Birds are the nomads of the animal world, ceaselessly traveling with the change in seasons. It must be their burden to carry in exchange for the gift of flight. Though some birds can remain in one area throughout the year, most are condemned to seasonal migrations to find adequate food and weather conditions.

After the autumnal equinox in the Northern Hemisphere (a day when the earth receives 12 hours of daylight and 12 hours of night), days gradually shorten. Cold arctic air pushes further south. The once insect-rich areas to the north — breeding grounds for many bird species — are no longer hospitable, and the skies begin to fill with birds migrating to warmer, more temperate climates to the south. These seasonal migrations allow birds to not only avoid harsh climate conditions, but also to take advantage of available food in each region.

Birds are well adapted for extensive flights. To prepare for these journeys, they store energy in the form of fat reserves. Many neotropical migrants, especially smaller birds, will fly at night. At sunrise, if possible, birds will land to forage for food and rest. Birds orient themselves in the desired direction and navigate by processing information from several sources. Land features such as rivers and mountain ranges, wind direction, the sun, stars, the earth's magnetic field, and even smell help to guide birds to their desired destinations.

In North America, birds migrate along four main routes or flyways: The Atlantic, Central, Mississippi, and Pacific. These “rivers of birds” are not specific lines the birds follow but broad areas thorough which the birds migrate. The Chesapeake Bay watershed lies within the Atlantic flyway. It is the ultimate winter destination for some birds, while others may stop to rest and refuel before continuing further south.

The Chesapeake Bay provides a wintering site for much of the nation's waterfowl. About 1 million waterfowl winter on the Bay between October and April. That is roughly one third of all waterfowl wintering along the Atlantic Coast. Swans, geese, and ducks from Alaska, Canada, North Central United States, and New England seek out the wetlands, shorelines and open water to provide food critical to their survival. In winter, waterfowl may eat up to their own body weight in food each day. Migrating waterfowl also need sufficient food reserves to fuel their migrations back to northern breeding grounds in the spring.

Swans are the largest of waterfowl. The tundra swan travels the farthest, more than 4,000 miles, to winter primarily on the Eastern Shore of the Bay. These large, white birds are easily recognized by their black bills and straight necks. Another type of swan, the mute swan, is an introduced species from Europe. It competes with other waterfowl for food and habitat. Their orange bills and S-shaped necks distinguish the mute swan from the tundra swan.

Autumn would not be complete without the V-shape of migrating geese in sky. Constant honking signals the arrival of the familiar Canada goose, with its black-and-white head, brown back and pale breast. A lesser known visitor is the snow goose. As its name implies, the snow goose is white except for black wing tips and pink feet and bills. The small black Atlantic bract also winters here.

A long list of ducks also winter on the Bay. Species of wintering ducks include the mallard; black duck; American widgeon; green-winged teal; northern pintail; northern shoveler; canvasback; redhead; greater and lesser scaup; old squaw; white-winged, surf, and black scoter; red-breasted, hooded, and common mergansers; and the ruddy duck.

National wildlife refuges provide some of the best opportunities to observe and photograph waterfowl and other wildlife. Visit any of the following refuges: Bombay Hook NWR, Smyrna, Del.: Blackwater NWR, Cambridge, Md.; Eastern Neck NWR, Rock Hall Md.; Back Bay NWR, Virginia Beach, Va.; Chincoteague NWR, Chincoteague, Va.; Eastern Shore of Virginia NWR, Cape Charles, Va.; and Mason Neck NWR, Woodbridge, Va. and Presquile NWR, Hopewell, Va.

Many birds besides waterfowl migrate through the Bay region. Known as neotropical migrants these birds breed in North America but winter in Mexico, the Caribbean, and Central and South America. These birds use forests and shoreline areas along the way to rest and refuel. Some lose as much as one fourth to one half of their total body weight during migration.

Some neotropical birds may fly more than 6,000 miles in a single year. Many of our more colorful and vocal songbirds are neotropical migrants. Species of warblers, vireos, thrushes, orioles, swallows, flycatchers, sparrows, and hummingbirds are included in this large category. Songbirds are not the only birds that complete these biannual trips. Raptors, such as the peregrine falcon; red- shouldered, red-tailed and sharp-shinned hawk; northern goshawk and Cooper’s American kestrel, merlin, and northern harrier. Many shorebirds, including species of plovers, sandpipers, curlews, terns and gulls, are also long-distance travelers.

Mountain chains to the west and coastal shorelines to the east serve as geographic boundaries that channel millions of migrating birds through the Bay region. As they migrate between the mountains and the coast, the land formation approaching the Bay changes, causing some migrants to funnel along the coast while the others are steered along the mountains.

Migrating raptors can be seen along the west-facing ridges in Pennsylvania, western Maryland and Virginia. Hawk Mountain, Pa., is especially rewarding for observing raptors.

Migratory birds also congregate on peninsulas, such as Cape Charles, Va. Here they await weather conditions favorable to water crossings. Cape Henlopen, Del.; the barrier islands of Assateague, Md. and Chincoteague, Va.; and all points south along the beaches to Cape Charles also provide excellent opportunities to observe the fall migration of songbirds, shorebirds, and raptors.