Help! Proper Fence to Set Boundaries for Chickens

[Flower Chick]

Our five chickens are just under 7 months old and we are planning on getting another five in the spring. We have just under two acres and the chickens have just started 'migrating' over to a neighbor's yard (we prefer to let the chickens free range during the day). We have decided to put up a picket fence to hopefully keep the chickens in the backyard (they will have almost an acre to roam). My question is: Should we put up a 4 ft. or 6 ft. fence? Any fence suggestions for us? Thanks so much!!!

 

[beetandsteet]

The higher the better! If you want to, you can build the shorter fence (which I assume would be cheaper for you) and clip or brail their wings to keep them from flying over the fence. I have contained chickens in a 4 foot fence before---some would fly out, but clipping their primary feathers on one wing stopped that pretty fast.