A few weeks ago, I was surfing Xfinity On Demand and happened to find an interesting 1 hour PBS channel special about crows. The show was called "Nature". They do different episodes of various animals, and in the episode I selected to watch, there were some bird experts in Seattle as well as some other people from other parts of the world who were studying crows.
What I found most interesting was the Seattle group around a college campus. They had done harmless observation experiments to see if young crows learn to recognize certain appearances of people the same as their adults. They can pick out a face in a crowd and they can remember it. Their long term memory lasts up to at least two years.
The group wore these masks during the experiment. The adult crows were cawing in warning when they did and soon after some crow chicks were old enough, they mimicked their parents before they were picked and tagged and studied as they grew up and eventually separated from their flock.
One young female selected to be tagged they named White Wing because of the white streaks under the tips of her wings. I always assumed they all looked black, so that crow was unlike any other one I've ever seen.
She didn't make it her first year of life though. A car had hit her.

Only one of the young crows was still alive and near adulthood when the head of the Seattle group put on a mask and walked by to see if it would make the same scorning warning call, and it had.
After seeing this, I've become a bit more curious around these interesting birds. I see a bunch of them around the area I work in, so I intend to make more time this week and watch them...
I think the one time I mimicked one of their caws, some months before I watched the show, and got them on alert. Apparently, they didn't approve. Their caws were a bit louder and high pitched for a little while. One flew close and fast over my head too. I'm not sure if the flock still remembers me doing that, probably not. Maybe they were sure I wasn't going to do that again. XD I dunno. I don't want my face scratched or pecked at, so I'll just watch them.