Common guillemots nest in dense colonies on sea cliffs with welfare linked to fish availability, entanglement risk, and climate impacts on prey distribution.
Guillemot welfare at cliff colonies is shaped by prey availability and the risk of gillnet entanglement at sea. Sand eel population shifts driven by climate change force adults to travel further for food, increasing exhaustion risk and reducing chick feeding rates. Gillnet entanglement drowns guillemots who dive through nets targeting fish. Colony disturbance causes egg loss when birds panic and eggs fall from narrow ledges. Welfare-focused seabird conservation combines fisheries management maintaining prey availability, reduction of entanglement risk through gear modifications, and protection of key colony sites from disturbance.