Sooty Tern

The sooty tern is a seabird of the tropical oceans that can fly for years at a time, skimming the sea surface for food and returning to land only to breed on islands throughout the equatorial zone. Six subspecies are currently accepted; the form nubilosus breeds across the Indian Ocean from the Red Sea to Indonesia and in the Philippines, with light grey underparts in fresh plumage (Wikipedia, general species account).

It was long known as Sterna fuscata. Nationally Critically Endangered (Sri Lanka National Red List 2012, listed as Sterna fuscata).