Species

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Justification
This species qualifies as Critically Endangered because it appears to survive in tiny numbers at only one locality, where its habitat continues to be destroyed and degraded, such that its overall range and population are likely to be declining.

Taxonomic note
Zosterops atrifrons (Sibley and Monroe 1990, 1993) has been split into Z. atrifrons, Z. nehrkorni and Z. stalkeri following Rasmussen et al. (2000b).

Identification
12 cm. Small, arboreal, warbler-like bird. Rich olive-green upperparts with striking yellow-green rump and darker green-black tail. Black forehead, broad white eye-rings. Bright yellow chin, throat and undertail-coverts, rest of underparts pearly-white with grey flanks. Pale orange bill and legs. Voice Contact call apparently thinner and higher-pitched than Z. atrifrons. Similar spp. The related Black-fronted White-eye Z. atrifrons is slightly smaller, duller and has darker bare parts.

Distribution and population
This species is restricted to Sangihe, Indonesia, where until 1996 it was known from only a single historical specimen and was thus quite possibly already rare by the 19th century. It was seen twice in 1996 and sound-recorded once out of 148 point counts in 1999 (Riley 2002) from one location (Gunung Sahendaruman and adjacent Sahengbalira). It is regarded as extremely rare and infrequently encountered in the remaining 8 km² of appropriate habitat. While there has been no population estimate, it is likely that fewer than 50 mature individuals survive.

Population justification
The population is estimated to number fewer than 50 individuals and mature individuals. This estimate was derived from analyses of recent records and area of remaining habitat (BirdLife International 2001).

Trend justification
Forest loss and degradation continues to be a threat on Sangihe island and as a result this species is suspected to be in decline, although the likely rate of decline has not been estimated.

Ecology
It frequents the mid-storey to upper canopy of primary broadleaved ridgetop forest, often with a high density of Pandanus sp., where it gleans insects from leaves and presumably also forages on fruit. It appears to be strictly confined to altitudes between 750 m and 1,000 m.

Threats
Virtually the entire island of Sangihe has been deforested and converted to agriculture. The very small population of this species in the area of habitat remaining suggests that it is constrained by some unknown specialism or threat, potentially the requirement for large ranges in which to search for fruit, or perhaps the depredations of introduced rats Rattus spp. Whatever the reason, the clear indication is that it is extremely vulnerable to continuing habitat loss at the lower fringes of forest. Government initiatives to plant exotic tree species, initially at lower altitudes, are now reportedly taking place at 700-900 m, further threatening the tiny remaining area of native forest (Sykes 2009).

Conservation actions underway
The Gunung Sahendaruman "protection forest" nominally conserves some remaining habitat, although few measures have been taken to ensure its efficacy. Since 1995, the "Action Sampiri" project has been working for biodiversity conservation in Sangihe and Talaud, conducting fieldwork, conservation awareness programmes (including village and school meetings, distribution of leaflets etc.), and developing ideas for future land-use through agreements between interested parties. As a result, plans are in progress to reclassify the existing 4 km² of "protection forest" on Gunung Sahengbalira as a wildlife reserve (with core areas as a strict nature reserve), although this process is likely to take 2-3 years. Furthermore, the Wildlife Conservation Society began four years of project work on Sangihe in 2007, which will provide opportunities for protecting remaining habitat and a basis for further work. The Wildlife Conservation Society has also worked on the island since 2007 trying to promote sympathetic land use and development by villages surrounding Gunung Sahengbalira (N. Brickle in litt. 2010).

Conservation actions proposed
Conduct further surveys for the species in remaining forest patches on the island (e.g. Gunung Awu). Ensure effective protection of habitat on Gunung Sahendaruman. Support proposals for the rapid gazetting of remaining forest on Gunung Sahengbalira as a strict nature reserve. Continue conservation education programmes. Encourage forestry staff to establish a permanent presence on the island.

References
Rasmussen, P. C.; Wardill, J. C.; Lambert, F. R.; Riley, J. 2000. On the specific status of the Sangihe White-eye Zosterops nehrkorni, and the taxonomy of the Black-crowned White-eye Z. atrifrons complex. Forktail 16: 69-81.

BirdLife International. 2001. Threatened birds of Asia: the BirdLife International Red Data Book. BirdLife International, Cambridge, U.K.

Riley, J. 2002. Population sizes and the status of endemic and restricted-range bird species on Sangihe Island, Indonesia. Bird Conservation International 12: 53-78.

Whitten, T. 2006. Cerulean Paradise-flycatcher not extinct: subject of the first cover lives. Conservation Biology 20: 918-920.

Sykes, B. 2009. OBC conservation: news update and requests for practical help. BirdingASIA 12: 107-108.

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.

Click here for more information about the Alliance for Zero Extinction (AZE)

Detailed species accounts from the Threatened birds of Asia: the BirdLife International Red Data Book (BirdLife International 2001).

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

Text account compilers
Benstead, P., Bird, J., Calvert, R., Symes, A., Taylor, J., Tobias, J.

Contributors
Brickle, N., Pangimangen, W.

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

Recommended citation
BirdLife International (2013) Species factsheet: Zosterops nehrkorni. 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.

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