Cotton is a 1 year old rabbit we rescued from a neglectful situation about a month ago.  He is our only pet, was neutered 8 days ago, had a slow and difficult recovery, but seems to be back on track now.  Today he seemed a little strange and was gnawing on his litter pan MUCH more than usual, then he cleared all the litter out of the box.  He’s been hanging out in there ever since.  He usually rests during the day like this, but generally stretches out on the floor of his cage not in the litter box.  We had a cold front come through today (in TX) with rain and temperatures dropping.  He’s indoors, but it was still a temperature degree drop in our house (from 75 to about 67 degrees).  Could the cold front be causing his behavior?  Should I put the litter back in the box once his rest time is over for the evening?  I’ve tried putting a small fleece blanket in his cage previously (though not during a cold front), but he hasn’t seemed to care for it and pushes it aside.