Grab the .22 and kill it, should be fairly easy if it is coming up to eat off the porch, once you sorted that one i'd make sure there isn't an easy option of cat food outside to draw more in.
I reared Grey Partridges in pens very similar to these, I put insulators a few inches up from the bottom screwed into some small lengths of wood so it was about 8 inches away from the side, and ran an electric wire around and put a battery fencer on the wire, you could run both coops off the...