Whiskered Tern

Chlidonias hybridus (Pallas, 1811)

2017-06-10 Selenga River delta, Kabansk District, Buryatia	©

Description

Whiskered Tern is a bit larger than Black and White-winged terns, but smaller than Common Tern. Adults in spring have black “cap”, upperpart slate-grey, gong lighter to the tail, wings and tail pale grey. Chin and cheeks white. Breast dark grey, belly blackish. Underwing and undertail-coverts white. Bill and legs bright- or dark-red. Iris reddish-brown. In general, the Whiskered Tern recalls the Common Tern, but differs with slate-grey coloration in the majority of body, contrasting with white cheeks, and with less forked tail. In winter, mantle pale grey, other parts of plumage white; dark brown band across eye, and narrow black streaks on crown. Bill and legs brownish. Young birds like winter adults, but having head and mantle with dark brown feathers with ochre margins being wider on shoulder feathers. Sizes (mm): wing 225-250, tarsus 27-34, bill 27-34.

Distribution

Distributed in Eurasia, Africa, and Australia, usually with disperse small parcels. In total, rare species. The breeding is known on some water pools in the steppe zone o Siberia, its range is very dynamic. The European nominative subspecies Ch.h.hybridus reaches the western part of Siberia from the west, and a smaller and darker subspecies Ch.h.javanicus inhabits the Eastern Siberia. l

Biology

A rare, in some locations occasional, breeding species. It lives on freshwater lakes, ponds, river mouths with dense vegetation and deep-water parts situated nearby. In spring, it appears in the end of May or in early June. Nesting usually in colonies not larger than 50 pairs, sometimes to 300 pairs, usually nearby to white-winged terns, black-necked grebes, or black terns, or single pairs within colonies of other terns. Nests are situated on water plants (leaves of water lilies, etc.), old stalks of reed, or on hillocks among reedbeds. The clutch containing 2-3 eggs is made in early – middle June (and earlier in the Western Siberia). Both parents incubate 18-20 days and then feed chicks, which start to fly in age more than 20 days. Flying juveniles appear in late July, and in August. The autumn migration is not obvious, birds are disappearing in breeding areas to middle August, and only single individuals can delay to early or middle September.

References

"Птицы Казахстана", том 2. Алма-Ата, 1962.
"Птицы дельты Селенги" / И.В.Фефелов и др. Иркутск, 2001.
В.К.Рябицев. "Птицы Сибири". Москва-Екатеринбург, 2014. <br>