Birds of Mongolia

ID Breeding adult confusable only with White-winged Tern, but readily distinguished by dull grey (vs. clear white) upper forewings above and tail, and pale grey (vs. black) underwing-coverts; also, dark (vs. red) legs. Non-breeding adult separated from White-winged by darker mantle; solid black cap and ‘sideburns’ (vs. pale, streaked cap and cheek spot); grey (vs. whitish) rump; and grey ‘halter marks’ at sides of breast. Juv distinguished from White-winged by less contrast between back and wings. See also Whiskered Tern. Voice At colonies gives a shrill, nasal kyeeh; contact call in flight is more abrupt ki ki or klip klip. Habitat Rivers, lakes and large pools with small fish. Behaviour Picks food from surface. Light, buoyant flight, usually low over water. Status Very rare breeding visitor at Lake Uvs and Sagil and Höndlön River valleys in north-west; and rare passage migrant in suitable habitat south to Valley of the Lakes and east through Hövsgöl and Khangai to Dornod, late April to late August.

ID Sparkling white wings that contrast sharply with largely black body make breeding adult highly distinctive. For comparison with similar non-breeding adult and juv plumages of Black Tern, see that species (see also Whiskered Tern). Voice Gives a soft kweek and harsher kwek kwek in flight; also a crackling crzzk. Habitat Nests in marshes and marshy edges of lakes; also frequents these and other aquatic habitats on migration. Behaviour Colonial, sometimes nesting with Black-headed Gulls. Feeding behaviour and manner of flight similar to Black Tern. Status Locally fairly common breeding visitor from Great Lakes Depression south to Valley of the Lakes and east to Hövsgöl, Khangai and Dornod. Common passage migrant across Mongolia, including lakes and wetlands in arid steppe and Gobi Desert, late April to late August. [Alt: White-winged Black Tern]

ID Breeding adult resembles a small, darker Common Tern more than other ‘marsh terns’ (Black and White-winged) with a dark cap, red bill and legs, and grey breast, rather than generally black body plumage. Distinguished from breeding adult Common Tern by smaller size and dark grey underparts, contrasting sharply with white cheeks. Flight pattern more like marsh terns. Non-breeding adult Whiskered also resembles Common Tern, with cap paler than Black Tern but darker and more extensive than White-winged Tern. Juv best distinguished from other marsh terns by brownish-tinged back with heavy black scaling pattern. Voice Flight call a dry kheh or grzzzt. Habitat Like other marsh terns, nests colonially in reedbeds and tussock sedges along lake and river shores. Behaviour Similar to other marsh terns. Status Rare and local breeding visitor in Great Lakes Depression and Valley of the Lakes and uncommon passage migrant across Mongolia, including lakes and wetlands in arid steppe and Gobi Desert, late April to mid-August.

ID The world’s largest tern, virtually unmistakable in all plumages due its enormous tomato-red bill. Squarish head shape, short tail and black wing-tips below are also distinctive. Voice A harsh throaty kraaaah or kraaaak. Juv gives whistling wee-ooo. Habitat Nests colonially on sandy or rocky beaches with sparse vegetation on shores of lakes and large rivers; uses other aquatic habitats on migration. Behaviour Plunge-dives for fish; also takes insects and small land animals. Status Rare breeding visitor to a number of lakes in Great Lakes Depression and Valley of the Lakes and rare passage migrant in northern and eastern Mongolia, late April to early September. Taxonomy Sometimes placed in genus Sterna.

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