A California company has developed a drone that looks like a hummingbird. This nano-hummingbird is smaller than drones now used by the United States military. The manufacturer, AeroVironment, develops and tests its drones near Los Angeles. The experimental bird-like aircraft is radio-controlled and has a camera. Matthew Keennon is supervising the project.

MATTHEW KEENNON: "It's being manipulated and controlled to allow the forward and backward flight, the rotation, and also the side to side flight. And all that's happening by just changing the curvature and the shape and different aspects of the wing movement at a very high speed."

The Defense Advanced Research Projects Agency paid for the project. Agency officials wanted a vehicle that could copy something in nature. Matthew Keennon says the challenge was huge and exciting.

MATTHEW KEENNON: "Because every time we made an improvement, got better, we were just so amazed."

AeroViroment has also been testing one of the world's largest drones. The company's Steven Gitlin says this one can fly in Earth's stratosphere.

STEVEN GITLIN: "And it's designed to fly for up to seven days at a time at about 65,000 feet [19.8 kilometers] altitude and carry a payload that either helps somebody see what they want to see or relays communication from one point to another."

AeroViroment says drones also have civilian uses -- for public safety, security, and search and rescue. And the nano-hummingbird can go places that larger drones cannot. I'm Steve Ember.