bird of passage

剑桥词典

UK
a bird that migrates (= moves from one area to another when the season changes )
候鸟

a person who stays for only a short period of time in one place , job , etc.
漂泊不定的人；过客
At present the organization has to rely on young , inexperienced graduates who are usually birds of passage . 目前该机构不得不依赖没有经验的年轻毕业生，可这些人通常会跳槽。 返回 bird of passage