Biology of Wolves in Alaska

Wolves have been present in Alaska for about 500,000 years and presently occur throughout most of mainland Alaska, on Unimak Island in the Aleutians, and in most parts of southeastern Alaska.

Before the end of the last ice age, about 10,000 years ago, most of Alaska was covered with grasslands, which supported a wide variety of animals including bison, horses, mammoths, caribou, muskoxen, Dall sheep, antelopes, yaks and elk. The wolf existed along with several other predators, including the American lion, brown bear, short-faced bear and wolverine. As the glaciers receded, the climate moderated and forests expanded. Many grazing animals and some predators became extinct. However, the wolf is adaptable and continues to thrive in the Alaskan environment.

Wolves occupy nearly all of their historic range and are common over about 85 percent of Alaska. They are well adapted to habitats ranging from rain forest to arctic tundra.

John Pezzenti Jr - Timber Wolf
Timber Wolf
John Pezzenti Jr
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The Alaska Department of Fish & Game periodically estimates wolf numbers, and in 1994-95 approximately 7,500 to 10,000 wolves in from 700 to 900 packs were believed to be in the state. Population densities range from about one wolf per 25 to 75 square miles in southern and interior areas to one wolf per 150 square miles in the coastal areas of northern and western Alaska.

Wolves are more scarce in some coastal areas for several reasons. They are vulnerable to man in open country, suitable prey populations exist at low numbers or are nonexistent, and rabies outbreaks in wolves are common. Wolf numbers are stable or increasing in all occupied habitats. In most areas wolf density is about as high as the food supply will allow.

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Heart to Heart
Teri Sodd
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Wolf distribution and abundance in recent years have been about as great as at any time since the turn of the century. The wolf population is prospering and is connected to a large and similarly thriving population that extends across most of Canada.

Since 1975, several hundred wolves in about 150 packs have been radio-marked in various parts of Alaska and studied for periods of two to eight years. In addition to dramatically increasing our understanding of the movements, food habits, and social behavior of wolf packs, these studies have shown that long-range dispersals of up to 500 miles by individual wolves occur regularly. Each year one or more wolves depart from most resident packs and travel to other regions in Alaska and Canada, sometimes joining or creating new packs.

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Spring Break
Alan Sandy Carey
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This probably explains why physical characteristics of wolves are similar over this vast area. It is also one reason why wolves quickly colonize suitable habitats.

Although most packs include 6-12 animals, packs as large as 20-30 wolves sometimes occur. In most areas packs remain within a home range used almost exclusively by pack members in winter. The home range of most Alaskan packs includes 200 to 800 square miles during the winter. The ranges of neighboring packs tend to overlap slightly in winter and substantially in summer.

Wolves that depend primarily on migratory caribou may abandon their home range for a while and travel long distances.

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First Song
Jim Brandenburg
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Wolves normally breed in February and March and litters averaging about five pups are born in May or early June. Most female wolves first breed when 22 months old but usually have fewer pups than do older females.

Wolves have a high reproductive rate. Nearly all of Alaska's wolf packs raise at least one litter of four to seven pups successfully each year. Most mature females come into heat and breed every year and, in some cases, two or three females in a pack produce litters.

Because they generally produce many pups, most populations can sustain harvests of 25-40 percent annually. With lower harvests, most populations can increase, unless food is scarce. In Alaska most wolf populations sustain harvests of from 10 to 30 percent.

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Indigo
Dave Merrick
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In the past decade the annual harvest of wolves ranged from 669 to 1,580 and averaged 1,081, or about 11 to 16 percent of the estimated population. Because they produce many pups and commonly immigrate into new areas, Alaskan wolf populations can rebound quickly from relatively high harvests or other reductions in numbers.

The diet of wolves varies according to season, location and prey species availability. Moose and caribou are their major prey over much of Alaska, but Dall sheep are also taken. In Southeast Alaska, deer and mountain goats are important big game food sources.

During winter, big game species constitute almost the entire diet of wolves. Snowshoe hares can be an important food source in years of hare abundance.

Timber Wolf in Trees
Timber Wolf in Trees
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During summer, young ungulates are often an important part of the diet, but adult animals are also killed. Small animals such as beavers, snowshoe hares, voles, ground squirrels, and occasionally birds and fish can be important supplements.

Predator-Prey Relationships of Wolves

Although wolves eat a wide variety of animals, they are dependent on large hoofed mammals, such as moose, caribou, deer, sheep and goats to sustain their populations in Alaska.

The number of different prey species available to wolves in an area, the abundance of each prey species, and other factors such as winter weather play an important role in determining how wolves affect prey populations.

Lise Gauthier - Loup Canadien
Loup Canadien
Lise Gauthier
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In addition, if other predators such as black or grizzly bears or human hunters are also taking prey animals, the interactions of wolves and prey can be dramatically different.

Wildlife studies show that where wolves are the only predator, wolves do not keep prey numbers low. Likewise, if bears are the only predator, bears do not keep prey numbers low. In contrast, studies show that the combination of wolf and bear predation (which occurs throughout most of Alaska), will often keep moose, deer and sometimes caribou numbers low for long periods of time when wolves and bears are lightly harvested.

Judi Rideout - Challenge (LE)
Challenge (LE)
Judi Rideout
22 in x 17 in
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When predation succeeds in keeping moose numbers much lower than the habitat could support, the moose population is often said to be in a "predator pit". This occurs where wolves and bears are at relatively high densities and are only lightly harvested. Wolves and bears keep moose in the predator pit by killing many moose, especially calves, that would otherwise live and reproduce.

Caribou herds may also remain at very low numbers when preyed upon by both wolves and bears. Caribou differ from moose, because caribou can sometimes escape the effects of wolf and bear predation by migrating, by selecting calving areas with few predators, and by greatly outnumbering predators. Predation has less effect on large caribou herds that it has on small herds.

A certain portion of any prey population must survive to reproduce and maintain the herd. The rest can be killed by wolves, bears, or people without causing a decline in numbers. The size of this excess portion will vary over time in different areas and can be affected by wildlife management.

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Grizzly Bear
John Pezzenti Jr
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Naturally low prey numbers do not necessarily create a management problem. If people are satisfied with a small share of the prey, predator-prey relationships may not need to be adjusted to provide for increased human harvests.

On the other hand, if people want a larger portion of the prey, the level of predation by wolves and/or bears may have to be reduced. Balancing the allocation of prey between wolves, bears and people then becomes an area-specific, wildlife management objective.

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