Biak Leaf-warbler (Phylloscopus misoriensis)

Biak Leaf-warbler Phylloscopus misoriensis

Current view: Data table and detailed info

Taxonomy

Taxonomic note

Phylloscopus poliocephalus and P. makirensis (Sibley & Monroe [1990, 1993]) have been lumped and subsequently split into P. poliocephalus, P. misoriensis and P. maforensis following del Hoyo and Collar (2016).

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.

IUCN Red List criteria met and history

Red List criteria met

Critically Endangered	Endangered	Vulnerable
-	-	-

Red List history

Year	Category	Criteria
2022	Near Threatened	B1b(ii,iii); C2a(ii)
2016	Vulnerable	C2a(ii)
2012	Not Recognised
2008	Not Recognised
2004	Not Recognised
2000	Not Recognised
1994	Not Recognised
1988	Not Recognised

Species attributes

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

Range

	Estimate	Data quality
Extent of Occurrence (breeding/resident)	3,600 km²
Area of Occupancy (breeding/resident)	3,000 km²
Severely fragmented?	no	-

Population

	Estimate	Data quality	Derivation	Year of estimate
Population size	2500-9999 mature individuals	poor	suspected	2021
Population trend	decreasing	-	suspected	2016-2026
Rate of change over the past 10 years/3 generations (longer of the two periods)	5-10%	-	-	-
Rate of change over the future 10 years/3 generations (longer of the two periods)	5-10%	-	-	-
Rate of change over the past & future 10 years/3 generations (longer of the two periods)	5-10%	-	-	-
Generation length	2.02 years	-	-	-
Number of subpopulations	1	-	-	-
Percentage of mature individuals in largest subpopulation	100%	-	-	-

Population justification: The species has been described as uncommon and possibly an order of magnitude lower than congeners (G. Dutson in litt. 2016); for example, two three-day visits to the island's forests in 2019 recorded the species only once (J. Bergmark in litt. 2021), and eBird (2021) data indicate that it is among the hardest of the island's endemics to see. Therefore, based on descriptions of abundance, population density estimates of congeners, and assuming only a proportion of habitat is occupied, the population size may fall below 10,000 mature individuals, and so is provisionally suspected to number 2,500-9,999 mature individuals until more robust, species-specific data are available. Given descriptions of this species' rarity, generating a robust population estimate should be considered a research priority.

Trend justification: Global Forest Watch (2021), using data from Hansen et al. (2013) and methods disclosed therein, indicate that between 2010 and 2020 this species lost 6-8% of forest cover (>30% canopy cover) in its range. As a forest dependent species, it is suspected to have declined at a similar rate. Forest loss in 2016-2020 occurred at the same rate, such that these declines are expected to continue in the future.

Country/territory distribution

Country/Territory	Presence	Origin	Resident	Breeding visitor	Non-breeding visitor	Passage migrant
Indonesia	extant	native	yes

Important Bird and Biodiversity Areas (IBA)

Country/Territory	IBA Name

Habitats & altitude

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Forest	Subtropical/Tropical Moist Lowland	suitable	resident
Forest	Subtropical/Tropical Moist Montane	major	resident
Altitude	0 - 740 m	Occasional altitudinal limits

Threats & impact

Threat (level 1)

Threat (level 2)

Impact and Stresses

Agriculture & aquaculture

Annual & perennial non-timber crops - Small-holder farming

Timing

Scope

Severity

Impact

Ongoing

Minority (<50%)

Slow, Significant Declines

Low Impact: 5

Stresses
Ecosystem degradation, Ecosystem conversion

Biological resource use

Logging & wood harvesting - Unintentional effects: (subsistence/small scale) [harvest]