Population and Distribution
Blakiston's fish owls have a fragmented distribution in the Russian Far East, northern Japan, and northeastern China. There are two generally-recognized subspecies, an island subspecies, which occurs on Hokkaido Island, Japan, and Kunashir and Shikotan Islands of the southern Kuril Islands, Russia, and a more broadly-distributed mainland subspecies, which ranges across Russia from Magadan in the north to Primorye in the south. The species may occur in North Korea, but political tensions have prevented recent survey attempts there.
Surveys suggest that the fish owl population in the southern Russian Far East (encompassing all of Primorsky Krai and Khabarovsky Krai south from the Amur River) is approximately 100-130 pairs. With extrapolation to the entire fish owl range, the population could be more than 800 pairs. Recent surveys estimate one pair of Blakiston's fish owls every 3.8 river km along the Samarga River in northern Primorye, possibly the highest natural concentration of this species globally. Concentrations of breeding pairs in suitable habitat are generally described as one pair every 6-12 river km.
A fish owl chick and egg.
Photo by Jon Slaght.
Blakiston's fish owls can form pair bonds as early as their second year, and reach sexual maturity by age 3. Pairs do not breed every year. Courtship occurs from January-February, with a clutch of one or two eggs laid in March. Young fledge up to 50 days post-hatching. Data on breeding success are scant: on Kunashir Island during a 6-year period breeding success was 24%; with six fledglings resulting from 25 eggs. Juveniles remain on their natal territory into their second year, apparently dispersing as late as July the following year.
Blakiston's fish owls require cavernous old-growth tree cavities in riparian habitat for suitable nest sites and stretches of productive rivers that remain at least partially unfrozen in winter.
The fish owl prey base is quite diverse, but even in winter, small fish are a primary target. In addition to fish, Blakiston's fish owls also prey on a variety of waterfowl species, small mammals, and amphibians. Reliance on certain prey species is seasonal: for example, in spring, frogs are particularly important and taken in great abundance.
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Read about threats facing Blakiston's fish owls.