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Atlantic Petrel Pterodroma incerta
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This species has been listed as Endangered because it has an extremely small occupied breeding range, and there is now evidence that that chick predation by introduced mice is causing very low breeding success and is likely to be causing the population to decline. It has not been recorded from Tristan de Cunha for 35 years, and, were it to be confirmed as extinct there, it may qualify for uplisting to Critically Endangered.

Taxonomic source(s)
AERC TAC. 2003. AERC TAC Checklist of bird taxa occurring in Western Palearctic region, 15th Draft. Available at: # _the_WP15.xls#.
Brooke, M. de L. 2004. Albatrosses and Petrels Across the World. Oxford University Press, Oxford.
Christidis, L.; Boles, W. E. 2008. Systematics and taxonomy of Australian birds. CSIRO Publishing, Collingwood, Australia.
del Hoyo, J.; Collar, N. J.; Christie, D. A.; Elliott, A.; Fishpool, L. D. C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Barcelona, Spain and Cambridge UK: Lynx Edicions and BirdLife International.
SACC. 2006. A classification of the bird species of South America. Available at: #

43 cm. Large, stocky, dark brown-and-white petrel. Uniformly dark chocolate-brown above and on upper breast. Head can appear grey in worn plumage. Sharp demarcation from brown upper breast to white lower breast and belly. Brown vent, undertail-coverts and tail. Uniform brown underwing. Similar spp. Soft-plumaged Petrel P. mollis has patterned underwing. Trindade Petrel P. arminjoniana has white wing flashes. Hints May flap at top of glides unlike most Pterodroma spp. Concentrates around subtropical convergence.

Distribution and population
Pterodroma incerta breeds only on Gough Island, Tristan da Cunha (St Helena to UK). It is absent from Nightingale where there is no suitable habitat, and probably also from Inaccessible, although it is possible that a small number of birds could breed there because there have been no surveys during the winter breeding season (P. G. Ryan in litt. 1999), and Tristan, where though the population was estimated to be 100-200 pairs in 1972-1974, there have been no records since then at it is now beleived to be extinct on that island (Richardson 1984, P. G. Ryan in litt. 1999). On Gough, the first quantitative population estimate indicates a total of around 1.8 million pairs (Cuthbert in press), considerably larger than the earlier estimate of at least 20,000 pairs (P. G. Ryan in litt. 1999). Recent evidence suggests that fledging success is very low, less than 20% during the last five years and perhaps as low as 2% in 2007, and this is likely to be driving a long term decline (Wanless et al. 2007, R. Wanless et al in litt. 2007, Cuthbert in press). At sea, it is practically restricted to the South Atlantic, occurring off the east coast of South America to the west coast of Africa (Enticott 1991, P. G. Ryan in litt. 1999), occasionally rounding the Cape of Good Hope into the Indian Ocean (Hobbs in litt. 2009).

Population justification
On Gough, Cuthbert in litt. (2001) estimated 1.8 million breeding pairs, suggesting a world population of around 5 million birds.

Trend justification
R. Wanless in litt. (2007) has commented that population models using data (except breeding success) from Bermuda Petrel Pterodroma cahow suggest the populaiton is declining at a rate of 1.3% per annum.

It feeds mainly on squid with some fish and crustaceans (Klages and Cooper 1997). It nests in burrows dug in peaty soils in fern-bush vegetation from 50-300 m on Gough and formerly, at higher elevations on Tristan. Nothing is known of age of first breeding, breeding frequency or survival (P. G. Ryan in litt. 1999). Heavily affected by Hurricane Catarina in March 2004, 354 birds were recorded blown inland, all in heavy moult and near starvation (Bugoni et al. 2007). Larger numbers of females among these were thought to be due to difference in at-sea distribution or in body condition (Bugoni et al. 2007). Evidence suggests moult is completed during exodus period and before egg-laying, which occurs from 15 June to 21 July (Cuthbert 2004).

This species was once of major economic importance to the Tristan Islanders as it was one of the few sources of food in winter but, by the 1940s, the birds had become scarce (Richardson 1984). It is very unlikely to be exploited today (P. G. Ryan in litt. 1999). On Tristan, rats and are present and have probably driven it to extinction (Richardson 1984, R. Wanless et al in litt. 2007). On Gough, the only potential introduced predator is the house mouse Mus musculus and recent research reveals that mice are predating chicks and causing very low breeding success which is driving the long-term decline (Wanless et al. 2007, R. Wanless et al in litt. 2007, Cuthbert in press, Cuthbert and Hilton in press). The large population of native Southern Skua Catharacta antarctica feed on seabirds including P. incerta (Richardson 1984). Night strikes (as a result of being attracted to lights) are a further threat. This has been ameliorated at the Gough meteorological station, but may still pose a problem on ships at sea (P. G. Ryan in litt. 1999). The mortality associated with Hurricane Catarina points to a potential threat from hurricane activity in the South Atlantic, postulated to increase in frequency with global warming (Bugoni et al. 2007).

Conservation Actions Underway
On Tristan, a programme to eradicate cats was successful in the 1970s. Gough is a nature reserve and World Heritage Site (Cooper and Ryan 1994). The first ever quantitative population survey was undertaken on Gough, 2000/1, coupled to research into breeding ecology and reproductive output (Cuthbert in press). During 2003-6, further research on reproductive output and mouse predation was conducted. Searches on Tristan da Cunha have failed to locate any birds (Wanless et al. 2007). Conservation Actions Proposed
Eradicate mice from Gough. Minimise the risk of further introduced species establishing on Gough, particularly any rat Rattus species (P. G. Ryan in litt. 1999). Confirm the status of the population on Tristan da Cunha.

Related state of the world's birds case studies

Brooke, M. De L. 2004. Albatrosses and petrels across the world. Oxford University Press, Oxford.

Bugoni, L.; Sander, M.; Costa, E. S. 2007. Effects of the first southern Atlantic hurricane on Atlantic Petrels (Pterodroma incerta). Wilson Journal of Ornithology 119(4): 725-729.

Cooper, J.; Ryan, P. G. 1994. Management plan for the Gough Island Wildlife Reserve. Government of Tristan da Cunha, Edinburgh, Tristan da Cunha.

Cuthbert, R., Cooper, J., Burle, M.H., Glass, C.J., Glass, J.P., Glass, S., Glass, T., Hilton, G.M., Sommer, E.S., Wanless, R.M., Ryan, P.G. 2009. Population trends and conservation status of the northern rockhopper penguin Eudyptes moseleyi at Tristan da Cunha and Gough Island. Bird Conservation International 19(1): 109-120.

Cuthbert, R.; Hilton, G. 2004. Introduced house mice Mus musculus: a significant predator of threatened and endemic birds on Gough Island, South Atlantic Ocean? Biological Conservation 117: 483-489.

Enticott, J. W. 1991. Distribution of the Atlantic Petrel Pterodroma incerta at sea. Marine Ornithology 19: 49-60.

Klages, N. T. W.; Cooper, J. 1997. Diet of the Atlantic Petrel Pterodroma incerta during breeding at South Atlantic Gough Island. Marine Ornithology 25: 13-6.

Richardson, M. E. 1984. Aspects of the ornithology of the Tristan da Cunha group and Gough Island, 1972-1974. Cormorant 12: 123-201.

Wanless, R. M.; Angel, A.; Cuthbert, R. J.; Hilton, G. M.; Ryan, P. G. 2007. Can predation by invasive mice drive seabird extinctions? Biology Letters 3: 241-244.

Further web sources of information
Alliance for Zero Extinction (AZE) species/site profile. This species has been identified as an AZE trigger due to its IUCN Red List status and limited range.

Click here for more information about the Alliance for Zero Extinction (AZE)

Explore HBW Alive for further information on this species

Search for photos and videos, and hear sounds of this species from the Internet Bird Collection

Text account compilers
Clay, R., Ekstrom, J., McClellan, R., Shutes, S., Stattersfield, A. & Temple, H.

Cuthbert, R., Hilton, G., Ryan, P. & Wanless, R.

IUCN Red List evaluators
Butchart, S., Symes, A.

Recommended citation
BirdLife International (2016) Species factsheet: Pterodroma incerta. Downloaded from on 23/10/2016. Recommended citation for factsheets for more than one species: BirdLife International (2016) IUCN Red List for birds. Downloaded from on 23/10/2016.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Additional resources for this species

ARKive species - Atlantic petrel (Pterodroma incerta) 0

Key facts
Current IUCN Red List category Endangered
Family Procellariidae (Petrels, Shearwaters)
Species name author (Schlegel, 1863)
Population size mature individuals
Population trend Decreasing
Distribution size (breeding/resident) 15,700,000 km2
Country endemic? Yes
Links to further information
- Additional Information on this species