Justification This species qualifies as Critically Endangered because it has a minute and fragmented occupied range, which is likely to be declining owing to continuing habitat loss. A large typhoon could plausibly lead to its extinction.

Family/Sub-family Zosteropidae

Species name author (Hartert, 1897)

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

Identification 14 cm. Medium-sized, all-dark, warbler-like bird. Uniform dark-brown with black bill, orange legs and conspicuous white "teardrop" below the eye. Voice Lively song, lilting warble very similar to song of Golden White-eye Cleptornis marchei of the Marianas. Hints Mostly found in remnant native forest, but ranges into disturbed areas nearby.

Population estimate

Population trend

Range estimate (breeding/resident)

Country endemic?

530

decreasing

34 km²

Yes

Range & population Rukia ruki has a tiny occupied range (c.4 km²) being recorded from four tiny islands in the Faichuk Group of the Chuuk (= Truk) lagoon, Federated States of Micronesia (numbers in brackets after each island indicate estimated population in 1984): Tol South (382), Wonei (19), Pata (32) and Polle (93)¹. Recent information indicates a population numbering in the hundreds⁴. There is no information on trend, but it is assumed to be declining.

Ecology: The species has been recorded in old and secondary-growth stands of native forest, particularly the rich and well-developed forest above 400 m on Mt Winipot (Tol South), where fig trees Ficus spp., native palms Clinostigma spp., Parinarium, Randia and the endemic poison tree Semecarpus kraemeri predominate, the latter possibly playing an important ecological role in the species's survival^1,5. It is also found in areas of native trees mixed with plantations¹ but densities are much lower². It feeds by foraging for insects in the foliage¹. It is territorial, breeding has been observed in April, and the only recorded nest was in a S. kraemeri tree, supporting the premise that a commensal and possibly mutual relationship exists between the two species³.

Threats The potential introduction of alien species to the islands is a concern, particularly brown tree snake Boiga irregularis which has caused the extirpation and extinction of birds on Guam (to USA)¹, although the lack of an airport and major port facilities reduces this possibility². Deforestation has occurred across much of Chuuk Archipelago, but forests on the plateau of Tol South where this species lives are apparently old-growth and relatively undisturbed⁵. Access to the plateau is difficult and hence the threat posed to the species is low.

Conservation measures underway None is known, although a stamp featuring the species was issued by the Republic of Naurau in 2005.

Conservation measures proposed Conserve native forest above 250 m on Mt Winipot¹. Identify and protect native forest on Polle¹. Promote local awareness of this endemic species through an education programme². Revisit the islands to establish the current population size and trends.

References 1. Engbring et al. (1990). 2. J. Lepson in litt. (1999). 3. Pyle and Engbring (1988). 4. G. Dutson in litt. (2003). 5. C. Collins in litt. (2007).

Further web sources of information

Alliance for Zero Extinction (AZE) species/site profile. This species has been identified as an AZE trigger due to its IUCN Red List status and limited range.

Text account compilers Jeremy Bird (BirdLife International), Andrew O'Brien (BirdLife International), Sue Shutes (BirdLife International), Alison Stattersfield (BirdLife International), Andy Symes (BirdLife International)

Contributors Chris Collins (Wildwings), Guy Dutson (Birds Australia), Jaan Lepson

IUCN Red List evaluators Jeremy Bird (BirdLife International), Stuart Butchart (BirdLife International), Andy Symes (BirdLife International)

Recommended citation BirdLife International (2009) Species factsheet: Rukia ruki. Downloaded from http://www.birdlife.org on 9/2/2010

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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