Abstract
I observed a breeding pair of Grey-faced Buzzards in 2013 and 2014 in Aomori City, Aomori Prefecture, northern Japan. In 2013 the pair fledged two young successfully in the normal way. In 2014, however, the male rarely fed the female during the incubating period. Instead they took turns to incubate their eggs. Moreover, another adult male helped the pair to raise their nestlings and they fledged three young in the year. The diet of the pair consisted primarily of small mammals such as Rodentia until the young hatched after the pair arrived at their breeding site, during which period temperatures are relatively low. After hatching, when it became warm, they preyed on small mammals, frogs, reptiles and insects. A cool climate in Aomori City would be responsible for a large proportion of rodents in the diet during the early breeding season.
