My 3 yo sulcata has been outside almost a full year now! He has a 3x4 heated house that he stayed in last winter! He dug a burrow this summer and spends his nights there! When the weather starts cooling off will he go back to his box or stay in his burrow? Do I need to fill in the burrow, cover the entrance or just assume he'll be smart enough to know it's too cold to stay out?