4-5-2018 ULAL DE BOLDOVI, VALENCIA - GULL BILLED TERN (Gelochelidon nilotica)

The gull-billed tern (Gelochelidon nilotica), formerly Sterna nilotica, is a tern in the family Laridae. It is widely distributed and breeds in scattered localities in Europe, Asia, northwest Africa, and the Americas. The Australian gull-billed tern was previously considered a subspecies.

This is a fairly large and powerful tern, similar in size and general appearance to a Sandwich tern, but the short thick gull-like bill, broad wings, long legs and robust body are distinctive. The summer adult has grey upperparts, white underparts, a black cap, strong black bill and black legs. The call is a characteristic ker-wik. It is 33–42 cm (13–17 in) in length and 76–91 cm (30–36 in) in wingspan. Body mass ranges from 150–292 g (5.3–10.3 oz).

In winter, the cap is lost, and there is a dark patch through the eye like a Forster's tern or a Mediterranean gull. Juvenile gull-billed terns have a fainter mask, but otherwise look much like winter adults.

4-5-2018 ULAL DE BOLDOVI, VALENCIA - GULL BILLED TERN (Gelochelidon nilotica)

Juvenile Sandwich terns have a short bill, and are frequently mistaken for gull-billed tern where the latter species is uncommon, such as North Sea coasts.

It breeds in warmer parts of the world in southern Europe, temperate and eastern Asia, both coasts of North America, eastern South America. This bird has a number of geographical races, differing mainly in size and minor plumage details.

All forms show a post-breeding dispersal, but the northern breeders are most migratory, wintering south to Africa, the Caribbean and northern South America, southern Asia and New Zealand.

The gull-billed tern is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies.

The gull-billed tern breeds in colonies on lakes, marshes and coasts (including bays and earthen levees). It nests in a ground scrape and lays two to five eggs. While widely distributed in freshwater areas in Eurasia, it is associated almost solely with saltwater, coastal areas in North America.

This is a somewhat atypical tern, in appearance like a Sterna tern, but with feeding habits more like the Chlidonias marsh terns, black tern and white-winged tern. It does not normally plunge dive for fish like the other white terns, and has a broader diet than most other terns. It largely feeds on insects taken in flight, and also often hunts over wet fields and even in brushy areas, to take amphibians and small mammals. It is also an opportunistic feeder, and has been observed to pick up and feed on dead dragonflies from the road.

Gull-billed Terns are graceful fliers that swoop above saltmarshes and beaches. They're pale silvery gray and white, with a shallowly forked tail, heavy bill, and (in summer) a neat black cap. The heavy bill is a key to its diet, which is broader than a typical tern's and does not center on fish. They forage in the air for insects, seize crabs and lizards from the ground, pluck fish from the water surface (without diving into the water), steal food from other birds, and even prey on chicks of other species.

Unlike most terns, Gull-billed Terns have a broad diet and do not depend on fish. Instead they commonly feed on insects, small crabs, and other prey snatched from the ground, air, or even bushes. They are also known to eat small chicks of other tern species.

Although mostly restricted to saltwater habitats in North America, Gull-billed Terns are found in a variety of freshwater habitats across Eurasia.

The oldest recorded Gull-billed Tern lived to be at least 20 years old and was found, and banded, in California.

The Gull-Billed Tern prefers inland waters although it is also present in coastal areas. To nest, it uses sandy islets of lagoons and reservoirs, marshes and salt flats. With regards to feeding this bird benefits from crops, olive groves, pastures, flooded areas and inland dry environments.

Summer species present in Malaga during the breeding period. It breeds in colonies at the end of April and makes an annual laying of 2 eggs. Nest on the ground. This tern feeds on insects, both terrestrial and flying, which hunts in flight at ground level. It also captures amphibians, fish, crustaceans and even micromammals or small birds.