Abstract
Based on field observations of the Japanese Crested Ibis Nipponia nippon, and 11 photopraphs taken by the autor in the field in various seasons in Sodo 1., he confirmed his earlier finding that the greyish wash of the plumage on the back is the indication of its nuptial adult phase in spring. This wash is entirely lost in winter individuals. In younger birds, however, the greyish wash does not occur even in the spring.
