Douglas Harper's Etymology Dictionary
Wikipedia
Bird-Brain
Bird-Brain is a fictional character appearing in American comic books published by Marvel Comics.
Usage examples of "bird-brain".
But it's time you bird-brained dopes realized that you have been outlawed.
While I can understand Felaras not wanting every bird-brained flitter-head in the Order to go flying off on tangents because of a little bad news, I rather resent that she feels she needn't tell those of us who are levelheaded until she's ready for us to hear things.
Not the family bird-brain, who was on patrol now, or, more likely, hitting on some nitwitted pigeon.