Zosterops nehrkorni 


Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Passeriformes Zosteropidae

Scientific Name: Zosterops nehrkorni
Species Authority: Blasius, 1888
Common Name(s):
English Sangihe White-eye
Taxonomic Notes: Zosterops atrifrons (Sibley and Monroe 1990, 1993) has been split into Z. atrifrons, Z. nehrkorni and Z. stalkeri following Rasmussen et al. (2000b).
Identification information: 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.

Assessment Information [top]

Red List Category & Criteria: Critically Endangered B1ab(ii,iii,v);C2a(i,ii);D ver 3.1
Year Published: 2015
Date Assessed: 2015-10-01
Assessor(s): BirdLife International
Reviewer(s): Symes, A.
Contributor(s): Brickle, N. & Pangimangen, W.
Facilitator/Compiler(s): Benstead, P., Bird, J., Calvert, R., Symes, A., Taylor, J., Tobias, J. & Wright, L
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.

Previously published Red List assessments:
2012 Critically Endangered (CR)
2009 Critically Endangered (CR)
2008 Critically Endangered (CR)
2004 Critically Endangered (CR)
2000 Critically Endangered (CR)
1994 Not Recognized (NR)
1988 Not Recognized (NR)

Geographic Range [top]

Range Description: 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). Another single sighting was recorded amongst 499 point counts in 2009 (Burung Indonesia 2009). 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.

Countries occurrence:
Indonesia (Sulawesi)
Continuing decline in area of occupancy (AOO): Yes
Extreme fluctuations in area of occupancy (AOO): No
Estimated extent of occurrence (EOO) - km2: 15
Continuing decline in extent of occurrence (EOO): Unknown
Extreme fluctuations in extent of occurrence (EOO): No
Number of Locations: 1
Continuing decline in number of locations: Unknown
Extreme fluctuations in the number of locations: No
Lower elevation limit (metres): 750
Upper elevation limit (metres): 1000
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: 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.

Current Population Trend: Decreasing
Additional data:
Number of mature individuals: 1-49 Continuing decline of mature individuals: Yes
Extreme fluctuations: No Population severely fragmented: No
No. of subpopulations: 1 Continuing decline in subpopulations: Unknown
Extreme fluctuations in subpopulations: No All individuals in one subpopulation: Yes
No. of individuals in largest subpopulation: 100

Habitat and Ecology [top]

Habitat and 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.

Systems: Terrestrial
Continuing decline in area, extent and/or quality of habitat: Yes
Generation Length (years): 3.5
Movement patterns: Not a Migrant

Threats [top]

Major Threat(s): 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 [top]

Conservation Actions: Conservation and Research 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 and Research 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.

Citation: BirdLife International. 2015. Zosterops nehrkorni. The IUCN Red List of Threatened Species 2015: e.T22728605A78396846. . Downloaded on 25 November 2015.
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