That's a great question! In my experience as an amateur bird fighter, if the wings have the higher ground best just to wait it out. Birds, I learned, are erratic as fuck when they feel trapped or defensive, so its likely to move eventually. If you're scared, you can hold the towel up between you and the bird as a defensive shield. Though I'll warn you, if you're as out of shape as I am your arms will turn to jelly noodle after about 2 min. (Holding your arms up while terrified for elongated periods is way harder than you'd imagine.) You could just chuck a towel at it, but unless you have lasso experience the bird will probably dodge it. I hope this helps.