Secondary Poisoning: How Rat Poison Kills Raptors and Other Wildlife

Rodenticide use in agriculture and pest control kills non-target wildlife through secondary poisoning — raptors, owls, and other predators that eat poisoned rodents accumulate lethal doses. Understanding this mechanism reveals preventable welfare harms at scale.

Key Facts

Second-generation anticoagulant rodenticides (SGARs) such as brodifacoum and bromadiolone cause internal bleeding over days
SGARs accumulate in the bodies of rodents eating multiple sublethal doses — predators eating these rodents accumulate lethal doses
Studies by the Wildlife Incident Investigation Scheme found SGARs in over 80% of red kites, barn owls, and buzzards tested
Barn owls are particularly vulnerable because they specialise on field voles and other small mammals that consume rodenticides
Red kites, whose UK population has recovered to around 4,600 pairs through reintroduction, regularly die from secondary poisoning
The Campaign for Responsible Rodenticide Use (CRRU) aims to reduce secondary poisoning through professional training
Alternatives to SGARs include first-generation anticoagulants (less persistent) and non-anticoagulant rodenticides
Integrated pest management can reduce rodent problems without blanket rodenticide use

Welfare Considerations

Secondary poisoning from rodenticides causes prolonged, painful deaths in raptors and other predators. Anticoagulant poisoning causes internal bleeding over 4-7 days, during which affected animals experience weakness, confusion, and respiratory distress before death. Barn owls found dead typically show massive haemorrhage in body cavities. Red kites that survive sublethal doses may recover but face repeated exposure in farming landscapes. The welfare harm is both direct (individual animal suffering) and population-level (ongoing mortality pressure on recovering raptor populations). Prevention requires switching to less persistent rodenticides, using bait stations that reduce access by non-target species, and adopting integrated pest management to reduce reliance on rodenticides.

What You Can Do

Avoid second-generation anticoagulant rodenticides in your garden and home
If using rodent control, use snap traps or first-generation anticoagulants with secured bait stations
Report dead raptors to the Wildlife Incident Investigation Scheme for toxicology analysis
Support the Barn Owl Trust and RSPB campaigns for rodenticide reform
Advocate for restrictions on SGAR use to professional pest controllers only
Donate to Wildlife Crime Prevention for raptor poisoning investigation
Engage with farmers and landowners about integrated pest management alternatives to blanket rodenticide use