One note about gerbils escaping their cage. Make sure you don't have any mousetraps (or electrical wires, for that matter) set up where he might come in contact. My [bleep]ing brother (who is no longer with us) set up a mousetrap in our house. I had a hamster and he escaped without my seeing. I was in the kitchen about to eat breakfast when something caught my eye. My hamster, dead, caught in the trap. I never forgave my brother for that.