LC
Vanikoro White-eye Zosterops gibbsi



Justification

Justification of Red List Category
Although this species has a very small global range, it does not qualify as Vulnerable under the range size criterion because the population and range size appear to be stable. The population size has been crudely estimated and falls outside the threshold for listing as Vulnerable (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.

Population justification
The species was common above 700 m on Vanikoro where it was recorded at a density of 25 individuals in 1.5 ha, but it was much less common in the lowlands. Vanikoro has a total area of 173 km2, much of which remains forested. Crude interpretation of this data suggests the population can be cautiously estimated to fall within the band 20,000-49,999 individuals.

Trend justification
The only plausible threat to the species posed by introduced rats Rattus spp. has been evident for decades but the species remains relatively common. There are no repeat counts to assess trends, but congeners on other Melanesian islands occur at comparable densities on rat-free and rat-infested islands so the population of this species is suspected to be stable.

Distribution and population

This species is known only from the island of Vanikoro, situated 118 km from the main Santa Cruz Islands, Solomon Islands. Based upon reported densities the population probably numbers in the tens of thousands, and while there have been no repeat counts to assess population trends it is assumed to be stable.

Ecology

The species is apparently commonest in lowland coastal forest including secondary growth and in hill forest above 350 m. It was the commonest species above 700 m where 21 individuals were recorded in an area of 1.5 ha. The species gleans arthropods from tree leaves and branches and feeds on small fruits.

Threats

The species appears to be tolerant to some degree of forest degradation and is unlikely to be detrimentally impacted by logging in the near future. The most plausible threat is posed by introduced species, but it apparently coexists with introduced rats Rattus spp. and other invasives are unlikely to colonise the island owing to the current lack of commercial traffic.

Acknowledgements

Text account compilers
Bird, J.

Contributors
Dutson, G.


Recommended citation
BirdLife International (2022) Species factsheet: Zosterops gibbsi. Downloaded from http://www.birdlife.org on 28/09/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 28/09/2022.