Origins and age structure of Red Knot Calidris canutus staging and wintering on the Atlantic coast of France

摘要: In western Europe, the coasts of Vendee and Charente-Maritime on central Atlantic shoreline France constitute most southern wintering site for Red Knot Calidris canutus islandica, welcoming around 37,000 individuals each winter, also represent a key stopover area C. c. (up to 60,000 individuals) between Africa Wadden Sea in spring. Nevertheless, origin birds arriving autumn is unclear, considering that first islandica start appear while could use same sites as their migration route Africa. We used biometric data from caught 1983 2008 assess staging France, we investigated age structure groups during three distinctive periods biological cycle: migration, spring migration. This assessment was completed by analysis ring recoveries over period 44 years isotopic ratio signatures feathers. The obtained results were conformity with general patterns distribution throughout year timing both subspecies Europe described previous reviews. this study highlights two unknown features part European distributions. First, very large predominance juveniles recorded at expense an extreme rarity adults early winter. prove presence canutus-knots among these juveniles, even later possibility there some them. Although coast welcomes only 9% population islandica-knots network estuarine bays crucial strategic juveniles. place liberated coming than already settled northern sites. It offers migrate south distance-limited stages order experiment flyway refuel join traditional African grounds.