Gray Wolf

The gray wolf 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. 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. It is listed as a species of least concern for extinction worldwide. For some regions including the Continental United States, the species is listed as endangered or threatened.

The Gray Wolf 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. These habitats include temperate forests, mountains, tundra, taiga, and grasslands. In the much of the world, with the exception of Northern regions, they are listed as endangered. They continue to be hunted in many areas of the world as perceived threats to livestock and humans, as well as for sport.

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 26 to 32 inches (0.6 to 0.8 m) at the shoulder, and weight can range anywhere from 50 to 130 lb (23 to 59 kg). This makes wolves the largest among all wild canids. Although rarely encountered, extreme specimens reaching over 170 lb (77 kg) have been recorded in Alaska and Canada. The smallest wolves come from the Arabian Wolf subspecies, the females of which may weigh as little as 22 lb (10 kg) at maturity. Females in a given population typically weigh about 20% less than their male counterparts. Wolves can measure anywhere from 4.5 to 6.5 feet (1.3 to 2 m) from nose to tail tip, with the tail itself accounting for approximately one quarter of overall body length.

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 6mph (10 km/h) pace, though they have been known to reach speeds approaching 40 mph (65 km/h) during a chase (wolves only run fast when testing potential prey). While sprinting thus, wolves can cover up to 16 feet (5 m) per bound.

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 stand and walk on their toes, 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. This is known as a dewclaw and it is absent on hind paws. Bristled hairs and blunt claws enhance grip on slippery surfaces, and special blood vessels keep paw pads from freezing. 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. The color varies 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.

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 to 16 weeks old. Though extremely unusual, it is possible for an adult wolf to retain its blue-colored eyes.

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.


Wolves howl for several reasons. Howling helps pack members keep in touch, allowing them to effectively communicate in thickly forested areas or over great distances. Furthermore, howling helps to summon pack members to a specific location. Howling can also serve as a declaration of territory. This is portrayed by a dominant wolf’s tendency to respond to a human imitation of a “rival” individual in an area that the wolf considers its own. This behavior is also stimulated when a pack has something to protect, such as a fresh kill. As a rule of thumb, large packs will more readily draw attention to themselves than will smaller packs. Adjacent packs may respond to each other’s howls, which can mean trouble for the smaller of the two. Thus, wolves tend to howl with great care.

Wolves will also howl for communal reasons. Some scientists speculate that such group sessions strengthen the wolves’ social bonds and camaraderie. This is similar to community singing among humans. During such choral sessions, wolves will howl at different tones and varying pitches, which tends to prevent a listener from accurately estimating the number of wolves involved. This concealment of numbers makes a listening rival pack wary of what action to take.

Observations of wolf packs suggest that howling occurs most often during the twilight hours, preceding the adults’ departure to the hunt and following their return. Studies also show that wolves howl more frequently during the breeding season and subsequent rearing process. The pups themselves begin howling soon after emerging from their dens and can be provoked into howling sessions relatively easily over the following two months. Such indiscriminate howling usually has a communicative intent, and has no adverse consequences so early in a wolf’s life. Howling becomes less indiscriminate as wolves learn to distinguish howling pack members from rival wolves.

Other vocalizations

Growling, used in tandem with bared teeth, is the most visual and effective warning wolves use. Wolf growls have a distinct, deep, bass-like quality, and are used much of the time as a threat, though they are not always necessarily used for defense. Wolves will also growl at other wolves while being aggressively dominant.

Wolves also bark, which they do when nervous or to warn other wolves of danger. Wolves bark very discreetly, and will not generally bark loudly or repeatedly as dogs do. They use a low-key, breathy “whuf” sound to get attention immediately from other wolves. Wolves will also “bark-howl” by adding a brief howl to the end of a bark. Wolves bark-howl for the same reasons they normally bark. Actually, pups bark and bark-howl much more frequently than adults. They use such vocalizations as cries for attention, care, or food.

Wolves can also whimper, which they usually do only while submitting to other wolves. Wolf pups will whimper when they need a reassurance of security from their parents or other wolves.

The pack

Wolves function as social predators and hunt in packs organized according to strict, rank-oriented social hierarchies. It was originally thought that this comparatively high level of social organization had more to do with hunting success. While this still may be true to a certain extent, emerging theories suggest that the pack has less to do with hunting and more to do with reproductive success.

The two individuals that sit atop the social hierarchy lead the pack. These two individuals are called the alpha male and the alpha female. The alpha pair has the greatest amount of social freedom compared to the rest of the pack, but they are not “leaders” in the human sense of the term. The alphas do not give the other wolves orders. They simply have the most freedom in choosing where to go, what to do, and when to do it. Possessing strong instincts for fellowship, the rest of the pack usually follows.

The size of the pack may change over time and is controlled by several factors. These factors include habitat, personalities of individual wolves within a pack, and food supply. Packs can contain 2 to 20 wolves, though an average pack consists of 6 or 7. New packs are formed when a wolf leaves its birth pack and claims a territory. Lone wolves searching for other individuals can travel very long distances seeking out suitable territories. Dispersing individuals must avoid the territories of other wolves because intruders on occupied territories are chased away or killed.


Today, there are over 300 wolves in the Greater Yellowstone Ecosystem and over 500 in Idaho. Both populations have long since met their recovery goals and the reintroduction experiment has been a resounding success.