The marsh warbler (Acrocephalus palustris) is one of Britain's rarest breeding birds, with fewer than 50 pairs recorded annually. Its welfare is tied to dense wetland vegetation and insect abundance.
With such a small breeding population, each individual's welfare and survival is significant at the population level. Nest failures from flooding, predation, or vegetation management at the wrong time can eliminate an entire year's productivity at a site. Conservation management that times cutting and grazing to avoid the breeding season (May-July) directly protects welfare. Insect abundance is critical — aerial invertebrate declines affect feeding success for chicks.