My cats cheek is swollen!?

My cat hunts and I was wondering if he could get an abscess from a bird pecking or scratching him? He lets me touch the golf ball sized welt on his face but I'm worried about him... It's been two days and this is the first time I've noticed the swelling. He is fine and has the same behaviors as always, but if it is an abscess I need to arrange to get it drained right away... What should I do?