Abstract
According to the check-list of Japanese birds, sixth revised edition, the Night Heron Nycticorax nycticorax is an irregular visitor in Hokkaido. Two breeding sites of the species were found in the southern part of Oshima Peninsula, south-western Hokkaido; at Nanae in 2000 and at Assabu in 1999. In Nanae 54 nests were counted in the spring of 2009 in a deciduous broad-leaved forest. In Asaabu four nests of the species were counted with 147 Grey Heron Ardea cinerea nests in May 1999 in a deciduous broad-leaved forest. In 2009 Night Herons were absent from the Assabu colony.
