HOBOKEN, N.J., March 10 (UPI) -- U.S. wildlife experts say American birds of prey are at greater risk than previously thought from a common pest control chemical.

Scientists from Maryland and Colorado studying American kestrels, a surrogate test species for raptors, suggest they are at greater risk from poisoning from diphacinone, a chemical used to control rodent pests, than had been thought, research published in the journal Environmental Toxicology and Chemistry reported.


"Recent restrictions on the use of some rodenticides may result in increased use of diphacinone," lead author Barnett Rattner of the U.S. Geological Survey said. "Very few controlled studies have examined its toxicity in birds so it is important to determine how lethal this chemical is to wildlife."

Surveillance programs have found detectable levels of rodenticide in birds of prey across France, Great Britain and Western Canada, revealing that several second-generation rodenticides can result in deaths in birds, with possible population-level implications, the researchers say.

The researchers estimated that an endangered hawk or owl would be at risk if it consumed 3 to 4 grams of liver from a poisoned rodent.