European shags are coastal seabirds that collect marine debris to line nests, inadvertently entangling themselves and chicks in plastic twine, fishing line, and packaging materials, causing injury and death.
Entanglement in nesting material causes slow, painful deaths and permanent injury. Adult birds may be unable to detect the welfare harm caused by their normal nest-building behaviour. Chicks trapped in nest material cannot escape if parents abandon the nest, leading to starvation or dehydration. The welfare harm is diffuse and difficult to monitor across remote cliff colonies.