I have an EE hen that is convinced she is the next Houdini. She is very small and light and an excellent flyer. The birds have an enclosed run that, when the door is opened, creates a large open run. Filet (or Puffy Cheeks as we call her) seems to think that the run is not big enough and will constantly escape by flying over the fence at the lowest point. I considered clipping a wing to prevent this but she can also squeeze under the door to get out as the enclosed run has a lip on it. Then my dad figured we could put a flower pot in front of the gap and clip her wing, but as he went to catch her on another escape run she CLIMBED straight up four feet of fence using her wings for stabilization. We have admitted defeat and let her come and go as she pleases. On the other end of the intelligence scale is her best friend and rooster, who crows and frets when she gets out because he can't defend her from his nemesis, the dog yard fence. He has yet to figure out any way to get to her.
P.S. They snuggle at night with her head tucked under his wing and her face on his back.
P.P.S. I think she is trying to tunnel her way out of the enclosed run.