Barn owls are accumulating dangerous levels of rodenticides in their bodies through secondary poisoning from eating contaminated prey, threatening both individual welfare and populations.
Barn owls dying from anticoagulant rodenticide poisoning experience prolonged internal bleeding and haemorrhage over multiple days before death. Animals in this condition show weakness, lethargy, and inability to hunt, leading to starvation alongside toxic effects. Sub-lethal exposure impairs hunting ability, reproductive success, and immune function. The cumulative poisoning of predator populations from widespread rodenticide use represents a landscape-scale welfare concern that extends well beyond barn owls to many birds of prey and mammalian predators.