I've never seen any of my Hookbills go more than a few inches off the ground. I don't think my pen fence is even 4' and they've never got close to the top, maybe not even half way. That being said, the food and water is in the pen so I don't think any of them have ever really tried to get out, just fluttering about when they get excited. The one duck we did keep is the most focused in our flock. She is always foraging or searching around the yard. We've had periods where she was really noisy. It's just one duck, I wouldn't base any breed judgements on just one.