GRAY WOLF
Also called the timber wolf, gray wolves are the largest members of the canine family. Devoted parents and families, they are also among the most social carnivores. Once possessed of the greatest range of any terrestrial mammals except humans, they are now restricted in North America mainly to Alaska, Canada and wilderness in the northern United States.
Physical Description
Depending on habitat location, the coloration of gray wolves can range from white to black with the majority exhibiting light brown or gray coloration. Their coloration provides camouflage while hunting. Being hidden is helpful when packs of wolves hunt at night to catch prey as a team, or lead prey into the remaining members of the pack as a trap.
Size
The largest members of the canine family, male wolves weigh males between 65 and 175 pounds (30 to 80 kilograms) and females weigh between 50 and 120 pounds (23 to 55 kilograms). They measure from 4 feet 3 inches to 6 feet 9 inches (130 to 205 centimeters) in total length.
Native Habitat
Historically, aside from humans, gray wolves had the greatest natural range of living terrestrial mammals. More recently, their distribution has been restricted to the open tundra and forests of North America, primarily in Alaska, Canada and the northern United States. Gray wolves are highly adaptable and have been known to survive in all habitats in the Northern Hemisphere except for tropical forests. Gray wolves maintain a stable population growth in these areas regardless of varying densities.
Communication
Gray wolves have a variety of visual, olfactory and auditory means of communicating. Vocalizations include growls, barks and howls. Different individuals have different howls that can be heard by other wolves at distances of 6 to 7 miles (10 to 11 kilometers). Howling functions as a way to keep the pack back together, stimulate a hunt and as a long-distance form of territorial expression. Howling can also return a lost wolf to its pack.
A "lonesome howl" is a shortened call that rises in pitch used by a wolf that is separated from its pack. If answered, the wolf switches to deep, even howls to inform the pack of its location and help it to be found. Howling increases during breeding season (January through April). Scent marking via scratching, defecation and urination are all means of maintaining pack territories.
Body language is a tool of communication for the wolf. Just as human postures and gestures express our intentions and feelings, the wolf also uses body language to communicate.
Dominant postures may include a partly erect tail, walking with the head held high and eyes directed straight towards other wolves. Dominant wolves may show raised hackles, and may also side-swipe or slam into the subordinate members of the pack. They may also growl, show bared teeth, a wrinkled forehead, and their ears may stand erect and pointed forward. They are usually first to eat at a kill. A dominant wolf may "ride up" on a subordinate wolf by placing its head or forelegs across that animal's shoulders.
Subordinate postures include lowered tails, a lowered body position, an exposed throat, small steps towards more dominant members, a peeling back of lips, ears folded back and can include urination while crouching or urination on themselves. They may also raise a hind leg to expose the groin area.
Food/Eating Habits
High speeds help wolves catch up to their prey while a wolf's sharp teeth and claws finish the job.
The gray wolf is a keystone predator and is integral to the ecosystem in which it is found. Gray wolves hunt cooperatively in packs and are able to take down prey larger than they are including caribou, moose, deer and bison. Wolves will also occasionally catch smaller prey such as beaver, rabbit, and fish, and will sometimes eat berries. Gray wolves eat around three to four pounds of food per day.
At the Smithsonian's National Zoo, the wolves are fed a mixture of dry canine kibble, meat, fish, bones, frozen prey (mostly rabbits) and vegetables.
Social Structure
The gray wolf is among the most social of carnivores. Wolf packs typically have five to eight wolves, but packs with as many as 36 wolves have been reported. The pack is essentially a family group consisting of an adult pair, called the dominant pair, and their offspring. The dominant pair usually initiates activity, guides movement and takes control at critical times, such as during a hunt. Essentially, the mother and father are teaching the rest of the pack how to hunt, survive, avoid threats and mark territory.
A wolf pack's dominant pair sometimes mate for life. They are typically the only wolves that mate within a pack, and they inhibit the sexual activity of others. The other wolves may have separate dominance hierarchies, reinforced by aggressive behavior and elaborate displays of greeting and submission by subordinate members. A pack leader may retain his position as the dominant male for years, but strife from increasing pack size or declining food supplies can result in the division of a pack or the splitting off of individuals.
Reproduction and Development
In a pack, typically only the dominant pair mates. Mating may occur anytime from January to April with births taking place in spring. Courtship can last for days or months with estrus lasting five to 15 days. The gestation period is 62 to 63 days with an average litter size of six.
At birth, wolf pups weigh about 16 ounces (450 grams) and are blind and deaf. After 11 to 15 days, their eyes open. They emerge from the den when they are 3 weeks old. Dens may be in rock crevices, hollow logs, or overturned stumps, but are usually in a burrow, either dug by the parents themselves or initially made by another animal and enlarged by the wolves. These tunnels, or maternity dens, are one of the only ways wolves will seek shelter, and the same den may be used repeatedly for years.
Depending on a variety of factors, a young wolf may stay with its parental pack or go out on its own. As a young wolf reaches maturity around 2 years of age, it may actively explore the fringes of its parental territory prior to leaving. Once a young wolf has left the pack it will either join another lone wolf in order to search for new territory, or it will establish itself in an area and wait for an animal of the opposite sex to arrive. Entering breeding age around 3 years old, a lone wolf may form a new pack with a member of the opposite sex.
Lifespan
In the wild, gray wolves can live between seven and eight years and up to 20 years in human care.