Get Outdoors - Destinations: Gates of the Arctic Mammals

The wildlife of Gates of the Arctic National Park and Preserve is representative of northern Alaska and the Brooks Range, characterized by few species and low populations. The populations of some animals, such as lynx and hare, experience ups and downs called cycles. These may be annual or spread over several years.A total of 36 species of mammals occur within the park, ranging in size from voles and lemmings to brown bears and moose.

Small Mammals.
Small mammals form the base of the arctic food chain and are a critical element in the survival of many raptors and large mammals. Singing, tundra, and red-backed voles and brown and collared lemmings convert plant resources to flesh on which a variety of predators depend. Collectively, small rodents may have a profound localized effect on tundra vegetation. Larger rodents include the arctic ground squirrel and Alaskan marmot. Arctic ground squirrels occur primarily on well drained soils along rivers or on slopes. They are commonly observed and can often be a problem at cabins, food caches, and camps.

Furbearers.
The furbearers common to Alaska are present, although many, such as marten and lynx, are mostly limited to the forested areas in the southern half of the park. Beaver, mink, and otter are present but are limited by a scarcity of suitable aquatic habitats. Red foxes, including the silver, black and cross fox color phases, occur throughout the area, and arctic foxes occur occasionally in the northernmost parts of the park. Wolverines are present throughout. The most important species trapped by subsistence users within the park are marten, lynx, beaver, fox, and wolf.Wolves occur throughout the park and preserve, traveling in packs or family groups as they hunt. The main prey of wolves in the central Brooks Range and on the arctic slope is caribou; however, other prey species may be used extensively if caribou are not available, principally Dall sheep, small mammals, moose, snowshoe hare, and beaver. Denning usually occurs on dry, well drained slopes where excavation of soils is not hindered by frozen ground. Litters average five or six pups. Wolves are a source of income for the resident of Anaktuvuk Pass and other villages, who trap and hunt them.

Brown bears (barren-ground grizzlies) occur throughout the park and preserve. They are among the earth''s largest predators, but in the Brooks Range they feed mostly as vegetarians, eating berries, sedges, hedysarum, and other plants. They also feed on small mammals and may spend hours excavating ground squirrel burrows, locally disrupting much of the ground surface in the pursuit of their prey. The bears will kill moose calves and caribou fawns and occasionally adults. Some scavenging also occurs. Brown bear populations concentrate along most of the major streams and rivers within the park. Although brown bears range through all habitat types, they are most commonly found in open alpine or tundra habitats. Brown bears gain weight rapidly during the late summer and fall and are waddling in fat just prior to denning. At this time most mature males weigh between 500 and 900 pounds with extremely large individuals weighing as much as 1,400 pounds. Females weigh one half to three quarters as much. There is an average of one brown bear for each 100 square miles of habitat in the Arctic.

Black bears, which are more common in the southern forested regions, have similar food habitats and behavior. Black bears are creatures of opportunity with it comes to matters of food. Upon emergence from hibernation in the spring, freshly sprouted green vegetation is the main food item, but blacks will readily take anything they encounter. Things such as winterkilled animals are readily eaten, but carrion is apparently taken only if little else is available. As summer progresses, feeding shifts to salmon if they are available. In areas without salmon, bears rely primarily on vegetation throughout the year. Berries, especially blueberries, are an important late summer-fall food item. Bears are cannibalistic on occasion. An "average" adult male in summer weighs about 180-200 pounds. Black bears have very poor eyesight but their senses of smell and hearing are well-developed.

Ungulate Mammals.
Moose, Dall sheep and caribou are the three ungulate mammals occurring in the area. Moose are most common in the forested regions south of the Brooks Range, but their range extends up mountain valleys into the larger northern drainages wherever trees and shrubs provide food and winter habitat. In summer moose frequently move into alpine habitat, but they are uncommon at the crest of the range.

Moose are an important subsistence resource for villages south and west of the park and residents of Anaktuvuk Pass harvest moose occasionally. Sport hunting for moose along the Kobuk River in the preserve is becoming a more popular activity. Hunters gain access by air or boat.

Dall sheep are widespread throughout the mountainous alpine areas of the park and preserve. Rugged terrain with cliffs, steep slopes and rocky outcrops is essential escape habitat. Mineral licks are seasonally very important, and the sheep may travel some distance to reach a lick site. Sheep find critical winter forage on windblown ridges where the snow has been blown away, leaving the vegetation exposed. The current sheep population in the park and preserve is estimated at 12,000-14,000 animals.Caribou of the western arctic herd today range over the entire region. The herd declined from a population of at least 242,000 animals in 1970 to an estimated 75,000 animals in 1976. Since that time the herd has increased in size,and in 1982 it was estimated at 171,699 animals. In 1984 the herd size was projected to number approximately 200,000. The herd migrates through the park and preserve as it moves from wintering grounds south and west of the park to calving areas northwest of the park and to summer range north of the park. Some of the animals use summer range along the northern reaches of the park, and some winter in the southern part of the park, especially in the Kobuk River valley.

The western arctic caribou herd is most widely dispersed in midwinter, when bands are scattered throughout the forests on the south slopes of the Brooks Range and in the adjacent lowlands, and again in midsummer, when they are scattered over the arctic slope west of the Sagavanirktok River. Spring movement to summer ranges begins in March, when bands of females travel northward up the Alatna, John, and North Fork of the Koyukuk drainages and cross the summit of the Brooks Range into the valleys of such rivers as the Killik, Chandler, and Anaktuvuk, which they follow or cross in a generally westward movement to calving grounds at the head of the Utukok and Colville. Males and some yearlings begin moving somewhat later. After calving in late May, the animals join increasingly larger groups to move to higher country on the North Slope and in the foothills of the Brooks Range. Once there they gradually disperse, using summer range from the Arctic Ocean to the summits of the Brooks Range by late July. A southward drifting of caribou begins in August, and in the park it is directed toward the Anaktuvuk Pass and Killik River areas. Migration continues through the rut in October, until the wintering grounds are reached.

Caribou have historically played an important role in human survival in arctic regions. Subsistence users still rely heavily on caribou. Since the range of the western arctic herd extends across many landownerships, management of the herd requires careful coordination between the Alaska Department of Fish and Game and the various landowners, as well as the hunters who harvest the herd.