Sediment ingestion of two sympatric shorebird species

Black-bellied plovers (Pluvialis squatarola) have short bills and primarily peck while foraging whereas Willets (Catoptrophorus semipalmatus) have long bills and primarily probe with bills open in sediments. Intestinal digesta were collected from these species at sympatric overwintering sites in southern California near San Diego to relate sediment ingestion to bill length and feeding behavior. Plover digesta contained an estimated 29% sediment, and Willet digesta an estimated 3% sediment. Techniques based on acid insoluble ash and on the elemental markers of Al, Fe, and Ti in digesta provided similar results. High Ca concentrations in Willet digesta along with our observations suggested that the Willets in our sample fed primarily on molluscs and crustaceans. Sediment ingestion may be species-specific, not necessarily linked to bill length or probing behaviors, and may greatly affect a bird's exposure to environmental contaminants in sediment.