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Pseudobulweria rostrata 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Procellariiformes Procellariidae

Scientific Name: Pseudobulweria rostrata
Species Authority: (Peale, 1848)
Common Name(s):
English Tahiti Petrel
Spanish Petrel de Tahití
Synonym(s):
Pterodroma rostrata rostrata Stotz et al. (1996)
Pterodroma rostrata rostrata Sibley and Monroe (1990, 1993)
Taxonomic Source(s): del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A. and Fishpool, L.D.C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Lynx Edicions BirdLife International, Barcelona, Spain and Cambridge, UK.
Identification information: 39 cm. Medium-sized gadfly petrel. Dark brown upperparts with paler upper tail coverts. Dark brown underwing, throat, Dark brown upper chest sharply demarcated from white underparts. Similar spp. Phoenix Petrel P. alba has pale throat patch (difficult to see), lacks paler upper tail coverts, has pale line across inner underwing coverts. Hints Distinctive straight-winged jizz, held perpendicular to body with tips curling upwards. Flight more languid than many Pterodroma species, giving albatross-like appearance.

Assessment Information [top]

Red List Category & Criteria: Near Threatened ver 3.1
Year Published: 2016
Date Assessed: 2016-10-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Barré, N., Bell, D., Bourgeois, K., Bretagnolle, V., Dromzée , S., Dutson, G., Kretzschmar, J., Meyer, J., Pandolfi, M., Raust, P., Rauzon, M., Spaggiari, J. & Thibault, J.
Facilitator/Compiler(s): Anderson, O., Benstead, P., Calvert, R., Mahood, S., McClellan, R., Moreno, R., O'Brien, A., Stattersfield, A., Temple, H.
Justification:
This species is classified as Near Threatened because, although it breeds on a relatively large number of islands, it still has a moderately small population which is declining owing to predation by introduced mammals, and, locally at least, mining.

Previously published Red List assessments:

Geographic Range [top]

Range Description:Pseudobulweria rostrata breeds in the Marquesas, Society  and Gambier (recorded in 1995, [Thibault 1996, Thibault and Bretagnolle 1999]) Islands, French Polynesia, Fiji, American Samoa and New Caledonia (to France) It used to breed in Vanuatu (V. Bretagnolle and M. Pandolfi Benoit in litt. 1999) and may breed on Rarotonga, Cook Islands (Pratt et al. 1987), as well as on other islands. Two subspecies are traditionally distinguished: trouessarti in New Caledonia and rostrata in French Polynesia, the subspecific status of birds from other archipelagos remaining unclear although Brooke (2004) assigned them to rostrata. This distinction is poorly supported by morphological (Villard et al. 2006) and genetic (Gangloff et al. 2012) data, and detailed analyses of vocalization differences between the two subspecies are missing. In the Marquesas, Pseudobulweria rostrata breeds on Nuku Hiva, Hiva Oa and Tahuata, totalling less than 500 pairs (Holyoak and Thibault 1984), and birds have been heard at night (possibly breeding) at Ua Pou, Ua Huka (J.-C. Thibault unpublished data) and Fatu Hiva (J.-Y. Meyer unpublished data). In the Society Islands, it breeds on Tahiti and Moorea (and perhaps Bora Bora [P. Raust in litt. 1999] and Raiatea to the southeast [Salducci 2007]), where the populations were estimated at less than 1,000 pairs and several thousand pairs respectively (Holyoak and Thibault 1984), although recent visits suggest a substantial decline (Bretagnolle and J.-C. Thibault unpublished data). In the Gambiers, there are 12-26 pairs on Mangareva, Akamaru and Manui (Thibault and Bretagnolle 1999). In Fiji, it breeds on Gau and Taveuni (Clunie et al. 1978, Plant et al. 1989, G. Dutson in litt. 2005), while, in American Samoa, it breeds on Ta'u and Tutuila (Engbring and Ramsay 1989). Hundreds of pairs may nest on Taveuni, where >150 were seen offshore in October 2003 and where the low open forest on steep unstable hill-sides is similar to nesting areas on New Caledonia (G. Dutson in litt. 2005). Nesting may also occur on Gau Island, where >20 individuals were seen following chumming in 2008 (T. Pym in litt. 2008). Based on vocal activity and extensiveness of the potential habitat, several thousand (maybe 2,000) pairs may breed over the Ta’u summit area (O’Connor and Rauzon 2004, Rauzon and Rudd 2014). Dozens of pairs may breed on Tutuila (O’Connor and Rauzon 2004). In New Caledonia, it breeds on Grand Terre in unknown numbers, particularly in the high mountains. Based on vocal activity, the identification of 16 certain (presence signs as eggshell, down or birds) plus 22 probable colonies and an average colony size set at 5-10 pairs, the breeding population in Massif du Koniambo (mostly included in an active mining site) was estimated at at least 200-400 pairs (Delelis et al. 2007). However, authors acknowledge that there was no proof that observed birds bred or had bred and this estimate should be treated with caution. Indeed, although vocalizations can be heard on several active mining sites, intensive nest search resulted in the localisation of only very few (<10) breeding burrows (e.g. Spaggiari and Baré 2004, Delelis et al. 2007, Le Breton 2008, S. Dromzée unpublished data), suggesting that birds might still come to former breeding sites that mining activity has destroyed or deteriorated to the point that they are no longer suitable for breeding. The species also breeds on 12 (out of 74) islets in the southern lagoon where there are estimated to be less than 100 pairs (Pandolfi Benoit and Bretagnolle 2002, Baudat-Franceschi 2012) and even as few as 20 pairs when only burrows with evidence of breeding are considered rather than vocal activity (Baudat-Franceschi 2012). There are signs of a substantial decline on at least one of these islets, with 50 pairs in 1986 reduced to less than 10 pairs in 1998 (M. Pandolfi Benoit and V. Bretagnolle unpublished data). In the non-breeding season it disperses widely, and birds have been recorded as far east as the coast of Central America (Ballance et al. 2002), particularly Peru, Mexico (Onley and Scofield 2007) and Costa Rica (R. Clay in litt. 2010), and as far west as the Mozambique Channel (Lambert 2004). 

Countries occurrence:
Native:
American Samoa (American Samoa); Australia; Fiji; French Polynesia; Guam; Micronesia, Federated States of ; New Caledonia
Regionally extinct:
Vanuatu
Vagrant:
Mexico; New Zealand; Solomon Islands
Present - origin uncertain:
Chile; Colombia; Cook Islands; Costa Rica; Ecuador; El Salvador; French Southern Territories; Guatemala; Indonesia; Japan; Kiribati; Marshall Islands; Nauru; Nicaragua; Niue; Norfolk Island; Northern Mariana Islands; Palau; Panama; Papua New Guinea; Peru; Philippines; Pitcairn; Samoa; Tokelau; Tonga; Tuvalu; United States Minor Outlying Islands; Wallis and Futuna
Additional data:
Continuing decline in area of occupancy (AOO):Unknown
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:68500000
Continuing decline in extent of occurrence (EOO):UnknownExtreme fluctuations in extent of occurrence (EOO):No
Continuing decline in number of locations:Unknown
Extreme fluctuations in the number of locations:No
Upper elevation limit (metres):2000
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:The overall population of the species probably does not exceed 10,000 pairs (i.e. 20,000 mature individuals) and 30,000 individuals. It is thus placed in the band 10,000-19,999 mature individuals, and thought to number 20,000-30,000 individuals in total.

Trend Justification:  There are no data, however the species is thought to be declining, mainly due to nest predation by introduced predators and open cast mining activities (opening track, light pollution, powerlines, earth material dumping, waste management…in addition to the mere extraction). Declines had been recorded in marine surveys (Balance et al. 2002).

Current Population Trend:Decreasing
Additional data:
Number of mature individuals:10000-19999Continuing decline of mature individuals:Unknown
Extreme fluctuations:NoPopulation severely fragmented:No
Continuing decline in subpopulations:Unknown
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:No

Habitat and Ecology [top]

Habitat and Ecology:The species generally nests at high altitudes within forest or scrub on mountain steep slopes or rims and craters of volcanic islands, but it also nests on low coralline or rocky hill islets and backshore. Eggs are laid in burrows or cavities located underneath large rocks, within cliffs or rocky boulders, or among large tree root systems. Birds generally nest in loose and small colonies. Indeed in New Caledonia, most of the recently discovered colonies are small (<10 pairs) and spread over large areas of several thousand square metres (Spaggiari and Baré 2004, Baudat-Franceschi 2006, Delelis et al. 2007, Le Breton 2008, S. Dromzée unpublished data). Breeding appears to occur throughout the year, although on Tahiti at least there appears to be a peak between March and July (Villard et al. 2006). 

Systems:Terrestrial; Marine
Continuing decline in area, extent and/or quality of habitat:Unknown
Generation Length (years):17.7
Movement patterns:Full Migrant
Congregatory:Congregatory (and dispersive)

Threats [top]

Major Threat(s): In the Marquesas and Society Islands, rat predation is an observed but unquantified problem. It is likely to have coexisted with black rats Rattus rattus for decades and they perhaps do not pose a major threat (G. Dutson in litt. 2003). Young birds are also attracted by lights at night, mainly on Tahiti in the urban areas around Papeete (P. Raust in litt. 1999) and in New Caledonia around Noumea, rural villages and active mining sites. Electric powerlines in the mountains of French Polynesia may also be a problem (P. Raust in litt. 2003). On Grand Terre, rats Rattus spp. may pose a threat to remaining colonies (although rats have been eradicated from all islets in the southern lagoon [D. Bell and M. Pandolfi Benoit unpublished data]). Feral cats are most likely impacting populations on Grande Terre as they can prey upon adults (adult mortality has a stronger impact on petrel demography than mortality of chicks) and petrel remains had been found in 1-8% of cat scats (n = 4166) on 5 sites out of 9 surveyed (Palmas et al. in prep.). Dogs and especially pigs are known to dig out adults or chicks from their burrow. Deers could also pose a threat to the breeding grounds and to the fledglings. The newly discovered sites in New Caledonia are all in areas threatened by nickel mining (Spaggiari and Baré 2004, Delelis et al. 2007, Le Breton 2008, S. Dromzée unpublished data). In colonies where the soil is deep enough for Wedge-tailed Shearwaters to nest there can be intense competition for burrows (Villard et al. 2006). Local people are known to take birds to use their white feathers for fishing lures (Holyoak and Thibault 1984). 

Conservation Actions [top]

Conservation Actions:

Conservation Actions Underway

In New Caledonia a plan to reduce the impact of mining exploitation on the Koniambo massif has been recently proposed to the KNS Mining Society. On the same island SCO has begun a campaign to collect and release birds that are disoriented by lights. In June 2007, an at sea transect from Noumea to the Chesterfield was established; repeated surveys along this line will be used to monitor long-term population trends. Census and population monitoring are being set up in New Caledonia.

Conservation Actions Proposed

Monitor key populations. Perform research on the species’ biology and ecology. Investigate whether the species nests on Taveuni. Improve census and population size estimates on every breeding site. Quantify the levels of chick predation by black rats and other predators. Continue to eradicate predators from known breeding islands. On large islands like Grande Terre, set up predator-proof fenced areas coupled with sound-system attraction and artificial burrows. Discourage the killing of birds for their feathers for fishing lures, providing white chickens as a substitute. Implement projects to tackle the threat of light pollution. Chick translocation is seen as a means to mitigate the impact of mining and a feasibility study is underway. Evaluate the impact of the various threats identified on population dynamics.



Citation: BirdLife International. 2016. Pseudobulweria rostrata. The IUCN Red List of Threatened Species 2016: e.T22697925A93647075. . Downloaded on 29 March 2017.
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