If, when you look just below where the squirl's tail is attached to its body, you see two good sized nuts - you'll know that the squirl's tail is bolted on and that he is a boy.
If, on the other hand, you see no nuts (and they are quite noticeable), you'll know you have a girl.
Other people asked questions on similar topics, check out the answers they received:
Other people asked questions on various topics, and are still waiting for answer. Would be great if you can take a sec and answer them