Justification This species has been uplisted to Endangered because it has a very small population and range, and it is now restricted to a single island where it is rare, local and declining owing to disturbance and degradation. Measures are urgently needed to regulate access to important breeding valleys and the collection of bamboo to slow its rate of decline.

Family/Sub-family Sylviidae

Species name author (Sparrman, 1786)

Taxonomic source(s) Sibley and Monroe (1990, 1993)

Identification 19 cm. Large, long-billed warbler with two colour-morphs. Most birds pale yellow, mottled with brownish-olive above. Dark morph all dark olive-brown. Similar spp. Tahiti Monarch Pomarea nigra blacker than dark morph, with pale blue, short bill. Voice Call a harsh churrr. Song a lively and varied series of whistles, churrs, and warbles; often long sustained. Hints Shy, skulking bird most easily located by its voice.

Population estimate

Population trend

Range estimate (breeding/resident)

Country endemic?

250-999

decreasing

270 km²

Yes

Range & population Acrocephalus caffer is found on Tahiti in the Society Islands, French Polynesia, having probably formerly occupied all the high islands in the group, including Moorea (probably went extinct between 1973 and 1986, although there is an unconfirmed recent report⁸), Huahine and Raiatea⁶. It is absent from the Tahiti peninsular (Tahiti Iti) and has been rare and local throughout the 20th century, being recorded in six valleys during the period 1920-1923 (out of 14 visited) and 12 during 1986-1991 (out of 39), and estimated to number a few hundred individuals².

Ecology: It occurs in bamboo thickets and second growth forests in river valleys and hillsides to 1,700 m. It feeds on insects but also takes lizards, small fish, crayfish, snails and nectar^3,6. It is thought to breed exclusively in bamboo thickets⁷.

Threats The development of hydro-electricity opened up the interior of the island with new roads and tracks⁷. This increased access has lead to a considerable increase in the exploitation of bamboo as well as invasion by the neotropical weed Miconia and an increase in pleasure trip in four-wheel drive vehicles. These factors have modified habitat considerably, and most worryingly caused a loss of breeding habitat, as well as causing disturbance to birds^4,7. The introduction of many alien bird species, including the aggressive Common Myna Acridotheres tristis, may also contribute to its rarity^5,6

Conservation measures underway Surveys are ongoing in the Papenoo Valley¹. The population will be re-surveyed in 2009⁷.

Conservation measures proposed Resurvey the species in order to establish trends¹. Control the exploitation of bamboo. Monitor numbers in easily accessible key sites. Investigate the severity of the threat caused by A. tristis and other predators. Consider control of predators at sites known to be important to the species. Protect important sites from habitat clearance through road and dam building and degredation by off-road vehicles.

References 1. C. Blainvillain verbally (2000). 2. Monnet et al. (1993b). 3. Pratt et al. (1987). 4. P. Raust in litt. (1999). 5. Seitre and Seitre (1991). 6. Thibault (1988). 7. P. Raust in litt. (2007). 8. A. Gouni in litt. (2007).

Text account compilers Simon Mahood (BirdLife International), Andrew O'Brien (BirdLife International), Mark O'Brien (Royal Society for the Protection of Birds), Sue Shutes (BirdLife International), Alison Stattersfield (BirdLife International)

Contributors Anne Gouni (Société d'Ornithologie de Polynésie "Manu"), Philippe Raust (Société d'Ornithologie de Polynésie "Manu")

IUCN Red List evaluators Stuart Butchart (BirdLife International), Simon Mahood (BirdLife International)

Recommended citation BirdLife International (2009) Species factsheet: Acrocephalus caffer. Downloaded from http://www.birdlife.org on 10/2/2010

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

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