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.
Listen to the sound of Zinos Petrel
Copyright remark: Most sounds derived from xeno-canto
recorded by Alexander Lees
|wingspan min.:||78||cm||wingspan max.:||83||cm|
|size min.:||32||cm||size max.:||33||cm|
|incubation min.:||51||days||incubation max.:||54||days|
|fledging min.:||83||days||fledging max.:||54||days|
Builds nest in boulder screes, on flat or steeply sloping ground. Colonial, with nests 0.3-2 m apart. Nest: burrow in ground or between rocks, or natural crevices between rocks. Building: no details. EGGS. Elliptical ovate; white. Clutch: 1. One brood. No information on replacements.
Video Zinos Petrel
copyright: Madeira wind birds
Pterodroma madeira has an estimated breeding population of 65-80 pairs, in the central mountain massif of Madeira, Portugal. Birds are only known to breed on six inaccessible ledges, with a recent survey noting 53 active nests out of a total of 72 identified. Previous studies have produced varying population estimates: a model conservatively estimated a population of 68 birds prior to the breeding season, assuming that P. madeira has a similar age distribution to the closely related P. cahow; and a larger population of 250-400 birds has been suggested, based on the number of birds flying over the colony on three nights in June 1989, and on comparing this with work carried out on the Chatham Island Taiko P. magentae. The true population is likely to lie between these two estimates. Subfossil bones from a lowland cave suggest that it was formerly more numerous and widespread. Little is known about the species’s range outside the breeding season. The gadfly-petrels, to which Zino’s Petrel belongs, are highly social and when courting tend to congregate at night in one particular area and call repeatedly, although they also call elsewhere. In the case of Zino’s Petrel courting occurs over the main breeding area, during the late evening and early morning hours. The birds return from sea to their breeding grounds in late March or early April and laying takes place from mid-May to early June. Nests are located in burrows about 140 cm deep, situated on well vegetated ledges which are generally inaccessible to man, goats and sheep. A single egg is laid, and hatching takes place in late July and early August, with the young usually fledging in late September or early October.