Tahiti reed-warbler  (Acrocephalus caffer)

The Tahiti reed-warbler is classified as Endangered (EN) on the IUCN Red List (1).

The large, slender Tahiti reed-warbler (Acrocephalus caffer) is unusual in having two different colour forms, or morphs. The most common morph has pale primrose-yellow plumage, with a mottled brownish-olive crown and upperparts. It has a distinctive dark stripe on the head that goes through the eye, and greenish-slate legs. The rarer dark morph is entirely dark olive-brown. Both forms have a very long bill and tail, and whilst males and females are similar, juveniles are darker than adults. This warbler sings a string of lively and varied whistling notes, which it repeats to form a characteristic song (3). When alarmed it has a harsh 'chrr' call (2) (4).

The Tahiti reed-warbler is found only on Tahiti, in the Society Islands, French Polynesia, in the southern Pacific Ocean (2).

The Tahiti reed-warbler occurs in bamboo thickets, secondary forest and coconut plantations, in river valleys and hillsides, up to an elevation of 1,700 metres (2) (4).

The Tahiti reed-warbler is a shy, skulking bird, which is more likely to be heard than seen (4). It is constantly on the move, searching for food, mainly in the forest canopy, where it feeds primarily on insects, but also on lizards, nectar and small seeds (3). It occasionally also consumes small fish and crayfish (2). The reed-warbler builds elaborate cup-shaped nests from plant materials such as grass and moss.

The Tahiti reed-warbler is restricted to only one island, which makes it very vulnerable to a number of threats, and its disappearance from three other Society Islands, (Moorea, Huahine and Raiatea), in the past, show the warbler’s susceptibility to extinction (2). At present it is estimated that there are only a few hundred individuals remaining, and these are threatened by habitat alteration and disturbance, as a result of an invasive weed, bamboo harvesting, road and dam construction, and four-wheel drive vehicles (2). It is very likely that the Tahiti reed-warbler is also affected by introduced species, such as the black rat, and the common myna, which may compete for nesting sites (2).

Luckily, despite this bird’s rarity, and possible threats, numbers of the Tahiti reed-warbler are thought to be stable. However, it is important that surveys are undertaken to determine whether this is correct, and also to monitor the effect that introduced species and habitat degradation has on this rare song-bird (4).

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

For further information on the Tahiti reed-warbler:

• BirdLife International:
  http://www.birdlife.org/datazone/species/index.html?action=SpcHTMDetails.asp&sid=7616&m=0