i hope you find him maybe leave a cat box in your garden with a blanket that has ernies smell on? Post leaflets to local houses asking people to check sheds etc, and if i where you id get some locks on the hutch if you keep them outside or maybe get a shed and move them in there to help stop this ever happening again because if they get out in a shed all they can do is make a mess (dont i know it lol)

I really hope hes found hes a beautiful boy