Thus whenever Du Fu saw a cuckoo, he would bow to it as if greeting a monarch. In the West, the cuckoo has also been used as a vehicle for advising kings. In Shakespeare's King Lear, Lear's fool warns him to beware his daughter Goneril, for "The hedge-sparrow fed the cuckoo so long, / That it's had it head bit off by it young."
西方卻拿杜鵑來勸戒帝王，莎士比亞的「李爾王」，讓弄臣提醒國王防範大女兒，因為「母籬雀長期哺育幼小的杜鵑，最後卻不免慘遭這小逆子啄去頭顱而亡。」