It pays to be nice to crows.
Crows recognize human faces. So in your back yard wear a mask if you're going to chase or trap crows. And not wear one if you're feeding them.
Crows Can Recognize You and Hold a Grudge
So, if you're studying crow behavior to record how crows react to negative stimuli you should wear a mask. Don't use your real face. If you do, you'll get scolded repeatedly by the agitated flock every time you approach.
Don't anger a crow. In 2011, a team from the University of Washington published a remarkable paper about local crows. They researched how well the birds could identify human faces. So they wore masks. One group threatened the birds the other group wore a different mask didn't. Without fail, the threatening group of masked scientists were greeted by angry scolds and dive-bomb attacks. A few years later, the crows not only held onto that grudge, but they told other crows and offspring about it as well.
Conversely if you feed a crow they may bring you a gift …and if you feed 22 Crows?
Note: What's the difference between a raven and a crow? A flock of crows is called a "murder of crows", sounds like a serious bird. A group of ravens is called an "unkindness" or "conspiracy", obviously less serious.