Vocalizations differ among the recognized subspecies. In the nominate subspecies from Japan, the male calls twice and the female responds with one note, whereas the mainland subspecies has a somewhat more elaborate, four-note duet: "HOO-hoo, HOOO-hoooo" (here, the male call is in capital letters ("HOO") and the female call in lower case ("hoo")). The transliterations of the calls of owls from Russia, representative of the owl's vocal variations, are "SHOO-boo" and "FOO-foo-foo". The territorial song or call in Russia in particular has been described as somewhat like a short, deep eagle-owl's call. Despite its slightly larger size, the Blakiston's fish owls voice is not as sonorous or as far-carrying as is the Eurasian eagle-owl's voice is. The fish owl's voice is rather deeper, however. As in most owls, vocal activity tends to peak directly before nesting activity begins, so peaks around February in this species. This duet of pairs of Blakiston's fish owl in the period leading up 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".