The Chatham Islands petrel, also known as the Chatham petrel or ranguru (Māori), is a medium-sized, grey, white and black gadfly petrel. It only breeds on the Chatham Islands, New Zealand, and until recently was restricted to the 218-hectare Rangatira or South-East Island.
Region
Southwest Pacific Ocean
Typical Environment
Breeding is confined to predator-managed sites on the Chatham Islands, where it occupies forested slopes and scrub with suitable soil for burrowing. Outside the breeding season it disperses widely over pelagic waters of the South Pacific, often ranging far from land. At sea it frequents shelf edges, upwelling zones, and oceanic fronts where prey is concentrated. Birds return to colonies only at night and are seldom seen near land by day.
Altitude Range
Sea level to 300 m
Climate Zone
Temperate
Ease of Keeping
Beginner friendly: 1/5
The Chatham Islands petrel (ranguru) is a medium-sized gadfly petrel that breeds only in the Chatham Islands of New Zealand. It nests in burrows and is strictly nocturnal around colonies, an adaptation to avoid predators and kleptoparasites. Intensive conservation work, including predator control, artificial burrows, and translocations, has helped its small population increase in recent decades.
Illustration by Joseph Smit, 1896
Chatham Islands petrel in nesting box, on egg
Temperament
pelagic and wary on land
Flight Pattern
dynamic soaring with rapid shearing arcs and short, stiff wingbeats between glides
Social Behavior
Nests in burrows in small, scattered colonies, typically under forest or dense scrub. Pairs are long-term monogamous with shared incubation and chick-rearing duties. Colony attendance is strictly nocturnal; birds call from the ground and in flight while exchanging shifts. Nest entrances are defended, and competition for burrows can be intense.
Migratory Pattern
Seasonal migrant
Song Description
At colonies it gives soft moans, chattering trills, and wailing calls, mostly at night. Calls are used for mate contact and territorial signaling around burrow entrances; birds are generally silent at sea.
Plumage
Grey-brown upperparts with a darker cap and contrasting white underparts; upperwings show a dark 'M' pattern. Underwings are mostly white with a distinct dark axillary patch and dusky margins. Feathers are sleek and water-repellent, suited to pelagic life.
Diet
Feeds mainly on small squid, fish, and crustaceans taken from or just below the sea surface. It often seizes prey at night or twilight when diel vertical migration brings organisms near the surface. The species may associate with predatory fish or dolphins that drive prey up, and occasionally takes fishery discards.
Preferred Environment
Open ocean habitats, especially along shelf breaks, frontal zones, and areas of local upwelling. Typically forages far offshore but may approach productive waters not far from the islands during breeding.
