Dear WW: here is a site that I think you may enjoy. It is intended for beginners, which I need. Dickens frequently mentions rooks. All I know about them is that they look like crows, but are slightly larger. I wonder why I never saw a rook in MA, or here in CA. I have found no anser yet, but this URL looks like a good place to begin:
http://www.mobirds.org/Ezine/Ornithology101/Ornithology101.htm