Train is a bit of a shorthand here, though. Basic operant conditioning probably won't cut it. But the idea itself came to me after encountering similar thread about crows on HN many years ago - both comments and referenced articles would contain personal anecdotes about human-crow relationships, and from those I gathered that it's possible to kind of befriend a crow (or a group), and teach them behaviors as a kind of play.

So, I don't expect it's easy to train crows like dogs and pigeons, where one person "pre-trains" them and gives/sells them to someone else. But I think it should be possible to "train" a crow for yourself - bond with it and have it voluntarily indulge you reliably enough that it's pretty much like training.

It’s interesting how our view of animal intelligence is massively shaped by the animals we see every day - pets, farm animals, zoo animals. All animals that have had their natural intelligence degraded substantially.

Badgers are incredibly smart and we seem to not be able to train them at all. There's a pair on YouTube that figure out how to escape their sanctuary

Honey badgers? I visited a place in Africa where a pair were housed in an old tile-sided swimming pool because they could get through anything else. Until someone left a long-handled garden tool in there and they used it to climb out. One of the two was never seen again. The other was caught in a lion enclosure - it had cornered of the lions who was trying to avoid a fight, allegedly.

A classic Honey Badger Meme: https://www.youtube.com/watch?v=4r7wHMg5Yjg

Dogs are wolves. All of them.

The inevitable result: https://cmarshall.com/images/WhatsTheWorst.jpg