I went out a little while ago to gather eggs and in my main run there was a little sparrow hawk beating him/herself up trying to get out. I'm not sure how she got in, but she was small enough that she could have fit thru the 2X4 openings in the fence. I've got smaller opening wire around the bottom of the pens. I've got flight netting over the top. I ran in and got a towel and went out and cornered her against the fence....went and showed her to the hubby and then set her free. She took off like a streak!! The hens didn't even seem upset about her. The roos were standing around watching her.