婉轉(zhuǎn)，清麗，高亢，鳥兒在枝頭歡唱。世界自然紀(jì)錄片之父愛登堡老爵爺講述鳥類鳴叫對于種群的意義。　　David Attenborough chooses seven of the most remarkable animal songs found in nature and explores the significance of these songs in the lives of their species.