Chlidonias hybrida Pallas, 1811

In summer plumage their black cap and white cheeks makes them look more like Common Terns than Black Terns but they have the short, broad wings and tails typical of 'marsh terns' and their underparts are such a deep grey that the white cheeks stand out boldly. In juvenile plumage, they have a dark mantle recalling the saddle effect which is a key feature of White-winged Black Terns. In winter, the forehead becomes white and the body plumage a much paler greyThe first winter plumage is intermediate between juvenile and adult winter, with patchy ginger on the back. In a Whiskered Tern, however, this saddle is paler, browner and is noticeably interrupted by pale scaly markings. Also, the rump is not as conspicuously white as on a White-winged Black Tern and the wings of a Whiskered Tern are a more uniform grey. These features are also helpful in winter plumage when the crown goes mostly white, leaving a definite dark horizontal line going back from the eye. Also the bill is heavier than in other 'marsh terns'