[order] PROCELLARIIFORMES | [family] Procellariidae | [latin] Pterodroma cookii | [authority] Gray, 1843 | [UK] Cooks Petrel | [FR] Petrel de Cook | [DE] Cook-Sturmvogel | [ES] Petrel de Cook | [NL] Cooks Stormvogel
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.
Small, grey-and-white petrel. White forehead merging into grey crown. Pale grey crown, neck, back, uppertail-coverts. Darker grey wings showing “M” in flight. Tail slightly darker grey than back. Darker still on tips of central feathers. Outer feathers can be white. White underparts. White underwing with dark tip and dark line along leading edge, extending indistinctly from carpal joint towards body.
Listen to the sound of Cooks Petrel
Copyright remark: Most sounds derived from xeno-canto
Pacific Ocean : widespread. Pterodroma cookii is endemic to New Zealand, where it breeds on Little Barrier, Great Barrier and Codfish Islands. On Great Barrier, only 12 burrows have been found during the last 25 years; there may be fewer than 20 pairs and it is extinct as a reproductively viable Pacific Oceanpulation. On Codfish the Pacific Oceanpulation declined from c.20,000 pairs in the early 1900s almost to extinction before predators were removed in 1982; it is now increasing and was estimated at 5,000 breeding pairs in 2007. The Pacific Oceanpulation on Little Barrier is also likely to be increasing, and modelling and spatial analysis has suggested that as many as 286,000 pairs may breed on Little Barrier Island annually. Birds migrate to the east Pacific Ocean, mainly between 34 degrees S and 30 degrees N.
It breeds in burrows on forested ridges and steep slopes between 300-700 m on Little Barrier and 4-350 m on Codfish; ideal breeding habitat is unmodified forest close to ridgetops with a low and open canopy and many large stems
The breeding season of Cook’s petrel extends from October to April, with eggs laid in early November on Little Barrier Island and a month later on Codfish Island. They dig burrows in the soil in colonies, into which one egg is laid and incubated for 47 to 51 days. Adults forage at sea for periods of 2 to 13 days whilst feeding chicks, and chicks fledge after 88 days
It feeds mainly on squid, crustaceans and small fish
copyright: Brooke Clibbon
This species has been listed as Vulnerable because although there have been rapid declines in the past, the improving status of the population and habitat, in particular following the successful eradication of the last introduced predators (Pacific rat) on Little Barrier Island (where by far the largest numbers breed), leading to an increase in fledging success from 5% to 70%. This key step in turning the fortunes of the species followed the earlier eradication of cats from Little Barrier Island in 1980, and Weka from Codfish Island in the early 1980s. Although tiny numbers still occur on Great Barrier Island it may have been effectively extinct as a reproductively viable population for several decades.
Migrates to E Pacific; some birds occur in breeding and wintering areas all year round, perhaps due to poorly synchronized migration; ranges N to Aleutian Is and Hawaii, and E to Californian and W South America