1) I would mention that snakes , chipmunks and squirrels actually have higher rates of predation than do crows.
2) I don’t see many crows near suburban area where I live. Most likely to see single crows spaced out along highway shoulder especially in rural ares. Never suspected crow nest, but will start to pay more attention.
3) No ravens likely in my area. Have seen crows. Recently on vacation on Grand Manan island, off coast of New Brunswick and found groups of crows and also ravens readily found.