We have seen signs of them in the middle of winter. My grandpa shot a doe with the muzzleloader after christmas 1 year, as we were trailing the deer, snow up to our knees and it was 10 degrees out, we ran into really big bear tracks trailing the same deer. We eventually lost the deer, the bear already drug it off. I think most males dont truly hibernate. They will venture out in the right conditions or smell food. I could be wrong though.