Birds that are black

They nest in the chimney pots opposite and they monopolise all the birdfeeders around. They seem to work in teams because if one spots something to eat then the rest of the gang soon show up. There are also nests in the large tree 3 gardens along. I have carefully studied my RSPB pocket guide to British Birds and they could be crows or rooks......but there again consideration must also be given to jackdaws and ravens. Confused on a street in Somerset.