Grey Noddy
Encyclopedia
Seabird
Seabirds are birds that have adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental problems and feeding niches have resulted in similar adaptations...
belonging to the tern
Tern
Terns are seabirds in the family Sternidae, previously considered a subfamily of the gull family Laridae . They form a lineage with the gulls and skimmers which in turn is related to skuas and auks...
family Sternidae. It was once regarded as a pale morph of the Blue Noddy
Blue Noddy
The Blue Noddy is a species of tern in the Sternidae family. It is also known as the Blue-grey Noddy.It is found in American Samoa, the Cook Islands, Fiji, French Polynesia, Kiribati, Marshall Islands, New Caledonia, Samoa, Tonga , Tuvalu and Hawaii. It has occurred as a vagrant in Australia and...
(Procelsterna cerulea) but is now often considered to be a separate species.
Description
It is 25 centimetre long with a wingspan of 46 centimetre and a weight of about 75 grams (2.6 oz). The tail is fairly long and notched. The plumagePlumage
Plumage refers both to the layer of feathers that cover a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage vary between species and subspecies and can also vary between different age classes, sexes, and season. Within species there can also be a...
is pale grey, almost white on the head and underparts but darker on the back, tail and wings. The wings have dark tips and a white hind edge and are mainly white underneath. The eye is black and appears large due to the black patch in front of it. There is a white patch behind the eye. The thin, pointed bill
Beak
The beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young...
is black and the legs and feet are also black apart from pale yellow webs.
Juvenile
Juvenile (organism)
A juvenile is an individual organism that has not yet reached its adult form, sexual maturity or size. Juveniles sometimes look very different from the adult form, particularly in terms of their colour...
birds are browner than the adults and have darker, more contrasting flight feather
Flight feather
Flight feathers are the long, stiff, asymmetrically shaped, but symmetrically paired feathers on the wings or tail of a bird; those on the wings are called remiges while those on the tail are called rectrices . Their primary function is to aid in the generation of both thrust and lift, thereby...
s.
The Grey Noddy is usually silent but has a soft, purring call.
Distribution
It occurs in subtropical and warm temperate waters of the south Pacific OceanPacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
. The subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
P. a. albivitta breeds on Lord Howe Island
Lord Howe Island
Lord Howe Island is an irregularly crescent-shaped volcanic remnant in the Tasman Sea between Australia and New Zealand, directly east of mainland Port Macquarie, and about from Norfolk Island. The island is about 11 km long and between 2.8 km and 0.6 km wide with an area of...
, Norfolk Island
Norfolk Island
Norfolk Island is a small island in the Pacific Ocean located between Australia, New Zealand and New Caledonia. The island is part of the Commonwealth of Australia, but it enjoys a large degree of self-governance...
, northern New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
(particularly the Kermadec Islands
Kermadec Islands
The Kermadec Islands are a subtropical island arc in the South Pacific Ocean northeast of New Zealand's North Island, and a similar distance southwest of Tonga...
) and southern Tonga
Tonga
Tonga, officially the Kingdom of Tonga , is a state and an archipelago in the South Pacific Ocean, comprising 176 islands scattered over of ocean in the South Pacific...
(on 'Ata
'Ata
Ata is a small, rocky island in the far south of the Tonga archipelago, situated on . It is also known as Pylstaart island. It should not be confused with Atā, which is an uninhabited, low coral island in the string of small atolls along the Piha passage along the northside of Tongatapu, nor should...
and probably 'Eua
'Eua
Eua is a smaller but still major island in the kingdom of Tonga. It is close to Tongatapu, but forms a separate administrative division. It has an area of 87.44 km2, and a population in 2006 of 5,165 people.- Geography :...
). P. a. skottsbergii is found on Henderson Island
Henderson Island (Pitcairn Islands)
Henderson Island is an uninhabited raised coral atoll in the south Pacific Ocean, that in 1902 was annexed to the Pitcairn Islands colony, a South Pacific Dependent Territory of the United Kingdom. Measuring long and wide, it has an area of and is located northeast of Pitcairn Island at . The...
, Easter Island
Easter Island
Easter Island is a Polynesian island in the southeastern Pacific Ocean, at the southeasternmost point of the Polynesian triangle. A special territory of Chile that was annexed in 1888, Easter Island is famous for its 887 extant monumental statues, called moai, created by the early Rapanui people...
and Sala y Gómez
Sala y Gómez
Isla Salas y Gómez, also known as Isla Sala y Gómez, is a small uninhabited Chilean island in the Pacific Ocean. It is the easternmost point in the Polynesian Triangle...
. P. a. imitatrix breeds on the Desventuradas Islands
Desventuradas Islands
thumb|Map of Desventuradas Islands The Desventuradas Islands, also known as Islas de los Desventurados, is a group of four small islands located off the coast of Chile, northwest of Santiago in the Pacific Ocean...
off the coast of Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
.
Behaviour
It feeds in shallow water, not moving far from the breeding colonies. It gathers in large feeding flocks which can contain thousands of individuals. They feed by hovering over the water and dropping down to pick food from the surface. PlanktonPlankton
Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...
forms the bulk of the diet and small fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
are also eaten.
Breeding takes place in colonies on rocky islands. The nest
Nest
A nest is a place of refuge to hold an animal's eggs or provide a place to live or raise offspring. They are usually made of some organic material such as twigs, grass, and leaves; or may simply be a depression in the ground, or a hole in a tree, rock or building...
site is a sheltered rocky surface or underneath a boulder or clump of vegetation. A single egg
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
is laid. It is whitish with dark markings and is incubated
Avian incubation
Incubation refers to the process by which certain oviparous animals hatch their eggs, and to the development of the embryo within the egg. The most vital factor of incubation is the constant temperature required for its development over a specific period. Especially in domestic fowl, the act of...
by both parents for about 32 days. The young birds are fed on regurgitated
Regurgitation (digestion)
Regurgitation is the expulsion of material from the mouth, pharynx, or esophagus, usually characterized by the presence of undigested food or blood.Regurgitation is used by a number of species to feed their young...
food and fledge
Fledge
Fledge is the stage in a young bird's life when the feathers and wing muscles are sufficiently developed for flight. It also describes the act of a chick's parents raising it to a fully grown state...
after around 35 days.