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LC
Great Shearwater Ardenna gravis

Justification
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be stable, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is extremely large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.

Taxonomic source(s)
AERC TAC. 2003. AERC TAC Checklist of bird taxa occurring in Western Palearctic region, 15th Draft. Available at: #http://www.aerc.eu/DOCS/Bird_taxa_of _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.
Cramp, S.; Perrins, C. M. 1977-1994. Handbook of the birds of Europe, the Middle East and Africa. The birds of the western Palearctic. Oxford University Press, Oxford.
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: #http://www.museum.lsu.edu/~Remsen/SACCBaseline.html#.

Taxonomic note
Ardenna gravis (del Hoyo and Collar 2014) was previously placed in the genus Puffinus.

Synonym(s)
Ardenna gravis Christidis and Boles (2008), Puffinus gravis (O'Reilly, 1818)

Identification
47$cm. Large, distinctly capped shearwater, mainly of the Atlantic. Dark blackish brown cap and white hind-neck create capped appearance. Brown back, upperwing and rump; paler fringes to feathers produce scaled effect. White rear uppertail-coverts. Dark brown tail. White underparts except for variable brown belly patch (can be difficult to see). White underwing except for dark trailing edge and wingtip. Pink legs and feet but for black outer side to tarsus and outer toe. Dark grey bill. Similar spp. Cory's Shearwater Calonectris diomedea is less obviously capped and has paler bill plus more extensive dark area under the wing tip.

Distribution and population
This species breeds at three main sites: Nightingale and Inaccessible islands in the Tristan da Cunha group, and Gough Island, Tristan da Cunha (to UK) (Snow and Perrins 1998, Carboneras 1992d). Birds also breed in small numbers in the Falkland Islands (Malvinas), where the only confirmed site is Kidney Island (no more than 15 pairs recorded in 1987 (Woods 1988)), though there is a slight possibilty of breeding near Wineglass Hill, East Falkland, where one has been caught (Woods and Woods 1997).

Population justification
Brooke (2004) estimated the global population to number at least 15,000,000 individuals. A minimum of 5,000,000 pairs are thought to breed at Tristan da Cunha, and 600,000 to 3,000,000 pairs at Gough (Carboneras 1992d).

Trend justification
The population is suspected to be stable in the absence of evidence for any declines or substantial threats.

Ecology
Adults begin a transequatorial migration in April, moving north-west to South America, up to Canada, past Greenland and onto the north-east Atlantic before returning south in November to the breeding islands (Carboneras 1992d, Harrison 1983). The species breeds on sloping ground, mainly in areas of tussock grass or Phylica woodland. It feeds mostly on fish, squid and fish offal (attending trawlers, sometimes in large numbers), and also on some crustaceans (Carboneras 1992d).

Threats
Several thousand adults and c.50,000 chicks are harvested every year from Nightingale Island by Tristan Islanders, which could lead to the collapse of the population without research into sustainable harvesting levels (Carboneras 1992d). Although there is no real evidence of threats to the tiny confirmed Falkland breeding population, predation by feral cats at Wineglass Hill would be a threat to any breeding there (R. Woods in litt. 1999).

Related state of the world's birds case studies

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

Carboneras, C. 1992. Procellariidae (Petrels and Shearwaters). In: del Hoyo, J.; Elliott, A.; Sargatal, J. (ed.), Handbook of the birds of the world, pp. 216-257. Lynx Edicions, Barcelona, Spain.

Harrison, P. 1985. Seabirds: an identification guide. Christopher Helm, London.

Snow, D. W.; Perrins, C. M. 1998. The Birds of the Western Palearctic vol. 1: Non-Passerines. Oxford University Press, Oxford.

Woods, R. W.; Woods, A. 1997. Atlas of breeding birds of the Falkland Islands. Anthony Nelson, Oswestry, U.K.

Further web sources of information
Detailed species account from Birds in Europe: population estimates trends and conservation status (BirdLife International 2004)

Detailed species account from Birds in Europe: population estimates, trends and conservation status (BirdLife International 2004)

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
Butchart, S., Ekstrom, J., Newton, P.

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

Recommended citation
BirdLife International (2014) Species factsheet: Ardenna gravis. Downloaded from http://www.birdlife.org on 02/09/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 02/09/2014.

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.

Key facts
Current IUCN Red List category Least Concern
Family Procellariidae (Petrels, Shearwaters)
Species name author (O'Reilly, 1818)
Population size mature individuals
Population trend Stable
Distribution size (breeding/resident) 60,000,000 km2
Country endemic? No
Links to further information
- Additional Information on this species