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State of the Birds Report

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Pollution

Pesticides_EPA.jpg
Photo courtesy of EPA

Pesticides, toxic chemicals, and heavy metals such as lead and mercury cause significant bird mortality and reduce breeding success. These effects are sometimes hard to detect, but can produce dramatic population declines over time. DDT caused the thinning and breakage of eggshells, nearly wiping out several bird species in the U.S., including Peregrine Falcons, Brown Pelicans, and Bald Eagles.

The U.S. applies approximately five billion pounds of pesticides annually. A pesticide poisoning database documents more than 2,500 incidents, including 113 pesticides implicated in the deaths of more than 400,000 birds. Carbofuran has been responsible for more than 20% of all incidents, and the deaths of more than 40,000 birds. Many of the pesticides highly toxic to birds have been eliminated from use in the U.S., but continue to be used legally in Latin America where migratory birds are exposed to them during the winter.

Lead, mercury, and selenium also harm birds. Ingested lead fragments and shot in game carcasses may have toxic effects on eagles, vultures, and other scavengers. Mercury deposition in forests and on surface waters from burning coal becomes concentrated in foods eaten by fish-eating birds and forest songbirds. High selenium concentrations in wetlands impair the hatching of eggs and reproduction of waterfowl and shorebirds. Industrial chemicals such as dioxins and PCBs, once linked to many poisonings, have been regulated and largely cleaned up, but new chemicals such as PBDE fire-retardants are emerging as contaminants that accumulate in plants and wildlife, with unknown effects on birds and humans.

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