You only clip one wing not both of them. It might well prevent them flying over but chickens can be very determined. A 4ft fence is definitely too low 6ft should be high enough.
I have lots of chickens and have 1 or 2 escape artists amongst them.
Clipping any type of bird's wings is horrible.
would you like it if someone cut your legs off so that you couldn't get away?
Nope
