It sings in reed and you don't see it: that is the sedge warbler. Fortunately, sedge warblers will also sing while balancing at the top of a reed or even while flying just above it. They brood in swamps. In the coastal region, the wet dune valleys, fields of reed beside dune lakes and overgrown salt marshes are ideal nesting areas. The bird eats mostly louse picked off of reed stalks.