Wild crows get a small food reward every time they drop a cigarette butt in
a special machine.



https://www.theguardian.com/environment/2022/feb/01/swedish-crows-pick-up-ci
garette-butts-litter



It sounds very clever, but I imagine this sort of thing would be very
difficult to optimally control. If there are too many crows getting well
fed, will the crow population of the city rise until they're considered an
urban pest, like pigeons? Or will the crows run out of cigarette butts
before it becomes an issue?



Louise Rutter

Kirkland