The past two or three weeks I have been watching a gray squirrel go up and down the tree in the backyard carrying leaves up and coming down for more. Looks like the squirrel is done having built a leaf shelter up in the tree to get out of the winter weather.
Could be a female planning on a shelter for her spring birthing of baby squirrels. Gestation for a gray squirrel is 8 weeks. That would bring the birthing date up to the middle of February or March. That is about the time for warm weather to come back in S.C.