Environmental heterogeneity, spatial segregation of prey, and the utilization of southwest Atlantic mudflats by migratory shorebirds

摘要: We studied the relationships between habitat use of migratory shorebirds and spatial distributions Southwestern Atlantic Fiddler Crab Uca uruguayensis, polychaetes, sediment characteristics tidal levels in Rio de La Plata estuary, Argentina, where U. uruguayensis is one most important intertidal species. Crabs have a well-defined patchy distribution that segregated spatially from polychaetes. density on surface varied across cycle, reaching maximum values during low tide. Polychaete decreased with depth but showed no change through cycle; however, given penetrability did same period, their availability to probing expected change. Habitat by followed prey; foraged polychaetes (White-rumped Sandpiper Calidris fuscicollis, Two-banded Plover Charadrius falklandicus Hudsonian Godwit Limosa haemastica) focused attention areas highest densities whereas species preyed mostly crabs (Ruddy Turnstone Arenaria interpres, Whimbrel Numenius phaeopus Grey Pluvialis squatarola) predominantly used crabs. This segregation occurred particularly tide, period which became fully available. Results show temporal heterogeneity mudflats relation types prey has strong effect shorebird use.