Data Zone
Justification of Red List category
This species is listed as Endangered because it has a very small range within which its habitat is likely to be continuing to decline in extent and quality as a result of development, encroachment of an invasive plant, and predation by introduced mammals.
Population justification
The species has been described as fairly common, but no censuses have been made (M. Booke in litt. 2012). The population was suspected to be c.2,000-3,000 individuals in 1998-1999, and 250-999 mature individuals in 2007 (E. Bell in litt. 2007). Therefore, it is here placed in the band 250 - 2000 mature individuals. The species has a very small range on one island, so there is likely to be just one subpopulation.
Trend justification
There are no quantitative data on population size and trends. In recent decades there has been an increase in the spread and range of Rose Apple (Syzigium jambos) which threatens the native Pitcairn vegetation (E. and D. Bell in litt. 2007). Pitcairn has been recently subject to several development proposals, and a new harbour has been constructed, reducing the habitat available for this species (C. Stringer in litt. 2016). The species's population size is therefore suspected to be declining as a result of habitat loss and degradation,
Acrocephalus vaughani is endemic to the tiny volcanic island of Pitcairn in the Pitcairn Islands (to UK).
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, occasionally, breeding in groups has been noted (E. and D. Bell verbally 1999).
Vegetation on the island has been greatly modified and today only remnants of forest remain with scrub and grassland elsewhere. In recent decades 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). Feral goats were subject to an eradication attempt, but goats remained on the island in 2019 (A. Bond in litt. 2020). It is likely to be predated by Pacific rats and feral cats, but it is not known whether they have caused population declines (M. Brooke in litt. 2012). The closely-related Henderson Reed-warbler A. taiti more than doubled in abundance following an unsuccessful rat eradication attempt on Henderon Island in 2011 (Bond et al. 2019). Pitcairn has been recently subject to several development proposals, and a new harbour has been constructed, reducing the habitat available for this species (C. Stringer in litt. 2016).
Conservation Actions Underway
There was an attempt to eradicate feral cats in 1997 (M. Brooke in litt. 2005), but it is unclear whether this was successful (M. Brooke in litt. 2012, and domestic cats were introduced to the wild by the island residents in 1999 - stating that it was to control the rats after the failure of efforts to eradicate Pacific rats (E. and D. Bell in litt. 2007). Numbers of feral cats have since increased (M. Brooke in litt. 2005). A programme to eradicate rats in 1997-1998 (Bell and Bell 1998) was unsuccessful. Feral goats were subject to an eradication attempt, but goats remained on the island in 2019 (A. Bond in litt. 2020).
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.
Text account compilers
Wheatley, H., Simkins, A.
Contributors
Bell, B., Bell, D., Bell, E., Bond, A., Brooke, M., Derhé, M., Hall, J., Mahood, S., O'Brien, A., Oppel, S., Stattersfield, A., Stringer, C., Symes, A. & Taylor, J.
Recommended citation
BirdLife International (2024) Species factsheet: Pitcairn Reed-warbler Acrocephalus vaughani. Downloaded from
https://datazone.birdlife.org/species/factsheet/pitcairn-reed-warbler-acrocephalus-vaughani on 18/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 18/12/2024.