I hate when you have to learn the hard way, but sometimes that's the only real way to learn. We are suburban so we were pretty sure our 5ft garden fences would keep a by foxes out that might wander into the built up area. 3 years we lived under this illusion until my daughter came yelling one morning that something was in with the chickens. We were lucky to lose just the one chicken and a quail the following night before we shored things up. It let us know where all our defenses were week though.