Common terns breed in noisy, dense colonies on coastal and inland shingle and islands. Their welfare is linked to sand eel availability, weather stability and freedom from disturbance.
Common tern chick welfare depends on consistent parental provisioning of sand eels and other small fish. Extended cold or stormy weather that disrupts fishing causes progressive chick starvation visible in reduced growth rates before fledging weight failure. Colony disturbance — from walkers, dogs and boats — causes mass flushing events where chicks are exposed to temperature extremes and gull predation. Wardening at key colony sites during the breeding season provides direct welfare benefit.