VU
Gizo White-eye Zosterops luteirostris



Justification

Justification of Red List Category
This species is confined to the island of Ghizo, where it is estimated to have a very small population comprising fewer than 1,000 mature individuals. The population is suspected to be stable and this species has proven relatively adaptable to habitat degradation. For this reason it is assessed as Vulnerable. However, if areas of remnant forest begin to be cleared, the population could decline quickly from an already low starting point and would be eligible for a higher threat category. 

Population justification
The species is described as locally common (Dutson 2011). An approximate population density of 46 birds/km2 was estimated in the 1990s (Buckingham et al. 1995). In 2020, 26 km2 of forest on its tiny range island (35 km2) was estimated to persist (Global Forest Watch [2021], using Hansen et al. [2013] data and methods disclosed therein). Even if 100% of forest was occupied, the population would number only 1,200 birds, equating to c.800 mature individuals. The population size is therefore placed in the band of 250-999 mature individuals, with a best estimates of 500-750 that assumes that most, but not all, of available habitat is occupied.

Trend justification
There are no robust data on the population trend of this species. Habitat trends over the past ten years are inferred to be stable based on the fact that only 2% of forest in its range has been lost over the past decade (Global Forest Watch [2021], using Hansen et al. [2013] data and methods disclosed therein) and the species is at least to some extent tolerant of secondary habitats (although perhaps only where there is adjacent forest). Consequently, while there may be some localised habitat degradation, the population is suspected to be stable, but this requires confirmation.

Distribution and population

Zosterops luteirostris is endemic to Ghizo in the Solomon Islands. Birds were found to be locally common in forest patches but less common elsewhere (Buckingham et al. 1995, Gibbs 1996, G. Dutson pers. obs. 1998, M. Iles verbally 1998).

Ecology

It is most common in forest edge, regrowth and mature secondary forest, and less common in scrub close to large trees and in plantations. It is not known whether these latter two habitats support sustainable breeding populations (Buckingham et al. 1995, G. Dutson pers. obs. 1998, M. Iles verbally 1998, Dutson 2011).

Threats

The majority of the island's old growth habitat was cleared by the 1980s. Remaining areas continue to be threatened for clearance for timber, firewood and gardens, although more recently remote sensing data have indicated almost no forest loss on the island (Global Forest Watch 2021, using methods of Hansen et al. 2013). Areas of secondary forest are occupied by this species and may be undergoing localised degradation that affects this species, although this remains unconfirmed. Climate change may prove a future threat to this species, as tropical storms become increasingly frequent and degrade habitat further.

Conservation actions

Conservation Actions Underway
None is known. 

Conservation Actions Proposed
Map the species' distribution across Ghizo related to habitat-types. Monitor numbers along line-transects and/or numbers of singing males in discrete forest blocks.
Support expansion of suitable forestry plantations. The species is likely to respond very positively to fairly minimal forest restoration efforts if they are imposed island-wide (C. Filardi in litt. 2012). Coordinate all conservation action through public awareness discussions. Publicise this species as endemic to Ghizo and ensure government engagement in conservation efforts.

Identification

12 cm. Bright, warbler-like bird with orange-yellow bill and legs. White eye-ring contrasts with black lores and dark olive upperparts whilst underparts are bright yellow. Similar spp. Female Olive-backed Sunbird Cinnyris jugularis has long, dark bill and no eye-ring. Voice Strong, short melodic song and loud tcheup contact calls. Hints Easily seen where the cross-Ghizo roads pass tall native trees and scrub.

Acknowledgements

Text account compilers
Berryman, A.

Contributors
Bergmark, J., Derhé, M., Dutson, G., Ekstrom, J., Filardi, C., Iles, M., Mahood, S. & Stattersfield, A.


Recommended citation
BirdLife International (2022) Species factsheet: Zosterops luteirostris. Downloaded from http://www.birdlife.org on 08/12/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 08/12/2022.