A second generation of more potent anticoagulant rodenticides (aka, rat poisons) are prevalent in raptors brought to the Tufts Veterinary School wildlife health clinic in Massachusetts, said Maureen Murray of Tufts at a session at the Northeast Fish and Wildlife Conference today.

She tested 161 raptors that were brought in dead or died at the clinic for residues of the second generation of rat poisons, which kill by causing the animal to bleed to death. She found that 86 percent of them had residues of the poison in their systems. She also found that amount of rat poison that was fatal to the raptors varied greatly between individuals. For example, on bird appeared to have died with 12 parts per billion (ppb) of the poison in its blood. Another had clearly died of other causes, even though it had 260 ppb.

Murray noted that the EPA has banned the sale of these second generation of poisons to the public, as of June. She suspects the incidence of the poisons in the environment will not decline significantly however, since they will still be available to pest control professionals.

Murray says that poisoning with these anticoagulant rodenticides should be considered when pondering unexplained raptor die-offs.