The Manx shearwater nests in burrows on offshore islands and undertakes remarkable trans-Atlantic migrations, with welfare linked to colony site integrity and prey availability.
Manx shearwater welfare at colony sites depends on burrow integrity, rat and gull predation management, and marine food availability. Brown rat predation at colonies has caused historical population crashes, and eradication programs on Lundy and other islands have resulted in dramatic breeding success recovery. Human disturbance of burrows and use of lights near colonies during the April to August breeding season disorients adults and causes nest abandonment. Plastic pollution ingestion in ocean feeding areas harms adults and is fed to chicks. Maintaining rat-free status on breeding islands is the single most important welfare intervention. The species' remarkable longevity makes individual welfare across a 50-year lifespan particularly significant.