The distribution and morphological characters of Eagle Owls Bubo bubo were investigated using specimens from museums. Eight of thirty-six specimens found in Japan were collected in Hokkaido. Of all the characteristics examined, wing length was the only one that varied between locations. However, morphological measurements overlapped in all investigated areas. Also, with plumage, individual variations were remarkably similar to geographical ones. Consequently it seems difficult to distinguish between Bubo bubo subspecies from morphological characters alone. Considering the numbers of Bubo bubo specimens were much fewer than those of Blakiston's Fish Owls Ketupa blakistoni, it can be suggested that Bubo bubo populations in Hokkaido have been unstable throughout this century.
