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

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

. 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 (horse-fly, horseflies). The flight ...

s and part of the subgenus ''Cookilaria'' Bonaparte, 1856, 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 A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

and

squid A squid (: squid) is a mollusc with an elongated soft body, large eyes, eight cephalopod limb, arms, and two tentacles in the orders Myopsida, Oegopsida, and Bathyteuthida (though many other molluscs within the broader Neocoleoidea are also ...

, with some

crustaceans Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of Arthropod, arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquat ...

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. The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or water column between the sur ...

except when nesting.

Habitat

Cook's petrel breeds only in

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

on three small islands:

Little Barrier Island Little Barrier Island, or Hauturu in Māori language, Māori (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 ...

Great Barrier Island Great Barrier Island () lies in the outer Hauraki Gulf, New Zealand, north-east of central Auckland. With an area of it is the sixth-largest List of islands of New Zealand, island of New Zealand. Its highest point, Mount Hobson, Great Barrier ...

, 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 speci ...

. The breeding season is the southern summer, October–May. It nests in burrows and rock crevices, preferring sites on thickly forested ridges. Its call is a three-part ''kek, kek, kek.''Harrison, P.; Perrow, M.; Larsson, H. (2021). Seabirds: The New Identification Guide. Lynx Edicions, Barcelona. 1-600 (400). 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. Some authorities consider it as the only extant member of the genus '' Gallirallus''. ...

(a flightless rail), preying on eggs and nestlings and reducing the population from an estimated 20,000 to 100. Fossils show that prior to the arrival of humans to New Zealand, Cook's petrel used to breed on the mainland New Zealand

North North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating Direction (geometry), direction or geography. Etymology T ...

and South Islands. Cook's petrel migrates to the

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

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 considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

References

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External links

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Cook's petrel Cook's petrel (''Pterodroma cookii''), or the tītī or blue-footed petrel, is a Procellariformes, Procellariform seabird. It is a member of the gadfly petrels and part of the subgenus ''Cookilaria'' Bonaparte, 1856, which includes the very simil ...

Birds of New Zealand Birds of the Cook Islands

{{Procellariiformes-stub