bird, confused

There's a tiny grey bird on the potato-vine bush outside my window and for the last 10 minutes it's been flitting from branch to branch. It flits, then swivels its head two or three times to look all around at the bush's branches, then flits again. Is it looking for a nest? What the hell is it doing? Could it be a very young bird practicing its flying? Why do I keep watching it? Which of us is more confused?