i think the councils help to find areas to release , the R.S.P.B release the birds so which one do you sue ? the building owner the R.S.P.B , the breeder of the bird , and how do you prove the birds actualy wild or not , most wild birds are rung on the nest , captive birds are supposed to be rung as well , so there lies the next problem proof and the only way to get that is to capture the bird thats attacking your birds and you would be prosicuted as you wouldnt have a licience to do so , so what next you ask R.S.P.B to capture the bird ? , i cant see that happening they would put it down to nature and one species is a preditor and the other ( pigeon ) nothing more than prey