The Lake Izunuma-Uchinuma was extensively flooded in 1998 and vast areas (a
pproximately 200 ha) of rice fields were submerged for the first time since
the land was reclaimed in 1963. When the numbers of birds in 1998 were com
pared with those in normal years (1995-1997), the numbers of black-crowned
night herons (Nycticorax nycticorax L.), cattle egrets (Bubulcus ibis L.) a
nd black kites (Milvus migrans Boddaert) increased during the flooding, and
the numbers of ducks, especially dabbling ducks (seven species of 11 Anas
spp.) were high even after the flooding, while the numbers of the little gr
ebe Tachybaputus ruficollis Pallas were diminished by the flooding.