It is well documented now that climatic changes affect the migration range and phenology of many birds. A fifteen year monitoring of the french breeding population of Avocets, based on color ringing, has shown a shift in the wintering migration strategy. The northern wintering increases whereas iberian recruitement in winter decreases. A systematic and more intensive monitoring of color ringed avocet both in France and in the iberian peninsula should help us to understand the mechanism of these changes.