Atlantic Petrel (Pterodroma incerta)

Atlantic Petrel

Subspecies

Genus	Species	subspecies	Region	Range
Pterodroma	incerta		AO	s

Genus

Genus Pterodroma, Pseudobulweria and Aphrodroma are also knwon as the Gadfly Petrels. They vary in size from rather small birds such as the Cookilaria-species, measuring about 26 cm, to the much larger and robust representatives of this group like the White-headed Petrel with an overall length of about 43 cm. Their plumages also vary a great deal from species to species; from completely black to light grey mantles and pure white bellies, and with different color phases within species. One feature shared by all of them is the black bill of which the shape also shows much variation. Some species are extremely rare and restricted to a very limited area, other are abundant and wander widely or have unknown pelagic ranges.
The group of the Gadfly Petrels counts over 35 species, mainly from the Southern Hemisphere. There are three genera: Pterodroma with about 30 species, Pseudobulweria counting four and Aphrodroma with only one. Many authors have tried to classify the large number of species of this group and to determine their relationships. This has resulted in a division in several subgenera and the grouping of several species which are considered to have a more or less close relationship. The taxonomic discussion has not come to an end yet: new species have been added or split recently and probably will be in the near future.

Physical charateristics

Large, stocky, dark brown-and-white petrel. Uniformly dark chocolate-brown above and on upper breast. Head can appear grey in worn plumage. Sharp demarcation from brown upper breast to white lower breast and belly. Brown vent, undertail-coverts and tail. Uniform brown underwing. Similar spp. Soft-plumaged Petrel P. mollis has patterned underwing. Trindade Petrel P. arminjoniana has white wing flashes. Hints May flap at top of glides unlike most Pterodroma spp. Concentrates around subtropical convergence.

wingspan min.:	0	cm	wingspan max.:	0	cm
size min.:	42	cm	size max.:	44	cm
incubation min.:	0	days	incubation max.:	0	days
fledging min.:	0	days	fledging max.:	0	days
broods:	1		eggs min.:	1
			eggs max.:	1

Range

Atlantic Ocean : South. Pterodroma incerta breeds only on Gough Island, Tristan da Cunha (St Helena to UK)

Habitat

This bird nests in colonies on islands, but is otherwise pelagic

Reproduction

It nests in burrows dug in peaty soils in fern-bush vegetation from 50-300 m on Gough and formerly, at higher elevations on Tristan. Nothing is known of age of first breeding, breeding frequency or survival

Feeding habits

It feeds mainly on squid with some fish and crustaceans

Conservation

This species has been listed as Endangered because it has an extremely small occupied breeding range, and there is now evidence that that chick predation by introduced mice is causing very low breeding success and is likely to be causing the population to decline. It has not been recorded from Tristan de Cunha for 35 years, and, were it to be confirmed as extinct there, it may qualify for uplisting to Critically Endangered.
Pterodroma incerta breeds only on Gough Island, Tristan da Cunha (St Helena to UK). It is absent from Nightingale where there is no suitable habitat, and probably also from Inaccessible, although it is possible that a small number of birds could breed there because there have been no surveys during the winter breeding season, and Tristan, where though the population was estimated to be 100-200 pairs in 1972-1974, there have been no records since then at it is now believed to be extinct on that island. On Gough, the first quantitative population estimate indicates a total of around 1.8 million pairs, considerably larger than the earlier estimate of at least 20,000 pairs. Recent evidence suggests that fledging success is very low, less than 20% during the last five years and perhaps as low as 2% in 2007, and this is likely to be driving a long term decline.

Migration

Disperses throughout South Atlantic, occurring off East coast of South America and rounding South Africa into Indian Ocean, North to at least 2 6degrees South

Distribution map

Atlantic Petrel distribution range map

Planet of Birds