White-winged tern ©Kenneth Lam

 

Common name: White-winged Tern
Scientific name:  Chlidonias leucopterus
Local names: Белокрылая крачка (Russian), 白翅浮鸥 (Simplified Chinese), 白翅浮鷗 (called in Hong Kong)，白翅黑燕鷗(called in Taiwan) (traditional Chinese), 흰죽지제비갈매기 (Korean), ハジロクロハラアジサシ(Japanese), Dara laut sayap putih (Indonesian), Camar Bermisai (Malayu), Nhàn xám (Vietnamese), นกนางนวลแกลบดำปีกขาว(Thai). Also known as White-winged Black Tern.

Conservation status: IUCN - Least Concern

The White-winged Tern is a Eurasian species. Medium-sized, distinctive in breeding plumage with black head and body while white wing, rump and tail. As the species breeds inland, it adapts to various habitats from freshwater wetlands to coastal wetlands.

Identification

  • Size: 23-27 cm; wingspan 58-67 cm.
  • Breeding plumage:
    • Blackhead, body and scapulars
    • Contrasting white and tail and greyish upper wing
  • Non-breeding plumage:
    • Black colour would fade and body become greyish on the body and upper wing
    • Head turned white with dusky crown and ear-coverts patch
  • Juveniles appear like non-breeding adults, but cap, wing and body feathers is blackish-brown, and upper wings are barred and ashy brown.
  • Beak: red to black
  • Legs: Reddish-black

Distribution range

Breeding range confined to Northern Hemisphere, from Central Europe to Russia reaching to Eastern China. Non-breeding range is towards the southern Hemisphere, including Africa, most of South and Southeast Asia, to New Guinea, Australia and New Zealand. The tern is vagrant to Alaska and elsewhere in the USA.

Habitat

  • Breeding habitat

Unlike many tern species, White-winged Tern breeds mainly inland, on freshwater lakes and swamps, rivers, and flooded grassland with areas of open water.

  • Non-breeding habitat

Non-breeding on migration or winter at various habitats from inland lakes, rivers, flood plains to coastal rocky shores, lagoons and mangrove swamps. The bird is also found feeding over wet fields, farmland and steppe grassland.

White-winged Tern roosting at the east coast of Aceh, Indonesia ©Qiran Altafunnisa

Behavior

White-winged Tern breeds at the age of 2. They breed in small colony from 3-100 pairs, but exhibit low site fidelity. The bird may skip breeding in drought years. Being inland breeders, the bird feed mainly on aquatic insects, sometimes terrestrial insects, and occasionally small fish or tadpoles.

Population estimate

Global estimated population: The global population is estimated to number c.3,100,000-4,000,000 individuals (Wetlands International 2015). East Asian-Australasian Flyway population is estimated c. 100,000 – 1,000,000 individuals (WPE5).

Main threats

  • Habitat destruction
  • Water regulation (increasing drainage schemes) degrades the habitats

Other threats

  • Pollution (including plastic pollution)
  • Feral dogs, cats and introduced predators such as raccoons and minks.
  • Susceptible to avian influenza

Conservation Work

Although it is not highlighted as a specially protected species in any country because of its Least Concern status according to IUCN, it is a species not well-studied. Protection of inland wetland systems and removal of feral and invasive predators (such as dogs, and raccoons) to these sites will benefit its survival.

Fun Fact

  • Although breeding mostly in Northern Hemisphere, there were four breeding records in New Zealand from the lower Rakaia River (1917, 3 chicks fledged), Opihi River, South Canterbury (December-February 1973-74), upper Acheron River, Marlborough (December 2012), and near Twizel (January 2015).
  • Its genus name Chlidonias is from Ancient Greek khelidonios, which means "swallow-like". In fact in many countries, terns are referred as ‘sea-swallows’ in local names.
  • Hybridization with Black Tern (Chlidonias niger) has been recorded in Europe.

References