C'mon. You'll have to do better than that
And why is that?
Well, for starters, not all animals hibernate. And unless someone sprinkled magic fairy dust on them causing them all to slumber peacefully for the entire duration, I assume that about 99% of them would be just a little too worried about whether their neighbor was going to eat them or claw their eyes out to catch some shut-eye.
Not all animals hybernate today ....you asked for an explanation, I gave you one. Certainly this is a possible scenereo, if one believes what our Lord stated.
Yeah, but... the Bible makes no mention of it. If you start speculating on what "might" have happened barring any Biblical evidence, don't be surprised if others not sharing your opinion do the same.