a little bird told me是一种非常诙谐的表达，意思是“有人告诉我”, 当你不想透露某个消息是谁告诉你时，就说是a little bird told me...
这个说法有个典故：在《圣经》里，人类祖先躲在诺亚方舟里，为了看洪水是否退去， 就派了一只鸟儿去打探，所以a little bird就演变成了消息灵通的人士了。
said if you know who gave you the information being discussed but do not want to say who it was
你知道告诉你信息的这个人，但是不想告诉别人他是谁;无可奉告，我不说
A; How did you know he was leaving?
你怎么知道他要走了?
B: Oh, let's just say a little bird told me.
噢，有人告诉我的。
