WatchList Species Account for Elegant Tern (Sterna elegans)

Qualifies for the list as a Rare Yellow List Species

Photo: Glenn and Martha Vargas © California Academy of Sciences

The Elegant Tern has the smallest breeding range of any North American tern. There are only 5 colonies of this bird, three in coastal California and two on islands in the Gulf of California, Mexico. Four of these 5 were established in the last 50 years. Favored nesting habitat is low, flat, sandy areas largely bare of vegetation. The vast majority (estimated as over 90% of breeding pairs) breeds at just one of these sites, Isla Raza in the Gulf of California, though numbers at the California coastal sites are expanding rapidly.

In the 1990s the world population was estimated at fewer than 30,000 pairs. The bird nests among larger, more aggressive larids, including Caspian Terns and the WatchList Heerman’s Gull. Introduced mammals have presumably contributed heavily to the loss of other breeding islands in the past. Guano mining, particularly in the 19th Century, impacted Isla Raza and in more recent years egg collection and other human disturbance had diminished the tern’s population there. The island was declared a sanctuary in 1964, and since then the numbers have increased. The birds typically feed in the shallow waters of estuaries and bays along the ocean.

During the winter, Elegant Terns are found along the Pacific Coast from central Mexico to Chile. Changes in ocean temperature with global warming and overfishing may change ranges and/or diminish numbers of the fish these birds depend on for food.