The standard answer is supposed to be hen, as it is the only bird.
I believe the standard answer is a "hen" because it's the only one that is gender-specific. In fact, it is distinctly the odd-one out because it doesn't even refer to a specific genus (or even family) of animal.
I'm all for creativity (I have the same complaint often) but there needs to be some sort of standardization in communication and society. A genius who can't communicate any of his/her ideas might as well be no genius at all.