understanding what we are, part five

Gray Wolf
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(Redirected from Wolf)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Family: Canidae
Genus: Canis
Species: C. lupus

Binomial name
Canis lupus
Linnaeus, 1758
The Gray Wolf (Canis lupus; also spelled Grey Wolf, see spelling differences; also known as Timber Wolf or Wolf) is a mammal in the order Carnivora. The Gray Wolf shares a common ancestry with the domestic dog (Canis lupus familiaris), as evidenced by DNA sequencing and genetic drift studies.[2] Gray wolves were once abundant and distributed over much of North America, Eurasia, and the Middle East. Today, for a variety of human-related reasons including widespread habitat destruction and excessive hunting, wolves inhabit only a very limited portion of their former range.

The Gray Wolf, being a keystone predator, is an integral component of the ecosystems to which it typically belongs. The wide range of habitats in which wolves can thrive reflects their adaptability as a species, and includes temperate forests, mountains, tundra, taiga, and grasslands. In the contiguous United States, with the exception of Minnesota and Wisconsin (where they have a threatened status), they are listed as endangered under the Endangered Species Act of 1973. They continue to be hunted in many areas of the world as perceived threats to livestock and humans, as well as for sport.

Anatomy, physiology, and reproduction

Features and adaptations
Wolf weight and size can vary greatly worldwide, though both tend to increase proportionally with higher latitudes. Generally speaking, height varies from 0.6–0.8 meters (26–32 inches) at the shoulder, and weight can range anywhere from 23–59 kilograms (50–130 pounds), making wolves the largest among all wild canids.[3] Although rarely encountered, extreme specimens reaching over 77 kg (170 lb) have been recorded in Alaska and Canada,[4] and the heaviest wolf on record, which was killed in Alaska in 1939, weighed 80 kg (175 lb).[5] The smallest wolves come from the Arabian Wolf subspecies, the females of which may weigh as little as 10 kg (22 lb) at maturity. Customarily, however, wolves will be of a more typical physical capacity, with the females in a given population weighing about 20% less than their male counterparts.[6] Wolves can measure anywhere from 1.3–2 meters (4.5–6.5 feet) from nose to tail tip, with the tail itself consisting of approximately one quarter of overall body length.[7]

Wolves are built for stamina, possessing features tailored for long-distance travel. Narrow chests and powerful backs and legs contribute to the wolf's proficiency for efficient locomotion. They are capable of covering several miles trotting at about a 10 km/h (6 mph) pace, though they have been known to reach speeds approaching 65 km/h (40 mph) during a chase (wolves only run fast when testing potential prey).[8] While sprinting thus, wolves can cover up to 5 meters (16 ft) per bound.

Wolves usually have blended pelages.Wolf paws are able to traverse easily through a wide variety of terrains, especially snow. There is a slight webbing between each toe, which allows wolves to move over snow more easily than comparatively hampered prey. Wolves are digitigrade, so the relative largeness of their feet helps to better distribute their weight on snowy surfaces. The front paws are larger than the hind paws, and feature a fifth digit, a 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.[10] Furthermore, scent glands located between a wolf's toes leave trace chemical markers behind, thereby helping the wolf to effectively navigate over large expanses while concurrently keeping others informed of its whereabouts.

A wolf sometimes seems more massive than it actually is due to its bulky coat, which is made of two layers. The first layer consists of tough guard hairs designed to repel water and dirt. The second is a dense, water-resistant undercoat that insulates. 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.

Coloration varies greatly, and runs 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.


Adolescent wolf with golden-yellow eyes.At birth, wolf pups tend to have darker fur and blue eyes that will change to a yellow-gold or orange color when the pups are 8–16 weeks old.[11] Though extremely unusual, it is possible for an adult wolf to retain its blue-colored eyes.[12]

Wolves have stout, blocky muzzles that help distinguish them from coyotes and dogs. Wolves also differ in certain skull dimensions, having a smaller orbital angle, for example, than dogs (>53 degrees for dogs compared to <45 degrees for wolves) while possessing a comparatively larger brain capacity.[13] Larger paw size, yellow eyes, longer legs, and bigger teeth further distinguish adult wolves from other canids, particularly 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.[14] 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. Powered by 1500 lb/sq. inch of pressure, a wolf's teeth are its main weapons as well as its primary tools.[5] Therefore, any injury to the jaw line or teeth could devastate an individual, dooming it to starvation or incompetence.


[edit] Courtship and mating
Usually, the instinct to pass on genetic material 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 who reached sexual maturity during the previous breeding season. It takes two such dispersals from two different packs for the process to take place, as dispersing wolves from the same maternal pack tend not to mate.[15] Once two dispersing wolves meet and begin traveling together, they immediately begin the process of seeking out territory, preferentially doing so in time for the next mating season. The bond that forms between such wolves often lasts for the shorter of the two lifetimes, with few exceptions.[16]

During the mating season, breeding wolves become extremely affectionate with one another in anticipation for the female's ovulation cycle. Overall, pack tension rises, as each mature wolf begins to feel the urge to mate. In fact, during this time, the alpha male and alpha female may be forced to aggressively prevent other wolves from mating with each other.[15] Under normal circumstances, a pack can only support one litter per year, so this type of dominance behavior is beneficial in the long run.[15]

When the alpha female goes into estrus—a phenomenon that occurs once per year and lasts 5–14 days,[17]—she and her mate will spend an increased amount of time in seclusion. Pheromones in the female's urine and the swelling of her vulva let the male know when his mate is in heat. She will be unreceptive for the first few days of estrus, during which time she sheds the lining of her uterus. Once the female begins to ovulate, mating occurs.

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 penis— 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 10–30 minutes, during which period the male will ejaculate multiple times.[18][19] 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.[19] The mating ordeal is repeated many times throughout the female's brief ovulation period, which occurs once per year per female, unlike female dogs, with whom estrus usually occurs twice per year.