How do hummingbirds hum?

Usually, the only sound of a hummingbird is the whirring or humming sound it makes with its rapidly beating wings.

A hummingbird flaps its wings nearly 60 times in the time it takes you to blink your eyes.  The wings move so fast that only a misty outline can be seen.  They make the air vibrate, and we hear a humming sound.

The delicate and brightly colored hummingbird usually measures less than four inches from bill to tail and weights about as much as a copper penny.

No other bird can fly in so many ways as the hummingbird.  It can quickly dart up, down, backward, forward or it can hover nearly motionless in the air like a helicopter.

The active little bird must eat every 10 to 15 minutes it is awake to maintain its tiring pace. It flits from flower to flower and hovers above each blossom.  

It sips the sweet nectar through its long, tube-shaped tongue and picks up any small insect that it may find in the flower. Most, but not all hummingbirds are tiny.  The largest is the giant hummer.  It grows nearly 9 inches long.-Dick Rogers