Image # 2040
adult taking flight Adult Red-tailed Hawk, southern New Jersey. Red-tailed hawks are one of the most common birds of prey in North America, but a study of red-tails in the Yellowstone and Grand Teton ecosystems raises concerns about the future well-being of this species. Analyzing 50 years worth of data, Derek Craighead and other biologists determined that the reproductive rate of red-tails has declined from a healthy ratio of 1.5 chicks or greater per nesting pair to a ratio of only 0.9 chicks per pair. Although blackflies and a parasite transmitted by the flies are responsible for some of the chick mortality, Craighead is also concerned about the integrity of the hawks' wintering grounds. Placing tiny backpacks with microtransmitters on the birds, Craighead tracked their southward migration to Nicaragua and Mexico. Journeying to Durango and Monterrey, Mexico, Craighead and fellow researchers discovered that family farms, which once had windbreaks of tall trees, were being converted into large industrialized farms and that 2,4-D, a toxic herbicide, was being routinely sprayed on the fields by unprotected workers. The decline of birds of prey, Craighead notes, is "a problem of international scope."
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