Common autumn passage migrant in Hong Kong, declining summer breeding visitor with small numbers in winter. Adult: Black plumage and deeply forked tail, often has small white spot below the eye. Juvenile: whitish scaling on underparts. 香港秋季常見過境遷徒鳥，夏季有本地繁殖，數量在下降中，冬季有少量。 成鳥：羽色為均匀黑色和尾部分义 幼鳥：下體有偏白色鱗狀紋…
