Species

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Justification
The majority of the population of this species occurs on the island of Saipan, where the brown tree snake Boiga irregularis may be in the process of becoming 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.

Taxonomic source(s)
Sibley, C. G.; Monroe, B. L. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven, USA.

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 ...

Distribution and population
Cleptornis marchei is endemic to the Northern Mariana Islands (to USA), occurring on Saipan where, in 2007, the population was estimated at 71,997 birds, and on the uninhabited Aguijan (4 km²), where the population was estimated at 1,169 birds (Camp et al. 2009, Amidon et al. in prep.). Populations on Saipan have declined since 1982 while surveys conducted in 2008 indicate that densities on Aguijan were significantly greater in 2008 than in 1982 (Camp et al. 2009, Amidon et al. in prep). On Saipan, estimated densities from surveys during 1991-1992 were among the highest ever reported for birds (up to 2,095 birds/km²), suggesting that numbers were likely to be at carrying capacity for the island (Craig 1996). Island-wide surveys on Saipan in 1997 indicated that the population may have been declining but no population estimates were calculated (USFWS 1999). Population densities were recalculated for 1982 and calculated for surveys conducted in 1997 and 2007 (Camp et al. 2009).  Population densities (birds per km² ±SE) on Saipan declined from 1,287.2 ± 191.0 in 1982, 995.5±160.0 in 1997 and 711.8±112.1 in 2007 (Camp et al. 2009).

Population justification
The species occurs on Saipan (71,997 individuals) and Aguijan (1,169 individuals) (Camp et al. 2009, Amidon et al. in prep.), equating to a global population of c.73,000 individuals.

Trend justification
An extremely rapid population decline, which may well have already begun, is projected over the next ten years owing to the possible establishment of the brown tree snake Boiga irregularis on Saipan.

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 (Pratt et al. 1987, Craig 1990, A. Tieber in litt. 2008, 2010). However, it is decidedly more common in limestone forest than in disturbed areas (Craig 1996), and higher nesting densities are recorded in limestone forest than tangan tangan thickets (Sachtleben 2005). 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 (Pratt et al. 1987, Craig 1990) and is typically seen in small groups of 2-4 individuals, thought to be family groups (A. Tieber in litt. 2008, 2010).

Threats
The species's ability to utilise different habitats may help to explain its persistence despite periodic typhoon damage and extensive, human-caused habitat change (Craig 1990). The potential establishment of brown tree snake Boiga irregularis on Saipan poses a major threat to the population (Rodda and Savidge 2007) and would likely lead to extremely rapid declines, as has been the case amongst the endemic avifauna of Guam (to USA) (A. Saunders in litt. 2003, Wiles et al. 2003, Williams 2004), but there are no data as yet on predation of the white-eye (A. Tieber in litt. 2008, 2010). Aguijan is difficult to get to and it is unlikely that snakes will be accidentally introduced there (J. Lepson in litt. 1999) - as of 2008 there had been no reports of snakes on the island (A. Tieber in litt. 2008, 2010). Having a distribution on relatively low-lying islands, this species is potentially susceptible to climate change through sea-level rise and shifts in suitable climatic conditions (BirdLife International unpublished data).

Conservation actions 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 immediately (N. Hawley in litt. 2007). Efforts are also underway to develop captive breeding techniques for the species. Golden white-eyes were translocated to the island of Sarigan in 2011 and a second translocation is proposed for 2012 (Berger et al. 2005). 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 future (A. Tieber in litt. 2008, 2010). As of 2010 there are currently 38 chicks dispersed throughout six institutions in the U.S., all developing captive breeding protocols. Two chicks were produced in 2009, though only one survived (A. Tieber in litt. 2008, 2010).

Conservation actions proposed
Monitor population trends through detailed censuses (G. Wiles in litt. 1999). 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. irregularis (F. Amidon in litt. 2007). Continue to develop techniques for establishing a captive population and establish new wild populations, as appropriate (F. Amidon in litt. 2007). Continue to monitor the translocated population on Sarigan.

Related state of the world's birds case studies

• Bird populations in the Northern Mariana Islands are being decimated by brown tree snakes

References
Pratt, H. D.; Bruner, P. L.; Berrett, D. G. 1987. A field guide to the birds of Hawaii and the tropical Pacific. Princeton University Press, Princeton.

Craig, R. J. 1990. Foraging behaviour and microhabitat use of two species of white-eyes (Zosteropidae) on Saipan, Micronesia. The Auk 107: 500-505.

Craig, R. J. 1996. Seasonal population surveys and natural history of a Micronesian bird community. Wilson Bulletin 108: 246-267.

Wiles, G. J.; Bart, J.; Beck, R. E. J.; Aguon, C. F. 2003. Impacts of the brown tree snake: patterns of decline and species persistence in Guam's avifauna. Conservation Biology 17: 1350-1360.

Williams, S. 2004. Endangered and threatened wildlife and plants; Endangered Status for the Rota Bridled White-Eye (Zosterops rotensis) from the commonwealth of the Northern Mariana Islands. Federal Register 69(14): 3022-3029.

Esselstyn, J., J. B. Cruz, L.L. Williams, and N. Hawley. 2003. Wildlife and vegetation surveys: Aguiguan 2002.

Sachtleben, T. 2005. Predation and nest success of forest birds in native and non-native habitat on Saipan, Mariana Islands. M.Sc. Thesis, Colorado State University.

Berger, G.M.; Gourley, J. Schroer, G. 2005. Comprehensive Wildlife Strategy for the Commonwealth of the Northern Mariana Islands.

Camp, R. J.; Pratt, T. K.; Marshall, A. P.; Amidon, F.; Williams, L. L. 2009. Recent status and trends of the land bird avifauna on Saipan, Mariana Islands, with emphasis on the endangered Nightingale Reed-warbler (Acrocephalus luscinia). Bird Conservation International 19(4): 323-337.

Rodda, G.H., and Savidge, J .A. 2007. Biology and impacts of Pacific Island invasive species. 2. Boiga irregularis, the brown tree snake (Reptilia: Colubridae). Pacific Science 61: 307-324.

Amidon, F., Camp, R. J., Marshall, A., Pratt, T. K., Williams, L., Radley, P. and Cruz, J. B. In prep. Status and trends of the land bird avifauna of Aguiguan, Mariana Islands.

Further web sources of information
Hear sounds for this species from xeno-canto, the community database of shared bird sounds from around the world.

View photos and videos, and hear sounds of this species from the Internet Bird Collection

Text account compilers
Benstead, P., Bird, J., Derhé, M., Mahood, S., O'Brien, A., Shutes, S., Stattersfield, A., Symes, A.

Contributors
Amidon, F., Hawley, N., Lepson, J., Saunders, A., Tieber, A., Wiles, G.

IUCN Red List evaluators
Butchart, S., Symes, A.

Recommended citation
BirdLife International (2013) Species factsheet: Cleptornis marchei. Downloaded from http://www.birdlife.org on 26/05/2013. Recommended citation for factsheets for more than one species: BirdLife International (2013) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 26/05/2013.

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.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Additional resources for this species

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