Justification of Red List Category
There are no confirmed recent records of the species, but at least two unconfirmed records have been reported since 2000 implying that the species may yet still persist in very small numbers.
The species has been considered extinct (Dyrz and de Juana 2016), but there have been at least two unconfirmed reports since 2000 (A. Gouni in litt. 2007, Cibois et al. 2008, A. Gouni in litt. 2011). The lack of any definitive reports suggest that, if it is extant, the population size is likely very low (probably less than 50 mature individuals).
The lack of recent confirmed records prevent an assessment of population trend: it is possibly extinct.
Acrocephalus longirostris was restricted to the island of Moorea in the Society Islands, French Polynesia. It is considered to be possibly extinct although there have been at least two unconfirmed reports since 2000 (A. Gouni in litt. 2007, Cibois et al.2008, A. Gouni in litt. 2011).
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 (Pratt et al. 1987, Thibault 1988). It is thought to breed exclusively in bamboo thickets (P. Raust in litt. 2007).
The development of hydro-electricity opened up the interior of the island with new roads and tracks (P. Raust in litt. 2007). 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 tourists in four-wheel drive vehicles. These factors have modified the habitat considerably, and most worryingly have caused a loss of breeding habitat, as well as causing disturbance to birds (P. Raust in litt. 1999, P. Raust in litt. 2007). The introduction of feral cats Felis catus, rats Rattus spp. (A. Gouni in litt. 2012) and many alien bird species, including the aggressive Common Myna Acridotheres tristis, may also contribute to its rarity (Thibault 1988, Seitre and Seitre 1991).
Conservation Actions Underway
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; occur in different valleys. 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.
Text account compilers
Khwaja, N., Mahood, S., O'Brien, M., Shutes, S., Stattersfield, A., Derhé, M. & Martin, R
Gouni, A., Raust, P. & Blainvillain, C.
BirdLife International (2019) Species factsheet: Acrocephalus longirostris. Downloaded from http://www.birdlife.org on 24/08/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 24/08/2019.