I hope you did not take my post for me saying that you could just leave them. No that is not what I meant. But they can and do survive in extreme tempratures.
If you want a good read check out. Bilateral Lesion of Anterior Hypothalamus and Regulation of Body Temperature in Rats. Medicina et Pharmacologia Experimentalis 1967;16:355-364 (DOI: 10.1159/000137011)