Pterodroma axillaris
The Chatham Islands Petrel (Pterodroma axillaris), affectionately known as Ranguru, is a medium-sized gadfly petrel, measuring approximately 30 cm in length with a wingspan of 63-70 cm. Its striking plumage features dark grey upperparts, including a distinctive 'M' pattern across its wings, contrasting with pristine white underparts. A key field mark is the prominent black diagonal band extending from the 'armpit' (axilla) across the underwing, giving the species its scientific epithet. Belon...
This highly pelagic seabird spends the majority of its life at sea, ranging across the open ocean. For breeding, it exclusively utilizes dense coastal forest and shrubland on predator-free islands within the Chatham Islands archipelago, where it digs burrows for nesting, typically at low elevations.
The Chatham Islands Petrel primarily consumes small squid, fish, and crustaceans, which it captures by surface-seizing or shallow plunge-diving in the open ocean.
Chatham Islands Petrels exhibit a fascinating dichotomy in their daily activity: they are strictly nocturnal at their breeding colonies to evade avian predators like skuas and gulls, yet are diurnal when foraging over the open ocean. Their foraging strategy involves surface-seizing or shallow plu...
The Chatham Islands Petrel is entirely endemic to the Chatham Islands archipelago, located approximately 800 km east of mainland New Zealand. Historically, its breeding range was more widespread across the islands, but by the time of its rediscovery, it was confined to a single, small, predator-f...
Endangered
- This species was believed extinct for over 100 years until its rediscovery in 1986. - Its name, Ranguru, is the traditional Māori name for the species, meaning "dark sky" or "dark cloud," referencing its nocturnal habits. - The scientific name "axillaris" literally means "of the armpit," referr...