Temporal variation in the mass and plumage of four Charadriiformes species on the north-eastern coast of Brazil

Abstract

Each year, thousands of Nearctic shorebirds migrate from breeding grounds in the northern hemisphere to wintering grounds in South America. At the wintering sites, in addition to moulting their flight feathers and plumage, shorebirds engage in feeding to increase body mass to gain sufficient energy for the return migration to the breeding grounds. This study aims to describe the temporal variation of body mass and plumage of the Semipalmated Plover (Charadrius semipalmatus), Spotted Sandpiper (Actitis macularius), Sanderling (Calidris alba) and Semipalmated Sandpiper (Calidris pusilla) during the wintering season on the north-eastern coast of Brazil and to evaluate the relationship between mass gain and plumage moulting. The lowest average masses for each of these species were recorded in October, November, December and January, usually when displaying non-breeding plumage. Shorebirds with intermediate and breeding plumage were frequently recorded in the migration preparation period beginning in April, with a significant increase in body mass. However, for some individuals low masses were recorded late during the wintering period and these were all found to be actively moulting. The highest values for body mass were recorded for shorebirds with breeding and intermediate plumage that were not actively moulting, nearing the end of wintering period.