All comments and suggestions appreciated.

What they mostly need is a place to get out of the wind. Animals will
curl up and generate their own heat. They're wearing fur coats, after
all. You can set up such a place and put an old blanket in it
for softness if you like, but there's no need for electric heating
anything, really. Unless it gets really bitter cold (like in the
minus double-digits), they'll be fine.

Jane