Spring migration of semipalmated sandpiper Calidris pusilla in the Amazonian coast of Brazil

The Brazilian Amazonian coast is one of the most important wintering areas for the semipalmated sandpiper (Calidris pusilla) in South America. Aerial surveys in South America recorded the presence of about 2.1 million individuals of small-bodied shorebird species, and the majority were identified as semipalmated sandpipers. The present study provides information of C. pusilla populations during the spring migration at three localities (Panaquatira Beach, Maiau Island and Macarico Beach) on the Brazilian Amazonian coast of Brazil, including data on mass gain and estimates of flight range. The first C. pusilla migrants arrive at the Amazonian coast by mid-August. Wintering populations varied between 2,000 individuals at Macarico and Panaquatira, and 4,500 birds at Maiau Island. Sharp decline in the number of reproductive adults of C. pusilla in mid-May was observed at the three areas. During this period, groups of 30 to 50 C. pusilla were observed on a daily basis, flying at a height of 100-150 m in the direction of the Atlantic Ocean, not subsequently returning to the island, suggesting that they had migrated. Flight range capacity of adult C. pusilla from the three areas in April and May would theoretically allow them flying nonstop to the eastern United States. However, the available data suggest that C. pusilla during spring migration in the Brazilian Amazonian coast may follow a different route from birds departing from the most northern wintering areas (Suriname, Guyana, French Guyana and Venezuela), not showing connectivity with birds departing from these areas.