Monitoring Anticoagulant Rodenticides in Birds of Prey in the Wildlife Rehabilitation Setting

Monitoring anticoagulant rodenticide (AR) exposures in birds of prey presented to a wildlife clinic or rehabilitation setting has several advantages and disadvantages. Advantages include the ability to document signs of toxicosis in live birds. Additionally, in birds that die due to AR toxicosis, post-mortem lesions in the non-frozen, non-autolyzed cadaver will illustrate patterns of AR-induced hemorrhage. In birds that die or are euthanized due to other causes, liver samples can be collected and analyzed for AR residues. Disadvantages include an inability to ascertain the dose of AR ingested. In birds with exposure to multiple ARs, the timing of ingestion is also unknown. The route of exposure and pathway through the food chain likewise are unknown. Importantly, determining the true incidence of toxicosis and mortality among the sampled birds is not possible because birds that are found and transported for care may not be reflective of mortalities in the overall population. Despite the limitations of this method of sampling, much useful information can be gathered, particularly in studies that are continued over time. Two such monitoring studies conducted in Massachusetts, USA over a ten-year period, showing widespread exposure among sampled birds, will be discussed. In addition, other information that is needed to enhance the data obtained by cadaver sampling will be high­lighted, particularly as these data gaps relate to evaluation of mitigation efforts