Justification The majority of the population of this species occurs on the island of Saipan, where brown tree snake Boiga irregularis appears to have become established. This is likely to lead to an extremely rapid population reduction in the near future, unless the snake can be controlled. It therefore qualifies as Critically Endangered.

Family/Sub-family Zosteropidae

Species name author (Oustalet, 1889)

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

Identification 14 cm. Medium-sized, bright, warbler-like bird. Golden-yellow or peach-coloured, browner above, with bright orange bill, legs, and feet. Yellowish-white eye-ring. Voice Flock calls a rasping schik and a loud whistle. Song a rolling warble SEE-ME-can-you-SEE-ME-I-can-SEE-YOU-can-you-SEE-ME ...

Population estimate

Population trend

Range estimate (breeding/resident)

Country endemic?

58,000

decreasing

130 km²

Yes

Range & population Cleptornis marchei is endemic to the Northern Mariana Islands (to USA), occurring on Saipan where, in 1982, the population was estimated at 55,522 birds, and on the uninhabited Aguijan (4 km²), where the population was estimated at 2,000¹. On Saipan, estimated densities from surveys 1991-1992 are among the highest ever reported for birds (up to 2,095 birds/km²), suggesting that numbers are likely to be at carrying capacity for the island². Island-wide surveys on Saipan in 1997 indicate that the population may be declining but no population estimates were calculated⁹. On Aguijan, surveys were conducted in 2000 and 2002 which indicate that the population has increased to over 9,000 individuals¹⁰.

Ecology: On Saipan, it occurs in all wooded habitats, including the native limestone forest, which is restricted to steep slopes and cliffs and covers c. 5% of the island, and introduced tangan tangan Leucaena leucocephala thickets on flat lowlands and plateaus (c. 28% of land cover), and also urban areas^1,4,15. However, it is decidedly more common in limestone forest than in disturbed areas², and higher nesting densities are recorded in limestone forest than tangan tangan thickets¹¹. It forages predominantly in the foliage of trees, particularly Cynometra ramifolia, feeding on invertebrates, flying insects, nectar, fruit and flowers and also taking insects from tree bark^1,4 and is typically seen in small groups of 2-4 individuals, thought to be family groups¹⁵.

Threats The species's ability to utilise different habitats may help to explain its persistence despite periodic typhoon damage and extensive, human-caused habitat change¹. The establishment of brown tree snake Boiga irregularis on Saipan poses a major threat to the population and is very likely to lead to extremely rapid declines, as has been the case amongst the endemic avifauna of Guam (to USA)^6,7,12, but there are no data as yet on predation of the white-eye¹⁵. Aguijan is difficult to get to and it is unlikely that snakes will be accidentally introduced there³ - as of 2008 there had been no reports of snakes on the island¹⁵.

Conservation measures underway Although not directed solely at the conservation of this species, extensive efforts are underway to determine the status of brown tree snake Boiga irregularis on Saipan and should an established population be identified, to control it immediately⁸. Efforts are also underway to develop captive breeding techniques for the white-eye and to explore the potential of establishing populations on additional islands¹³. In 2007 and 2008 a total of 46 birds were taken into captivity as part of the Marianas Avifauna Conservation Plan with the intention of beginning captive breeding in the near future¹⁵.

Conservation measures proposed Monitor population trends through detailed censuses⁵. Continue to control Boiga irregularis population by trapping at ports and monitor its spread. Develop and implement techniques to control small incipient populations of B. irregularis¹⁴. Continue to develop techniques for establishing a captive population and establish new wild populations, as appropriate¹⁴.

References 1. Craig (1990). 2. Craig (1996). 3. J. Lepson in litt. (1999). 4. Pratt et al. (1987). 5. G. Wiles in litt. (1999). 6. A. Saunders in litt. (2003). 7. Williams (2004). 8. N. Hawley in litt. (2007). 9. USFWS (1999). 10. Esselstyn et al. (2003). 11. Sachtleben (2005). 12. Wiles et al. (2003). 13. Berger et al. (2005). 14. F. Amidon in litt. (2007). 15. A. Tieber in litt. (2008).

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 Phil Benstead (BirdLife International), Jeremy Bird (BirdLife International), Simon Mahood (BirdLife International), Andrew O'Brien (BirdLife International), Sue Shutes (BirdLife International), Alison Stattersfield (BirdLife International), Andy Symes (BirdLife International)

Contributors F. A Amidon (US Fish & Wildlife Service), Nate Hawley (Division of Fish and Wildlife), Jaan Lepson, Alan Saunders (Department of Conservation), G. Wiles (Massey University)

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

Recommended citation BirdLife International (2009) Species factsheet: Cleptornis marchei. 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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