Tahiti petrel  (Pseudobulweria rostrata)

Classified as Near Threatened (NT) on the IUCN Red List (1).

The largest member of its genus (4), the Tahiti petrel is a dark brown seabird, with slightly paler uppertail-coverts, and white underparts which are clearly demarcated from the brown upper chest (3) (5). The central part of the dark underwing bears a thin, pale stripe (2) (3). The beak is black and particularly robust, and, like other petrels, bears characteristic tubular nostrils (3) (6). The male and female are similar in appearance (3), and the juvenile Tahiti petrel resembles the adult (2). Although similar to the Phoenix petrel, Pterodroma alba, the Tahiti petrel can be distinguished by its larger size, the paler uppertail-coverts, the absence of a pale throat patch, and the more central pale stripe on the underwing (2) (3). The Tahiti petrel also has a distinctive, straight-winged flight that is more leisurely than in many other petrel species. The call of the Tahiti petrel is a long and elaborate series of whistles, ending with a hooting sound (3).

Two subspecies are currently recognised: Pseudobulweria rostrata trouessarti has a larger, more bulky beak than Pseudobulweria rostrata rostrata, and the two may have slightly different calls (2) (3). A third, smaller subspecies, Pseudobulweria rostrata becki (2), is now treated as a separate species, Beck’s petrel (Pseudobulweria becki).

The Tahiti petrel is found in the tropical Pacific, including French Polynesia, Fiji, American Samoa, New Caledonia and Australia (2) (3) (5). The species disperses widely outside of the breeding season (5), and has been recorded as far east as Mexico and Peru, and possibly also around southern African (2) (3) (7).

Spending most of its life far out at sea, the Tahiti petrel rarely approaches land except to breed. Nesting occurs on volcanic islands, typically on hills and slopes with dense coverings of trees and shrubs, up to 12 kilometres inland and at altitudes of up to 2,000 metres (2) (3), as well as on coral islets in atolls such as in New Caledonia (4).

Little is known about the feeding habits of the Tahiti petrel, but it is believed to seize prey from the sea surface, foraging exclusively for dead squid (2) (6). The large beak and long legs are likely to be adaptations for ripping flesh from squid that are too large to be swallowed whole. An efficient glider, the Tahiti petrel is able to cover large areas in search of prey (6).

The Tahiti petrel nests solitarily or in loose colonies, where it is strictly nocturnal. Breeding is thought to take place throughout the year, though there may be certain peaks, depending on the location. A single egg is laid, within a burrow or rock crevice, and hatches after an incubation period of around 55 days, with the young fledging at about 110 to 120 days (2) (3) (4) (5). In some areas, the Tahiti petrel may face strong competition for nest cavities with the wedge-tailed shearwater, Puffinus pacificus (4).

Although it breeds on a relatively large number of islands, the Tahiti petrel has a moderately small population, which is declining as a result of predation by introduced mammals, such as cats, dogs, pigs and rats (2) (3) (5). Local threats also include mining, human disturbance, and the taking of birds to use the white feathers as fishing lures (4) (5) (8). In some areas, the Tahiti petrel may be killed by collisions with power lines, and in urban areas, particularly on Tahiti, the young birds are often attracted to lights at night (5).

The subspecies Pseudobulweria rostrata trouessarti is endemic to New Caledonia, and occurs within the Lagoons of New Caledonia, a World Heritage Site (9). Conservation measures already underway in New Caledonia include plans to reduce the impact of mining, and a campaign to collect and release birds that have become disorientated by lights (5). Sea transects have also been put in place to monitor long-term population trends of the Tahiti petrel (5). Further conservation measures proposed include monitoring of key populations, investigating levels of chick predation by introduced predators, and elimination of these predators from known breeding islands, as well as projects to tackle the problem of light pollution. The killing of the Tahiti petrel for its feathers should also be discouraged, with white chicken feathers being suggested as an alternative (5).

To find out more about petrel conservation visit:

Agreement on the Conservation of Albatrosses and Petrels:
http://www.acap.aq/en/

To read more about petrel species see:

Brooke, M. (2004) Albatrosses and Petrels across the World. Oxford University Press, Oxford.

Authenticated (12/10/09) by Dr Michael Brooke, Department of Zoology, University of Cambridge, and (01/11/09) by Dr Vincent Bretagnolle, Centre d’Etudes Biologiques de Chizé (CEBC), Centre National de la Recherche Scientifique.
http://www.cebc.cnrs.fr/

• Coverts: small feathers concealing the bases of larger flight feathers, usually on the wings or tail.
• Endemic: a species or taxonomic group that is only found in one particular country or geographic area.
• Genus: a category used in taxonomy, which is below ‘family’ and above ‘species’. A genus tends to contain species that have characteristics in common. The genus forms the first part of a ‘binomial’ Latin species name; the second part is the specific name.
• Incubation: the act of incubating eggs, that is, keeping them warm so that development is possible.
• Nocturnal: active at night.
• Subspecies: a population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.

1. IUCN Red List (February, 2009)
   http://www.iucnredlist.org
2. del Hoyo, J., Elliott, A. and Sargatal, J. (1992) Handbook of the Birds of the World. Volume 1: Ostrich to Ducks. Lynx Edicions, Barcelona.
3. Brooke, M. (2004) Albatrosses and Petrels across the World. Oxford University Press, Oxford.
4. Villard, P., Dano, S. and Bretagnolle, V. (2006) Morphometrics and the breeding biology of the Tahiti petrel Pseudobulweria rostrata. Ibis, 148: 285 - 291.
5. BirdLife International (February, 2009)
   http://www.birdlife.org/datazone/species/index.html?action=SpcHTMDetails.asp&sid=3880&m=0
6. Spear, L.B. and Ainley, D.G. (1998) Morphological differences relative to ecological segregation in petrels (Family: Procellariidae) of the Southern Ocean and tropical Pacific. Auk, 115(4): 1017 - 1033.
7. Lambert, K. (2004) Does the Tahiti petrel Pseudobulweria rostrata visit the western Indian Ocean?. Marine Ornithology, 32: 183 - 184.
8. Benoit, M.P. and Bretagnolle, V. (2002) Seabirds of the Southern Lagoon of New Caledonia: distribution, abundance and threats. Waterbirds, 25(2): 202 - 213.
9. UNEP-WCMC: Lagoons of New Caledonia: Reef Diversity and Associated Ecosystems, New Caledonia, France (February, 2009)
   http://www.unep-wcmc.org/sites/wh/pdf/New%20Caledonia.pdf