Genesis 7:8

and of fowls There is no mention of a distinction between clean and not clean in the birds and the creeping things, see note on Genesis 7:3. The mention of a distinction between "clean" and "unclean" beasts (behêmah, "cattle" or "domestic animals" of Genesis 6:20) is certainly a later insertion by the compiler. The account in Genesis 6:19-20 (P) does not recognize the distinction of clean and unclean.