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

Justification of Red List category
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence under 20,000 km² combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population size has not been quantified, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (under 10,000 mature individuals with a continuing decline estimated to be over 10% in ten years or three generations, or with a specified population structure). The population trend appears to be stable, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (over 30% decline over ten years or three generations). For these reasons the species is evaluated as Least Concern.

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.

Text account compilers
Rutherford, C.A.

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 23/12/2024.
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 23/12/2024.