Pitcairn reed-warbler  (Acrocephalus vaughani)

Classified as Endangered (EN) on the IUCN Red List (1).

A fairly large warbler with a relatively short beak, the Pitcairn reed-warbler is olive-brown above and creamy yellow below, with a dark stripe through the eye, and a pale ‘eyebrow’, or supercilium. The wings and tail bear variable and often irregular amounts of white feathering, while the feathers of the rump have broad creamy-buff tips, and the beak and legs are dark. The male and female Pitcairn reed-warbler are similar in appearance, while the juvenile is more reddish-brown above and tawny below, with little white feathering (2) (3). The calls of this species include a rather monotonous chirp and a loud ‘chack, chack’ (2).

Although previously classified together with the closely related Henderson reed-warbler (Acrocephalus taiti) and Rimatara reed-warbler (Acrocephalus rimatarae), the Pitcairn reed-warbler is now considered a separate species, based on differences in the amount of white plumage, and on the large distances of open ocean separating the three forms (2) (3).

As its common name suggests, the Pitcairn reed-warbler is endemic to the tiny volcanic island of Pitcairn, in the Pitcairn Islands of southern Polynesia (2) (3).

The Pitcairn reed-warbler is usually found in patches of tall forest, but sometimes also occurs around human habitations and in scrubland. The species tends to avoid cliffs and areas of open ground (2) (3), and is rarely found at ground level, possibly due to the presence of cats and humans on the island (3) (4).

The Pitcairn reed-warbler feeds on insects, foraging mostly in trees and bushes, and rarely on the ground (2) (3). Breeding occurs between August and January (2), and, like the closely related Henderson reed-warbler, the Pitcairn reed-warbler may breed in small groups, although breeding pairs appear to be more usual (2) (3) (5). The nest is a deep cup, constructed from grass and banana fibres, and situated in a tree or at the base of a rau-ti (Cordyline terminalis) leaf. Two eggs are normally laid, and hatch after an incubation period of around 14 days, with fledging occurring at around 14 days old (2). Both adults help feed the young (2), and it is likely that within breeding groups all adults contribute to incubation of the eggs and care of the young, whether or not they are the parents (5).

The population of the Pitcairn reed-warbler was estimated at around 2,000 to 3,000 individuals in 1998 to 1999, at which time it was increasing dramatically following partial control of introduced cats and Pacific rats (Rattus exulans) (2) (3). However, by 2005 the numbers of cats and rats had recovered, and after two unsuccessful eradication attempts there may be little support for a third (3). Habitat degradation is also a threat, due to clearance for crops and gardening, browsing by goats, overexploitation for wood, and the spread of introduced plants such as the rose apple. Today, only remnants of the original vegetation remain (3) (4). The highly restricted range of the Pitcairn reed-warbler, covering just the five square kilometres of Pitcairn, puts it at particular risk, as does its small population, which is continuing to decline due to ongoing predation and habitat loss (2) (3).

Although eradication programmes for cats and rats have previously been undertaken on Pitcairn, rat eradication was unsuccessful, leading the island residents to reintroduce cats in an effort to control rat numbers. However, further attempts to control or eradicate these predators have been recommended (3). The Pitcairn reed-warbler is protected from killing or egg-collection under Local Government Regulations 1971 (4), and it has been suggested that the islanders be involved in monitoring its population. Protection of the remaining forest habitat, as well as preventing the introduction of further alien species, will also be important for the reed-warbler’s survival (3). Organisations such as the RSPB are undertaking a variety of conservation work in the Pitcairn Islands and other UK Overseas Territories, helping in the efforts to protect the Pitcairn reed-warbler and other threatened island species (6).

View information on this species at the UNEP World Conservation Monitoring Centre.

To find out more about conservation in the Pitcairn Islands and other UK Overseas Territories see:

• UK Overseas Territories Conservation Forum:
  http://www.ukotcf.org/
• RSPB: The UK Overseas Territories - The UK’s hidden natural treasures:
  http://www.rspb.org.uk/ourwork/projects/details.asp?id=tcm:9-200664
• Joint Nature Conservation Committee (JNCC) - The Pitcairn Islands:
  http://www.jncc.gov.uk/pdf/OT_pitcairn.pdf

For more information on this and other bird species see:

• BirdLife International:
  http://www.birdlife.org/