Cook's petrel breeds only in New Zealand on three small islands: Little Barrier Island, Great Barrier Island, and Codfish Island.
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 Little Barrier Island'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 (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 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.
Cook's petrel breeds only in New Zealand on three small islands: Little Barrier Island, Great Barrier Island, and Codfish Island. 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 Little Barrier Island'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 (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 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.
Cook's petrel