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Press Release

U.S. Department of the Interior
U.S. Geological Survey
National Wetlands Research Center
700 Cajundome Blvd.
Lafayette, LA 70506

Contact: Gabrielle Boudreaux Bodin
Phone: 337-266-8655
Fax: 337-266-8541
For Release: March 8, 1999

Migratory Birds and Habitat Fact Sheet

Almost anywhere, any time during the day, you can go outside and hear birds singing. Scientists estimate that about 9,000 species of birds exist worldwide. About 660 species breed in North America.

Some, termed resident birds, stay in one area all year long. Others migrate as the seasons change. Some travel short distances and remain within the United States. Others migrate longer distances and travel into South America.

Approximately 350 species of birds migrate to tropical regions of Mexico, Latin America, and the Caribbean. These species are known as "neotropical" migratory birds and include raptors, waterfowl, shorebirds, and songbirds such as orioles, tanagers, warblers, thrushes, hummingbirds, and others. "Neo" refers to the "new" world, or the Americas and "tropical" refers to the latitudinal region between the Tropic of Cancer and the Tropic of Capricorn.

Although most birds are still common, populations of some migratory birds are declining. The neotropical migratory birds are at great risk. Declines in some species are gradual while others are more dramatic. Some species including the wood thrush, cerulean warbler, bobolink, grasshopper sparrow and the western bluebird are declining sharply.

Causes for the declines of neotropical migrants are complex and not completely understood. Of the several environmental threats to these birds, loss of habitat has had the most far-reaching impact. From upland forests to coastal wetlands, habitats needed by migratory birds have been dramatically reduced.

The United States has lost more than half of its wetlands, a land area equivalent to the state of California. Louisiana alone continues to lose 25-35 square miles of wetlands every year, much of it coastal.

prothonotary warblerGrasslands across the nation have been reduced by nearly 95%, and grassland birds are among the fastest declining species.

Finally, the effects of habitat deterioration are often subtle. Forest fragmentation reduces forest interior habitat required for successful nesting of many species. The edge habitat created by fragmentation contributes to increasing populations of predators, such as opossums, raccoons, cats, blue jays and crows. Open spaces interrupting intact forest attract the brown-headed cowbird, a brood parasite that lays its eggs in the nests of many neotropical migrants, reducing their nesting success.

"We believe that deteriorating and lost habitat is behind the declines in numbers of many of our songbird species," says Dr. Carroll Cordes of the National Wetlands Research Center. "Prothonotary warblers are listed as species of management concern in Louisiana and depend on adequate habitat in and around Lafayette to breed," he added.

The good news for migrants is that many communities and organizations are coming together to reverse the decline of neotropical migrant birds. One such group is the U.S. Geological Survey's National Wetlands Research Center in Lafayette, La., which researches migratory birds and is sponsoring the fourth annual celebration of Acadiana Migratory Bird Day April 9-10.

As the nation's largest water, earth and biological science and civilian mapping agency, the USGS works in cooperation with more than 2,000 organizations across the country to provide reliable, impartial scientific information to resource managers, planners and other customers. This information is gathered in every state by USGS scientists to minimize the loss of life and property from natural disasters, to contribute to the conservation and the sound economic and physical development of the nation's natural resources and to enhance the quality of life by monitoring water, biological, energy and mineral resources.

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