Cook's petrel (''Pterodroma cookii'') or the blue-footed petrel, is a Procellariform

seabird Seabirds (also known as marine birds) are birds that are adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same envir ...

. It is a member of the

gadfly petrel The gadfly petrels or ''Pterodroma'' are a genus of about 35 species of petrels, part of the seabird order Procellariiformes. The gadfly petrels are named for their speedy weaving flight, as if evading gadflies ( horseflies). The flight action is ...

s and part of the subgroup known as Cookilaria petrels, which includes the very similar

Stejneger's petrel Stejneger's petrel (''Pterodroma longirostris'') is a species of seabird and a member of the gadfly petrels. The bird is 26–31 cm in size, with a 53–66 cm wingspan. This species is highly pelagic, rarely approaching land, except t ...

Morphology

One of the smallest petrels, Cook's petrel is typically in length with a wingspan and a weight of around . Its colouration is typical of gadfly petrels: pale grey upperparts with a dark grey "M" on the wings and white underparts. The bill is long and black with tubular nostrils on both sides. As in all members of the order Procellariiformes, this nostril configuration enables an exceptionally acute sense of smell, which the birds use to locate food and nest sites in the dark.

Diet

Cook's petrel feeds mostly on

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% ...

and

squid True squid are molluscs with an elongated soft body, large eyes, eight arms, and two tentacles in the superorder Decapodiformes, though many other molluscs within the broader Neocoleoidea are also called squid despite not strictly fitting ...

, with some

crustaceans Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean gr ...

taken. The species is highly

pelagic The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or w ...

except when nesting.

Habitat

Cook's petrel breeds only in

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 List of islands of New Zealand, smaller islands. It is the ...

on three small islands:

Little Barrier Island Little Barrier Island, or Hauturu in Māori language (the official Māori title is ''Te Hauturu-o-Toi''), lies off the northeastern coast of New Zealand's North Island. Located to the north of Auckland, the island is separated from the mainla ...

Great Barrier Island Great Barrier Island ( mi, Aotea) lies in the outer Hauraki Gulf, New Zealand, north-east of central Auckland. With an area of it is the sixth-largest island of New Zealand and fourth-largest in the main chain. Its highest point, Mount Hobso ...

, and

Codfish Island Codfish Island / Whenua Hou is a small island () located to the west of Stewart Island in southern New Zealand. It reaches a height of close to the south coast. The island is home to Sirocco, an internationally famous kākāpō, a rare spe ...

. The breeding season is the southern summer, October–May. It nests in burrows and rock crevices, preferring sites on thickly forested ridges. The species was formerly more numerous; the current population estimate is 1,258,000 and declining. It is classified as vulnerable because it breeds on only three small islands. While

's population remains stable, the other two populations are decreasing. On Great Barrier Island, introduced pigs, dogs, rats and cats attack nests and burrows, as do native

weka The weka, also known as the Māori hen or woodhen (''Gallirallus australis'') is a flightless bird species of the rail family. It is endemic to New Zealand. It is the only extant member of the genus '' Gallirallus''. Four subspecies are recog ...

(a flightless rail), preying on eggs and nestlings and reducing the population from an estimated 20,000 to 100. Cook's petrel migrates to the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the contine ...

from New Zealand when it is not breeding. It has sometimes been seen off the west coast of the United States and off the west coast of tropical

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the souther ...

References

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External links

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Cook's petrel Cook's petrel (''Pterodroma cookii'') or the blue-footed petrel, is a Procellariformes, Procellariform seabird. It is a member of the gadfly petrels and part of the subgroup known as Cookilaria petrels, which includes the very similar Stejneger's ...

Birds of New Zealand Birds of the Cook Islands

{{Procellariiformes-stub