Food and fattening of migrating warblers in some french marshlands

Abstract

Seven warbler species were studied in autumn at three marshes in western France. The extent of pre-migratory fattening and the diets of each are described. Diets overlapped considerably, though there were differences between sites within species. Between species there were differences of size and taxa of prey taken as well as height of feeding places and of methods used. Sedge and Savi’s Warblers only gained weight when food in the form of aphids or mayflies was super-abundant. Great Reed and some Reed Warblers were able to gain weight in the absence of such abundant small prey items by virtue, it is suggested, of their more active and versatile feeding methods. Further work on foods and fattening rates would be a valuable contribution to the understanding of migration patterns studied by ringing methods alone. © 1983 Taylor & Francis Group, LLC.