WatchList Species Account for Elegant Tern (Sterna elegans)

Qualifies for the list as a Declining Yellow List Species

 

Elegant Tern

Photo: Glen Tepke

The Elegant Tern has the smallest breeding range of any North American tern. There are only five colonies of this bird known, three in coastal California and two on islands in the Gulf of California, Mexico. Four of these five were established in the last 50 years. Introduced mammals have presumably contributed heavily to the loss of other breeding islands in the past.

 

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 of this species was estimated at fewer than 30,000 pairs.

 

Favored nesting habitat is low, flat, sandy areas largely bare of vegetation. The tern nests among larger, more aggressive larids, including Caspian Terns and the WatchListed Heerman’s Gull. The birds typically feed in the shallow waters of estuaries and bays along the ocean.

 

Guano mining, particularly in the 19th century, impacted Isla Raza, and in more recent years egg collection and other human disturbance have diminished the tern’s population there. Isla Raza was declared a sanctuary in 1964, and since then the numbers of Elegant Tern there have increased.

 

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