Their beaks are so strong they can demolish even wire feeders to get at the contents, we now have ones with an outer cage so only small birds can get through. The are aggressive towards the small birds as well and the screech is unbelievably obtrusive.
They cause inestimable damage in Kew Gardens because they also eat the growing shoots and buds on all the trees and stop them developing.
Fortunately we seem to have won a Peregrine falcon and I havn't seen as many recently.
But one is too many!