Blakiston's fish owl (Bubo blakistoni) is the largest living species of owl. It belongs to a fish owl, a sub-group of eagle owls which specialize in hunting in riparian areas. This species is a part of the family known as typical owls (Strigidae) which contains most species of owl. Henry Seebohm named this bird after the English naturalist Thomas Blakiston, who collected the original specimen in Hakodate on Hokkaidō, Japan, in 1883.
The Blakiston’s fish owl somewhat resembles the Eurasian eagle-owl but is more monochromatically brown to tan in color. Like other fish owls but unlike most eagle-owls, the Blakiston's fish owl has relatively broad and ragged ear tufts which hang slightly to the side and that do not appear upright. The upperparts are buff-brown and heavily streaked with darker brown coloration. The underparts are a paler buffish brown and less heavily streaked. The throat is white. The iris is yellow. In terms of structure, the Blakiston's fish owl is more similar to eagle-owls than it is to other fish owls but it shares a few characteristics with both types of owl. Like all fish owls, its bill is relatively long, the body relatively husky, and the wings are relatively long compared to eagle-owls. It also shares with other fish owls a comparatively long tarsi, although relative to their size the three smaller fish owl have a proportionately longer tarsus. Other than these few characteristics, a Blakiston's fish owl skull and skeleton are practically the same as that of a Eurasian eagle-owl. The talons of the Blakiston's fish owl are similar in shape and size to those of the Eurasian eagle-owls.
Blakiston's fish owls occur in Russia, China, and Japan. They don't migrate and live in dense old-growth forests near waterways or wooded coastlines. Their preferred habitat is riparian forest, with large, old trees for nest sites, near lakes, rivers, springs, and shoals that don't freeze in winter.
Blakiston's fish owls are primarily active at dusk and dawn but may also hunt during the day and night when rearing their young. For owls, they spend unusual amounts of time on the ground and may even trample out a regular footpath along riverbanks which they use for hunting. Blakiston's fish owls are generally solitary and highly territorial; however, as many as 5-6 owls may sometimes gather near rapids and non-freezing springs when feeding. Blakiston's fish owls use two most common hunting methods; these are wading through river shallows and perching on the river bank or logs and waiting for movement in the water. In this behavior, an owl may wait for four hours until it detects prey. Blakiston's fish owls communicate using various types of calls. As in most owls, vocal activity usually peaks directly before nesting begins. This duet of pairs of Blakiston's fish owls in the period leading up to the breeding season is so synchronized that those unfamiliar with the call often think it is only one bird calling. When an individual bird calls, it may sound like 'hoo-hooo'. Juveniles have a characteristic shriek, typically a startling and slurred 'phee-phee-phee'.
Blakiston's fish owls are carnivores (piscivores) and feed on a variety of aquatic prey. Their main prey type is fish such as pike, catfish, trout, and salmon. During winter they also take a wide variety of mammalian prey including rodents, martens, hares, rabbits, foxes, cats, and even small dogs.
Blakiston's fish owls are monogamous and form long-term pair bonds. They do not breed every year due to fluctuations in food supply and conditions. Courting usually occurs in January or February and the laying of eggs begins as early as mid-March when ground and trees are still covered with snow. These owls prefer nesting in hollow tree cavities 2-18 m (6 ft 7 in-59 ft 1 in) high of the ground. The female lays a clutch of 1 to 3 eggs, but usually 2. The male provides food for the incubating female and later the nestlings. The incubation period is about 35 days. The owlets are altricial (helpless) when they hatch and leave the nest within 35-40 days but are often fed and cared for by their parents for several more months. Juveniles linger on their parents' territory for up to 2 years before dispersing to find their own. Blakiston's fish owls can form pair bonds as early as their second year and reach reproductive maturity by age 3.
This species is endangered due to the widespread loss of riverine forests, increasing land development along rivers, and dam construction. In Russia, Blakiston's fish owls are killed by fur trappers, drown in nets set for salmon, and are shot by hunters. In Japan, they are often hit by cars and killed by power lines. Additionally, cases of exposure to lead or lead poisoning, possibly from bioaccumulation but also perhaps lead bullets in carrion, have been reported in these owls in at least Japan.
According to the IUCN Red List, the total population size of the Blakiston's fish owl is 1,500-4,000 individuals. The total population size of this species in Japan is 140 individuals. Currently, the Blakiston's fish owl is classified as Endangered (EN) on the IUCN Red List, and its numbers today are decreasing.
Blakiston's fish owls play an important role in the ecosystem they live in. They control populations of fish and other prey items and their presence is a good indicator of the health and disturbance level of a forest.
