Roseate terns are one of Europe's rarest seabirds, with breeding colony welfare critically dependent on rat eradication and management at island nest sites.
Roseate terns at rat-invaded colonies suffer acute welfare impacts: rats kill incubating adults sitting on eggs at night, causing both the welfare harm of a painful death and the loss of breeding productivity. Chicks killed by rats die through biting injuries. The fear response of adults disturbed by nocturnal rat presence may cause colony abandonment. Effective rat management including trapping and bait stations directly prevents these welfare harms, enabling colony productivity and reducing predation-related suffering.