Until this year I found putting squirrel cages round all my bird feeders kept the big birds away. They knew they couldn't get at the food so didn't try. Suddenly this year it all changed and as soon as food was out the tree was covered with big black birds and the little ones only got in when I went out and shouted or banged on the window. In the end I stopped feeding but want to start again soon for the winter. Has anyone else noticed there seem to be far more rooks and jackdaws around? Huge flocks of rooks flying past and jackdaws on every building. They're becoming a plague and I don't know how to keep them off my feeders short of putting a cage round the whole tree.