This might be a baby hummingbird with a few juvenile feathers left. They don't get much time to be babies because they have to learn to fly like little helicopters right away. It could also be an adult that had a rough migration from the south because when they are cold, they will fluff out like this, but it's not cold right now.
He's the roughest looking hummer I've ever seen - the breeze shows skin between gaps in the feathers and all.