YOU SAID:
I am not a bird, dad.
INTO JAPANESE
鳥ではない父さん。
BACK INTO ENGLISH
My father is not a bird.
INTO JAPANESE
私の父は、鳥ではないです。
BACK INTO ENGLISH
My father is not birds.
INTO JAPANESE
私の父は、鳥ではないです。
BACK INTO ENGLISH
My father is not birds.
That didn't even make that much sense in English.