Magpie trade bottle-caps for food video

https://www.youtube.com/watch?v=7oclPZx520k Finally, my Crowbox experiment reaches an important milestone. One of the four magpie-chicks has found out how to trade bottle-caps for food. Still, they think the 'payment', the bottle-cap has to be placed just where the food appears, however, after a some testing he/she tries out the other slots. These slots leads to a small metal-detector that detects the bottle-cap and starts the food dispenser. Bottle-caps are collected in a small basket below the 'table'. I spread the bottle-caps out in the garden, a few hours later, the bottle-caps are back in the basket. ---