Marsh warblers breed in dense, tall vegetation near wetlands and have declined across much of Europe due to loss of suitable wet grassland and reedbed edge habitats.
Marsh warblers face welfare challenges from habitat loss that forces pairs into suboptimal marginal sites with higher nest failure rates. In degraded habitats, pairs must spend more energy establishing territories and nesting in structurally unsuitable vegetation, reducing breeding success. Late-arriving summer migrants, they face habitat loss at both African wintering sites and European breeding areas. Restoration of tall-herb wetland edge vegetation and maintenance of traditional wet meadow management creates optimal breeding habitat and reduces the welfare costs of habitat scarcity.