Birds appear in a variety of idiomatic expressions, including:
"A little bird told me" (a nameless person told me)
"A bird in the hand is worth two in the bush" (one thing that you do possess is worth more than two that you do not)
"Bird-brained" (small-brained = stupid)
Then there are idioms related to specific types of birds:
"Duck or grouse" (lower your head or complain as you bang it on a low beam or doorway)
"What's good for the goose is good for the gander" (if it is good for the female it must be equally good for the male)
"You're chicken!" (You are afraid)
Of course there are many more bird related idioms to explore such as:
"The goose that lays the golden egg"
"To feather one's nest"
"The early bird catches the worm"
Remember, the most important things to find out about each idiom are whether it is in common use, whether it is used as a joke or is intended as serious, and ultimately whether it is appropriate for your intended purpose, or not.
Click here to buy the Oxford Idioms Dictionary for Learners of English.