River Tern vs White-fronted Tern

River Tern

Sterna aurantia

Medium166 gRiverine

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

Photo: Parth Kansara · CC BY 4.0

White-fronted Tern

Sterna striata

Medium129 gCoastal

The white-fronted tern is an average-sized tern; its dimensions are 35–43 cm (14–17 in) in length, with a wingspan between 79 and 82 cm (31 and 32 in); the male weighs on average 130 g (4.6 oz). Females are marginally smaller than males, but this is difficult to determine when observing individuals in the wild. Breaking down their monochromatic colouring, the white-fronted tern's lightest features are its all-white body, tail and underwing, with the upper side of the wings a light silvery-grey hue. Voice: A very dull crek is used in courtship when the male is flying above groups, individuals may respond with the same noise. When descending upon intruders, they will let out a continuous keark. Generally calling between individuals is a high-pitched siet used frequently during flight, it will be repeated over and over in particular intervals.

ID text from Wikipedia, CC BY-SA 4.0

Photo: Joe Dillon · CC BY 4.0

Photos and recordings are credited to their authors under the licence shown. Full profiles: River Tern and White-fronted Tern.