Don't use the .22LR unless it's a dead gimme for a head shot. Not enough real oomph. A light bullet in the .280 looks like your best bet for a rifle.
If your 12-gauge is full-choke, or you have the screw-in type and the tube, #2 or 0 buck or 00 buck will do. I'd limit myself to 35 or 40 yards, generally. Good forest/brush gun at those typically under 25-yard close ranges...
I knew a Highway Patrol guy who used to call them up to his patrol car, and shoot them with his service revolver.
FWIW, Art
[This message has been edited by Art Eatman (edited February 15, 2000).]