If you have information, but you do not want to reveal who told you it, you can say 'a little bird told me'.
A little bird told me that it's your birthday today!
We're looking for someone to take on this new project, and a little bird told me that you might be interested in the job?
A little bird told me that you've got a crush on someone in our class…
Don't confuse it with
If you are a person who likes to get up early in the morning, you may be called 'an early bird'.
Give me a call in the morning: it doesn't matter what time, I'm such an early bird, I'll definitely be awake.
Thousands of waxwings have descended on Great Britain after the failure of the birds' food sources in their native Scandinavian breeding grounds. The birds are thought to be the sign of a harsh winter to come.