I wish I had known what was about to happen so I could have gotten a video of it. One of my chickens just hopped up on the wire wall of their pen about three feet up and proceeded to climb the rest of the eight foot height by flapping non-stop for lift and walking up the wall foot over foot to the next piece of wire until it got to the top where it settled down to perch. It wasn't just residual inertia, it took about 10 to 15 seconds to climb the wall and looked hard, but the chicken seemed to know what it was doing and went in a straight line up. Has anybody else ever seen or heard of this? I didn't know a chicken could climb a vertical surface this way.