CHATHAM PETREL} Pterodroma axillaris
DESCRIPTION: The Chatham petrel is a medium-sized bird about 30 centimeters long. It is easily distinguished from other petrels by its unique underwing pattern and its gray upper wing with dark, moderately distinct “M” marks, as well as the black mark behind its eye.
HABITAT: This seabird spends most of its life at sea, except when it returns to the Chatham Islands to breed. Its breeding habitat is the canopy cover of the islands’ temperate rainforests. The forests on the islands are dominated by ribbonwood.
RANGE: The species is endemic to the Chatham Islands, New Zealand. Although historically the birds were distributed throughout the larger islands of the archipelago, until 2002 they were restricted to the Rangatira or South East Island. Recently, an intense conservation plan reintroduced the petrel to the main Chatham and Pitt islands.
MIGRATION: This petrel migrates to the North Pacific Ocean during the winter.
BREEDING: The young birds of this species remain at sea for at least two years before returning to land to breed and nest. The average breeding age is five years old. The petrel’s breeding season lasts from November to June. It has a clutch size of one egg. The Chatham petrel is a burrowing petrel, preferring to burrow under mature forest cover, and it tends to keep the same mate from one year to the next.
LIFE CYCLE: Because much of the Chatham petrel’s life is spent at sea, little is known about the bird’s life cycle.
FEEDING: Although limited data is available, the bird’s diet is known to consist of small fish and squid.
THREATS: The Chatham petrel’s main threat to survival is competition with the broad-billed prion, another burrow-nesting bird whose habitats include the same islands as those the Chatham petrel uses for breeding.
POPULATION TREND: This bird’s population is decreasing. Currently, only 800 to 1,000 individuals survive. It is estimated that fewer than 200 birds breed per year.