Wild Barn Owl Winter Survival and Rodenticide Threats

Barn owls are highly vulnerable to winter mortality and rodenticide poisoning, with second-generation anticoagulants found in a majority of tested carcasses in the UK.

Key Facts

Second-generation anticoagulant rodenticides (SGARs) were detected in 79% of barn owl carcasses tested in a UK study
SGARs accumulate in barn owl livers through prey consumption and cause internal bleeding
Barn owls have little fat reserve and can starve within days during prolonged snow cover
Winter mortality is the primary population regulator for barn owls in temperate climates
Barn owls cannot break through ice or snow to access prey, making snow cover periods critical

Welfare Considerations

Barn owls face two major winter welfare threats: starvation during periods of snow and ice that prevent hunting, and chronic rodenticide poisoning from consuming contaminated prey. Rodenticide poisoning causes subclinical anticoagulation that weakens owls, making them vulnerable to trauma and infection, before eventually causing fatal haemorrhage. The widespread use of SGARs in agricultural and domestic settings creates a diffuse but pervasive poisoning source across barn owl territories. Stewardship schemes that reduce rodenticide use and promote alternative pest control protect barn owl populations at scale.

What You Can Do

Use only first-generation rodenticides or non-chemical alternatives where possible
If using SGARs, follow manufacturer stewardship guidance strictly to reduce wildlife exposure
Support barn owl winter feeding programmes by monitoring nest boxes and providing supplementary prey during snow
Report dead barn owls to the Barn Owl Trust for post-mortem examination and rodenticide monitoring