Presence of anticoagulant rodenticide residues in five predatory birds species of the canary islands, 2002-2011

Abstract

Anticoagulant rodenticide (AR) levels were studied in liver of 61 dead raptors of five of the eleven species of the Canary Islands. The animals were delivered to our laboratory from the Centro de Recuperación de Fauna Silvestre de Tafira (Gran Canaria). Anticoagulant residues were detected in 42 (69%) of the studied animals, but only 1 may have died by AR poisoning according to the clinical information, necropsy findings and toxicological analysis. Of the studied raptors Tyto alba and Accipiter nisus were the species with more frequency and higher levels of anticoagulants (85% and 89%). Residues of 5 anticoagulants were detected, all of them of second generation, being the most frequently detected bromadiolone, brodifacoum and difenacoum. A large number of samples (63%) presented more than one residue of anticoagulants in their livers, and we have found as much as 4 different residues in one animal. It was remarkable that most of the animals that had suffered polytraumatism by collision presented residues of anticoagulants, and that species such as the hawk that mainly eat birds frequently presented anticoagulant residues. The results of this study suggest that the high use of anticoagulant rodenticides in the natural environment involves their incorporation into the food chain, and this can affect wildlife species in which these products may cause side effects. This means that the application of anticoagulant rodenticides in open spaces poses a threat to the conservation status of biodiversity in the Canary Islands.