Post by Vilks on Feb 21, 2014 9:40:06 GMT -6
History
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 the coyote. 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 true wolves derive. 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 the modern-day red wolf, which colonised Eurasia by crossing the Bering land bridge. The new Eurasian C. priscolatrans population gradually evolved into C. mosbachensis, which closely resembled modern wolves found in the Arabian Peninsula and South Asia, which were once distributed in Europe in the early Quaternary glaciation until about 500,000 years ago (see Subspecies). C. mosbachensis subsequently evolved in the direction of C. lupus.
Anatomy
The gray wolf is a slender, powerfully built animal with a large, deeply descending ribcage and a sloping back. Its abdomen is pulled in, and its neck heavily muscled. Its limbs are long and robust, with comparatively small paws. The front paws have five toes each, while the back paws have four. The forelimbs are seemingly pressed into the chest, with the elbows pointed inward, and the feet outward, thus allowing both fore and hind limbs on the same side to swing in the same line. The wolf's legs are moderately longer than those of other canids. This 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. Compared to its smaller 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.
Wolf trotting, Denali National Park. When moving, the wolf generally places its hind paws in the tracks made by the front paws.
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. The canine teeth are robust and relatively short (26 mm). The wolf 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. In cold climates, the wolf can reduce the flow of blood near its skin to conserve body heat. The warmth of the footpads is regulated independently of the rest of the body, and is maintained at just above tissue-freezing point where the pads come in contact with ice and snow.
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. A running wolf holds its head slightly low and cocked to one side, directing one ear forward and the other back. This posture allows the wolf to continually make use of its exceptional hearing.
The 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 colour ranges from almost pure white through various shades of blond, cream, and ochre to grays, browns, and blacks. Variation in fur color tends to increase in higher latitudes. Differences in coat colour between sexes are largely absent, though females may have redder tones. Fur color doesn't seem to serve any camouflage purpose, with some experts concluding that the blended colors have more to do with emphasizing certain gestures during interaction. 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.
Behavior
Although some wolves are solitary, most are highly gregarious animals. The basic social unit of a wolf pack is the mated pair, accompanied by the pair's adult offspring. In ideal conditions, the mated pair produces pups every year, with such offspring typically staying in the pack for 10–54 months before dispersing. The average pack consists of a family of 5–11 animals (1–2 adults, 3–6 juveniles and 1–3 yearlings), or sometimes two or three such families, with exceptionally large packs consisting of 42 wolves being known. 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 stayed in the vicinity of the parental group, while other individuals have been recorded travelling great distances of 390 km, 206 km, and 670 km from their natal packs. A new pack is usually founded by an unrelated 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 (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. During times of ungulate abundance (migration, calving etc.), different wolf packs may temporarily join forces.
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 or when the pups reach the age of 6 months, thus having the same nutritional needs as adults. Wolf packs travel constantly in search of prey, covering roughly 9% of their territory per day (average 25 km/d or 15 mi/d). The core of their territory is on average 35 km2 (14 sq mi), in which they spend 50% of their time. Prey density tends to be much higher in the territory's surrounding areas, though wolves tend to avoid hunting in the fringes of their territory unless desperate, due to the possibility of fatal encounters with neighboring 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 a 6,272 km2 (2,422 sq mi) area. Wolf packs are typically settled, and usually only leave their accustomed ranges during severe food shortages.
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. Scent marks are generally left every 240 metres throughout the territory on regular travelways and junctions. Such markers can last for 2–3 weeks, and are typically placed near rocks, boulders, trees or the skeletons of large animals. When scent marking and howling fail to deter strange wolf packs from entering another's territory, violent interactions can ensue. Territorial fights are among the principal causes of wolf mortality: one study on wolf mortality in Minnesota and the Denali National Park and Preserve concluded that 14–65% of wolf deaths were due to predation by other wolves.
Reproduction
The gray wolf is generally monogamous, with mated pairs usually remaining together for life, unless one of the pair dies. Upon the death of one mated wolf, pairs are quickly re-established. Since males often predominate in any given wolf population, unpaired females are a rarity. If a dispersing male wolf is unable to establish a territory or find a mate, he mates with the daughters of already established breeding pairs from other packs. Such wolves are termed "Casanova wolves" and, unlike males from established packs, they do not form pair bonds with the females they mate with. Some wolf packs may have multiple breeding females this way, as is the case in Yellowstone National Park. Gray wolves also practice alloparental care, in which a wolf pair may adopt the pup or pups of another. This might take place if the original parents die or are for some reason separated from them. This behavior is common and is seen in many other animal species like the elephant.
In addition to heterosexual behavior, homosexual behavior has been observed in wolves. Male wolves often mount each other when the highest ranking female in the pack comes into heat.
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 in order to better exploit abundant resources. This is further demonstrated by the fact that captive wolves have been known to breed as soon as they reach 9–10 months, while the youngest recorded breeding wolves in the wild were 2 years old. Females are capable of producing pups every year, with one litter annually being the average. Unlike the coyote, the gray wolf never reaches reproductive senescence. Estrus typically occurs in late winter, with older, multiparous females entering estrus 2–3 weeks earlier than younger females. When receptive, the female averts the base of her tail to one side, exposing the vulva. During mating, the male's bulbus glandis expands, locking the pair into a copulatory tie which may last 5–36 minutes. Wolves are able to separate from a copulatory tie more readily than domestic dogs. When a male wolf ejaculates, his final pelvic thrust may be slightly prolonged. Ejaculation is induced by pelvic thrusting and undulation of the cervix. After the first ejaculation, the male lifts his leg over the female and faces the opposite direction. The male wolf usually ejaculates multiple times during copulation. Because estrus in wolves lasts only a month, male wolves do not abandon their mates to find other females to inseminate as dogs do.
Pups
During pregnancy, female wolves remain in a den located away from the peripheral zone of their territories, where violent encounters with other packs are more likely. Old females usually whelp in the den of their previous litter, while younger females typically den near their birthplace. The gestation period lasts 62–75 days, with pups usually being born in the summer period. Wolves bear relatively large pups in small litters compared to other canid species. The average litter consists of 5–6 pups, with litter sizes tending to increase in areas where prey is abundant, though exceptionally large litters of 14–17 pups occur only 1% of the time. Pups are usually born in spring, coinciding with a corresponding increase in prey populations. Pups are born blind and deaf, and are covered in short soft grayish-brown fur. They weigh 300–500 grams at birth, and begin to see after 9–12 days. The milk canines erupt after one month. Pups first leave the den after 3 weeks. At 1.5 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 3–4 weeks. Pups 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 3 weeks, though unlike young foxes and coyotes, their bites are inhibited. Actual fights to establish hierarchy usually occur at 5–8 weeks of age. This is in contrast to young foxes and coyotes, which may begin fighting even before the onset of play behavior. By autumn, the pups are mature enough to accompany adults on hunts for large prey.
Hunting
Although social animals, single wolves or mated pairs typically have higher success rates in hunting than do large packs, with single wolves having occasionally been observed to kill large prey such as moose, bison and muskoxen unaided. A wolf hunt can be divided into five stages:
Locating prey: The wolves travel in search of prey through their power of scent, chance encounter, and tracking. Wolves typically locate their prey by scent, though they must usually be directly downwind of it. When a breeze carrying the prey's scent is located, the wolves stand alert, and point their eyes, ears and nose towards their target. In open areas, wolves may precede the hunt with group ceremonies involving standing nose-to-nose and wagging their tails. Once concluded, the wolves head towards their prey.
The stalk: The wolves attempt to conceal themselves as they approach. As the gap between the wolves and their prey closes, the wolves quicken their pace, wag their tails, and peer intently, getting as close to their quarry as possible without making it flee.
The encounter: Once the prey detects the wolves, it can either approach the wolves, stand its ground, or flee. Large prey, such as moose, elk, and muskoxen, usually stand their ground. Should this occur, the wolves hold back, as they require the stimulus of a running animal to proceed with an attack. If the targeted animal stands its ground, the wolves either ignore it, or try to intimidate it into running.
The rush: If the prey attempts to flee, the wolves immediately pursue it. This is the most critical stage of the hunt, as wolves may never catch up with prey running at top speed. If their prey is travelling in a group, the wolves either attempt to break up the herd, or isolate one or two animals from it.
The chase: A continuation of the rush, the wolves attempt to catch up with their prey and kill it. When chasing small prey, wolves attempt to catch up with their prey as soon as possible, while with larger animals, the chase is prolonged, in order to wear the selected prey out. Wolves usually give up chases after 1–2 km (0.62–1.3 mi), though one wolf was recorded to chase a deer for 21 km (13 mi). Both Russian and North American wolves have been observed to drive prey onto crusted ice, precipices, ravines, slopes and steep banks to slow them down.
Killing a caribou in typical fashion: biting the hindquarters (1909 drawing by A. R. Harding)
The actual killing method varies according to prey species. With large prey, mature wolves usually avoid attacking frontally, instead focusing on the rear and sides of the animal. Large prey, such as moose, is killed by biting large chunks of flesh from the soft perineum area, causing massive blood loss. Such bites can cause wounds 10–15 cm in length, with three such bites to the perineum usually being sufficient to bring down a large deer in optimum health. With medium-sized prey such as roe deer or sheep, wolves kill by biting the throat, severing nerve tracks and the carotid artery, thus causing the animal to die within a few seconds to a minute. With small, mouse-like prey, wolves leap in a high arc and imobilize it with their forepaws. When prey is vulnerable and abundant, wolves may occasionally surplus kill. Such instances are common in domestic animals, but rare in the wild. In the wild, surplus killing primarily occurs during late winter or spring, when snow is unusually deep (thus impeding the movements of prey) or during the denning period, when wolves require a ready supply of meat when denbound. Medium-sized prey are especially vulnerable to surplus killing, as the swift throat-biting method by which they are killed allows wolves to quickly kill one animal and move on to another. Surplus killing may also occur when adult wolves are teaching their young to hunt.
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 in order 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, though as it is they who usually work the hardest in killing prey, they may rest after a long hunt and allow the rest of the family to eat unmolested. Once the breeding pair has finished eating, the rest of the family tears off pieces of the carcass and transport them to secluded areas where they can eat in peace. Wolves typically commence feeding by consuming the larger internal organs of their prey, such as the heart, liver, lungs and stomach lining. The kidneys and spleen are eaten once they are exposed, followed by the muscles. A single wolf can eat 15–19% of its body weight in a single feeding.
Information from Wikipedia
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 the coyote. 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 true wolves derive. 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 the modern-day red wolf, which colonised Eurasia by crossing the Bering land bridge. The new Eurasian C. priscolatrans population gradually evolved into C. mosbachensis, which closely resembled modern wolves found in the Arabian Peninsula and South Asia, which were once distributed in Europe in the early Quaternary glaciation until about 500,000 years ago (see Subspecies). C. mosbachensis subsequently evolved in the direction of C. lupus.
Anatomy
The gray wolf is a slender, powerfully built animal with a large, deeply descending ribcage and a sloping back. Its abdomen is pulled in, and its neck heavily muscled. Its limbs are long and robust, with comparatively small paws. The front paws have five toes each, while the back paws have four. The forelimbs are seemingly pressed into the chest, with the elbows pointed inward, and the feet outward, thus allowing both fore and hind limbs on the same side to swing in the same line. The wolf's legs are moderately longer than those of other canids. This 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. Compared to its smaller 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.
Wolf trotting, Denali National Park. When moving, the wolf generally places its hind paws in the tracks made by the front paws.
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. The canine teeth are robust and relatively short (26 mm). The wolf 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. In cold climates, the wolf can reduce the flow of blood near its skin to conserve body heat. The warmth of the footpads is regulated independently of the rest of the body, and is maintained at just above tissue-freezing point where the pads come in contact with ice and snow.
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. A running wolf holds its head slightly low and cocked to one side, directing one ear forward and the other back. This posture allows the wolf to continually make use of its exceptional hearing.
The 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 colour ranges from almost pure white through various shades of blond, cream, and ochre to grays, browns, and blacks. Variation in fur color tends to increase in higher latitudes. Differences in coat colour between sexes are largely absent, though females may have redder tones. Fur color doesn't seem to serve any camouflage purpose, with some experts concluding that the blended colors have more to do with emphasizing certain gestures during interaction. 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.
Behavior
Although some wolves are solitary, most are highly gregarious animals. The basic social unit of a wolf pack is the mated pair, accompanied by the pair's adult offspring. In ideal conditions, the mated pair produces pups every year, with such offspring typically staying in the pack for 10–54 months before dispersing. The average pack consists of a family of 5–11 animals (1–2 adults, 3–6 juveniles and 1–3 yearlings), or sometimes two or three such families, with exceptionally large packs consisting of 42 wolves being known. 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 stayed in the vicinity of the parental group, while other individuals have been recorded travelling great distances of 390 km, 206 km, and 670 km from their natal packs. A new pack is usually founded by an unrelated 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 (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. During times of ungulate abundance (migration, calving etc.), different wolf packs may temporarily join forces.
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 or when the pups reach the age of 6 months, thus having the same nutritional needs as adults. Wolf packs travel constantly in search of prey, covering roughly 9% of their territory per day (average 25 km/d or 15 mi/d). The core of their territory is on average 35 km2 (14 sq mi), in which they spend 50% of their time. Prey density tends to be much higher in the territory's surrounding areas, though wolves tend to avoid hunting in the fringes of their territory unless desperate, due to the possibility of fatal encounters with neighboring 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 a 6,272 km2 (2,422 sq mi) area. Wolf packs are typically settled, and usually only leave their accustomed ranges during severe food shortages.
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. Scent marks are generally left every 240 metres throughout the territory on regular travelways and junctions. Such markers can last for 2–3 weeks, and are typically placed near rocks, boulders, trees or the skeletons of large animals. When scent marking and howling fail to deter strange wolf packs from entering another's territory, violent interactions can ensue. Territorial fights are among the principal causes of wolf mortality: one study on wolf mortality in Minnesota and the Denali National Park and Preserve concluded that 14–65% of wolf deaths were due to predation by other wolves.
Reproduction
The gray wolf is generally monogamous, with mated pairs usually remaining together for life, unless one of the pair dies. Upon the death of one mated wolf, pairs are quickly re-established. Since males often predominate in any given wolf population, unpaired females are a rarity. If a dispersing male wolf is unable to establish a territory or find a mate, he mates with the daughters of already established breeding pairs from other packs. Such wolves are termed "Casanova wolves" and, unlike males from established packs, they do not form pair bonds with the females they mate with. Some wolf packs may have multiple breeding females this way, as is the case in Yellowstone National Park. Gray wolves also practice alloparental care, in which a wolf pair may adopt the pup or pups of another. This might take place if the original parents die or are for some reason separated from them. This behavior is common and is seen in many other animal species like the elephant.
In addition to heterosexual behavior, homosexual behavior has been observed in wolves. Male wolves often mount each other when the highest ranking female in the pack comes into heat.
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 in order to better exploit abundant resources. This is further demonstrated by the fact that captive wolves have been known to breed as soon as they reach 9–10 months, while the youngest recorded breeding wolves in the wild were 2 years old. Females are capable of producing pups every year, with one litter annually being the average. Unlike the coyote, the gray wolf never reaches reproductive senescence. Estrus typically occurs in late winter, with older, multiparous females entering estrus 2–3 weeks earlier than younger females. When receptive, the female averts the base of her tail to one side, exposing the vulva. During mating, the male's bulbus glandis expands, locking the pair into a copulatory tie which may last 5–36 minutes. Wolves are able to separate from a copulatory tie more readily than domestic dogs. When a male wolf ejaculates, his final pelvic thrust may be slightly prolonged. Ejaculation is induced by pelvic thrusting and undulation of the cervix. After the first ejaculation, the male lifts his leg over the female and faces the opposite direction. The male wolf usually ejaculates multiple times during copulation. Because estrus in wolves lasts only a month, male wolves do not abandon their mates to find other females to inseminate as dogs do.
Pups
During pregnancy, female wolves remain in a den located away from the peripheral zone of their territories, where violent encounters with other packs are more likely. Old females usually whelp in the den of their previous litter, while younger females typically den near their birthplace. The gestation period lasts 62–75 days, with pups usually being born in the summer period. Wolves bear relatively large pups in small litters compared to other canid species. The average litter consists of 5–6 pups, with litter sizes tending to increase in areas where prey is abundant, though exceptionally large litters of 14–17 pups occur only 1% of the time. Pups are usually born in spring, coinciding with a corresponding increase in prey populations. Pups are born blind and deaf, and are covered in short soft grayish-brown fur. They weigh 300–500 grams at birth, and begin to see after 9–12 days. The milk canines erupt after one month. Pups first leave the den after 3 weeks. At 1.5 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 3–4 weeks. Pups 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 3 weeks, though unlike young foxes and coyotes, their bites are inhibited. Actual fights to establish hierarchy usually occur at 5–8 weeks of age. This is in contrast to young foxes and coyotes, which may begin fighting even before the onset of play behavior. By autumn, the pups are mature enough to accompany adults on hunts for large prey.
Hunting
Although social animals, single wolves or mated pairs typically have higher success rates in hunting than do large packs, with single wolves having occasionally been observed to kill large prey such as moose, bison and muskoxen unaided. A wolf hunt can be divided into five stages:
Locating prey: The wolves travel in search of prey through their power of scent, chance encounter, and tracking. Wolves typically locate their prey by scent, though they must usually be directly downwind of it. When a breeze carrying the prey's scent is located, the wolves stand alert, and point their eyes, ears and nose towards their target. In open areas, wolves may precede the hunt with group ceremonies involving standing nose-to-nose and wagging their tails. Once concluded, the wolves head towards their prey.
The stalk: The wolves attempt to conceal themselves as they approach. As the gap between the wolves and their prey closes, the wolves quicken their pace, wag their tails, and peer intently, getting as close to their quarry as possible without making it flee.
The encounter: Once the prey detects the wolves, it can either approach the wolves, stand its ground, or flee. Large prey, such as moose, elk, and muskoxen, usually stand their ground. Should this occur, the wolves hold back, as they require the stimulus of a running animal to proceed with an attack. If the targeted animal stands its ground, the wolves either ignore it, or try to intimidate it into running.
The rush: If the prey attempts to flee, the wolves immediately pursue it. This is the most critical stage of the hunt, as wolves may never catch up with prey running at top speed. If their prey is travelling in a group, the wolves either attempt to break up the herd, or isolate one or two animals from it.
The chase: A continuation of the rush, the wolves attempt to catch up with their prey and kill it. When chasing small prey, wolves attempt to catch up with their prey as soon as possible, while with larger animals, the chase is prolonged, in order to wear the selected prey out. Wolves usually give up chases after 1–2 km (0.62–1.3 mi), though one wolf was recorded to chase a deer for 21 km (13 mi). Both Russian and North American wolves have been observed to drive prey onto crusted ice, precipices, ravines, slopes and steep banks to slow them down.
Killing a caribou in typical fashion: biting the hindquarters (1909 drawing by A. R. Harding)
The actual killing method varies according to prey species. With large prey, mature wolves usually avoid attacking frontally, instead focusing on the rear and sides of the animal. Large prey, such as moose, is killed by biting large chunks of flesh from the soft perineum area, causing massive blood loss. Such bites can cause wounds 10–15 cm in length, with three such bites to the perineum usually being sufficient to bring down a large deer in optimum health. With medium-sized prey such as roe deer or sheep, wolves kill by biting the throat, severing nerve tracks and the carotid artery, thus causing the animal to die within a few seconds to a minute. With small, mouse-like prey, wolves leap in a high arc and imobilize it with their forepaws. When prey is vulnerable and abundant, wolves may occasionally surplus kill. Such instances are common in domestic animals, but rare in the wild. In the wild, surplus killing primarily occurs during late winter or spring, when snow is unusually deep (thus impeding the movements of prey) or during the denning period, when wolves require a ready supply of meat when denbound. Medium-sized prey are especially vulnerable to surplus killing, as the swift throat-biting method by which they are killed allows wolves to quickly kill one animal and move on to another. Surplus killing may also occur when adult wolves are teaching their young to hunt.
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 in order 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, though as it is they who usually work the hardest in killing prey, they may rest after a long hunt and allow the rest of the family to eat unmolested. Once the breeding pair has finished eating, the rest of the family tears off pieces of the carcass and transport them to secluded areas where they can eat in peace. Wolves typically commence feeding by consuming the larger internal organs of their prey, such as the heart, liver, lungs and stomach lining. The kidneys and spleen are eaten once they are exposed, followed by the muscles. A single wolf can eat 15–19% of its body weight in a single feeding.
Information from Wikipedia