@Rasta A few years ago, there were a series of train derailments, and in order to identify the culprit, the railway company installed surveillance cameras. What they caught on camera were crows placing stones on the tracks.
Seeing your post reminded me of this episode.
Crows don't like stones and what they were getting out of derailing the train has deepened the mystery🤷
However, thank you for sharing your fascinating story about the crows!