Rodenticide poisoning through secondary exposure from eating poisoned prey is a significant welfare and conservation threat to barn owls.
Rodenticide poisoning causes a prolonged, painful death from internal haemorrhage. Barn owls die slowly from exposure that accumulates over multiple poisoned prey items. The extensive exposure rates detected in UK barn owls indicate that rodenticide use is pervasive and that secondary poisoning is endemic. Switching to mechanical traps and habitat management reduces rodent populations without wildlife collateral casualties.