The UK holds the majority of the world population of Manx shearwaters, nesting in vast burrow colonies on offshore islands that must be free of introduced predators for breeding success.
Manx shearwater welfare depends absolutely on predator-free island colonies. Rat and mink predation at burrows causes direct mortality and abandonment. Island biosecurity programmes have enabled dramatic population recovery. The species remarkable longevity means individual welfare spans decades, making any mortality particularly significant.