The yellow-legged gulls, which circle in groups above the Saint-Michel islet, are the most easily observable birds of the Lac de Serre-Ponçon. The site, in the extension of the Durance and on the Camargue-Central and Northern Europe migration axis, is the last important refuge area for migrating birds before crossing the Alpine chain. Many species of waterbirds and shorebirds rest or overwinter there.