The white tern (Gygis alba) is a small seabird found across the tropical oceans of the world. The White Tern (Gygis alba) is perhaps the most elegant and delicate seabird, The small eyes surrounded by black rings make them seem much larger. Adults look the same, but juveniles have a brownish-gray back and gray on their neck, with a black mark behind their eye. These dainty terns fly in an undulating pattern with deep, slow wingbeats, which, although it appears erratic, is very strong and enables sustained periods of hovering. This might be the reason why the White Tern got its common name. In Maldives, white tern is locally known as "Dhondheeni" and is mostly found in the southern uttermost atoll in Maldives known as "Addu Atoll". However, the White Tern is commonly found across the tropical seas of the world and in the Indian Ocean.
The white tern has a wingspan of 76–87 cm (30–34 in). It has white plumage and a long black bill. Nesting on coral islands, usually on trees with small branches but also on rocky ledges and on man-made structures, the white tern feeds on small fish which it catches by plunge diving.
This species is notable for laying its egg on bare thin branches in a small fork or depression without a nest. This behaviour is unusual for terns, which generally nest on the ground, and even the related tree-nesting black noddy constructs a nest. It is thought that the reason for the absence of nests is the reduction in nest parasites, which in some colonial seabirds can cause the abandonment of an entire colony. In spite of these benefits there are costs associated with tree nesting, as the eggs and chicks are vulnerable to becoming dislodged by heavy winds. For this reason the white tern is also quick to relay should it lose the egg. The newly hatched chicks have well developed feet with which to hang on to their precarious nesting site. It is a long-lived bird, having been recorded living for 18 years.
The White Tern primarily feed on smaller fish which it catches by plunge diving down on the surface, but it does not submerge fully.
This small sea bird is well-known for laying a single speckled egg on exposed thin branches in a small joint or depression without a nest. The thin branches it chooses is act of predator-avoidance behavior, crows (Corvus splendens maledivicus) and even rats avoid sitting or climbing small branches. However, terns are vulnerable to strong winds and the chicks have sophisticated sharp clawed feet to cling on fragile branches.