抄録
From 1979 to 1989 76 birds of Dendrocopos major (DMA) and 22 birds of D. minor (DMI) were ringed with a numbered metal ring and a combination of celluloid coloured rings in the farm and campus of Obihiro University and its surrounding areas, eastern Hokkaido. Of 31 adult males of DMA ringed, 50% disappeared within 1 month and 3% were observed in the study area for 6 years. Of 25 adult females ringed, 70% disappeared within 1 month and were not observed after the fifth year. More juveniles disappeared than adults. Of 76 birds, ringed 17 were observed for 1 to 6 years. They occurred in wood islands in the university farm and the wooded areas of the campus. Of 22 birds of DMI ringed only 9% were observed for 1 year or more.
