In 2005 the US Army commissioned the University of Maryland's Robotics Center to produce a mechanical bird capable of remote surveillance. It took eight years and several evolutions, but they've finally come up with a working prototype. Using 3D printed components, the Maryland team produced a robotic raven with movements so realistic they even fool other birds.

"It already attracts attention from birds in the area, which tends to hide its presence," said John Gerdes, a mechanical engineer at Aberdeen Proving Ground. The development team has noticed seagulls and crows flying in formation next to the robo-bird and it's been attacked by neighboring hawks.

"Generally we don't see them coming," Gerdes said. "They will dive and attack by hitting the bird from above with their talons, then they typically fly away."