Tahiti Petrel Pseudobulweria rostrata Scientific name definitions
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Species names in all available languages
Language | Common name |
---|---|
Afrikaans | Tahitistormvoël |
Catalan | petrell de Tahití |
Chinese | 黑背白腹穴鳥 |
Chinese (SIM) | 钩嘴圆尾鹱 |
Czech | buřňák tahitský |
Dutch | Tahitistormvogel |
English | Tahiti Petrel |
English (United States) | Tahiti Petrel |
French | Pétrel de Tahiti |
French (France) | Pétrel de Tahiti |
German | Tahitisturmvogel |
Icelandic | Krókdrúði |
Indonesian | Petrel tahiti |
Japanese | セグロシロハラミズナギドリ |
Norwegian | brunhodepetrell |
Polish | burzyk tahitański |
Russian | Таитянский тайфунник |
Serbian | Burnica sa Tahitija |
Slovak | víchrovník čierno-biely |
Spanish | Petrel de Tahití |
Spanish (Costa Rica) | Petrel de Tahiti |
Spanish (Mexico) | Petrel de Isla Tahiti |
Spanish (Panama) | Petrel de Tahití |
Spanish (Spain) | Petrel de Tahití |
Swedish | tahitipetrell |
Turkish | Tahiti Fırtınakuşu |
Ukrainian | Тайфунник таїтійський |
Pseudobulweria rostrata (Peale, 1849)
Definitions
- PSEUDOBULWERIA
- rostrata
- Rostrata
The Key to Scientific Names
Legend Overview
Introduction
Despite its name, the Tahiti Petrel has been recorded from such far-flung localities as Oman, South Africa and the United States, perfectly illustrating the endlessly astonishing dispersal capacities of most of the truly pelagic seabirds. Of course, these records represent rather extraordinary acts of vagrancy, the species’ regular range instead being limited to the equatorial Pacific, with breeding outposts in Fiji, American Samoa, the Society Islands, Marquesas Islands, Gambier Islands, Vanuatu and New Caledonia, and possibly also on Rarotonga (in the Cook Islands), although to date just one egg has been found and the Tahiti Petrel’s breeding ecology is to all intents and purposes unknown. This is a largely dark, large- and bulbous-billed gadfly petrel with a white abdomen and wedge-shaped tail, elongated body, and a long neck but relatively small head. Two races are recognized, although trouessarti differs from the nominate only in its, on average, slightly larger bill. Another Pacific seabird, the even rarer and more poorly known Beck’s Petrel (Pseudobulweria becki) is identical in plumage to the present species, but is considerably smaller with a proportionately more slender bill, and appears plumper bodied, flying with looser, languid and more elastic wingbeats, and shorter, more swooping glides. Nevertheless, good views and, preferably also, experience are necessary to appreciate these differences.
Field Identification
Dark, large-billed gadfly petrel with white abdomen , and wedge-shaped tail ; elongated body, with long neck but relatively small head , and very stout, bulbous bill . Long-winged, particularly the ‘arm’.
Similar Species
Recalls smaller Phoenix Petrel (Pterodroma alba), and there is extensive overlap between their at-sea ranges in the East Pacific (1), but is larger-billed, with different underwing pattern (lacking diagnostic whitish leading edge), pale tail base (1), and throat has no white (this feature is variable in P. alba) (1); however, all of these features are difficult to see at longer range, when the more albatross-like appearance of P. rostrata (narrower wings usually held straight and perpendicular to body) becomes useful (Pterodroma alba usually holds wings slightly forward and bent at carpal joint) (1). Atlantic Petrel (Pterodroma incerta) also has a white abdomen, but differs in having a brown vent and undertail-coverts, and plain central underwing; in worn plumage looks paler and grayer, with paler throat, and dark patch around eye. Separation of Beck’s Petrel (P. becki) is covered under that species.
Plumages
Natal down
Apparently undescribed.
Juvenile
Similar to adult.
Adult
Nominate race has plain dark brown hood and upperparts, often slightly darker on hood and paler on rump and uppertail-coverts; underwing dark brown with slightly paler remiges and whitish line along median coverts; dark hood extending through side of breast to axillaries, undertail-coverts white, often with variable amount of brown spots or blotches. Female averages slightly smaller in most measurements.
Molts
No published information.
Bare Parts
Bill
Black (2).
Iris
Dark brown (2).
Legs and Feet
Legs and base of feet pale pink to pale flesh, rest of feet black (2).
Measurements
Linear Measurements
Overall length 38–40 cm (P. r. rostrata), or 38–42 cm (3).
Linear measurements (in mm, mean plus standard deviation, from de Naurois and Erard 4, and range plus mean from Murphy 5).
Males (n =5) | Females (n =7) | Males (n = 10) | Females (n = 5) | |
P. r. rostrata | ||||
Wing length | 298 ± 8.67 | 293 ± 5.05 | 288–308 (297) | 286–302 (295) |
Tail length | 117 ± 1.45 | 116 ± 1.45 | 110–120 (115) | 107–120 (114) |
Bill length | 35.2 ± 1.35 | 35.0 ± 1.32 | 36–39 (37) | 35–39 (37) |
Bill depth (at nostrils) | 16.2 ± 0.44 | 15.2 ± 0.50 | ||
Tarsus length | 47.2 ± 1.06 | 46.4 ± 1.17 | 47–50 (49) | 45–49 (47) |
P. r. trouessarti | (n =8) | (n =5) | ||
Wing length | 299 ± 7.95 | 296 ± 3.19 | ||
Tail length | 114 ± 2.87 | 117 ± 4.06 | ||
Bill length | 36.3 ± 1.33 | 35.4 ± 1.11 | ||
Bill depth (at nostrils) | 17.2 ± 0.62 | 16.6 ± 0.54 | ||
Tarsus length | 48.5 ± 0.83 | 46.7 ± 0.53 |
Mass
315–506 g (2).
Wingspan
Systematics History
Editor's Note: This article requires further editing work to merge existing content into the appropriate Subspecies sections. Please bear with us while this update takes place.
Until recently considered conspecific with Beck’s Petrel (Pseudobulweria becki) (which see) (6). P. aterrima was also considered a race of the present species (6), but a comprehensive molecular phylogeny of the group confirms species status for all of these taxa (7,8).
Geographic Variation
Only differences afforded nomenclatural recognition are mensural (see Measurements), but some West Pacific birds have a broad whitish stripe on the underwing (3).
Subspecies
Two subspecies recognized, although it has been suggested that the species might be better considered monotypic (8).
P. r. rostrata (Peale, 1848)—west-central Pacific Ocean, breeding in Fiji, American Samoa, Society Islands, Marquesas Islands, Gambier Islands, and possibly also on Rarotonga (Cook Islands).
P. r. trouessarti (Brasil, 1917)—tropical and subtropical Pacific Ocean, breeding in Vanuatu and New Caledonia. Much like the nominate, but has a slightly larger bill on average.
Pseudobulweria rostrata rostrata Scientific name definitions
Distribution
Pseudobulweria rostrata rostrata (Peale, 1849)
Definitions
- PSEUDOBULWERIA
- rostrata
- Rostrata
The Key to Scientific Names
Legend Overview
Pseudobulweria rostrata trouessarti Scientific name definitions
Distribution
Pseudobulweria rostrata trouessarti (Brasil, 1917)
Definitions
- PSEUDOBULWERIA
- rostrata
- Rostrata
- trouessarti
The Key to Scientific Names
Legend Overview
Distribution
Occurs across the tropical and subtropical Pacific Ocean, breeding in Fiji, American Samoa, the Society Islands, Marquesas Islands, Gambier Islands, Vanuatu, and New Caledonia, and possibly also on Rarotonga, in the Cook Islands. Recorded in comparatively large numbers between the equator and 10ºN, and 150–100ºW (9).
Habitat
Marine and highly pelagic, rarely approaching land except at colonies. Breeds on volcanic islands, occupying hills and slopes usually on crests and narrow ridges, but also at the base of cliffs, always with dense covering of trees and shrubs, at elevations of 200–2,000 m, and up to 12 km inland on Tahiti, but also nests on low coralline islands (2,10).
Movement
Very little known, but recorded all year in the vicinity of its breeding islands. However, the species also disperses across tropical and subtropical waters of the Pacific, apparently preferring waters with surface temperatures of > 25ºC, and abundance in equatorial and subtropical waters of the East Pacific is perhaps related to El Niño events (11). Race <em>trouessarti</em> is said to range north at sea from New Caledonia as far as the Bismarck archipelago (12); some occur off eastern Australia during November–April (13) south to central New South Wales ( 2), and around New Guinea (14,15,16), where there are regular sightings off Port Moresby (17). Also recorded off Taiwan, in the Timor and Banda Seas (2,18), with three records north to the Philippines (Luzon, May 1926; Negros, August 1963; Babuyan Islands, April 2004) (19,20), and several south to northern New Zealand (all in June–August 1988) (21,22), and in East Pacific, between western Mexico (north to Colima (23) and Revillagigedo Islands, May 1990 (24) and southeast Hawaii, in November 1984 (25) south to the waters off Peru (26,27,28). A record west of Cape Comorin (India) was either P. rostrata or, more likely, Atlantic Petrel Pterodroma incerta (29,30,31), but there is a photographic record from the Chagos Islands, in November 2012 (32), while sight records off Delagoa Bay, southern Mozambique, in November 1987 and December 1990 (33), one photographed off Durban, South Africa, in November 2018 (34), and another, also photo-documented, off southern Oman, in February 2019 (Facebook), hint that P. rostrata might regularly penetrate the western Indian Ocean during the non-breeding season. Even more exceptional is the single Atlantic Ocean record, off Cape Hatteras, North Carolina, USA, in late May 2018 (Seabirding blogspot).
Diet and Foraging
All recorded observations involve surface-seizing (2). Diet basically unknown, although recorded taking the sea skaters Halobates splendens, H. micans, H. sericeus (35). Has been recorded in association with other feeding seabirds and also with surfacing pilot whales (Globicephala sp.). No further information available.
Sounds and Vocal Behavior
Nominate rostrata utters long, elaborate series of whistles terminating with a hooting sound at its breeding grounds, either in flight or from the ground, both within and outside its burrow (2); these apparently differ from those of trouessarti (36), which are described as being a long upslurred series of whistles (in flight) or a drawn-out braying whistle comprised of five main parts—a hiccup, pause, harmonics, whistle and moan—and usually given from ground (12). In American Samoa (rostrata) both a ground call and an aerial call have been heard; the ground call consists of seven parts that allow variation to occur in duration and frequency in any portion of the call; the aerial call appears to be a condensed version of the ground call, used when approaching the colony in fog and darkness, and may have echolocating qualities (37).
Breeding
Laying dates for nominate rostrata are dispersed throughout year on Tahiti, Raiatea, and the Marquesas (10), although peak egg-laying on Tahiti is apparently during March–July, with most fledglings recovered there between July and September (10), and overall season probably March–October (2). Forms loose colonies; nests in burrows or rock crevices, at up to 500 m elevation on Grand Terre, New Caledonia (race trouessarti) (12), and elsewhere perhaps formerly up to 1,900 m (10). Single egg, size 70 mm × 45 mm, mass 72 g (n = 1) (2); no data on incubation and fledging periods (2).
Conservation Status
Not globally threatened. Currently considered Near Threatened. Poorly known. Overall population probably between 10,000 and 30,000 pairs, although (BirdLife International 2016) suggests that there might be only 10,000–20,000 mature individuals. Reported to be the commonest petrel at sea in the seas around Fiji (38). Nominate race is currently regarded as Near Threatened and is seen regularly, with breeding populations in tropical Pacific estimated at < 500 pairs on Marquesas, with at least formerly < 1,000 pairs on Tahiti, and several thousand pairs on Moorea (both in the Society Islands), but probably fewer in recent years, and c. 12–26 pairs on three islands in the Gambiers, where first detected in 1995 (36,39), with unknown populations in Fiji, American Samoa, and possibly still in the Cook Islands (2,10), but that in Vanuatu is apparently extinct; introduced rats (Rattus spp.) and feral cats (Felis catus) are abundant on many island groups in this part of the Pacific, while predator control is urgently required even within protected areas such as the American Samoa National Park (40), and the permanent opening of tracks and roads into mountainous areas has accelerated access for predators to this species’ breeding areas (10). Natural predators include Swamp Harrier Circus approximans (10). Until the 1970s the species was subject to some harvesting by humans, especially in the Society Islands, with adults being taken at their nests, and their body feathers used as fishing lures (10). Race trouessarti breeds (hundreds or thousands of pairs) (41,12) on Grand Terre, New Caledonia, and on eleven (of 70) islets in its southern lagoon (2); this race is threatened by nickel mining and by feral pigs (Sus scrofa), cats and wild dogs, with evidence of decreases in recent decades on some of these islets, although rats have now been eradicated. Light-induced mortality, which typically affects recently fledged juveniles more than adults, is a threat in French Polynesia and New Caledonia, although rescue schemes are in place on some of the relevant islands (42).