I have seen them go back in the nest box but they tend to stay in the hallway and look outside or stand on the ledge, then one day they are just gone. I wonder if this little guys leg is a developmental abnormality. I was looking back at the earlier clips because it had bothered me that when he was less than a week old he would often be on his back with his legs kicking in the air. I had never seen an owl chick or any other chick do that after the first day or so. Maybe he already had a problem at that point. The Mom here is thought to be a first timer, she really dotes on the chick.