Nah squirrels don't hibernate I don't think. I always see them in winter, got 2 of them this winter nicking all of our bird feed! ( http://www.squirrels.org/faq.html#Q8 ) But the mild winters have really been messing up the wildlife, so it is good for them that we are finally getting a normal one so they don't get confused! Although that hedgehog hasn't got the message...