Post-breeding migration ecology of reed Acrocephalus scirpaceus, Moustached A. melanopogon and Cetti's Warblers Cettia cetti at a Mediterranean stopover site

We analysed and compared body mass and capture-recapture data of a long-distance migrant, the Reed Warbler Acrocephalus scirpaceus, and of two partial and short-distance migrants, the Moustached Warbler A. melanopogon and the Cetti's Warbler Cettia cetti. Data were collected during two consecutive autumn seasons at a Mediterranean stopover site in southern France. Mean stopover duration of Reed Warbler was 8.5 days. It increased from 6.1 days at the end of July to 11.1 days at the end of October. The fuel deposition rate of Reed Warblers was 0.29 g day-1 at the peak of migration (end of September) and 0.40 g day-1 in late October. The gain in body mass during stopover was 0.37 g in late July and 4.48 g in late October. Although the stopover duration was longer at the end of the season, the longer potential flight range may -have enabled them to achieve a higher migration speed. In contrast to the Reed Warbler, immigration and emigration probabilities of Moustached and Cetti's Warblers to and from the stopover site were low, resulting in long stopover duration during which they did not significantly change body mass, irrespective of moult, sex or age. We discuss possible migration strategies of these three warbler species under consideration of ring recoveries. (Résumé d'auteur