中海本庄工区で観察された水鳥の個体数変化

This paper describes the result of the investigation of the seasonal changes in number of water birds in Honjou area, Lake Nakaumi, from October 1996 to October 1997. A total of 45 species were found during the study period in which such rare species as Great Crested Grebe(Podiceps cristatus), Bewick's Swan (Cygnus columbianus), and Osprey (Pandion haliaetus) were included, which are listed in the Japanese Red Data Book. While more than 40,000 individuals were observed during winter, less than 100 individuals were observed during spring and summer. Winter dominant species were Pochard(Aythya ferina), Tufted Duck(Aythya fuligula) and Greater Scaup(Aythya marila).