Justification This species qualifies as Critically Endangered owing to its extremely small breeding range and a projected population decline. Modelled population declines of at least 80% over three generations (70 years) are a consequence of very low adult survival owing to incidental mortality in longline fisheries, compounded by low fledging success caused by predation of chicks by introduced mice.

Family/Sub-family Diomedeidae

Species name author Mathews, 1929

Taxonomic source(s) Brooke (2004), Robertson and Nunn (1998)

Synonyms Diomedea chionoptera Robertson and Nunn (1998)

Taxonomic note Diomedea exulans (Sibley and Monroe 1990, 1993) has been split into D. exulans, D. dabbenena and D. antipodensis following Brooke (2004), contra Robertson and Nunn (1998) who also split antipodensis into T. antipodensis and T. gibsoni.

Identification 110 cm. Huge albatross, very similar in plumage to Wandering Albatross D.exulans. Probably indistinguishable in field, but plumage generally darker. Separated by smaller size (e.g. bill c.25 mm shorter)⁸ and slower acquisition of white adult plumage, never attaining very white plumage of old male D. exulans.

Population estimate

Population trend

Range estimate (breeding/resident)

Country endemic?

9,000 - 15,000

decreasing

14,000,000 km²

Yes

Range & population Diomedea dabbenena breeding populations are essentially restricted to Gough Island, Tristan da Cunha, St Helena (to UK), having become extinct on Tristan (although birds were seen prospecting in 1999¹⁴), and in some years one pair breeds on Inaccessible Island^15,20. Three consecutive counts of chicks from 1999-2001 indicate considerable between-year variation in breeding numbers¹⁵, and the annual breeding population is estimated to be between 1,300¹⁴ and 2,400¹⁵ pairs, equivalent to a total population of 9,000-15,000 birds for this biennially breeding species. Recent counts suggest that the population on Gough has decreased by 28% over 46 years, whereas population modelling predicts annual decline rates of 2.9-5.3%¹⁴. Predation of chicks by mice has led to very low fledging success; during the last seven years it has averaged 32.4%, roughly half of other studied Diomedea colonies^15,16,20,21. In January 2008 1,764 adult albatrosses were incubating eggs on Gough but only 246 chicks survived to fledging²². During the breeding season the length and range of foraging trips varies considerably, depending on the stage of the breeding cycle^17,19. Outside the breeding season, it disperses to South Atlantic and South African waters, with numerous recent records from Brazilian waters^8,9 and one from Australia¹⁴, suggesting that birds may occasionally disperse into the Indian Ocean.

Important Bird Areas Click here to view map showing IBAs where species is recorded and triggers any of the IBA criteria.

Ecology: It nests at 400-700 m (rarely to 300 m)¹³, primarily in wet heath. It feeds on cephalopods and fish³, and probably follows ships and trawlers for offal and galley refuse.

Threats On Inaccessible Island, its decline was probably due to predation by feral pigs (now absent) and humans^7,12. The failure to recover is unclear, but may be because young birds become entangled in thick vegetation^12,13. On Tristan, its extirpation was probably the result of human exploitation³, although predation by rats may have been a factor⁷. On Gough, predation by the introduced house mouse Mus musculus causes very low breeding success and alone is sufficient to drive a population decline of over 50% over three generations^15,16,21. An additional threat on Gough is peat slips caused by storms burying and killing nestlings and adults, though this is probably a very rare event¹¹. The main threat comes from interactions with longline fisheries, with a high proportion of "Wandering" Albatross bycatch in southern Brazilian waters being of this species^8,9, including a few birds banded at Gough^3,6. Satellite tracking of breeding birds indicates considerable overlap between birds and areas of longline fishing¹⁷, although due to lag times associated with albatross demography, we are probably only now likely to start to pick up population trends associated with longline mortality²⁰.

Conservation measures underway ACAP Annex 1. On Tristan, a programme to eradicate cats was successful in the 1970s. Gough and Inaccessible are nature reserves and Gough is a World Heritage Site. Both islands are uninhabited, apart from a meteorological station on Gough². Satellite tracking to determine foraging areas during the breeding season was undertaken in 2000-2001¹⁵. Censuses of large chicks and/or incubating adults were carried out during 1999-2003, and a monitoring protocol was devised¹⁸. Satellite tracking of non-breeders, further monitoring and demographic work, and an investigation of mouse predation on chicks was initiated during 2003-2006. Initial results from a feasibility study into the removal of the mice appear promising.²²

Conservation measures proposed Annually survey numbers and assess breeding success on Gough. Confirm taxonomic status⁵. Continue research of at-sea distribution and foraging behaviour, particularly of non-breeding birds. Promote adoption of best-practice mitigation measures in all fisheries within the species's range, particularly via intergovernmental mechanisms such as ACAP, FAO and Regional Fisheries Management Organisations. Use decoys to assist re-establishment of birds on Tristan, and to attract birds to Long Ridge on Inaccessible¹³. Confirm the feasiblity of the eradication of mice from Gough and begin a programme of eradication as soon as possible.

References 2. Cooper and Ryan (1994). 3. J. Cooper in litt. (19996. Croxall and Gales (1998). 7. Fraser et al. (1988). 8. Neves et al. (2000). 9. Olmos et al. (2000). 11. Ryan (1993). 12. Ryan et al. (1990). 13. P. G. Ryan in litt. (1999). 14. Ryan et al. (2001). 15. Cuthbert et al. (2003). 16. Cuthbert and Hilton (2004). 17. Cuthbert et al. (2005). 18. Cuthbert and Sommer (2004). 19. BirdLife International (2004). 20. R. Wanless in litt. (2007). 21. Wanless et al. (2007). 22.BirdLife International (2008).

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.

Australian Govt - Action Plan for Australian Birds 2000 - Recovery Outline

Text account compilers Simon Mahood (BirdLife International), Rachel McClellan (BirdLife International), Deon Nel (WWF South Africa), Deon Nel (BirdLife Seabird Programme), Sue Shutes (BirdLife International), Alison Stattersfield (BirdLife International), Ben Sullivan (BirdLife International Global Seabird Programme), Andy Symes (BirdLife International)

Contributors John Cooper (Avian Demography Unit, Cape Town), John Croxall (British Antarctic Survey), Richard Cuthbert (Royal Society for the Protection of Birds), Geoff Hilton (Royal Society for the Protection of Birds), Peter G. Ryan (Percy FitzPatrick Institute of African Ornithology), Ross Wanless

IUCN Red List evaluators Jeremy Bird (BirdLife International), Stuart Butchart (BirdLife International), Andy Symes (BirdLife International)

Recommended citation BirdLife International (2009) Species factsheet: Diomedea dabbenena. Downloaded from http://www.birdlife.org on 10/2/2010

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.

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