Critters in the Night

I love waking up in the morning after fresh snow has fallen to see all the tracks in our backyard. We have a crabapple tree and the birds and other animals like to eat the mushy, rotten crabapples. But I  worry because we have been so very cold. They are predicting again -40 degree wind chills on Monday and Tuesday. How do the deer and bunnies keep warm? I'm sure schools will be closed again. They said we haven't had a winter this cold since 1982 and we were living here that winter. I'm really looking forward  to Spring this year:)