Acrocephalus rimitarae 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Passeriformes Acrocephalidae

Scientific Name: Acrocephalus rimitarae (Murphy & Mathews, 1929)
Common Name(s):
English Rimatara Reed-warbler, Rimatara Reed-Warbler
Acrocephalus rimatarae (Murphy & Mathews, 1929) [orth. error]
Taxonomic Source(s): del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A., Fishpool, L.D.C., Boesman, P. and Kirwan, G.M. 2016. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 2: Passerines. Lynx Edicions and BirdLife International, Barcelona, Spain and Cambridge, UK.
Taxonomic Notes: Acrocephalus rimitarae (del Hoyo and Collar 2016) was previously listed as A. rimatarae.
Identification information: 17 cm. Large warbler with relatively short bill. Adult olive-brown above, yellowish-white below, with dark streak through eye and pale supercilium. White feathers variably and often asymmetrically scattered among darker feathers, often producing large blotches. Voice Loud chack-chack or high-pitched chirp. No song reported.

Assessment Information [top]

Red List Category & Criteria: Vulnerable D1+2 ver 3.1
Year Published: 2017
Date Assessed: 2016-10-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Dutson, G., Millett, J. & Raust, P.
Facilitator/Compiler(s): Derhé, M., Mahood, S., O'Brien, A., Pilgrim, J., Shutes, S. & Stattersfield, A.
This species is listed as Vulnerable because it is confined to one very small island where although it is currently not uncommon, it would have to be uplisted were a decline detected.

Previously published Red List assessments:

Geographic Range [top]

Range Description:Acrocephalus rimatarae is endemic to Rimatara in the Austral Islands, French Polynesia. In 1989, it was found to be common and widespread at lower elevations (Seitre and Seitre 1991), and in 2004 population density was estimated at just over 3 birds per hectare in good habitat (Thibault and Cibois 2006). Population estimates vary widely depending on the methods used: some place the population at between 1,777 and 2,567 individuals, whilst others believe the number of individuals to be much lower: 740 (2002) or 675 (2004) (Thibault and Cibois 2006). Recent observers consider it to be abundant over much of the island and relatively stable (P. Raust in litt. 2012).

Countries occurrence:
French Polynesia
Additional data:
Continuing decline in area of occupancy (AOO):Unknown
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:10
Continuing decline in extent of occurrence (EOO):UnknownExtreme fluctuations in extent of occurrence (EOO):No
Number of Locations:1Continuing decline in number of locations:Unknown
Extreme fluctuations in the number of locations:No
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:Various population estimates have been made which differ widely depending on methods used. Thibault and Cibois (2006) estimated the population to be between 1,777 and 2,567 in 2004, in the same publication they report on other recent estimates, notably 740 (in 2002) and 675 (in 2004), without commenting on the relative accuracy of these estimates. This range of estimates approximately 680-2,600 individuals) roughly equates to 450-1,700 mature individuals.

Trend Justification:  No trend data are available, it is common in degraded habitat and is therefore suspected to be stable.
Current Population Trend:Stable
Additional data:
Number of mature individuals:450-1700Continuing decline of mature individuals:No
Extreme fluctuations:NoPopulation severely fragmented:No
No. of subpopulations:1Continuing decline in subpopulations:Unknown
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:Yes
No. of individuals in largest subpopulation:100

Habitat and Ecology [top]

Habitat and Ecology:The species is found throughout the island, even in swamps and the central fern-covered hills (Thibault and Cibois 2006a,b). Breeding however mainly occurs in wooded areas such as the undergrowth of coconut groves, mixed horticulture, coastal forests and natural forest on limestone substrates (Thibault and Cibois 2006a,b).

Systems:Terrestrial; Freshwater
Continuing decline in area, extent and/or quality of habitat:Unknown
Generation Length (years):4.4
Movement patterns:Not a Migrant

Threats [top]

Major Threat(s): Since the species requires forest for nesting, habitat destruction is a concern; the recent construction of an airport destroyed over a third of remaining native forest (Thibault and Cibois 2006), although much suitable breeding habitat still remains (J. Millett in litt. 2007). Feral cats are likely to cause some mortality (Thibault and Cibois 2006a,b). The introduction of alien species, particularly Common Myna Acridotheris tristis, is a grave concern given the species's very small range and the declines it has caused in populations of other Pacific Acrocephalus species (Thibault and Cibois 2006a,b). Polynesian rat Rattus exulans and brown rat R. norvegicus are present on the island, but not black rat R. rattus (McCormack and Künzle 1996, P. Raust in litt. 2012), implicated in the decline and extinction of many birds on oceanic islands; its arrival might be a cause for concern, although other Pacific Acrocephalus species coexist with it (Seitre and Seitre 1991).

Conservation Actions [top]

Conservation Actions: Conservation Actions Underway
A population survey and assessment of the threats have been conducted (Thibault and Cibois 2006a,b). Biosecurity measures to prevent the introduction of black rats R. rattus to Rimatara are in place at the wharf, managed by the agriculture officer with support from SOP Manu.

Conservation Actions Proposed
Continue regular monitoring of the population to assess trends. Implement a programme to ensure that R. rattus and A. tristis are not accidentally introduced (McCormack and Künzle 1996). Set aside an area of native habitat for protection. Consider controlling feral cats in breeding habitat.

Amended [top]

Amended reason: Extent of occurrence (EOO) updated and added missing Taxonomic Notes and associated references.

Citation: BirdLife International. 2017. Acrocephalus rimitarae. (amended version published in 2016) The IUCN Red List of Threatened Species 2017: e.T22714826A113088141. . Downloaded on 22 November 2017.
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