A rook is different from a crow (or a raven). A rook looks a lot like a crow, but nests in colonies, rather than singly. Large trees in the UK are often full of a goup of large nests known as a rookery -- interesting sight in the fall (sorry, autumn) when the trees come off the trees. Ravens are bigger birds, about the size of a hawk.
Thanks. I learn so much on FR.
Damn, glad my ancestors left England, raking trees must suck. ;-)