Species Details

Details of White Tern will be displayed below

White Tern   

Common Name: Angel Tern, Fairy tern, White noddy
Scientific Name: Gygis alba
Local Name: Dhon'dheeni
Dhivehi Name: ދޮންދީނި
Animalia  (Kingdom)
Chordata  (Plylum)
Aves  (Class)
Laridae  (Family)
Gygis   (Genus)

White Tern's description

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. 

White Tern's Behavior & Ecology

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.

White Tern's Feeding

The White Tern primarily feed on smaller fish which it catches by plunge diving down on the surface, but it does not submerge fully. 

White Tern's Reproduction

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.

White Tern habitat

This species feeds mainly upon small fish, but will also take squid and crustaceans. The proportions vary locally, with 50% of its diet comprising of fish on Christmas Island compared to 85% on Hawaii. Prey are caught by diving. Its breeding season varies locally, nesting on coral islands, usually with vegetation, nesting in trees and bushes, on rocky slopes and cliffs, and also on artificial substrates. It lays a single egg on a bare branch, usually within a slight depression at a fork or on the midrib of a palm frond or banana leaf. It is resident year round on some islands though is a seasonal visitor on others where its non-breeding movements are not known (del Hoyo et al. 1996).

White Tern threats

The White Tern is at risk from the impacts of invasive species, with rats Rattus spp. threatening to extirpate the breeding population on Clipperton Island (Pitman et al. 2005). Cats Felis catus have been observed to predate White Terns (Bell 1912), and they likely predate both chicks and nesting adults. They are known to exist as an invasive species in many areas within the species' range, including Raoul Island where it is thought their eradication would benefit the few White Terns left on the island (Fitzgerald 1991). Pied Currawong Strepera graculina and Masked Owls Tyto novaehollandiae are known predators of White Terns on Lord Howe Island (Carlile and Priddel 2015), and Barn Owls Tyto alba impose a significant predation pressure on Aride Island, Seychelles, but is currently subject to a control programme (Gochfield et al. 2018). Human exploitation also poses a problem in some areas, with the extreme example of a corrupt warden in Rodrigues causing the population on the island to collapse by killing adults and collecting eggs (Gochfield et al. 2018).

White Tern's status