How did I miss this for 24 hours? From the Times Magazine's 8th Annual Year in Ideas issue - Vending Machine for Crows:
In June, Josh Klein revealed his master's-thesis project to a flock of crows at the Binghamton Zoo in south-central New York State. 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.