About Gygis alba (Sparrman, 1786)
The white tern (Gygis alba) measures 23–30 cm (9.1–11.8 in) in length, with a wingspan of 76–87 cm (30–34 in). It has pure white plumage; for the subspecies G. a. candida, this plumage is marked only by a dark streak running along the shafts of the outer primary feathers. A black eye is accentuated by a narrow ring of black feathers surrounding the eye, and it has a long black to bluish-black bill. Its tail is shallowly forked, and, similar to the tails of noddies, the longest tail feathers are the second-from outermost, unlike the tails of other terns where the outermost feathers are longest. Leg color is dark grey, and is paler grey in the subspecies G. a. leucopes and G. a. microrhyncha. Juvenile white terns have white plumage mottled with grey or greyish-brown. White terns nest on coral islands, most often on trees with small branches, but they may also nest on rocky ledges and man-made structures. They feed on small fish, which they catch via plunge diving. This species is pelagic and epipelagic. The Atlantic population of Gygis alba is found across many islands; the bird lives along coasts, and moves into wooded areas during the breeding season.
