Crows are intelligent birds and learn quickly – even from each other. In Sweden, they are used to collect cigarette butts and bring them to a machine that automatically rewards them with peanuts. Here some links provides by users: https://journals.sagepub.com/doi/10.1177/25166042241296275 and: https://www.heise.de/news/Schwedisches-Start-up-hinter-Kippenstummel-sammelnden-Kraehen-meldet-Insolvenz-an-11094091.html