Anticoagulant Rodenticides in Nocturnal Birds of Prey: A European Perspective

Anticoagulant rodenticides are biocides that interfere with normal blood clotting, inhibit the vitamin K cycle in the liver, and cause death by hemorrhages. Even though the main target of these compounds is rodents, they may affect non-target species such as nocturnal birds of prey that feed on those rodents. To study secondary exposure to ARs, select species that specialize in rodent prey, such as nocturnal birds of prey. Besides their specialized diet in rodents, nocturnal birds of prey are one of the most widely distributed birds in Europe and live in rural and non-rural habitats, making them excellent sentinel species for several studies’ ecotoxicology studies. There are numerous studies regarding secondary AR exposure in raptor species all around the world, but evidence for population-level effects is still absent. The objective of this review is to show how ARs have influenced wild nocturnal birds of prey in Europe in the last decades, most affected species, and in summary, explain how they act and the main clinical signals/ lesions that can be observed in poisoned birds. Overall, a total of 19 works were included in this review, between the years 1983 to 2021 that satisfied all literature criteria. These 19 papers corresponded to 44 observations of different species, regarding eight types of anticoagulant rodenticide. In the future, more caution is needed in the use of anticoagulants for rodent control where avian predators may be exposed to poisoned prey. Some combinations can be highly lethal to the predator, putting it at risk species that are already treated, therefore new eco-friendly alternatives should be found.