Bird orchestras

How animatronic robot bird corpses revealed that birds conduct little orchestras...

Magpie-larks are one of around 200 species of birds that duet like this. Yet unlike many of these other birds, magpie-larks also produce a strange visual duet at the same time. They simultaneously raise their wings, shrug their shoulders or flick their tails up in the air. This physical element of the performance was baffling, because the magpie-larks did it even when rival birds were not within visual range.

In an attempt to unravel this, Ręk turned to robotics. He took the skins of male and female magpie-larks, which he had found dead, and stuffed them with mechanical skeletons. He was able to programme these "robo-birds" to replicate some of the movements performed by the real birds during their duets, and to coordinate them.

While the wild birds reacted aggressively to the recorded songs, they appeared less bothered by the visual performances alone. This suggests the visual displays do not send any message to rival pairs. Instead, Ręk suggests that it helps the couples coordinate their songs.
http://www.bbc.com/earth/story/20160803-the-strange-reason-magpie-larks-dance-when-nobody-is-looking