How does a hummingbird hum?
It can’t carry a tune, but its wings flap so fast about 50 times a second that it produces a humming sound. You can’t see the wings flapping because their speed turns them into a blur, just like a helicopter’s fast-turning blades. And like a chopper, a hummingbird can fly vertically and hover in one place for example, when it is drinking nectar from a plant.