don't mean to scare you fallinstar, but it could have been the same person who took your bikes and now knows that your dogs don't bark etc. it could even be someone who lives near you so knows you and your dogs. so making your house secure is a better option and making sure your doors are locked even when you are at home. you can get those little alarms that sit on your windows and doors and go off when they get opened. my mate got robbed in the middle of the night, she disturbed them when she got up for a pee, but they took her car. then came back three weeks later when she had got a new one and tried to get that but again were disturbed. shes got these alarms all over now, but has had a terrible time sleeping, cause these people must have been watching her. as for teaching your dog to bark, i don't know if they do this naturally or not. my gsd did, but my husky x mals don't.