Active bird nests are protected under UK law, and disturbance during the nesting season causes significant welfare harm to breeding birds and their young through abandonment and chick mortality.
Nest disturbance causes welfare harm through two primary mechanisms: abandonment of the nest by parent birds leaving eggs or young to die, and direct injury to eggs or chicks from handling or vegetation disturbance. The stress response of incubating or brooding adult birds to sudden disturbance causes physiological harm and disruption to the incubation temperature stability critical for egg development. Abandoned nests with eggs lose the constant temperature regulation that egg development requires; abandoned chicks die from cold or starvation within hours. Public awareness of the nesting season, the legal protection of active nests, and practical guidance on timing garden maintenance to avoid the March-August period directly reduces the welfare harm of inadvertent nest disturbance.