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.:||95||cm||wingspan max.:||105||cm|
|size min.:||38||cm||size max.:||42||cm|
|incubation min.:||53||days||incubation max.:||57||days|
|fledging min.:||100||days||fledging max.:||110||days|
Video Providence Petrel
copyright: Tom Tarrant
On Norfolk Island, its demise was due to hunting and introduced species. The presence of cats and rat species on Norfolk Island continues to limit re-establishment. On Lord Howe Island, it has withstood the introductions of pigs, cats, goats, black rat Rattus rattus and Masked Owl Tyto novaehollandiae castaneothorax. The main causes of death on Lord Howe Island are predation by the threatened Lord Howe Rail Gallirallus sylvestris and flooding of burrows. Rat predation of eggs and chicks was not considered a problem during the 2001 and 2002 breeding seasons. It also risks death from drowning in longline fishing gear, but this cause of mortality is unlikely to be significant. Diet samples have contained traces of plastic; however, no obvious adverse affects have been detected.