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 <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 trend is not known, but the population is not believed to be decreasing sufficiently rapidly to approach the thresholds under the population trend criterion (>30% decline over ten years or three generations). The population size has not been quantified, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
Very little is known about the global population size given recent taxonomic splits. Around 85 pairs of the toyoshimai race were estimated to occur throughout the Bonin Islands in 2000 (Suzuki & Kato 2000). There is no data on population size or trends for the oshiroi race, however it is very rare and has been listed as Critically Endangered on the Red List of Threatened Species of Japan. Up to 800 pairs of the nominate race are estimated to occur in the southern Sikhote-Alin region of Primorskii Province, and more than 1,000 individuals were counted during spring migration in the valley of the lower Razdolnaya River near Ussuriysk (Shokhrin et al. 2020).
Very little is known about population trends due to recent taxonomic splits and uncertainty over the impacts of habitat modification on population sizes.
On the Ogasawara (Bonin) Islands, Japan, intraspecific competition and human disturbance are thought to be factors contributing to low breeding productivity (Chiba and Suzuki 2011). In Primorski Krai, Russia, two individuals were found dead due to electrocution from power lines, and three cases of shooting by local residents are known (Shokhrin et al. 2020).
Conservation actions underway
The species is listed on CITES Appendix II, CMS Appendix II, Raptors MoU Category 3.
Conservation actions proposed
Due to recent taxonomic splits, very little is known about the population size or trends of this species, therefore further research is needed throughout its range.
Text account compilers
Calvert, R., Taylor, J., Khwaja, N., Ashpole, J, Symes, A. & Slaght, J.
BirdLife International (2022) Species factsheet: Buteo japonicus. Downloaded from http://www.birdlife.org on 27/05/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 27/05/2022.