NT
Giant White-eye Megazosterops palauensis



Justification

Justification of Red List Category
The species is known from only two small islands, where the availability of suitable habitat is declining due to forest loss and degradation. Nevertheless, the species remains common at many localities. Apart from habitat loss, the species is also threatened by a possible introduction of the Brown Tree Snake in the future, which could potentially wipe out large parts of the population within a short time. Therefore, the species is listed as Near Threatened.

Population justification
Engbring (1992) estimated the total population to number 13,876 individuals, which is rounded here to 13,900 individuals. This is roughly equivalent to 9,200-9,300 mature individuals. No more recent population estimates are available for this species.

Trend justification
The population trend has not been quantified directly. The species is suspected to be in decline as a result of habitat degradation and loss. Ongoing deforestation has resulted in a significant loss of habitable area for the species with only very limited forest remaining throughout its range (Tracewski et al. 2016). Consequently, the population of mature individuals is suspected to be in slow decline at a rate of <20% over three generations.

Distribution and population

Megazosterops palauensis is endemic to Palau, where it is common on the islands of Ngeruktabl and Peleliu (Engbring 1988, 1992). There is also one record from Babeldaob Island (Olsen and Eberdong 2009), but it is not known why the species does not occur on other neighbouring islands (van Balen 2019).

Ecology

Megazosterops palauensis is found in limestone forest, dense vines and introduced tangan-tangan Leucaena leucocephala thickets (van Balen 2019). The species feeds on insects, including caterpillars and ants, alongside fruits and nectars from flowering trees. It lives both solitarily and in pairs, only tending to form flocks in December. It forages in the tops of low trees and brambles, displaying a preference for the upper part of tall vine-draped trees or vine tangles close to the ground (van Balen 2019).

Threats

The most severe threat to the species is habitat degradation and loss. Ongoing deforestation has resulted in a significant loss of forest cover, with only very limited forested area remaining throughout the range (Tracewski et al. 2016). Furthermore, whilst not currently a threat, the possible introduction of the Brown Tree-snake (Boiga irregularis) onto the islands could have a devastating impact on the species, as it did to birds on Guam (Wiles et al. 2013). Should this species be introduced, a rapid decline could be expected. Changing weather patterns as a result of climate change may also threaten the species in the future.

Conservation actions

Conservation Actions Underway

None is known.

Conservation Actions Proposed

Monitor populations to determine trends. Conserve important areas of habitat on both islands of occurrence. Ensure Boiga irrelgualris does not reach Ngeruktabl and Peleliu.

Identification

Giant White-eye is a large, approximately 13.5-14cm in length, relatively dull white-eye with a heavy bill. The supercilium is pale yellowish from before the eye, widening backwards. It has a narrow, indistinct, pale yellow eye-ring, and dusky loral area leading to dark greyish ear-coverts with irregular pale yellow mottling. Dark fulvous olive above with crown feathers greyish towards the base, giving a mottled appearance. Pale fulvous olive below, flanks slightly more buffy. Iris greyish to dark rufous-brown. The bill is pale brown above, orange-yellow below. Its legs are tawny or olive-green with yellowish soles. Sexes alike. Juvenile currently remains undescribed (van Balen 2019).

Acknowledgements

Text account compilers
Shutes, S., Everest, J., Stattersfield, A., Mahood, S., Derhé, M., O'Brien, A.


Recommended citation
BirdLife International (2022) Species factsheet: Megazosterops palauensis. Downloaded from http://www.birdlife.org on 07/10/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 07/10/2022.