crow vending machine

This is an old one, even for me, but it's just such a sweet project I can't resist. I'll keep it short so you can just check out the project itself.

The New York University graduate student offered the birds coins and peanuts from a dish attached to a vending machine he’d created, then took the peanuts away. Klein designed the machine so that when the crows searched for the missing peanuts, they pushed the coins out of a dish into a slot, causing more peanuts to be released into the dish. The Binghamton crows quickly learned that dropping nickels and dimes into the slot produced peanuts, and the most resourceful members of the flock began looking for more coins. Within a month, Klein had a flock of crows scouring the ground for loose change.