it can take days to find prey that can be killed without great risk.

Moose and deer live singly in the summer. Caribou live in herds of thousands which presents dangers for wolves. Elk live in small herds and these are a safer target.

Wolves carry their heads at the same level as their back, raising it only when alert.

In one study, wolves detected moose using scent 10 times, vision six times, and once by following tracks in the snow. Their vision is as good as that of humans, and they can smell prey at least 2.4 km (1.5 mi) away. One wolf travelled to a herd 103 km (64 mi) away.

A human can detect the smell of a forest fire over the same distance if it is downwind. The wolf's sense of smell is at least comparable to that of the domestic dog. Both have a sense of smell at least 10,000 times more sensitive than that of humans.

Feeding

Once prey is brought down, wolves begin to feed excitedly, ripping and tugging at the carcass in all directions, and bolting down large chunks of it.

The breeding pair typically monopolizes food to continue producing pups. When food is scarce, this is done at the expense of other family members, especially non-pups.

The breeding pair typically eats first. They usually work the hardest at killing prey, and may rest after a long hunt and allow the rest of the family to eat undisturbed.

Once the breeding pair has finished eating, the rest of the family tears off pieces of the carcass and transports them to secluded areas where they can eat in peace.

Wolves typically commence feeding by consuming the larger internal organs, like the heart, liver, lungs, and stomach lining. The kidneys and spleen are eaten once they are exposed, followed by the muscles. A wolf can eat 15–19% of its body weight in a single feeding.

Reproduction

Wolves are monogamous, mated pairs usually remaining together for life. Should one of the pair die, another mate is found quickly.

With wolves in the wild, inbreeding does not occur where outbreeding is possible.

Wolves become mature at the age of two years and sexually mature from the age of three years.

The age of first breeding in wolves depends largely on environmental factors: when food is plentiful, or when wolf populations are heavily managed, wolves can rear pups at younger ages to better exploit abundant resources. Females are capable of producing pups every year, one litter annually being the average.

Oestrus and rut begin in the second half of winter and lasts for two weeks.

Dens are usually constructed for pups during the summer period. When building dens, females make use of natural shelters like fissures in rocks, cliffs overhanging riverbanks and holes thickly covered by vegetation. Sometimes, the den is the appropriated burrow of smaller animals such as foxes, badgers or marmots. An appropriated den is often widened and partly remade.

On rare occasions, female wolves dig burrows themselves, which are usually small and short with one to three openings. The den is usually constructed not more than 500 m (550 yd) away from a water source.

It typically faces southwards where it can be better warmed by sunlight exposure, and the snow can thaw more quickly. Resting places, play areas for the pups, and food remains are commonly found around wolf dens.

The odor of urine and rotting food emanating from the denning area often attracts scavenging birds like magpies and ravens. Though they mostly avoid areas within human sight, wolves have been known to nest near domiciles, paved roads and railways.

During pregnancy, female wolves remain in a den located away from the peripheral zone of their territories, where violent encounters with other packs are less likely to occur.

The gestation period lasts 62–75 days with pups usually being born in the spring months or early summer in very cold places such as on the tundra. Young females give birth to four to five young, and older females from six to eight young and up to 14. Their mortality rate is 60–80%.

Newborn wolf pups look similar to German Shepherd Dog pups.

They are born blind and deaf and are covered in short soft grayish-brown fur.

They weigh 300–500 g (11–18 oz) at birth and begin to see after nine to 12 days. The milk canines erupt after one month. Pups first leave the den after three weeks. At one-and-a-half months of age, they are agile enough to flee from danger.

Mother wolves do not leave the den for the first few weeks, relying on the fathers to provide food for them and their young. Pups begin to eat solid food at the age of three to four weeks. They have a fast growth rate during their first four months of life: during this period, a pup's weight can increase nearly 30 times.

Wolf pups begin play-fighting at the age of three weeks, though unlike young coyotes and foxes, their bites are gentle and controlled. Actual fights to establish hierarchy usually occur at five to eight weeks of age.

This is in contrast to young coyotes and foxes, which may begin fighting even before the onset of play behaviour. By autumn, the pups are mature enough to accompany the adults on hunts for large prey.