Cayenne Tern (Sterna eurygnatha)

[order] Charadriiformes | [family] Sternidae | [latin] Sterna eurygnatha | [UK] Cayenne Tern | [FR] Sterne caugek | [DE] Brandseeschwalbe | [ES] Gaviotin Brasilero | [IT] Beccapesci | [NL] Grote Stern

Subspecies

Physical charateristics

Cayenne Tern tends to have a darker mantle than Sandwich Tern but considerable overlap occurs. Breeding individuals of both races have a slight pinkish flush on the underparts. Caribbean and central South American populations of Cayenne Tern have a Northern Hemisphere moult cycle similar to that of Sandwich Tern. Southern South American populations of Cayenne Tern breed during the austral winter and have a Southern Hemisphere moult cycle. Sandwich Tern and northern populations of the Cayenne Tern are fairly similar in bill length and bill size. However, Cayenne Tern populations from southern South America have notably larger bills and body sizes.

Range

The North American race of the Sandwich Tern breeds along the Atlantic and Gulf of Mexico coasts of North America, and on islands in the northern Caribbean Sea. It winters primarily in the Caribbean and along the coasts of South America, where it strays as far south as Argentina. The similar ?Cayenne? Tern breeds on islands in the southern Caribbean Sea and along the Atlantic coast of South America, and has been recorded several times along the Atlantic coast of North America and once along the Pacific coast of Colombia.

Habitat

Strictly coastal and prefers warm-water bodies. prefers open unvegetated sandy , gravelled or muddy areas. Outside breeding season also open rocky or more elevated sandy areas, but always close to large waterbodies.

Reproduction

A monogamous species, breeding in colonies, often mixed with other terns, especially Royal terns. A simple nest on coastal beaches and islands, in the open above tidemark, unlined or lined with debris. Clutch consists of 1-3 pale cream to pink-buff eggs with brown, black, and grey markings. Incubation takes 21-29 days and is cared for by both sexes. Fledging periode about 28-32 days. One brood per year.

Feeding habits

Prefers to feed at sea; Usually hovers, then dives from great heights to catch prey under water. Small fish including young garfish and small mullets.

Conservation

This species has a large range, with an estimated global extent of occurrence of 100,000-1,000,000 km2. It has a large global population estimated to be 460,000-500,000 individuals (Wetlands International 2002). Global population trends have not been quantified, but the species is not believed to approach the thresholds for the population decline criterion of the IUCN Red List (i.e., declining more than 30% in ten years or three generations). For these reasons, the species is evaluated as Least Concern.

Migration

North American birds move South through Caribbean and along both coasts of Central America to South America. Some linger in South East USA and Caribbean, others reach Uruguay and West South America. Sometimes numerous on Central coast of Peru. Race eurygnatha winters in South Caribbean and along Atlantic coast of South America to Argentina. Some post-breeding wandering in Gulf Stream North to North Carolina, few sightings from Colombia, including one on Pacific Coast. In Uruguay, eurygnatha is uncommon along coast in breeding season, while typical acuflavidus appears in winter from North America.

Distribution map