Data Zone
Justification of Red List category
This owl has a very small, rapidly declining population due to widespread loss of riverine forest, increasing development along rivers and dam construction. It therefore qualifies as Endangered. However, recent information suggests the population size may be greater than previously thought. If this is confirmed, the species may warrant downlisting to Vulnerable.
Population justification
The global population is estimated to number a few thousand birds, based on estimates of 250-400 in Primorye alone [or up to 80 pairs] (J. Slaght in litt. 2012). It is precautionarily placed in the band 1,000-2,499 mature individuals, equating to 1,500-3,749 individuals in total, rounded here to 1,500-4,000 individuals. The total population size in Japan is 140 individuals (Hayashi in litt. 2016). Surveys throughout its range are required to gain a more accurate estimate than this.
Trend justification
A number of threats exist which impact negatively upon this species, owing to its requirement for clean, stocked, relatively undisturbed waterways. Hence it is suspected to be declining rapidly.
Bubo blakistoni is found in the coastal mountain ranges of Russia's Far East, north to Magadan, including Sakhalin Island (although there has not been a verified record here since 1974), the southern Kuril Islands and the Amur Basin (J. Slaght in litt. 2012); the mountains of Heilongjiang, Jilin and eastern Inner Mongolia, China, and central and eastern Hokkaido, Japan. It may occur in North Korea. The population numbers 250-400 birds (up to 80 pairs) in Primorye, Russia, an area representing the extreme south of its range, and by extension the total population size is likely to be a few thousand (J. Slaght in litt. 2012; 450-500 pairs on the mainland, and ~60 pairs in the island subspecies). It is declining in Russia and China but is increasing slightly in Hokkaido (Hayashi in litt. 2016).
It inhabits dense forest, with large, old trees for nest-sites, near lakes, multi-channeled rivers, springs and shoals that do not freeze in winter (J. Slaght in litt. 2012). Nest trees were most commonly Japanese poplar and all nests were in broken top cavities, with nest tree height being 18.1 ± SE 1.5 m. Shallow, fast flowing rivers with cobble substrate and a glide riffle were characteristics associated with nesting sites (Slaght et al. 2013a). Freshwater fish forms the main part of the diet but marine fish, small mammals, birds, amphibians, insects and crustaceans are also taken. Juveniles remain in their home territory for up to 18 months, and don't begin to breed for themselves until their third year (Slaght 2009).
Logging of riverine forest, conversion of forest to farmland, development (including roads) along riverbanks and the construction of dams are the major threats. Over-harvesting of fish, especially salmonids, has reduced food availability in Russia and Japan. Disturbance is a problem across its range and river pollution, hunting and trapping are also threats (J. Slaght in litt. 2012). On Hokkaido, birds are killed through collision with powerlines and traffic and drowning in nets on fish-farms. Incidences of close inbreeding have been reported on Hokkaido, likely as a result of the small population there numbering just c.35 pairs (Hayashi 2009). Much of the species optimal habitat in Primorye, Russia is unprotected, leaving it vulnerable to threats such as unsustainable resource use (Slaght and Surmach 2016).
Conservation Actions Underway
CITES Appendix II. It is legally protected in all range states. It has been recorded from several protected areas including Sikhote-Alinski, Magadanski, Botchinski, Verkhnekhorskiy and Kuril'ski (Russia), Changbai Shan (China), and Shiretoko and Nemuro (Japan). Recent protected area designations along Anyuy River (Annui National Park in 2009) and Bikin River (Bikin National Park in 2015) also protect fish owl habitat, but population sizes there are unknown. These parks should be surveyed. Some habitat outside protected areas in Japan are within preservation areas of the National Forest Agency where commercial timber harvest is precluded (Hayashi in litt. 2016). For the past thirty years in Japan, there has been a programme of supplementary feeding, nest-box provision and fledgling ringing to facilitate individual identification for population estimation (Hayashi in litt. 2016). The Blakiston's Fish-owl Project was initiated in 2005 in Russia as a collaborative study between the Wildlife Conservation Society and the Amur-Ussuri Center for Avian Biodiversity, to conduct research on a variety of issues, including habitat-use and nest monitoring, as well as building scientific capacity and increasing conservation awareness (Anon. 2008, Slaght and Surmach 2008, Slaght 2009, J. Slaght in litt. 2012). Collaborative activities in Primorye, based on recent conservation recommendations, are ongoing and include working with logging companies to avoid disturbance in forest patches containing important fish owl habitat components and close unneeded logging roads to reduce disturbance(recommended in Slaght & Surmach 2016), and erection of artificial nest boxes at sites lacking large trees (recommended in Slaght et al. 2013a, 2013b). In Kuril’ski Reserve, researchers are also erecting nest boxes and are manually widening tree cavity openings to allow for fish owl entry (http://kurilskiy.ru/newspost/635).
Conservation Actions Proposed
Conduct surveys of river basins along the Okhotsk Sea coast, the lower Amur Valley (Russia) and in China and North Korea. Create a system of specially protected areas in the Khor River Basin (Russia). Develop and extend the current captive breeding programme in Japan with possible coordination with population restoration efforts in Kuril Islands and Sakhalin Island (Russia). Design and implement a recovery plan for the river systems and forests in Hokkaido (Japan). Provide nest-boxes especially where nest trees have been removed. Draft regulations to restrict human access to key sites during the breeding season and to ban fishing on stretches of river used by the species. Eliminate use of potential nest trees for bridge construction. Continue to foster institutionalization of logging road closures post-harvest (as a necessary component of compliance with Forest Stewardship Council certification) to reduce human access to riparian zones (J. Slaght in litt. 2012). Develop methods to reduce mortality due to collision with power-lines and traffic and drowning in nets. Instigate public awareness and education campaigns in all range states.
60-72 cm. Massive owl with long, broad, horizontal ear-tufts. Pale grey-brown facial disc. Buff-brown, broadly streaked upperparts. Buff and dark brown barred wings. Pale tail with dark bars. White throat. Pale buffish-brown underparts with long streaks. Orange-yellow iris. Grey-horn bill with yellowish tip. Voice Call of a single adult bird is a short, deep, hu-HUUU. Males and females also duet, with the structure differing between subspecies. Begging call a long, loud, slurred peeeeer-peeeeer-peeeeer.
Text account compilers
Benstead, P., Bird, J., Chan, S., Derhé, M., Peet, N., Khwaja, N., Martin, R, North, A.
Contributors
Surmach, S., Slaght, J.
Recommended citation
BirdLife International (2024) Species factsheet: Blakiston's Eagle-owl Bubo blakistoni. Downloaded from
https://datazone.birdlife.org/species/factsheet/blakistons-eagle-owl-bubo-blakistoni 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.