Exposure of non-target wildlife to anticoagulant rodenticides in California

The California Department of Fish and Game collected and analyzed tissue samples from non-target birds and mammals for anticoagulant rodenticides from 1994 through 1999. Many of these animals were collected in recently urbanized areas adjacent to wildlands where they were either found dead or trapped and euthanized as vertebrate pests. The results of the analyses indicate a high frequency of exposure to the anticoagulant rodenticide brodifacoum. Fifty-eight percent of the animals examined had been exposed to brodifacoum, 19 % to bromadiolone, 9 % to diphacinone and 8 % to chlorophacinone. All of the identified anticoagulants are registered for use to control commensal rodents found in and around structures and are available for sale "over-the-counter" for homeowner use. Brodifacoum and bromadiolone are registered exclusively for commensal rodent control. This paper assesses the frequency of anticoagulant rodenticide residues in tissues of non-target mammalian and avian wildlife and the possible impacts.