A few years ago when I got my first chickens, I decided to clip one wing on all of my pullets who kept jumping my 4 foot chainlink fence, my 5 foot barn fence, ad all other fences. It was a waste of time. My hens could fly straight up in the air to the top of my coop run without a problem. Whe they get older and fatter, some will stop jumping on the fence, but not all. I have found the best luck with the electric fence netting---since they can't jump up to perch and then fly over, they usually stay on the inside.