I had a friend years ago who saw a white crow out in the countryside near this town, and I was jealous too! Never thought I would see one. It's a rare thing.
Most birds do see in color, and crows are known for their sharp vision and intelligence, so I'm sure they can see the difference. The crows tend to work in groups, and they naturally protect each other, but also protect the other animals in the forest with their language, warning anyone who will listen. I can't be certain that they were specifically protecting the white bird for any reason, but I translated my own feelings to the birds, and their calls suggested cooperation with each other up there. I've never seen crows act aggressively, even when the blue jays are diving and pecking at them, they stay cool.