Dietary relationships among Nearctic and Neotropical migratory shorebirds in a key coastal wetland of South America

MARTÍNEZ CURCI N.S.; AZPIROZ AB; ISACCH JP; ELÍAS, R

EMU

CSIRO PUBLISHING

Lugar: Collingwood; Año: 2015

0158-4197

Dietary requirements influence the structure of shorebird assemblages. This information is key for understanding why and when particular species use an area and how competition for food shapes their geographic distribution. We describe diet and food resource co-use patterns for four migratory shorebirds at Samborombón Bay, Argentina, one of the most important sites for shorebirds in the Western Hemisphere. Although birds consumed at least 15 taxa few items were identified as main trophic resources. Shorebirds exhibited dietary flexibility that was influenced by season and tidal level. Co-occurring species showed complementary differentiation throughout two dimensions (taxonomic composition and size-class) of their trophic niche. The largest differences in taxonomic composition were observed between Red Knots, which fed mainly on molluscs, and the other three species that fed mainly on polychaetes. Polychaete consumers that co-occurred during autumn (Hudsonian Godwit and White-rumped Sandpiper) focused on different prey sizes. Alternatively, shorebirds that co-occurred during winter (Hudsonian Godwits and Two-banded Plovers) fed mainly on similar polychaete sizes but exhibited differences in taxonomic composition. Interspecific competition for food resources might shape the composition of shorebirds assemblage present at our study area during the austral autumn and winter.