Gull-billed Tern

The Gull-billed Tern, Gelochelidon nilotica, is a robust bird, akin in stature to the Sandwich Tern. It boasts a stout, gull-like bill, broad wings, and lengthy legs. In its summer plumage, the adult displays grey upperparts, stark white underparts, a jet-black cap, and matching black bill and legs. The species measures 33–42 cm in length with a wingspan of 76–91 cm, and weighs between 150–292 g.

Identification Tips

In its non-breeding attire, the Gull-billed Tern loses its black cap, revealing a dark eye patch reminiscent of a Forster's Tern or a Mediterranean Gull. Juveniles bear a paler mask and resemble winter adults. The juvenile Sandwich Tern, with its shorter bill, is often mistaken for the Gull-billed Tern in regions where the latter is scarce.

Habitat

The Gull-billed Tern is found in a variety of habitats, including lakes, marshes, and coastal regions such as bays and earthen levees. In Eurasia, it is commonly seen in freshwater areas, whereas in North America, it is almost exclusively associated with saltwater coastal environments.

Distribution

This species enjoys a wide distribution, breeding in southern Europe, temperate and eastern Asia, North America's coasts, and eastern South America. It exhibits post-breeding dispersal, with northern populations migrating to winter in Africa, the Caribbean, northern South America, southern Asia, and New Zealand.

Behaviour

The Gull-billed Tern is known for its colony breeding habits. It lays two to five eggs in a ground scrape. The species is covered by the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA), highlighting its migratory nature.

Song & Calls

The bird's vocalization is a distinctive ker-wik, which can be heard during its flight.

Breeding

Breeding colonies are established on lakes, marshes, and coasts. The Gull-billed Tern's nesting preference for ground scrapes is a notable aspect of its reproductive behavior.

Diet and Feeding

Unlike its plunge-diving relatives, the Gull-billed Tern has a varied diet, feeding on insects in mid-flight, amphibians, and small mammals. It is also known to scavenge, having been observed feeding on dead dragonflies found on roads.

Conservation status

The Gull-billed Tern is currently listed as Least Concern by the IUCN, indicating that it is not at immediate risk of population decline or habitat loss at a global scale.