夜莺悦耳的歌声,曾受到诗人济慈的赞美,但如果看到夜莺,可能会感到失望,因为它一点也不美。一般说来,能发出悦耳歌声的鸟,其羽毛多半是素朴的,却多半栖身茂林树丛;而生态环境使视觉讯号并不重要,所以它们改以悦耳动听的鸣叫声来吸引异性。布谷乌、柬鸟、夜莺等就属于这种鸟类。 The melodious singing of the nightingale was once praised by the poet Keats, but if he saw the nightingale, he might feel disappointed because it was not beautiful at all. Generally speaking, the birds that can produce pleasant singing voices are mostly simple but most of them are in Maolin Grove. The ecological environment makes the visual signals not important, so they use beautiful sounding sounds to attract the opposite sex. Bugu Ukrainian, Cambodian bird, nightingale and so on belong to this kind of bird.