Barn Owl Welfare and Rodenticide Secondary Poisoning

Barn owls across Europe and North America are suffering population declines linked to second-generation anticoagulant rodenticide accumulation in their prey, causing internal bleeding and death in non-target predators.

Key Facts

Second-generation anticoagulant rodenticides including brodifacoum and bromadiolone persist in rodent tissue
Barn owls that eat poisoned rodents accumulate rodenticide in their livers over time
Over 80% of barn owls tested in UK post-mortem studies contain second-generation rodenticides
Barn owls eat 4-6 rodents per night and are therefore exposed at every meal in treated areas
Rodenticide regulations require outdoor use restrictions but enforcement and compliance are inconsistent
UK barn owl populations have declined by over 70% since the 1950s from multiple causes

Welfare Considerations

Rodenticide secondary poisoning causes anticoagulant-induced death — internal bleeding that may take days or weeks to be fatal. Affected barn owls become lethargic, unable to hunt effectively, and increasingly susceptible to other harms including starvation and trauma. The exposure is continuous because rodents in treated areas carry sublethal doses that accumulate with each prey item eaten. Barn owl nest box schemes maintain breeding habitat but cannot compensate for the chronic physiological harm of rodenticide exposure. Transitioning to first-generation rodenticides with lower secondary poisoning risk, improving carcass removal after rodenticide use, and using bait stations that reduce rodent access by non-target species all reduce secondary poisoning welfare harm.

What You Can Do

Avoid second-generation anticoagulant rodenticides in gardens and buildings
Support barn owl nest box schemes and local barn owl monitoring groups
Advocate for tighter restrictions on second-generation rodenticide outdoor use
Donate to barn owl population monitoring and conservation breeding programmes
Raise awareness about rodenticide secondary poisoning as a systemic threat to owl and raptor welfare