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Eagles and Kestrels, a Tale of Celebration and Concern

Eagles and Kestrels, a Tale of Celebration and Concern

All through the fall they came on the wind - 20,000 to 25,000 of them: hawks, eagles, falcons - in search of a warmer climate and more abundant food. They are funneled here, Hawk Mountain Sanctuary in Pennsylvania, and use this ridge as a guiding beacon, a leading line for their grand and miraculous journey to places as far south as Argentina.
I come for the eagles, and this year they came in abundance. The last bird tallied as the count closed on Saturday, December 15, was an immature bald eagle. The eagle is one of North America's success stories. This past June they were removed from the federal Endangered Species List. Their comeback was due to a ban on the pesticide DDT in the United States, an aggressive re-introduction program, habitat protection and a crackdown on exploitation.
In contrast to the eagle's success story, many other birds, including the American kestrel, North America's smallest falcon, have suffered substantial population declines. The causes of the kestrel's decline also tell us something about the losses other species are suffering.
More data on migrating raptors has been collected at Hawk Mountain Sanctuary than any place on earth and Chris Farmer, North American bird monitoring coordinator at Hawk Mountain, suggests four factors that may contribute to the kestrel's population decline.
Exposure to environmental contaminants such as insecticides, including DDT, which continues to be used in Mexico and Central America, may be a factor. Lab experiments have shown that DDT interferes with successful reproduction in the American kestrel and some insecticides can kill the sensitive birds outright and reduce the numbers of insects available for them to eat.
West Nile Virus is also a suspect. Ninety-five percent of the adult kestrels using nest boxes near Hawk Mountain have been exposed to the virus. The virus has been particularly deadly for crows and jays, but has been found in at least 59 species of native birds.
Another culprit could be a marked increase in the numbers of larger birds of prey, like the Cooper's hawk, that prey on the small kestrel.
However, the most significant factor, for the kestrel and many other birds, may be habitat loss. Much of the falcon's range along the Atlantic coast has been developed. Suburbia and sprawling urbanization have replaced fields. Farming practices have changed. Corn and soybean fields have replaced hay fields and meadows, fields rich with insects kestrels eat. Hedgerows that provided kestrels hunting perches and the dead trees with cavities that provided nest sites have been eliminated. In fact, bird species relying on grasslands are suffering some of the greatest declines in North America. They include birds like the bob-o-link, the eastern meadowlark, the upland sandpiper and the short-eared owl.
Habitat loss is also affecting birds that need forests, says Laurie Goodrich, a senior biologist at Hawk Mountain. Goodrich is in charge of migration counts, of both large and small birds, and the research connected to it. She says the melodious wood thrush and some warblers have been hit the hardest by forest fragmentation. Our large areas of forest are being chopped up by roads and sprawl development. Nesting and feeding habitat is destroyed, while places that support bird predators such as opossums, raccoons, skunks, crows, and blue jays, are created. In fact, according to the National Audubon Society, one in four of our bird species are threatened, primarily by climate change, habitat lost to development, and invasive species.
There's a lot we can do to help the kestrel and all birds. Goodrich suggests creating and protecting connectors of wild land between remaining large tracts of forest and meadow. Organizations such as Pheasants Forever, Ducks Unlimited, and conservation programs run by state natural resource departments are dedicated to this goal. Supporting these conservation groups helps. Restoring habitat is also important. For example, kestrels nest in cavities and where the old snag trees that would naturally be their homes have been destroyed, putting up nest boxes can help. Finally, it is vital we are careful with insecticides, use as few as possible, and eliminate as environmental contaminates.

Cindy Ross lives in Pennsylvania and has written 6 books about the outdoors. This column is distributed by Bay Journal News Service.

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