We identified environmental variables and grassland characteristics that affect the use of natural grasslands by four migratory shorebird species (Patagonian: Rufous-chested Dotterel (Charadrius modestus) and Tawny-throated Dotterel (Oreopholus ruficollis); Nearctic: American Golden Plover (Pluvialis dominica) and Buff-breasted Sandpiper (Tryngites subruficollis)) during the non-breeding season in the flooding pampa region of Argentina. Birds were recorded using fixed-radius point count method, every 15 days between April 1999 and January 2000. A stepwise forward logistic regression was used to examine the relationship between the presence of shorebirds and grassland characteristics and environmental variables. All species correlated positively with the variable “previous use” suggesting strong site fidelity within years to a wintering site. All species correlated negatively with the percentage of high grass cover, and the American Golden Plover and Buff-breasted Sandpiper both correlated negatively with soil water content. Tawny-throated Dotterel correlated positively with the presence of Stipa neesiana. Previous studies have identified the coastal grasslands of Buenos Aires province as important sites for wintering nearctic and Patagonian grassland shorebirds. This study confirms the importance of this area, and highlights the important role that sheep management plays in maintaining suitable habitat conditions (short grass) for grassland shorebirds.