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.
|wingspan min.:||53||cm||wingspan max.:||66||cm|
|size min.:||26||cm||size max.:||31||cm|
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Predation by feral cats, introduced brown rats Rattus norvegicus9 and house mice Mus mus has been documented and may be causing a population decline. In mixed colonies with P. externa, cats prefer to take the smaller P. longirostris. Introduced goats (c.6,000) are destroying suitable breeding habitat. In 1995, a fire destroyed habitat within part of the colony, although it is not known if the species was nesting in that part of the colony. In 2002, a massive rainstorm caused multiple landslides within the colony, although the effects of this on the species were unquanitified. The species is potentially threatened by climate change because it has a geographically bounded distribution: its altitudinal distribution falls entirely within 2,000 m of the highest mountain top within its range (1,649 m)