The Great Bird was a mechanical flying apparatus invented by Leonardo da Vinci.
The great bird featured in the Leonardo da Vinci's workshop holoprogram. In late 2373, while running the program, USS Voyager Captain Kathryn Janeway noticed some sketched of what looked like a flying machine. Leonardo da Vinci expressed dissapointment with the design, which led Janeway to suggest that instead of emulating the flapping of a bat or sparrow, he should focus on the gliding of a hawk. (VOY: "Scorpion")
In 2374, Janeway and Leonardo attempted to launch a prototype of the glider from a bridge in Florence. They immediately fell into the Arno and had to retreat in embarrassment to da Vinci's workshop. Leonardo felt further humiliated because he had been bragging about the device for months.
Later, when the hologram was stolen from Voyager by spacefaring pirates and outfitted with The Doctor's mobile emitter, he spent several days on a trading center planet, where he rebuilt his "Great Bird" using duranium. He and Janeway used it to escape pursuers after they had recovered Voyager's stolen goods. The "Great Bird", with Janeway and da Vinci aboard, was beamed from mid-air to Voyager's cargo bay. (VOY: "Concerning Flight")