Biology:Whiskered tern

Short description: Species of bird

Whiskered tern
C. h. delalandii summer (breeding) plumage, South Africa
C. h. hybrida winter (non-breeding) plumage, Sri Lanka
Conservation status
Least Concern (IUCN 3.1)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Charadriiformes
Family:	Laridae
Genus:	Chlidonias
Species:	C. hybrida
Binomial name
Chlidonias hybrida (Pallas, 1811)
Subspecies
C. h. hybrida – (Pallas, 1811) (Eurasian Whiskered Tern) C. h. delalandii – (Mathews, 1912) (African Whiskered Tern) C. h. javanicus – (Horsfield, 1821) (Australasian Whiskered Tern)
Range of Ch. hybrida   Breeding   Resident   Non-breeding   Vagrant (seasonality uncertain)
Synonyms
Chlidonias hybridus

The whiskered tern (Chlidonias hybrida) is a tern in the family Laridae. The genus name is from Ancient Greek khelidonios, "swallow-like", from khelidon, "swallow". The specific hybridus is Latin for hybrid; Peter Simon Pallas thought it might be a hybrid of white-winged black tern and common tern, writing "Sterna fissipes [Chlidonias leucopterus] et Hirundine [Sterna hirundo] natam".

This bird has a number of geographical races, differing mainly in size and minor plumage details.

C. h. hybrida breeds in warmer parts of Europe and the Palearctic (northwestern Africa and central and southern Europe to southeastern Siberia, eastern China and south to Pakistan and northern India). The smaller-billed and darker C. h. delalandii is found in east and south Africa, and the paler C. h. javanicus from Java to Australia .

The tropical forms are resident, but European and Asian birds winter south to Africa and the Indian Subcontinent. A tagged whiskered tern was spotted at Manakudi Bird Sanctuary, Kanniyakumari District of Tamil Nadu, India in the month of April 2021.

This species breeds in colonies on inland marshes, sometimes amongst black-headed gulls, which provide some protection. The scientific name arises from the fact that this, the largest marsh tern, show similarities in appearance to both the white Sterna terns and to black tern.

Description

Whiskered tern in flight

The size, black cap, strong bill (29–34 mm in males, 25–27 mm and stubbier in females, with a pronounced gonys) and more positive flight recall common or Arctic tern, but the short, forked-looking tail and dark grey breeding plumage above and below are typically marsh tern characteristics. The summer adult has white cheeks and red legs and bill. The crown is flecked with white in the juvenile, and the hindcrown is more uniformly blackish, though in the winter adult this too is flecked with white. The black ear-coverts are joined to the black of the hindcrown, and the space above is mottled with white, causing the black to appear as a C-shaped band. The sides of the neck are white; this sometimes continues across the nape. The collar is less sharply defined. All through the year the rump is pale grey. In the juvenile, the mantle has a variegated pattern. The feathers of the back and scapulars are dark brown, with prominent broad buff edgings and often subterminal buff bars or centers. There is usually an admixture of new gray feathers, especially on the mantle, quite early in the fall. The mantle is silvery-gray in the adult. The call is a characteristic krekk.

In winter, the forehead becomes white and the body plumage a much paler grey. Juvenile whiskered terns have a ginger scaly back, and otherwise look much like winter adults. The first winter plumage is intermediate between juvenile and adult winter, with patchy ginger on the back.

The whiskered tern eats small fish, amphibians, insects and crustaceans.

Eggs of Chlidonias hybrida

External links

• Whiskered tern in The Atlas of Southern African Birds

Wikidata ☰ Q233616 entry