Seabirds are among the animals most severely affected by marine plastic pollution, with ingestion causing malnutrition, internal injury, and death at epidemic scale.
Seabird plastic ingestion causes multiple overlapping welfare harms. Large plastic pieces physically block digestion and cause ulceration. The false satiation from a stomach full of indigestible material leads to progressive starvation while the bird appears to be feeding normally. Chemical pollutants adsorbed onto plastic particles disrupt hormonal systems and immune function. Chicks fed plastic by well-intentioned parents are particularly vulnerable, as they cannot self-select food and depend entirely on parental provisioning quality. The welfare harm is global in scale and requires systemic reduction of plastic ocean pollution.