Introduced rats on oceanic islands devastate seabird colonies by predating eggs, chicks, and even adults, causing immense wildlife welfare harm.
Seabirds on rat-invaded islands experience welfare harm from direct predation and chronic vigilance stress. Incubating adults are attacked at night. Chicks are eaten alive. Parents returning to destroyed nests show distress behaviors. The long-term psychological effect of chronic predator presence on colonial nesters includes reduced reproductive success from stress-induced breeding failures. Rat eradication directly eliminates this ongoing welfare burden for entire seabird colonies.