I'm in the Bay Area in California, and I'm just entering the first winter with my bunnies. It's started to get a bit chilly, and I've noticed that they don't really want to come out and play quite as much recently... How cold is too cold for the bunnies? When should I start getting concerned about the temperature? It's chilly in my house sometimes now - cold enough that sometimes I'll want to put on a sweater just to hang around.

Also, any ideas for making the coolness more tolerable for them? If I put a blanket in their pen for them to snuggle with, would that possibly help?