Sterna sumatrana

General description: 

Adults are largely white, with: a very pale-grey back, rump and uppertail-coverts and upperwings; a bold, black band extending from the lores, where narrow, across the nape; and a thin blackish outer web to the outermost primary, forming a dark leading edge to the outerwing in flight and to a dark lower edge to the folded wing. The underparts can have a faint pinkish tinge at times. The bill, legs and feet are black, and the eyes dark brown. Juveniles are similar to adults but with a less clear-cut black nape-band, and with dark mottling and wash to the crown; and dark crescents and white scaling to the saddle and tertials, extending diffusely onto the rear upperbody. The tail has fine dark edges and is less deeply forked than in the adult, and the upperwing is also scaled with black and marked with dusky cubital and secondary bars. The bill is black with a paler base, but the bare parts are otherwise like those of the adult. Black-naped Terns are often gregarious, especially when they are breeding and roosting, although less so when they are foraging. They occur in groups ranging from a few birds up to approximately 100. They are often seen standing with Crested Terns (Thalasseus bergii), Lesser Crested Terns (T. bengalensis), Bridled Terns (Onychoprion anaethetus = Sterna anaethetus) and Roseate Terns (Sterna dougallii), in large mixed groups, though there tends to be some segregation in these congregations. Black-naped Terns are more likely to land near a group of terns (even another species) than where there are no terns. They often forage with other species of terns and noddies, such as Bridled and Roseate Terns and Black Noddies (Anous minutus). However, during the breeding season, they forage singly.

Conservation status: 

Not Threatened.

Diagnostic description: 

Adults are largely white, with: a very pale-grey back, rump and uppertail-coverts and upperwings; a bold, black band extending from the lores, where narrow, across the nape; and a thin blackish outer web to the outermost primary, forming a dark leading edge to the outerwing in flight and to a dark lower edge to the folded wing. The underparts can have a faint pinkish tinge at times. The bill, legs and feet are black, and the eyes dark brown. Juveniles are similar to adults but with a less clear-cut black nape-band, and with dark mottling and wash to the crown; and dark crescents and white scaling to the saddle and tertials, extending diffusely onto the rear upperbody. The tail has fine dark edges and is less deeply forked than in the adult, and the upperwing is also scaled with black and marked with dusky cubital and secondary bars. The bill is black with a paler base, but the bare parts are otherwise like those of the adult. Black-naped Terns are often gregarious, especially when they are breeding and roosting, although less so when they are foraging. They occur in groups ranging from a few birds up to approximately 100. They are often seen standing with Crested Terns (Thalasseus bergii), Lesser Crested Terns (T. bengalensis), Bridled Terns (Onychoprion anaethetus = Sterna anaethetus) and Roseate Terns (Sterna dougallii), in large mixed groups, though there tends to be some segregation in these congregations. Black-naped Terns are more likely to land near a group of terns (even another species) than where there are no terns. They often forage with other species of terns and noddies, such as Bridled and Roseate Terns and Black Noddies (Anous minutus). However, during the breeding season, they forage singly.

Behaviour: 

Size: 

The Black-naped Tern is a small and slender marine tern (total length 30–32 cm; mean weight approximately 105 g) with a long and deeply forked tail

Phylogeny: 

Taxonomy:

    Sterna Sumatrana Raffles, 1822, Sumatra. Thought to be closely related to S. dougallii, with which sometimes nests, but chick pattern very different. Sometimes considered monotypic, but divided into races on basis of shape. Two subspecies recognized. (source: Handbook of the Birds of World)
Distribution: 

Subspecies and Distribution:

    * sumatrana Raffles, 1822 - Andaman and Nicobar Is E to S Japan and China, and S through Malaysia, Philippines, Indonesia and New Guinea to NE & E Australia and Pacific islands (Yap, Marshall Is, Ponapé, Micronesia), with breeding also suspected (at least formerly) in Bengal, Bangladesh and S Myanmar; birds from Japan and China winter to S. * mathewsi Stresemann, 1914 - Aldabra, Amirante, Chagos and Maldive Is, W Indian Ocean.
Habitat: 

In northern and north-eastern Australia, Black-naped Terns breed and roost on islands, which are very occasionally close to or attached to the mainland at low tides, and forage in seas surrounding colonies. Black-naped Terns are mainly associated with small, offshore sand and coral cays, coral reefs and lagoons, and sandy and rocky islands and islets, and in the surrounding seas. The species is only occasionally recorded in inshore waters away from their breeding colonies. Black-naped Terns usually nest in exposed, open sites, in simple, usually unlined depressions on bare sand or shingle beaches of cays, reefs and islands, typically in the narrow strip just above the high-water mark where debris collects. Occasionally they nest on spits, bare rock or among coral rubble or, more rarely, on top of logs or on structures, such as shipwrecks. Nests are usually away from vegetation or occasionally near the edge of vegetation, among grass and shrubs, or, rarely, beneath trees.

Trophic strategy: 

Black-naped Terns feed solely on fish, mainly Engaulidae, Exocoetidae, Atherinidae and Clupeidae. In Australia, fish eaten include species of: Apogonidae, Atherinidae (including Atherinomorus lacunosus, Pranesus capricornensis, Hypoatherina uisila), Blenniidae (including Belnnies), Carangidae, Clupeidae (including Spratelloides delicatulus, Amblygaster sirm, Herklotsichthys quadrimaculatus), Coryphaenidae, Engraulidae (including Encrasicholina, Engraulis australis), Exocoetidae, Gobiidae, Hemiramphidae, Labridae, Mugilidae, Parapercidae, Pinguipedidae, Pomacentridae, Scombridae and Sphryroenidae. Mean length of prey 35 mm, but take fish up to 100 mm long.

Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith