Diomedea dabbenena

Taxonomy

Assessment Information

Geographic Range

Population

Habitat and Ecology

Threats

Conservation Actions

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Taxonomy [top]

Kingdom	Phylum	Class	Order	Family
ANIMALIA	CHORDATA	AVES	Procellariiformes	Diomedeidae

Scientific Name:

Diomedea dabbenena

Species Authority:

Mathews, 1929

Common Name/s:

English

–

Tristan Albatross

Synonym/s:

Diomedea chionoptera

Assessment Information [top]

Red List Category & Criteria:

Critically Endangered A4ade ver 3.1

Year Assessed:

2009

Assessor/s

BirdLife International

Evaluator/s:

Bird, J., Butchart, S., Symes, A.(BirdLife International)

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.

History:

2008	–	Critically Endangered
2007	–	Endangered
2005	–	Endangered
2004	–	Endangered
2003	–	Endangered
2000	–	Endangered
1994	–	Not Recognized
1988	–	Not Recognized

Geographic Range [top]

Range Description:	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.
Countries:	Native: Angola; Argentina; Brazil; Namibia; Saint Helena; South Africa; Uruguay
FAO Marine Fishing Areas:	Native: Atlantic – southeast; Atlantic – southwest; Atlantic – Antarctic; Indian Ocean – western; Indian Ocean – Antarctic
Range Map:	(click map to view full version)

Population [top]

Population:	Breeding populations are essentially restricted to Gough Island. The annual breeding population is estimated to be between 1,300 pairs (Ryan et al. 2001) and 2,400 pairs (Cuthbert et al. 2003), equivalent to a total population of 9,000-15,000 birds for this biennially breeding species.
Population Trend:	Decreasing

Population:

Breeding populations are essentially restricted to Gough Island. The annual breeding population is estimated to be between 1,300 pairs (Ryan et al. 2001) and 2,400 pairs (Cuthbert et al. 2003), equivalent to a total population of 9,000-15,000 birds for this biennially breeding species.

Population Trend:

Decreasing

Habitat and Ecology [top]

Habitat and 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.
Systems:	Marine

Threats [top]

Major Threat(s):	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.

Major Threat(s):

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 Actions [top]

Conservation Actions:	Conservation actions 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 actions 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.

Conservation Actions:

Conservation actions 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 actions 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.

Citation:	BirdLife International 2009. Diomedea dabbenena. In: IUCN 2009. IUCN Red List of Threatened Species. Version 2009.2. <www.iucnredlist.org>. Downloaded on 09 February 2010.
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