Acrocephalus vaughani 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Passeriformes Acrocephalidae

Scientific Name: Acrocephalus vaughani
Species Authority: (Sharpe, 1900)
Common Name(s):
English Pitcairn Reed-warbler, Pitcairn Reed Warbler, Pitcairn Reed-Warbler
Taxonomic Source(s): del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A., Fishpool, L.D.C., Boesman, P. and Kirwan, G.M. 2016. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 2: Passerines. Lynx Edicions and BirdLife International, Barcelona, Spain and Cambridge, UK.
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 B1ab(iii)+2ab(iii) ver 3.1
Year Published: 2016
Date Assessed: 2016-10-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Bell, B., Bell, D., Brooke, M., Hall, J., Stringer, C., Bond, A., Oppel, S. & Bell, E.
Facilitator/Compiler(s): Derhé, M., Mahood, S., O'Brien, A., Stattersfield, A., Symes, A., Taylor, J., Stringer, C.
Justification:
This species is listed as Endangered because it has a very small population which may be continuing to decline on the one tiny island where it occurs, as a result of habitat degradation and predation by introduced mammals. In the absence of robust evidence on population trend or size, it is suggested that a precautionary approach should be taken and it should be assumed that this species is at risk due to the tiny area it occupies, and the likely impact of introduced and invasive species.

Previously published Red List assessments:

Geographic Range [top]

Range Description:Acrocephalus vaughani is endemic to the tiny volcanic island of Pitcairn in the Pitcairn Islands (to UK).

Countries occurrence:
Native:
Pitcairn
Additional data:
Estimated area of occupancy (AOO) - km2:5Continuing decline in area of occupancy (AOO):Unknown
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:5
Continuing decline in extent of occurrence (EOO):UnknownExtreme fluctuations in extent of occurrence (EOO):No
Number of Locations:2Continuing 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: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 catus 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. Efforts are now being made to obtain a more definite population estimate (A. Schofield, pers. comm. 2016).

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:Unknown
Additional data:
Number of mature individuals:250-999Continuing decline of mature individuals:Unknown
Extreme fluctuations:NoPopulation severely fragmented:No
No. of subpopulations:1Continuing decline in subpopulations:Unknown
Extreme fluctuations in subpopulations:NoAll 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 (E. and D. Bell verbally 1999).

Systems:Terrestrial
Continuing decline in area, extent and/or quality of habitat:Yes
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 (Syzigium jambos) which is encouraged for honey production but threatens 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 other introduced plant 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 is scepticism about the chances of a third attempt succeeding. Pitcairn is currently subject to several development proposals, and a new harbour has just been constructed, reducing the habitat available for this species (C. Stringer in litt. 2016). Feral goats were subject to an eradication attempt, but it unclear whether the island remains free of feral goats in 2016.

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 efforts to eradicate Pacific rats (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 probably the result of temporarily reduced predation pressure, as has been seen with A. taiti on Henderson Island (A Bond, S. Oppel in litt. 2016). Numbers of feral cats have since increased (M. Brooke in litt. 2005).

Conservation Actions Proposed
Obtain a robust population estimate. Determine habitat preferences. Establish a monitoring programme (e.g. regular point counts) and involve the Pitcairn Islanders in its implementation. If socially acceptable, re-attempt the eradication of Pacific rats and feral cats. 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.

Classifications [top]

1. Forest -> 1.6. Forest - Subtropical/Tropical Moist Lowland
suitability:Suitable season:resident major importance:Yes
3. Shrubland -> 3.6. Shrubland - Subtropical/Tropical Moist
suitability:Suitable season:resident major importance:No
14. Artificial/Terrestrial -> 14.4. Artificial/Terrestrial - Rural Gardens
suitability:Suitable season:resident major importance:No
1. Land/water protection -> 1.2. Resource & habitat protection
2. Land/water management -> 2.2. Invasive/problematic species control
4. Education & awareness -> 4.2. Training

In-Place Research, Monitoring and Planning
  Action Recovery plan:No
  Systematic monitoring scheme:No
In-Place Land/Water Protection and Management
  Conservation sites identified:Yes, over entire range
  Occur in at least one PA:No
  Invasive species control or prevention:Yes
In-Place Species Management
  Successfully reintroduced or introduced beningly:No
  Subject to ex-situ conservation:No
In-Place Education
  Subject to recent education and awareness programmes:No
  Included in international legislation:No
  Subject to any international management/trade controls:No
1. Residential & commercial development -> 1.2. Commercial & industrial areas
♦ timing:Future ♦ scope:Minority (<50%) ♦ severity:Slow, Significant Declines ⇒ Impact score:Low Impact: 3 
→ Stresses
  • 1. Ecosystem stresses -> 1.1. Ecosystem conversion
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation

11. Climate change & severe weather -> 11.1. Habitat shifting & alteration
♦ timing:Future ♦ scope:Whole (>90%) ♦ severity:Unknown ⇒ Impact score:Unknown 
→ Stresses
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation
  • 1. Ecosystem stresses -> 1.3. Indirect ecosystem effects

2. Agriculture & aquaculture -> 2.1. Annual & perennial non-timber crops -> 2.1.2. Small-holder farming
♦ timing:Ongoing ♦ scope:Majority (50-90%) ♦ severity:Slow, Significant Declines ⇒ Impact score:Medium Impact: 6 
→ Stresses
  • 1. Ecosystem stresses -> 1.1. Ecosystem conversion
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation

5. Biological resource use -> 5.2. Gathering terrestrial plants -> 5.2.2. Unintentional effects (species is not the target)
♦ timing:Ongoing ♦ scope:Whole (>90%) ♦ severity:Negligible declines ⇒ Impact score:Medium Impact: 6 
→ Stresses
  • 1. Ecosystem stresses -> 1.1. Ecosystem conversion
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation

8. Invasive and other problematic species, genes & diseases -> 8.1. Invasive non-native/alien species/diseases -> 8.1.1. Unspecified species
♦ timing:Ongoing ♦ scope:Whole (>90%) ♦ severity:Slow, Significant Declines ⇒ Impact score:Medium Impact: 7 
→ Stresses
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation

8. Invasive and other problematic species, genes & diseases -> 8.1. Invasive non-native/alien species/diseases -> 8.1.2. Named species [ Syzygium jambos ]
♦ timing:Ongoing ♦ scope:Whole (>90%) ♦ severity:Slow, Significant Declines ⇒ Impact score:Medium Impact: 7 
→ Stresses
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation

8. Invasive and other problematic species, genes & diseases -> 8.1. Invasive non-native/alien species/diseases -> 8.1.2. Named species [ Felis catus ]
♦ timing:Ongoing ♦ scope:Majority (50-90%) ♦ severity:Slow, Significant Declines ⇒ Impact score:Medium Impact: 6 
→ Stresses
  • 2. Species Stresses -> 2.1. Species mortality

8. Invasive and other problematic species, genes & diseases -> 8.1. Invasive non-native/alien species/diseases -> 8.1.2. Named species [ Capra hircus ]
♦ timing:Ongoing ♦ scope:Majority (50-90%) ♦ severity:Slow, Significant Declines ⇒ Impact score:Medium Impact: 6 
→ Stresses
  • 1. Ecosystem stresses -> 1.2. Ecosystem degradation

8. Invasive and other problematic species, genes & diseases -> 8.1. Invasive non-native/alien species/diseases -> 8.1.2. Named species [ Rattus exulans ]
♦ timing:Ongoing ♦ scope:Majority (50-90%) ♦ severity:Slow, Significant Declines ⇒ Impact score:Medium Impact: 6 
→ Stresses
  • 2. Species Stresses -> 2.1. Species mortality

1. Research -> 1.3. Life history & ecology
3. Monitoring -> 3.1. Population trends

Bibliography [top]

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.

IUCN. 2016. The IUCN Red List of Threatened Species. Version 2016-3. Available at: www.iucnredlist.org. (Accessed: 07 December 2016).

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. and Monroe, B.L. 1993. A supplement to 'Distribution and Taxonomy of Birds of the World'. Yale University Press, New Haven, USA.

Sibley, C.G.; Monroe, B.L. 1990. Distribution and Taxonomy of Birds of the World. Yale University Press, New Haven, USA.


Citation: BirdLife International. 2016. Acrocephalus vaughani. In: The IUCN Red List of Threatened Species 2016: e.T22714832A94429444. . Downloaded on 10 December 2016.
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