Acrocephalus vaughani 


Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Passeriformes Sylviidae

Scientific Name: Acrocephalus vaughani
Species Authority: (Sharpe, 1900)
Common Name(s):
English Pitcairn Reed-warbler, Pitcairn Reed Warbler, Pitcairn Reed-Warbler
Taxonomic Notes: 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 information: 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.

Assessment Information [top]

Red List Category & Criteria: Endangered C2a(i,ii) ver 3.1
Year Published: 2014
Date Assessed: 2014-07-24
Assessor(s): BirdLife International
Reviewer(s): Butchart, S.
Contributor(s): Bell, B., Bell, D., Brooke, M., Hall, J. & Stringer, C.
Facilitator/Compiler(s): Derhé, M., Mahood, S., O'Brien, A., Stattersfield, A., Symes, A. & Taylor, J.
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 introduced mammals, which have recovered fairly quickly since control efforts.

Previously published Red List assessments:
2012 Endangered (EN)
2008 Endangered (EN)
2004 Vulnerable (VU)
2000 Vulnerable (VU)
1996 Vulnerable (VU)
1994 Not Recognized (NR)
1988 Not Recognized (NR)

Geographic Range [top]

Range Description: 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 individuals 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 Pacific rats and feral cats had recovered (M. Brooke in litt. 2005), which may have been accompanied by a reduction in numbers of the species.

Countries occurrence:
Estimated area of occupancy (AOO) - km2: 5
Continuing decline in area of occupancy (AOO): Unknown
Extreme fluctuations in area of occupancy (AOO): No
Estimated extent of occurrence (EOO) - km2: 5
Continuing decline in extent of occurrence (EOO): Unknown
Extreme fluctuations in extent of occurrence (EOO): No
Continuing decline in number of locations: Unknown
Extreme fluctuations in the number of locations: No
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: The total population is placed in the band for 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.
Current Population Trend: Decreasing
Additional data:
Number of mature individuals: 250-999 Continuing decline of mature individuals: Yes
Extreme fluctuations: No Population severely fragmented: No
No. of subpopulations: 1 Continuing decline in subpopulations: Unknown
Extreme fluctuations in subpopulations: No All individuals in one subpopulation: Yes
No. of individuals in largest subpopulation: 100

Habitat and Ecology [top]

Habitat and 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).

Systems: Terrestrial
Continuing decline in area, extent and/or quality of habitat: Unknown
Generation Length (years): 4.4
Movement patterns: Not a Migrant

Threats [top]

Major Threat(s): 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 rats and feral cats; however, after two unsuccessful eradication attempts there may be little public support for a third attempt. Pitcairn is currently subject to several development proposals, such as a new harbour, which would involve the destruction of potential habitat for this species (C. Stringer in litt. 2013).

Conservation Actions [top]

Conservation Actions: 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.

Citation: BirdLife International. 2014. Acrocephalus vaughani. The IUCN Red List of Threatened Species 2014: e.T22714832A61675754. . Downloaded on 25 November 2015.
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