Birds in the Arctic Refuge
During the brief arctic summer, the North Slope is home to millions of birds. Many come to nest and raise their young. Others come to molt or simply to pass through on migration. A few species are present year-round.
Rock and Willow Ptarmigan are the most abundant birds during winter and are found in patches of willows where they feed mainly on the buds. Ravens are the most conspicuous winter birds. A few Gyrfalcons and Snowy Owls may also be present, depending on the abundance of prey.
Late May and early June bring long days, warmer temperatures, and flocks of migrating birds-ducks, geese, shore birds, jaegers, gulls, terns, songbirds, and others. Some of these stay in the Refuge, while others continue to destinations elsewhere in Alaska and Canada. Those that do stop congregate wherever bare ground or open water may be found. River deltas, flooded by meltwater, and shallow ponds are heavily used at this time, as are patches of snow-free tundra. As spring progresses, the birds disperse to occupy suitable habitats.
The migratory birds have come great distances from the far reaches of the globe. Dunlins have wintered along the coast of China, Yellow Wagtails and Northern Wheatears in southern Asia and Africa, and Arctic Terns in the Antarctic. Buff-breasted Sandpipers have come from the pampas of Argentina, Red Phalaropes from off the coast of Chile, and Tundra Swans from the Chesapeake Bay area.
Brant use the Coastal Plain primarily as a migration corridor, resting and feeding on vegetated mud flats while en route to their main breeding grounds in Canada. Snow Geese feed and rest in wet sedge meadows during their migration to colonial nesting grounds on Banks Island and at the mouth of the Anderson River in Canada.
Almost immediately upon arrival, the birds begin to establish territories and attract mates. By late June most birds are on their nests and incubating eggs, and bird activity on the tundra is less evident. Part of the decline in apparent activity is due to the effort of incubating birds to be inconspicuous, but in addition, many birds actually do leave. In several species, only one parent, usually the female, incubates the eggs and cares for the chicks. For example, while female ducks incubate their eggs, the males migrate to communal molting areas. In contrast to the usual pattern, male phalaropes tend the nest and chicks while the females migrate to wintering areas soon after egg-laying.
A variety of birds nest in the mosaic of habitats provided by the tundra. Red Phalarope, Northern Phalarope, Pectoral Sandpiper, Semipalmated Sandpiper, Buff-breasted Sandpiper, Dunlin, Lapland Longspur, and Savannah Sparrow are small species that nest in the area. Several species of waterfowl nest in wetlands. Tundra Swan, Canada Goose, Pintail, Old Squaw, Common Eider, King Eider, and Spectacled Eider all are relatively common. Arctic and Red-throated loons breed on small lakes, as do Sabine's Gulls and Arctic Terns.
Most of the eggs have hatched by mid-July, and the majority of young birds are able to fly and are independent of their parents by the end of July. Waterfowl are the exception. Most young ducks and geese are unable to fly until sometime in August, although they must fledge before the onset of freeze-up.
During molt, birds shed old feathers and replace them with new ones. All birds molt at least once each year, and some two or three times. Ducks, geese, swans, and some other groups of birds lose all of their flight feathers at once, rendering them flightless and vulnerable to predators. In addition, the molt is metabolically stressful owing to the demands for growing new feathers. Thus, in advance of this molt, waterfowl move to areas where food is abundant and they are safe from predation. For example, Old Squaw move to sheltered lagoons along the Beaufort Sea coast. There they feed in the protected waters and rest on the beaches of the islands that usually are free of mammalian predators, such as foxes.
By mid-August most waterfowl are again able to fly. Some species, such as Canada Geese, Brant, and Snow Geese, congregate in coastal areas and graze on vegetation in saline and brackish meadows, laying on fat for energy to carry them south on the fall migration. In late August and early September, numerous flocks of waterfowl migrate along the coast or over the tundra. Waterfowl leave northern Alaska by several routes. Brant fly west along the Beaufort coast and then southward, ultimately ending up in Baja California. Snow Geese and Greater Whitefronted Geese fly eastward to the Mackenzie River Valley and then turn southward toward destinations in the southern United States and Mexico.
By the time the tundra and Beaufort Sea freeze over and become snow covered, most of the birds have left northern Alaska and the tundra becomes quiet again until the next spring.
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