I keep one broody hen at a time in an enclosed part of the pen. 3 different hens each hatched 5-6 chicks each (over the summer) of which all but 3 disappeared. The current hen went from 3 chicks to 1 this week. No bodies, no trauma, no disturbed pen/holes. All I can figure is rat snakes. The pen is inside another pen and is covered with a mix of mesh wires, a couple of different types. (the net/mesh mess is tight enough to contain new chicks. The top is covered partly by tin, plus woven fence wire and poultry netting over the whole run. I have removed and relocated 2 snakes that were in nest boxes (eating eggs) in the open parts of the run this summer. Could I be overlooking a different predator? I really don't want to cover the whole broody pen with hardware cloth, are there any other options that would be snake proof?