Nearly the entire (98%) and over a third of the East Asian population of Brent Geese stage in Notsuke Bay and nearby sites of eastern Hokkaido, Japan, during autumn and spring migration, respectively,. Despite the region’s importance as a refueling site for migrating Brent Geese, little is known about how these migrants use specific sites within this region. In this study, we investigated the seasonal variation in the movements and use of four key sites in the eastern Hokkaido using radio telemetry. Notsuke Bay was the primary staging area for Brent Goose in both seasons, but there were frequent movements between Furen Lake in fall and between Kunashiri Island in spring. The three sites lie in close proximity to one another in the Nemuro Strait, enabling relatively quick (<30 minutes) flights between sites. Consequently, these sites may be considered as one continuous habitat during migration. Brent Geese primarily foraged on eelgrass beds at night in fall and during the day in the spring. The occupancy rates of marked geese within the protected areas of Notsuke Bay and Furen Lake were 74% and 71% during autumn, and 64% and 87% during spring, respectively. However, extending the buffer to 3 km from the boundaries of the protected areas resulted in residency rates exceeding 90% during both seasons. To effectively conserve these important staging sites in the Nemuro Strait, we recommend expanding the protected areas and including connecting waters between Notsuke Bay and Kunashiri Island and Furen Lake.