noun
birdbrain; scatterbrain; forgetful person
Colloquial and mildly self-deprecating or teasing term for someone who is very forgetful or has a poor memory, likening them to a bird's supposedly small brain.
また約束を忘れたの？本当に鳥頭だね。
You forgot our plans again? You're such a birdbrain.
私は鳥頭だから、すぐにメモを
I'm so forgetful that I have to write things down right away or I'll forget.