The interplay of elevation, permafrost, surface water, fire, and aspect creates an extensive patchwork of ecological types. Joint Venture(s) in this BCR: Pacific Coast, Eastern Habitatīird Conservation Region 4 – Northwestern Interior Forest Taiga passerines, such as Gray-cheeked Thrush and Yellow Warbler, reach the region along drainage systems, and raptors, including Gyrfalcon and Rough-legged Hawk, nest commonly along major rivers. Several Old World species, including the Arctic Warbler and Bluethroat, penetrate the region from the west. The most abundant breeding birds on the coastal plain include Northern Pintail, King Eider, Oldsquaw, American Golden-Plover, Semipalmated Sandpiper, Pectoral Sandpiper, Red-necked Phalarope, and Lapland Longspur. Because of the wetness, waterfowl and shorebirds dominate the avian community and passerines are scarce. The ocean surface is generally frozen 9 to 10 months of the year, and the ice pack is never far from shore. Freezing and thawing form a patterned mosaic of polygonal ridges and ponds, and many rivers bisect the plain and flow into the Arctic Ocean. Because of thick and continuous permafrost, surface water dominates the landscape (20–50 percent of the coastal plain). This region includes low-lying, coastal tundra and drier uplands of the Arctic mountains across the entire northern edge of North America. Mainland sea cliffs are occupied by nesting colonies of Black-legged Kittiwake, Common Murre, and Pelagic Cormorant.īird Conservation Region 3 – Arctic Plains and Mountains Gyrfalcon and Rough-legged Hawk nest along the riverine cliffs. Passerine diversity is greatest in tall, riparian shrub habitats, where Arctic Warbler, Gray-cheeked Thrush, and Blackpoll Warbler nest. The coast of the Alaska Peninsula supports high concentrations of wintering sea ducks, including Steller’s Eider, Harlequin, Oldsquaw, Surf Scoter, and Black Scoter. Intertidal areas here and lagoons of the northern side of the Alaska Peninsula support millions of shorebirds during migration, including Dunlin, Western Sandpiper, Red Knot, and Bar-tailed Godwit. High densities of breeding waterfowl and shorebirds are found on the coastal plain of the Yukon and Kuskokwim Rivers. Permafrost is continuous, except in southern parts of the region. Forests of spruce and hardwoods penetrate the region on the eastern edge. Tall shrub communities are found along rivers and streams, and low shrub communities occupy uplands.
Wet and mesic graminoid herbaceous communities dominate the lowlands, and numerous ponds, lakes, and rivers dot the landscape. This region consists of the Subarctic Coastal Plain of western Alaska and the Alaska Peninsula Mountains.
Joint Venture(s) in this BCR: Pacific Coastīird Conservation Region 2 – Western Alaska However, McKay’s Bunting, the only endemic Alaskan passerine, is restricted to this area. The breeding diversity of passerines (mainly Lapland Longspur, Snow Bunting, and Gray-crowned Rosy-Finch), and shorebirds (including Black Oystercatcher, Dunlin, Ruddy Turnstone, and Rock Sandpiper) is low. Southern Hemisphere procellariiforms occur regularly in the offshore waters of the southern Bering Sea and northern Gulf of Alaska during Alaskan summers. Seabirds are a dominant component of this region’s avifauna, and several species, including the Red-legged Kittiwake, Least Auklet, and Whiskered Auklet, breed only in this region. Sea ice does not extend to the Aleutians and permafrost is generally absent however, sea ice is an important feature of the Bering Sea. Meadows and marshes of herbs, sedges, and grasses are plentiful, and some islands have ericaceous bogs. Vegetation at higher elevations consists of dwarf shrub communities, mainly willowand crowberry. The Aleutian chain is volcanic in origin, with a maritime climate in which wind is ever present. Included in this region are the Aleutian Islands, extending westward from the Alaskan mainland for 1,100 miles, and the Bering Sea islands, including the Pribilofs, St. Planicie Costera y Lomeríos Húmedos del Golfo de Méxicoīird Conservation Region 1 – Aleutian/Bering Sea Islands.Planicie Costera y Lomeríos Secos del Golfo de México.Planicie Costera y Lomeríos del Pacífico Sur.Planicie Costera, Lomeríos y Cañones de Occidente.