White-winged tern

Voice

A dry, short, rasping kersh or kerrek, higher and sharper than Black Tern and with a nasal edge. At colonies an agitated, continuous rattle. In western Europe it is rarely heard, at most from migrants over a lake in May or August, and the call then makes a useful confirmation of a difficult bird.

Identification

In breeding plumage head, body and underwing coverts are black, cutting sharply against white primaries; the upperwing coverts, rump and tail are white, the bill dark red and the legs bright red. In winter it is white with a finely streaked crown and a small ear patch separated from the crown, a clean white rump and no dark breast-side patch. Juveniles show a dark brown, strongly contrasting saddle.

Confusion species

In autumn Black Tern is the pitfall. Look for the dark breast-side patch in front of the wing bend, which White-winged always lacks, and for the white rump contrasting with the grey back. Head streaking is more restricted, so the black ear patch looks isolated; the bill is shorter and the wingbeat shallower and more bouncing.

Habitat

Shallow, densely vegetated freshwater marshes, flooded steppe lakes, fish ponds and wet meadows well inland. Breeds in loose colonies on floating mats of sedge and waterweed. Hunts over flooded grassland, reedbeds and arable land for insects, taking most of them in the air or from vegetation and rarely from the water.

Range and movements

A breeder of eastern Europe and Central Asia, centred in Belarus, Ukraine and Russia; further west it nests only in wet years and then irregularly. In the Netherlands it is a scarce passage migrant with occasional influx-like May arrivals; in Spain it is likewise scarce but annual, mainly in the Ebro delta and the southern lagoons.

• Breeding (summer)
• Winter
• Passage
• Migration direction
• dark = core range, pale = thinly spread

Where and when to look

May and the second half of August offer the best chances. In warm weather with easterly winds, scan marsh tern flocks over large inland waters such as the Lauwersmeer, the Oostvaardersplassen or the Rhine floodplain. Come in the evening, when terns gather over shallow water and the light falls low and sideways.

Conservation status

Not globally threatened, with a large but strongly fluctuating eastern population that tracks water levels in steppe marshes. Drainage, canalisation and the conversion of floodplains to arable land shrink the breeding range. Numbers recorded in western Europe partly depend on drought in the core areas, so records vary considerably from year to year.