You may eat any clean bird, ___________?
What kind of question tag goes into the above blank?
It is a contraction, as I'm sure you will have guessed, of 'may you not' and is correct English, if a bit archaic.
You may eat any clean bird. (positive statement) Therefore we use negative tag and we have to add "not" in 'MAY EAT'.
You may eat any clean bird, may not you? (wrong)
In question tag, we must use short form(contraction). Therefore we must use:
You may eat any clean bird, mayn't you?
Hope you understand very well.
Most users would reword the whole sentence, so that they could use some other modal in the tag question - 'can't we?' or 'couldn't I?' for example.