WarriorX, my DH used to hunt rats that lived in tunnels under his dad's hogpen. These weren't any ordinary rats -- they were the big South Georgia wharf rats. He'd lie in wait for them with his rifle many a day. When it got dark he'd pour some gasoline down the holes and light them and shoot the fireballs that ran out.
Sounds like you could use a good mouser or two. A couple of lean, slender cats with large ears, large eyes, long legs, and long tails should do the trick.
"Oir is leatsa an rioghachd, agus an cumhachd, agus a gloir, gu siorraidh, Amen." ("For Thine is the kingdom, and the power, and the glory, forever, Amen" -- Scots Gaelic)