Incidence of 10 anticoagulant rodenticides on 71 raptors which entered Tafira's Wildlife Rehabilitation Centre in 9 months

Abstract

Anticoagulant rodenticides are widely and disproportionately used in the archipelago for the control of plagues in cities and rural areas being a threat for wildlife health. Therefore, Tafira’s Wildlife Rehabilitation Centre aimed to assess the incidence of anticoagulant rodenticides in raptors which entered in a period of 9 months. The concentration of 5 first generation and 5 second generation anticoagulant rodenticides in 48 liver and 23 blood samples (n = 71) were analyzed for 6 different raptor species (Accipiter nisus, Buteo buteo, Falco pelegrinoides, Falco tinnunculus canariensis, Asio otus canariensis and Tyto alba). The study confirmed that 81.69 % were positive to at least one second generation rodenticide as first-generation ones were not detected in any sample. The most frequent substance detected was brodifacoum (80.28 %) in concentrations between 0.66 ng/ml and 201.24 ng/ml. In addition, the most common combination was brodifacoum + bromadiolone in 45.07 % of the animals. At least 75% of all species individuals had detectable levels of rodenticides in their blood or liver. Moreover, common kestrels (Falco tinnunculus canariensis) had the highest total concentration with a median value of 56.47 ng/ml. Remarkably 14.08 % of raptors had total concentration levels above 100 ng/g assuming the “potential lethal range”. Furthermore, orphaned birds were exposed to rodenticides in 62.5 % of the cases. In conclusion, it is suggested, due to the high levels found, that anticoagulant rodenticides may be integrated in the trophic chain affecting wild raptors in the Canary Islands.