[order] PROCELLARIIFORMES | [family] Procellariidae | [latin] Pterodroma lessonii | [authority] Garnot, 1826 | [UK] White-headed Petrel | [FR] Petrel de Lesson | [DE] Weisskopf-Sturmvogel | [ES] Petrel Cabeciblanco | [NL] Witkopstormvogel
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.
It has a white head and underbody that contrast with the dark underwings. The white of the throat and head becomes grey on the mantle, darkening towards the tail, and a broad, dark eye line gives them a masked appearance.
Southern Ocean : widespread. This species has a circumpolar range and is found throughout the Southern Oceans. It breeds on Macquarie Island, the Auckland Islands and Antipodes Islands (New Zealand), Crozet and Kerguelen Islands (French Southern Territories) and Pacific Oceanssibly on the Prince Edward Islands (South Africa).
The White-headed Petrel is marine and highly pelagic, rarely approaching land except at colonies, but has been recorded inshore during stormy weather. Breeding starts in October in loose colonies, nesting in burrows dug in soft soil or scree near the coast or inland up to 300 m above sea level
The birds returned to land in November, and the chicks hatched at the end of January and fledged in May. These incubation and fledging periods are among the longest known in the family Procellariidae. Successful birds normally bred every two years, which has not previously been reported for any member of this family. It breeds alone or in colonies in burrows dug among tussocks and herbfields on subantarctic islands. It lays one egg, incubated for about 60 days. The chicks fledge after 102 days. Some successful breeders may nest only in alternate years.
It feeds mostly on squid and crustaceans, which is catches mostly at night by surface-seizing and dipping
Video White-headed Petrel
copyright: Peter Fraser
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is very large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
Disperses widely over Southern Ocean, probably in circumpolar range, generally S of 30 degrees S; absent from colonies for only 2 months. Adults apparently less mobile than juveniles; large numbers in Straits of Magellan in Dec, thought to be immatures. Ranges S to pack ice, but also N into subtropical zone.