Pterodroma atrata

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	PROCELLARIIDAE

Scientific Name:

Pterodroma atrata

Species Authority:

Mathews, 1912

Common Name/s:

English

–

Henderson Petrel

Taxonomic Notes:

Pterodroma arminjoniana (Sibley and Monroe 1990, 1993) has been split into P. arminjoniana, P. heraldica and P. atrata following Brooke (2004).

Assessment Information [top]

Red List Category & Criteria:

Endangered B2ab(v) ver 3.1

Year Published:

2012

Assessor/s:

BirdLife International

Reviewer/s:

Butchart, S. & Symes, A.

Contributor/s:

Brooke, M., Hall, J. & Wragg, G.

Justification:
This species qualifies as Endangered as it probably breeds at fewer than five locations (although currently only known from one) and its population is suspected to be declining as a consequence of predation by rats.

History:

2010	–	Endangered
2008	–	Endangered
2007	–	Endangered
2006	–	Endangered
2004	–	Endangered
2000	–	Endangered
1994	–	Not Recognized
1988	–	Not Recognized

Geographic Range [top]

Range Description:	Pterodroma atrata is known to breed only on Henderson Island, Pitcairn Islands (to UK), but may have also bred on Pitcairn Island in the past and has apparently become extirpated from Ducie, also in the Pitcairn Islands (Brooke 1995a). It is likely to breed on other islands in the region too (Murphy and Pennoyer 1952), such as the Gambier and Marquesas Islands (French Polynesia) (Murphy and Pennoyer 1952, Thibault and Bretagnolle 1999). In 1991-1992, the breeding population on Henderson was estimated at c.16,000 breeding pairs and it was suggested that the species could be undergoing a long-term decline (Brooke 1995a). While its non-breeding range is not well known, it has been sighted at Easter Island (A. Jaramillo in litt., 2011).
Countries:	Native: Pitcairn Present - origin uncertain: French Polynesia; Kiribati
Range Map:	Click here to open the map viewer and explore range.

Population [top]

Population:	Brooke (2004).
Population Trend:	Decreasing

Population:

Brooke (2004).

Population Trend:

Decreasing

Habitat and Ecology [top]

Habitat and Ecology:	Like P. heraldica it may feed predominantly on cephalopods, also taking fish and crustaceans (Imber et al. 1995). On Henderson, it nests exclusively on the plateau, scattered in the dense forest, though nearer to the coast than P. heraldica (Brooke 1995a, Brooke and Rowe 1996). Breeding success is low, with less than 20% of eggs yielding fledglings and failure mostly occurring at the early chick stage (Brooke 1995a). In other absence of other known colonies elsewhere, there is no source of immigrants to sustain the Henderson petrel population (Brooke 2010).
Systems:	Terrestrial; Marine

Habitat and Ecology:

Like P. heraldica it may feed predominantly on cephalopods, also taking fish and crustaceans (Imber et al. 1995). On Henderson, it nests exclusively on the plateau, scattered in the dense forest, though nearer to the coast than P. heraldica (Brooke 1995a, Brooke and Rowe 1996). Breeding success is low, with less than 20% of eggs yielding fledglings and failure mostly occurring at the early chick stage (Brooke 1995a). In other absence of other known colonies elsewhere, there is no source of immigrants to sustain the Henderson petrel population (Brooke 2010).

Systems:

Terrestrial; Marine

Threats [top]

Major Threat(s):	Predation by Polynesian rat Rattus exulans is believed to be the main cause of chick mortality on Henderson, although predation by crabs Coenobita spp. is also a possibility (Brooke 1995a). In August 2011, a rat eradication operation was carried out on Henderson Island to eradicate R. exulans from the island (J. Hall in litt. 2012). If it ever bred on Pitcairn, it is likely to have been extirpated there because of predation by feral cats and introduced rats (Brooke 1995a). The species is potentially threatened by climate change because it has a geographically bounded distribution: it is restricted to an island with a maximum altitude of 33 m (BirdLife International unpublished data).

Major Threat(s):

Predation by Polynesian rat Rattus exulans is believed to be the main cause of chick mortality on Henderson, although predation by crabs Coenobita spp. is also a possibility (Brooke 1995a). In August 2011, a rat eradication operation was carried out on Henderson Island to eradicate R. exulans from the island (J. Hall in litt. 2012). If it ever bred on Pitcairn, it is likely to have been extirpated there because of predation by feral cats and introduced rats (Brooke 1995a). The species is potentially threatened by climate change because it has a geographically bounded distribution: it is restricted to an island with a maximum altitude of 33 m (BirdLife International unpublished data).

Conservation Actions [top]

Conservation Actions:	Conservation Actions Underway In 1997, feral cats were eradicated from Pitcairn, but subsequently re-introduced by residents. A programme to eradicate rats in 1997-1998 (Bell and Bell 1998) was unsuccessful, although petrels were observed prospecting the island during a period of no cats and low rat numbers (G. Wragg in litt. 1999). In the same year, rats were eradicated on Oeno and Ducie to increase the chance of another population becoming established there (Bell and Bell 1998). Several follow-up visits to Oeno and Ducie have not found any signs of rats (M. de L. Brooke in litt. 2000, 2003). Following a feasibility study (Brooke and Towns 2008) a rat eradication operation was carried out on Henderson Island in August 2011 (J. Hall in litt. 2012). A follow-up monitoring expedition is planned for 2013 to assess the success of the rat eradication. In 1988, Henderson was designated a World Heritage Site. A rudimentary monitoring protocol was established on Henderson in 2003 (M. de L. Brooke in litt. 2000, 2003). Conservation Actions Proposed Periodically resurvey the species to establish and monitor any trends. Periodically check Oeno and Ducie for rats, and ensure that further alien species are not accidentally introduced to the Pitcairn Islands.

Conservation Actions:

Conservation Actions Underway
In 1997, feral cats were eradicated from Pitcairn, but subsequently re-introduced by residents. A programme to eradicate rats in 1997-1998 (Bell and Bell 1998) was unsuccessful, although petrels were observed prospecting the island during a period of no cats and low rat numbers (G. Wragg in litt. 1999). In the same year, rats were eradicated on Oeno and Ducie to increase the chance of another population becoming established there (Bell and Bell 1998). Several follow-up visits to Oeno and Ducie have not found any signs of rats (M. de L. Brooke in litt. 2000, 2003). Following a feasibility study (Brooke and Towns 2008) a rat eradication operation was carried out on Henderson Island in August 2011 (J. Hall in litt. 2012). A follow-up monitoring expedition is planned for 2013 to assess the success of the rat eradication. In 1988, Henderson was designated a World Heritage Site. A rudimentary monitoring protocol was established on Henderson in 2003 (M. de L. Brooke in litt. 2000, 2003).

Conservation Actions Proposed
Periodically resurvey the species to establish and monitor any trends. Periodically check Oeno and Ducie for rats, and ensure that further alien species are not accidentally introduced to the Pitcairn Islands.

Citation:	BirdLife International 2012. Pterodroma atrata. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <www.iucnredlist.org>. Downloaded on 20 June 2013.
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