In the United States, much of the northeast portion of the state of Alaska is within the Arctic Circle. The animals that live in this harsh region of the world must deal with very cold conditions in the winter and very short summers. Many birds use the Arctic as a breeding ground, and several species of mammals live here as well.

Nearly 200 types of birds either call the Arctic home or migrate there to breed before wintering in much warmer climates. Ducks, geese, loons, grebes, teals, scaup, plovers, terns, gulls, cranes and herons are some of the water birds that nest in the Arctic. Bald eagles, golden eagles, ospreys, owls, northern harriers, peregrine falcons, hawks, kestrels and merlins are some of the raptors that feed on other birds and small Arctic mammals. Woodpeckers, shrikes, larks, swallows, flycatchers, dippers, ravens, crows, nuthatches, chickadees, kinglets, waxwings, warblers, finches and sparrows are also present in great numbers

Shrews are some of the smallest mammals, and the Arctic contains such species as the dusky shrew, pygmy shrew, barren ground shrew, masked shrew and tundra shrew. The only member of the hare or rabbit clan in the Arctic is the snowshoe hare, an inhabitant of the thickets and forests. Many kinds of rodents exist in the Arctic, with the red squirrel, tundra vole, Arctic ground squirrel and lemmings among them.

There are various predatory species in the Arctic. The Arctic fox has a range throughout this region, as does the gray wolf. Coyotes and red foxes prowl the southern borders of the Arctic. The Canadian lynx is the only cat in the Arctic, while polar bears, brown bears and black bears exist in certain parts. The wolverine, pine martin, ermine and weasel hunt in the Arctic’s warmer climes.

Caribou are in large numbers all through the Arctic in Alaska. Moose stay in the deep thickets and wetlands in the south. The hardy thick-haired musk ox inhabits the tundra, where permafrost lies beneath the first few feet of soil. Dall sheep come down from the mountains and feed in the meadows when the weather allows. All these species fall in the classification of ungulates, having hooves with two "toes."

Three kinds of seals swim in the coastal waters off Alaska’s Arctic frontier. The spotted seal, the ringed seal and the bearded seal, as well as the occasional walrus, are the pinnipeds found here. Bowhead whales, gray whales and beluga whales are three marine mammals that live in Arctic waters.