Hover fly

Black-headed Gulls aren't really built for hovering, but they do their best when food is being thrown and they're hoping to catch some. There's a small footbridge at the town end of the Bancroft Basin, and today when I saw some people standing there throwing bread for the assembled birds, I placed myself close enough to catch this behaviour on camera. 

The process seems to involve the gull flying in quite a wide circle, slowing as it approaches the place where it wants to stop, then lifting its head and dropping its feet until it looks to be almost standing in the air. Having reached stalling speed, it flaps its wings furiously for a second or two until it starts to drop from the sky, and then banks away into another circuit. It's impressive that they can perform this manoeuvre at all, but some of them can simultaneously track the trajectory of a piece of flying bread, and adjust their position to intercept it if it's reasonably close. And of course, the whole performance is usually accompanied by a loud running commentary.