The young hawks have to develop their hunting skills. Their powers of observation are keen, but their kill-skill is inept at this point. I've seen this behavior before...... notice movement, swoop down, and then bobble around the ground lifting branches because potential meal was seen moving under the branch. Branch-lifting is good, strengthens leg muscles and wings, but often it's all for naught. This youngster swooped to a corner of the field that's fenced. The grass was tall, so I couldn't see the branch well without getting too close. Had I backed off further I would have toppled backwards down the hill, so I was stuck in one spot. It was a food search for the young hawk. It was a ballet-like obervation from the camera's point of view. Awesome. And when the hawk finally flew to a branch it was greeted by enraged mockingbirds who are protecting their family.