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Gray Wolf
The 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 member of the genus Canis and also the most well known of wolves. Its shoulder height ranges from 0.6 to 0.9 meters (26–36 inches) and its weight typically varies between 32 and 62 kilograms (70–135 pounds). As evidenced by DNA sequencing and genetic drift studies, the gray wolf shares a common ancestry with the domestic dog (Canis lupus familiaris).
The gray wolf was once abundant over much of North America and Eurasia. However, as a result of habitat destruction and widespread hunting, it now inhabits a very limited portion of its former range. In some regions, gray wolves are listed as endangered or threatened, although considered as a whole, wolves are regarded as a species of least concern for extinction according to the International Union for the Conservation of Nature and Natural Resources. Wolves are still hunted in many areas of the world for sport and as perceived threats to livestock. Kazakhstan is currently thought to have the largest wolf population of any nation in the world, with as many as 90,000, versus some 60,000 for Canada, which is three and a half times larger.
Being apex predators, gray wolves are integral components of the ecosystems they typically occupy. The diversity of such ecosystems reflects its adaptability as a species, as the ecosystems in which wolves have been known to thrive include, but are not limited to, temperate forests, deserts, mountains, tundra, taiga, and grasslands.
Wolves feature in folklore and mythology of cultures ancient to modern across the northern hemisphere; from the Norse legend of the giant Fenrir to more sympathetic depictions in Central Asia and the suckling of Romulus and Remus in the foundation of Rome. More familiar still are the fairy tales where the wolf appears as a villain such as Little Red Riding Hood and the Three Little Pigs. Wolf legends have also given rise to the popular horror figure of the werewolf.
Behavior and physiology
Wolf weight and size can vary greatly worldwide, tending to increase proportionally with latitude as predicted by Bergmann's Rule. In general, height varies from 0.6 to 0.95 meters (26–38 inches) at the shoulder and weight ranges from 32 to 62 kilograms (70–135 pounds), which together make the gray wolf the largest of all wild canids. Although rarely encountered, extreme specimens of more than 77 kg (170 lb) have been recorded in Alaska and Canada. The heaviest wild wolf on record, killed in Alaska in 1939, was 80 kg (175 lb). The smallest wolves come from the Arabian Wolf subspecies, the females of which may weigh as little as 10 kg (22 lb) at maturity. Females in any given wolf population typically weigh about 20% less than their male counterparts. Wolves can measure anywhere from 1.3 to 2 meters (4.5–6.5 feet) from nose to the tip of the tail, which itself accounts for approximately one quarter of overall body length.
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. While thus sprinting, wolves can cover up to 5 meters (16 ft) per bound.
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. 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, 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 designed to 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. North American wolves typically have longer, silkier fur than their Eurasian counterparts.
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 certainly not uncommon for an individual or an entire population to be entirely one color (usually all black or all white). 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. Though extremely unusual, it is possible for an adult wolf to retain its blue-colored irises.
Wolves' long, powerful muzzles help distinguish them from other canids, particularly coyotes and golden jackals, which have more narrow, pointed muzzles. 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.[19] 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 are designed to hold and subdue the prey. Capable of delivering up to 10,000 kPa (1450 lb/sq. inch) of pressure, a wolf's teeth are its main weapons as well as its primary tools.[6] Therefore, any injury to the jaw line or teeth could devastate a wolf, dooming it to starvation or incapacity.
Reproductive physiology and life cycle
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. The bond that forms between these wolves often lasts until one of them dies.
Generally, mating occurs between January and April — the higher the latitude, the later it occurs. A pack usually produces a single litter unless the alpha 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, in fact, the alpha male and alpha female may be forced to prevent other wolves from mating with one another. Under normal circumstances, a pack can only support one litter per year, so this dominance behavior is beneficial in the long run.
When the alpha 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 male wolf will mount the female firmly from behind. After achieving coitus, the two form a copulatory tie once the male's bulbus glandis—an erectile tissue located near the base of the canine p***s—swells and the female's vaginal muscles tighten. Ejaculation is induced by the thrusting of the male's pelvis and the undulation of the female's cervix. The two become physically inseparable for anywhere from 10 to 30 minutes, during which the male will ejaculate multiple times. After the initial ejaculation, the male may lift one of his legs over the female such that they are standing end-to-end; this is believed to be a defensive measure. The mating ritual is repeated many times throughout the female's brief ovulation period, which occurs once per year per female—unlike female dogs, whose estrus usually occurs twice per year.
The gestation period lasts between 60 and 63 days. The pups, at a weight of 0.5 kg (1 lb), are born blind, deaf, and completely dependent on their mother. There can be anywhere from 1 to 14 pups per litter, with the average litter size being about 4 to 6. Pups reside in the den and stay there for no longer than two months. The den is usually on high ground near an open water source, and has an open "room" 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. They begin eating regurgitated foods after 2 weeks — by which 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 8 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, or, less often, coyotes, foxes, 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 be killed by other predators occasionally, rival wolf packs are often their most dangerous non-human enemy. A study on wolf mortality concluded that 14–65% of wolf deaths were inflicted by other wolves.
Wolves are susceptible to the same infections that affect domestic dogs, such as mange, heartworm, rabies, parvovirus and canine distemper. Epidemics of these can drastically reduce wolf populations in a given area. Wolves are reported to carry over 50 types of parasites, including echinococci, cysticercocci, coeruni (all of which can attach humans) and the trichinellidae family.
Behavior - Body Language
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.
* Dominance – A dominant wolf stands stiff legged and tall. The ears are erect and forward, and the hackles bristle slightly. Often the tail is held vertically and curled toward the back. This display asserts the wolf's rank to others in the pack. A dominant wolf may stare at a submissive one, pin it to the ground, "ride up" on its shoulders, or even stand on its hind legs.
* Submission (active) – During active submission, the entire body is lowered, and the lips and ears are drawn back. Sometimes active submission is accompanied by muzzle licking, or the rapid thrusting out of the tongue and lowering of the hindquarters. The tail is placed down, or halfway or fully between the legs, and the muzzle often points up to the more dominant animal. The back may be partly arched as the submissive wolf humbles itself to its superior; a more arched back and more tucked tail indicate a greater level of submission.
* Submission (passive) – Passive submission is more intense than active submission. The wolf rolls on its back and exposes its vulnerable throat and underside. The paws are drawn into the body. This posture is often accompanied by whimpering.
* Anger – An angry wolf's ears are erect, and its fur bristles. The lips may curl up or pull back, and the incisors are displayed. The wolf may also arch its back, lash out, or snarl.
* Fear – A frightened wolf attempts to make itself look small and less conspicuous; the ears flatten against the head, and the tail may be tucked between the legs, as with a submissive wolf. There may also be whimpering or barks of fear, and the wolf may arch its back.
* Defensive – A defensive wolf flattens its ears against its head.
* Aggression – An aggressive wolf snarls and its fur bristles. The wolf may crouch, ready to attack if necessary.
* Suspicion – Pulling back of the ears shows a wolf is suspicious. The wolf also narrows its eyes. The tail of a wolf that senses danger points straight out, parallel to the ground.
* Relaxedness – A relaxed wolf's tail points straight down, and the wolf may rest sphinx-like or on its side. The wolf may also wag its tail. The further down the tail droops, the more relaxed the wolf is.
* Tension – An aroused wolf's tail points straight out, and the wolf may crouch as if ready to spring.
* Happiness – As dogs do, a wolf may wag its tail if in a joyful mood. The tongue may loll out of the mouth.
* Hunting – A wolf that is hunting is tensed, and therefore the tail is horizontal and straight.
* Playfulness – A playful wolf holds its tail high and wags it. The wolf may frolic and dance around, or bow by placing the front of its body down to the ground, while holding the rear high, sometimes wagged. This resembles the playful behavior of domestic dogs.
To learn more about wolves such as the gray wolf, visit http://en.wikipedia.org/wiki/Wolf
 lady_inuyasha_sama · Fri Nov 16, 2007 @ 08:31pm · 0 Comments |
