Forster's Tern
Sterna forsteri
Forster's tern is a medium-sized tern with a slender body, deeply forked long tail and relatively long legs. In its non-breeding plumage, the crown is white and a black comma-shaped patch covers the eye and the ear-covert. The wings are gray with the primaries being dark silvery gray, while the underside is white. The bill is black and the legs are a dull brownish red. When breeding, an intense black cap extending down the neck appears. The wings and the back are pale gray while the underside is bright white. It has a black-tipped orange bill and bright orange legs. Voice: The common call of the Forster's tern is a descending kerr. The threat call used in defensive attack is a low harsh zaar. A succession of kerrs is used by the female as a begging call during courtship.
ID text from Wikipedia, CC BY-SA 4.0
River Tern
Sterna aurantia
It is a medium-large tern, 38–46 cm long with an 80–85 cm wingspan, distinctly larger than any other species in Sterna and more comparable in size to a Sandwich tern (Thalasseus sandvicensis) or a lesser crested tern (T. bengalensis). It has dark grey upperparts, white or very pale grey underparts, a forked tail with long flexible streamers, and long pointed wings with pale grey primaries. The bill is stout for a tern, bright yellow in summer and duller yellow with a dusky tip in winter, and the legs bright red.
ID text from Wikipedia, CC BY-SA 4.0
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Play today's Daily BirdPhotos and recordings are credited to their authors under the licence shown. Full profiles: Forster's Tern and River Tern.