In the 300 km2 of coastal wetlands around Rochefort and Brouage, western France, the remaining swampy meadows are drained and progressively replaced by croplands. Consequently, there is a decrease in species richness, diversity, and population density of the breeding birds community. The study here reported points out that preserving the ditches in former marshland, together with the former basins of the old salt marshes, allows the preservation of a diverse marsh birds community, even in the middle of intensively cultivated areas. The key factor for the maintenance of both marsh passerines’ and harrier’s breeding populations is the maintenance of adequate reedbed cover.