Anticoagulant Residues in Non-Target Wildlife – Assessing Sublethal Exposure to Brodifacoum without Lethal Sampling

Residues of brodifacoum and other second-generation anticoagulant rodenticides are reported worldwide in a range of non-target wildlife, especially predatory or scavenging birds and mammals. Determination of exposure to brodifacoum in such cases relies on analysis of liver tissue. This limits current monitoring efforts to either destructive sampling of live birds or mammals to obtain liver, but more commonly opportunistic post-mortem liver sampling from carcasses in suitable condition. Also, detection of brodifacoum in liver often cannot be confirmed as a contributor to mortality, and within a potential ‘sublethal’ concentration range the toxicological significance of its presence is uncertain. We sought to determine whether dried blood spot (DBS) sampling could form the basis of a non-lethal, minimally invasive method for determining sublethal exposure to brodifacoum in live birds. Validation of a method for detecting brodifacoum in DBS samples, and preliminary comparison of brodifacoum concentrations in DBS and plasma samples, are described