A small, delicate tern, the blue noddy (Procelsterna cerula) is distinctive due to its pale plumage, with an all-grey head and upperparts and even paler white-grey underparts. The upperwing is slightly darker than the rest of the body, with greyer or brown tinged coverts and blackish primaries. The short tail is shallowly forked, and the black bill is short and slender. There is usually a white ring around the eyes, and a small black spot between the eye and the bill. The legs and feet are black, with pale webs (2)(3)(4)(5). The male and female blue noddy do not differ in appearance, and juveniles are similar to the adults, but with brownish colouration on the upperparts, especially the crown (5).
There are five recognised subspecies of the blue noddy: Procelsterna cerulean saxatilis, Procelsterna cerulea nebouxi, Procelsterna cerulea cerulean, Procelsterna cerulean teretirostris and Procelsterna cerulea murphyi (1).
Also known as
blue ternlet, blue-gray noddy, blue-grey noddy, blue-grey ternlet, grey ternlet.
With the narrowest gape of all terns (2), the blue noddy is restricted to feeding on tiny fish, squid, sea-skaters and small crustaceans. It generally forages in small groups close to the shore, flying low over the water using quick, shallow wing-beats before dipping to snatch prey from the surface. The blue noddy also often hovers close to the water, pattering its feet on the surface, when searching for prey (2)(5)(6).
The time at which breeding begins varies with location, but typically commences in September in Australia (5), from August to November in Kiritimati, and June to August in the Phoenix Islands (2). In Hawaii, the blue noddy is known to breed all year round, with a peak in egg-laying between February and March (2)(6). Usually, a single egg is laid in a roughly constructed nest, made from shreds of grass and seaweed, which has been placed on a cliff face in a crevice or hollow, or under a ledge or vegetation (2)(3)(5). The egg is incubated by the male and female adult blue noddy for around 32 days, and the chick is brooded continuously by the adults for around 2 to 3 weeks after hatching. The chick typically fledges at around 37 days old, although both adults continue to feed the juvenile by regurgitation for some time (2)(5).
The blue noddy is widely distributed in the Pacific Ocean, where it is found in American Samoa, the Cook Islands, Fiji, French Polynesia, Kiribati, Marshall Islands, New Caledonia, Samoa, Tonga, Tuvalu and the Hawaiian Islands (1)(4)(6). It also occurs on the east coast of Australia and on Lord Howe Island (off Australia) (3)(5).
Primarily an inhabitant of tropical oceanic islands, the blue noddy roosts and breeds mainly on inaccessible cliffs or, less often, in areas of sheltered rocky ground, beaches, or clumped or bushy vegetation. The blue noddy forages over lagoons and inshore areas, often around upwelling currents (2)(5).
Although the blue noddy is not currently threatened with extinction, several localised threats may negative impact the breeding success of this species. Predation of eggs and young may cause problems at some breeding locations, such as Lord Howe Island, and the introduction of rodents to offshore islands is a cause for concern (3). The blue noddy is limited by its cliff nesting habitat (2), especially where there is potential competition for nest sites with other species.
Intensive fishing operations around feeding grounds is thought to pose a risk to the blue noddy, possibly increasing mortality due to collisions with fishing gear, and by the removal of prey (3)(5). The development of areas close to breeding habitat may also threaten this species in future (5).
The blue noddy is listed as a Vulnerable Species on Schedule 2 of the New South Wales Threatened Species Conservation Act 1995 (5)(7). Recommendations for conservation of the blue noddy include preserving its existing breeding and roosting habitat and monitoring the impact of fishing operations on the population (5), as well as controlling rodent populations (3).
Further research on the habitat and ecology of the blue noddy is also required (5).
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Small feathers concealing the bases of larger flight feathers, usually on the wings or tail.
Diverse group of arthropods (a phylum of animals with jointed limbs and a hard chitinous exoskeleton) characterised by the possession of two pairs of antennae, one pair of mandibles (mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps, woodlice and barnacles.
The base of the beak, where the upper and lower parts join.
To keep eggs warm so that development is possible.
In birds, the main flight feathers projecting along the outer edge of the wing.
A population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.
The upward movement of cold, nutrient-rich water from the ocean depths, usually as a result of winds and currents.
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