• Summary
• Text account
• Data table and detailed info
• Distribution map
• Reference and further resources

Taxonomic source(s)
del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A., Fishpool, L.D.C., Boesman, P. and Kirwan, G.M. 2016. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 2: Passerines. Lynx Edicions and BirdLife International, Barcelona, Spain and Cambridge, UK.

Red List criteria met

Critically Endangered	Endangered	Vulnerable
-	-	-

Red List history

Year	Category	Criteria
2022	Near Threatened	D2
2016	Near Threatened	D2
2012	Near Threatened	D2
2008	Near Threatened	D2
2004	Near Threatened
2000	Lower Risk/Near Threatened
1994	Lower Risk/Near Threatened
1988	Lower Risk/Least Concern

Migratory status	not a migrant	Forest dependency	medium
Land-mass type		Average mass	-

	Estimate	Data quality
Extent of Occurrence (breeding/resident)	184 km2	medium
Area of Occupancy (breeding/resident)	184 km2
Severely fragmented?	no	-

	Estimate	Data quality	Derivation	Year of estimate
Population size	40000-80000 mature individuals	poor	estimated	1984
Population trend	stable	poor	suspected	-
Generation length	2.61 years	-	-	-
Percentage of mature individuals in largest subpopulation	100%	-	-	-

Population justification: Within its small range it is considered common and widespread, with 2-15 individuals found in every c.100 m stretch of forest edge (van Balen 2020). Engbring et al. (1990) estimated the population to number 86,864 individuals, roughly equating to 60,000 mature individuals and placed here in the range 40,000-80,000 mature individuals. Although there is no more recent population estimate or trend assessment, Yap Plain White-eye remains among the most commonly encountered avian species on Yap (Robertson and Robertson 2016).

Trend justification: Most species surveyed on Yap in 2004 appeared to be less abundant than in Engbring et al.'s (1990) surveys (Robertson and Robertson 2016). The reasons for this are uncertain but could be attributed to Typhoon Sudal in 2004, difference in survey methods or changes in habitat availability (Robertson and Robertson 2016). However, there has been no recent trend assessment; the species is thought to be common and it tolerates a wide range of habitats. Currently the population is suspected to be stable in the absence of any recent evidence for any declines or substantial threats.

Country/Territory	Presence	Origin	Resident	Breeding visitor	Non-breeding visitor	Passage migrant
Micronesia, Federated States of	extant	native	yes

Country/Territory	IBA Name
Micronesia, Federated States of	Yap Island

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Forest	Subtropical/Tropical Moist Lowland	major	resident
Grassland	Subtropical/Tropical Seasonally Wet/Flooded	suitable	resident
Savanna	Moist	suitable	resident
Shrubland	Subtropical/Tropical Moist	suitable	resident
Altitude	0 - 170 m	Occasional altitudinal limits

Threat (level 1)	Threat (level 2)	Impact and Stresses
Climate change & severe weather	Habitat shifting & alteration	Timing		Scope		Severity		Impact
		Future		Whole (>90%)		Unknown		Unknown
		Stresses Indirect ecosystem effects, Ecosystem degradation
Invasive and other problematic species, genes & diseases	Invasive non-native/alien species/diseases - Boiga irregularis	Timing		Scope		Severity		Impact
		Future		Whole (>90%)		Very Rapid Declines		Medium Impact: 7
		Stresses Species mortality

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Recommended citation
BirdLife International (2024) Species factsheet: Yap Plain White-eye Zosterops hypolais. Downloaded from https://datazone.birdlife.org/species/factsheet/yap-plain-white-eye-zosterops-hypolais on 25/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from https://datazone.birdlife.org/species/search on 25/12/2024.