Bird feeder

The birds have discovered my bird seed, and now they are out in force. I was lying in bed wondering where they go at night when it's cold, I suppose they have warm little nests somewhere. And where do the deer go? They must huddle together for warmth deep in the trees or something since they can't build nests. Which got me to thinking, which animals don't cuddle together to stay warm? I know of one example, the Tasmanian Devil, which is so unfriendly it's a wonder they get close enough to reproduce (it's not a date movie moment either.) Definitely not on the short list for evolving into a house pet. It has been cold, with a wicked wind from the North West and when it blows from that direction there is no way to keep the house warm so I'm mostly staying in bed when I can.