But they do not (as, for example, lice do) live on their hosts continually. Once a bird fledges, therefore, it leaves its parasites behind.

但是它们不会一直寄生在它们的宿主身上(虱子才会)，当鸟儿羽翼丰满时，鸡蚤就会离开。

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In the same way, species of lice on living animals and birds reflect the splits in animal and bird ancestry back to the time that lice first arose.

通过分析动物以及鸟类身上的虱子，同样能够折射出鸟兽的进化历程。

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