Tahiti Petrel | Pseudobulweria rostrata

Voice

At sea it is silent. At the colony, at night and high in the mountains, it is anything but: prolonged nasal shrieks and a long series of whistles ending in a hollow, hooting note. At the New Caledonian colonies that sound carries through the forest edge and gives away where the burrows are.

Identification

Thirty-eight to forty centimetres, four hundred to five hundred and twenty grams, with an eighty-four centimetre wingspan. Head, neck and upper breast form a dark brown hood that meets the white breast and belly along a clean straight line — a contrast visible at long range and the first thing to catch the eye. The upperparts are uniform dark brown, the underwing dark with a narrow pale stripe down the centre of the wing. The bill is black, short, deep and conspicuously bulbous with a heavy hook; the legs are flesh-pink with black toes. The flight is calmer than that of most petrels: long straight wings, low gliding in broad arcs, broken by short bursts of shallow flapping.

Confusion species

In the tropical waters of this region the large dark hood down to the breast is fairly unambiguous, but dark and intermediate morphs of Kermadec Petrel (Pterodroma neglecta) can suggest it; that species has white primary shafts flashing as a pale patch above and below, a far smaller bill and a livelier, more angular flight. Bulwer's Petrel (Bulweria bulwerii) shares the family trait of the heavy little bill but is less than half as long, all dark and without a white belly. Dark-morph Wedge-tailed Shearwater (Ardenna pacifica) also lacks the white underparts, and has a thin pale bill and a wedge tail. Flesh-footed Shearwater (Ardenna carneipes) is wholly dark with flesh-pink legs and a pale bill. In short: dark hood down to the breast, plus heavy black bill, plus the slow, straight-winged flight.

Habitat

Deep, warm tropical and subtropical ocean, usually far from the coast and favouring the shelf break and seamounts. It breeds ashore in burrows on forested mountain ridges and hills or in rock crevices under forest cover, between a hundred and fifty and two thousand metres and up to twelve kilometres inland — a surprisingly inland nest site for a seabird.

Range and movements

It does not breed within this guide's map window: the nearest colonies are on New Caledonia, with further breeding grounds in Fiji, American Samoa and French Polynesia. In Australian waters it is a regular visitor to the Coral Sea and the warm water off Queensland, and over recent decades it has increasingly been seen off south-eastern Queensland and New South Wales as well, above all on summer pelagics. For New Zealand it is a vagrant with only a handful of records: a beach-wrecked bird in June 1988 and three sightings in July and August 1998.

Where and when to look

Book a pelagic out of Southport, Mooloolaba or Wollongong in the warm months and watch for a large dark petrel that sails rather than bounds: the straight-held wings and the languor of the flight register before the colour does. Then look at the border between brown breast and white belly, which runs dead straight, and at the thick black bill. On birds passing at long range the narrow pale stripe down the dark underwing is the last feature to survive.

Conservation

Near Threatened (NT): the world population is put at about ten thousand breeding pairs and is declining. The causes all lie ashore on the breeding islands: introduced cats, dogs, pigs and rats taking adults and chicks from the burrows. To that add collisions with power lines near towns and loss of forest floor to nickel mining on New Caledonia, and on several islands fledglings are disoriented by street lighting and come down in settled country. At sea within this region it gives little cause for concern: it rarely follows ships and has little contact with fisheries.

Scientific name

Pseudobulweria rostrata | (Peale, 1849)

Titian Peale described the species in 1849 as Procellaria rostrata, in the ornithological volume of the report of the United States Exploring Expedition under Charles Wilkes; because the genus has since changed, author and year are bracketed. rostrata means 'large-billed', from Latin rostrum 'bill' — the bird's most conspicuous feature. The genus Pseudobulweria was introduced by Mathews in 1936 and means literally 'false Bulweria', because its species resemble Bulwer's Petrel in build and bill shape without being closely related to it. The type locality is a mountainside at about six thousand feet on Tahiti — an odd place to find a seabird, but exactly where it nests.