Arctic National Wildlife Refuge - Geography

Geography

The refuge supports a greater variety of plant and animal life than any other protected area in the Arctic Circle. A continuum of six different ecozones spans about 200 miles (300 km) north to south.

Along the northern coast of the refuge, the barrier islands, coastal lagoons, salt marshes, and river deltas of the Arctic coastal tundra provide habitat for migratory waterbirds including sea ducks, geese, swans, and shorebirds. Fish such as dolly varden and arctic cisco are found in nearshore waters. Coastal lands and sea ice are used by caribou seeking relief from biting insects during summer, and by polar bears hunting seals and giving birth in snow dens during winter.

The Arctic coastal plain stretches southward from the coast to the foothills of the Brooks Range. This area of rolling hills, small lakes, and north-flowing, braided rivers is dominated by tundra vegetation consisting of low shrubs, sedges, and mosses. Caribou travel to the coastal plain during June and July to give birth and raise their young. Migratory birds and insects flourish here during the brief Arctic summer. Tens of thousands of snow geese stop here during September to feed before migrating south, and musk oxen live here year-round.

South of the coastal plain, the mountains of the eastern Brooks Range rise to over 9000 feet (3,000 m). This northernmost extension of the Rocky Mountains marks the continental divide, with north-flowing rivers emptying into the Arctic Ocean and south-flowing rivers joining the great Yukon River. The rugged mountains of the Brooks Range are incised by deep river valleys creating a range of elevations and aspects that support a variety of low tundra vegetation, dense shrubs, rare groves of poplar trees on the north side and spruce on the south. During summer, peregrine falcons, gyrfalcons, and golden eagles build nests on cliffs. Harlequin ducks and red-breasted mergansers are seen on swift-flowing rivers. Dall sheep and wolves are active all year, while grizzly bears and arctic ground squirrels are frequently seen during summer but hibernate in winter.

The southern portion of the Arctic Refuge is within the Interior Alaska-Yukon lowland taiga (boreal forest) ecoregion. Beginning as predominantly treeless tundra with scattered islands of black and white spruce trees, the forest becomes progressively denser as the foothills yield to the expansive flats north of the Yukon River. Frequent forest fires ignited by lightning result in a complex mosaic of birch, aspen, and spruce forests of various ages. Wetlands and south-flowing rivers create openings in the forest canopy. Neotropical migratory birds breed here in spring and summer, attracted by plentiful food and the variety of habitats. Caribou travel here from farther north to spend the winter. Year-round residents of the boreal forest include moose, lynx, marten, wolverines, black and grizzly bears, and wolves.

Each year, thousands of waterfowl and other birds nest and reproduce in areas surrounding Prudhoe Bay and Kuparuk fields and a healthy and increasing caribou herd migrates through these areas to calve and seek respite from annoying pests.