This species is a closed relative of Western Marsh Harrier (Circus aeruginosus), and occurs the eastern part of Eurasian continent and some neighboring islands. The plumage of these two species is somewhat different.

Although a number of the harriers come from the continent in autumn, and winter in Japan, the breeding population in Japan is estimated only ca. 100 pairs. Most of the breeding sites are in Hokkaido and northern Japan. In our area, Mie, this harrier breeds in Kisozaki Reclaimed Land. Two or three pairs try to breed there in spring. But recently only one pair gets breeding success.

The breeding area in the reclaimed land is recently reduced. Joining with the other two conservation groups, our society periodically observes the breeding behavior of the harrier in the reclaimed land.