Also called crested ternor swift tern, is a tern in the family Laridae that nests in dense colonies on coastlines and islands in the tropical and subtropical Old World. Its five subspecies breed in the area from South Africa around the Indian Ocean to the central Pacific and Australia, all populations dispersingwidely from the breeding range after nesting. This large tern is closely related to the royal and lesser crested terns, but can be distinguished by its size and bill colour. Terns have red oil droplets in the cone cells of the retinas of their eyes. This improves contrast and sharpens distance vision, especially in hazy conditions. Birds that have to see through an air/water interface, such as terns and gulls, have more strongly coloured carotenoid pigments in the cone oil drops than other avian species. Around September to February this aves can be spotted perched onto the floating buoy nearby Labuan island offshore especially at the westcoast of the island.