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

Taxonomic note

Horornis diphone (del Hoyo and Collar 2016) was previously listed as Cettia diphone.

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
2024	Least Concern
2016	Least Concern
2012	Least Concern
2009	Least Concern
2008	Least Concern
2004	Least Concern
2000	Lower Risk/Least Concern
1994	Lower Risk/Least Concern
1988	Lower Risk/Least Concern

Migratory status	full migrant	Forest dependency	low
Land-mass type		Average mass	-

	Estimate	Data quality
Extent of Occurrence (breeding/resident)	3,220,000 km2	medium
Severely fragmented?	no	-

	Estimate	Data quality	Derivation	Year of estimate
Population size	unknown	-	-	-
Population trend	stable	-	suspected	-
Generation length	2.53 years	-	-	-

Population justification: The global population size has not been quantified, but in its non-breeding range, the species is described as uncommon to locally fairly common. Race restricta is now considered to be extinct. The introduced populations on Hawaii are now considered to be common to abundant on Oahu and spreading to other islands (del Hoyo et al. 2006). National population estimates include: c.10,000-100,000 breeding pairs and c.1,000-10,000 individuals on migration in China; < c.50 individuals on migration and < c.50 wintering individuals in Taiwan; c.10,000-100,000 breeding pairs and c.1,000-10,000 individuals on migration in Korea; c.10,000-100,000 breeding pairs in Japan and c.10,000-100,000 breeding pairs and c.1,000-10,000 individuals on migration in Russia (Brazil 2009). The population is suspected to be stable in the absence of evidence for any declines or substantial threats.

Trend justification: The population is suspected to be stable in the absence of evidence for any declines or substantial threats.

Country/Territory	Presence	Origin	Resident	Breeding visitor	Non-breeding visitor	Passage migrant
China (mainland)	extant	native
Japan	extant	native
North Korea	extant	native
Philippines	extant	native
Russia	extant	native
Russia (Asian)	extant	native
South Korea	extant	native
Taiwan, China	extant	native
USA	extant	introduced

Country/Territory	IBA Name
Japan	Mount Hyonosen
Japan	Mounts Nogo-hakusan and Ibuki
Russia (Asian)	Lower Tumen river

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Forest	Temperate	suitable	non-breeding
Forest	Temperate	suitable	breeding
Grassland	Subtropical/Tropical Dry	suitable	non-breeding
Grassland	Subtropical/Tropical Dry	suitable	breeding
Shrubland	Subtropical/Tropical Moist	suitable	non-breeding
Shrubland	Subtropical/Tropical Moist	suitable	breeding
Altitude	0 - 3000 m	Occasional altitudinal limits

Purpose	Scale
Pets/display animals, horticulture	subsistence, national

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Recommended citation
BirdLife International (2024) Species factsheet: Japanese Bush-warbler Horornis diphone. Downloaded from https://datazone.birdlife.org/species/factsheet/japanese-bush-warbler-horornis-diphone on 23/11/2024.
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 23/11/2024.