I don't think that 3-4 foot fence is high enough to contain hens. Sorry. My hens are in an enclosed area but they can "hop" up onto a ladder that is 5' high. I've heard that clipping their wings will discourage wandering but it also prevents them from getting away when flight is needed. If you release the hens for only a few hours a day, and they have plenty to eat and scratch around in, they may be fine. Good luck! I hope it works out.
