English: These van Rossem's Gull-billed Terns Gelochelidon nilotica vanrossemi were photographed at the San Diego National Wildlife Refuge located in southern California. They are a medium-sized migratory seabird that feed on a variety of small prey items, including crabs, lizards, insects, chicks of other bird species, and fish. They are also a ground-nesting species whose nests consist of shallow scrapes with pieces of rocks, shells, or fish bones. (Eric Kershner/USFWS)