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Pitcairn Reed-warbler Acrocephalus vaughani
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Justification
This species is listed as Endangered because it has a very small population which is continuing to decline on the one tiny island where it occurs, as a result of habitat degradation and predation by feral cats which have recovered fairly quickly since control efforts. The species may warrant downlisting to a lower threat category if the population is no longer considered to be declining.

Taxonomic source(s)
Sibley, C. G.; Monroe, B. L. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven, USA.

Taxonomic note
Acrocephalus vaughani (Sibley and Monroe 1990) has been split into A. vaughani, A. rimatarae and A. taiti following Sibley and Monroe (1993). Note that Collar et al. (1994) followed Sibley and Monroe (1990) in treating these three taxa as a single species, A. vaughani.

Identification
17 cm. Large warbler with relatively short bill. Adult olive-brown above, yellowish-white below, with dark streak through eye and pale superciliary. White feathers variably and often asymmetrically scattered among darker feathers. Immatures brown above, rich tawny below without white feathers.

Distribution and population
Acrocephalus vaughani is endemic to the tiny volcanic island of Pitcairn in the Pitcairn Islands (to UK). In 1998-1999, its population was estimated at c.2,000-3,000 and increasing dramatically following the partial, but temporary control of feral cats Felis cattus and Pacific rats Rattus exulans (B. and D. Bell verbally 1999, M. Brooke in litt 2005). However by 2005 numbers of R. exulans and feral cats had recovered (M. Brooke in litt 2005), which may have been accompanied by a reduction in numbers of the species.

Population justification
The total population is placed in the band 250-999 mature individuals (E. Bell in litt. 2007), equating to 375-1,499 individuals in total, rounded here to 350-1,500 individuals.

Trend justification
There are no new quantitative data on population size and trends; however, since the unsuccessful eradication of feral cats and Pacific rats, the species is suspected to be declining at a slow rate as the populations of these pests recover.

Ecology
It is most common in patches of tall forest, and present in low numbers around dwellings and in scrubland, but absent from cliffs and patches of open ground (Pratt et al. 1987). It is insectivorous, rarely foraging at ground-level perhaps because of the presence of cats and humans. It appears to breed only in pairs, unlike Henderson Reed-warbler A. taiti which forms breeding groups, possibly related to the greater disturbance and consequent year-to-year instability of the habitat on Pitcairn (Brooke and Hartley 1995). However, more recently, breeding in groups has been noted (B. and D. Bell verbally 1999).

Threats
Vegetation on the island has been greatly modified and today only remnants of forest remain with scrub and grassland elsewhere. In recent years there has been an increase in the spread and range of Rose Apple which without control will threaten the native Pitcairn vegetation (E and D Bell in litt.2007). Clearance of native vegetation for gardening and browsing by goats also decreases the range of available habitat for the bird as does the subsequent spread of lantana, grass and other weed species (E and D Bell in litt.2007). It is likely to be predated by Pacific rat Rattus exulans and feral cats, however after two unsuccessful eradication attempts there may be little public support for a third attempt.

Conservation Actions Underway
The feral cat eradication was successful in 1997(M. Brooke in litt 2005). Domestic cats were reintroduced to the wild by the island residents in 1999 - stating it was to control the rats after the failure of the rat eradication (E and D Bell in litt.2007). A programme to eradicate rats in 1997-1998 (Bell and Bell 1998) was unsuccessful. The increases in numbers of A. vaughani in 1998-1999 were no doubt the result of temporarily reduced predation pressure. Numbers of feral cats have since increased (M. Brooke in litt 2005). Conservation Actions Proposed
Monitor the population. Involve the Pitcairn Islanders in the monitoring program. If socially acceptable, re-attempt the eradication of Pacific rats and feral cats (B. and D. Bell verbally 1999). Control rats and feral cats in key areas for the species. Ensure that further alien species are not accidentally introduced. Set aside an area of forest for protection.

References
Bell, B.; Bell, D. 1998. Pitcairn paradise preserved. World Birdwatch 20: 8-11.

Brooke, M. De L.; Hartley, I. R. 1995. Nesting Henderson Reed-warblers (Acrocephalus vaughani taiti) studied by DNA fingerprinting: unrelated coalitions in a stable habitat? The Auk 112: 77-86.

Graves, G. R. 1992. The endemic land birds of Henderson Island, southeastern Polynesia: notes on natural history and conservation. Wilson Bulletin 104: 32-43.

Pratt, H. D.; Bruner, P. L.; Berrett, D. G. 1987. A field guide to the birds of Hawaii and the tropical Pacific. Princeton University Press, Princeton.

Sibley, C. G.; Monroe, B. L. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven, USA.

Sibley, C. G.; Monroe, B. L. 1993. A supplement to 'Distribution and taxonomy of birds of the world'. Yale University Press, New Haven, USA.

Text account compilers
Derhé, M., Mahood, S., O'Brien, A. & Stattersfield, A.

Contributors
Bell, D., Brooke, M. & Bell, B.

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

Recommended citation
BirdLife International (2014) Species factsheet: Acrocephalus vaughani. Downloaded from http://www.birdlife.org on 17/04/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 17/04/2014.

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.

Additional resources for this species

ARKive species - Pitcairn reed-warbler (Acrocephalus vaughani) 0

Key facts
Current IUCN Red List category Endangered
Family Sylviidae (Old World warblers)
Species name author (Sharpe, 1900)
Population size 250-999 mature individuals
Population trend Decreasing
Distribution size (breeding/resident) 5 km2
Country endemic? Yes
Links to further information
- Additional Information on this species