batwrangler and I once witnessed an obviously young and confused redtail lose a fight with a squirrel.
It had *caught* the squirrel, but didn't know how to kill it, and the squirrel was holding the hawk off by sheer force of personality. And teeth. Eventually, the hawk let go--obviously by accident--and the squirrel darted into the bushes.
The hawk hopped after it, wings half-open, with an expression that anybody could see boiled down to, "But wait! I didn't eat you yet! Come back!"