抄録
Lake Izunuma, Miyagi Pref., has the largest population of geese wintering in Japan. On 8 October 1980 we found a juvenile Swan Goose Anser cygnoides at the lake in a flock of White-fronted Geese (Fig. 1). This bird, the sole Swan Goose recorded in the winter of 1980-81 in Japan, was always observed together with White-fronted Geese. We followed up the Swan Goose, as a marker of the movement of the Izunuma White-fronts, during the northbound migration. It took the course from Lake Izunuma to Hachiro-gata in Akita Pref. (observed 13 March 1981) and then to Seika-ko in Hokkaido (observed 8 April to 5 May 1981) (Fig. 2). The route thus brought out is a second northbound migration course of the Izunuma White-fronted Geese, the main route being the course from Lake Izunuma to Hachiro-gate and then to Ishikari Plain in Hokkaido (Fig. 3).
