Courtesy Kenn Kaufman
Elegant Terns breed in only five nesting colonies—two in southern California, and three in northwestern Mexico. More than 90% of the world's Elegant Terns nest on Isla Rasa in Mexico's Gulf of California. Following the breeding season, birds typically disperse northward to central and northern California, but they can move as far north as Oregon and Washington. In southern California, breeding success and dispersal patterns appear related to oceanographic conditions, which affect the distribution of the birds' key prey, the northern anchovy. In winter, Elegant Terns are found along the Pacific Coast from central Mexico south to Chile.
Elegant Terns are typically found along the shallow waters of estuaries and bays along the ocean. During the breeding season, they nest on isolated sandy or rocky islands, usually in the company of larger, more aggressive birds, such as Heermann's Gulls and Caspian Terns.
Elegant Terns forage by hovering over shallow water and then plunging into the water after fish. This tern can transport a single fish at a time crosswise in its bill. Elegant Terns forage on a variety of different schooling fish, with northern anchovy (Engraulis mordax
) being their most important prey item. Other prey species include sardines, silversides, gobies, mackerels, and rarely, crustaceans. When feeding in flocks, these gregarious terns call frequently.
A strongly social bird, this tern nests in tight groups. Like many other terns, Elegant Tern nests consist of a shallow scrape on the ground. Their typical clutch size is one egg, buff to white marked with dark brown, which is probably incubated by both parents. After a period of at least three weeks, the single chick hatches and spends a few days in the nest before joining a creche—a group of young birds who are still fed by their own parents. Post-fledging parental care lasts up to six months, during which time the chicks learn foraging skills.
After breeding, Elegant Terns disperse north along the Pacific coast to northern California, or, in years of warm water intrusions, to southern British Columbia. These terns winter primarily in South America, but small numbers winter locally along the Pacific coast north to Nayarit, Mexico.