This file displays the distribution and average seasonal abundance of gulls at the South Bay salt ponds. Birds were identified and counted monthly from January 2003 through August 2005 within 3 hours of high tide. Data presented herein are average monthly counts per season: winter (December-February), spring (March-May), summer (June-August), and fall (September-November). We assigned species to foraging guilds, groups of species with similar habitat requirements. These included: 1) dabbling ducks (e.g. northern shovelers Anas clypeata); 2) diving ducks (e.g. ruddy ducks Oxyura jaimaicensis); 3) eared grebes (e.g. Podiceps nigricollis); 4) piscivores (e.g. double-crested cormorants Phalacrocorax auritis); 5) gulls (e.g. ring-billed gulls Larus delawarensis); 6) herons and egrets (e.g. great egrets Ardea alba); 7) medium shorebirds (e.g. marbled godwits Limosa fedoa); 8) phalaropes - (e.g. Wilson's phalaropes Phalaropus tricolor); and 9) small shorebirds (e.g. western sandpipers Calidris mauri). The gull guild included the following species: Black skimmer, black tern, Bonaparte's gull, California gull, caspian tern, elegant tern, Franklin's gull, glaucous-winged gull, herring gull, least tern, mew gull, ring-billed gull, Thayer's gull, and Western gull