Monitoring of Red Knot (Calidris canutus rufa) during northward migration in five sites in Argentina and the Uruguayan-Brazilian border: Phenology and carry over effects

GONZÁLEZ PM; BENEGAS L; BARRETO T; FERRARI S; BALA L; D'AMICO VL; PETRACCI P; SARRÍA R; ALDABE J; ROCCA P; FAILLA M; BAKER AJ; MORRISON G

VANCOUVER

Congreso; IV Western Hemisphere Shorebird Group Meeting; 2011

From January to May 2009 and 2010 we conducted simultaneous censuses and resightings of color marked red knots during their northward migration along 2,800 km from a wintering site at Río Grande, Tierra del Fuego, to the Uruguayan-Brazilian border, including 4 intermediate stopover sites. The phenology of migration was heterogeneous. Some knots moved to nearby areas like Río Gallegos before migration. Other flocks flew 1500 km or more to staging areas in northern Patagonia or southern Buenos Aires province in Argentina, and some remained there a few days while other knots spent up to 1 or 2 months. The Uruguayan-Brazilian border was used by birds that later moved to nearby areas to complete their pre-migratory refuelling. Red knots began their transcontinental migration from Rio Grande do Sul, Brazil, and also, surprisingly, from northern Patagonia and southern Buenos Aires. The analysis of diet and food resources showed that when the availability of profitable sizes of prey was depressed in Río Grande, some birds arrived later in northern Patagonia and were affected in their subsequent condition measured by abdominal profile scores at departure time. This is the first study that connects critical sites for a long distance migrant shorebird in three countries of the Southern Cone of South America.