 They also vary the orientation and enlarge the collective surface area of their tail feathers into the shape of a fan.While hovering, the visual system of a hummingbird is able to separate apparent motion caused by the movement of the hummingbird itself from motions caused by external sources, such as an approaching predator.In natural settings full of highly complex background motion, hummingbirds are able to precisely hover in place by rapid coordination of vision with body position.