Re:Ground Hornbills

Talking of Ground Hornbills, I heard of them in Langata a while ago and they announced their presence by breaking windows on a door. Now in Usa River we are losing loads of windows to them...one house had 26 windows broken, including those on upper balconies! Anyone got any tried and tested ways to stop them? We cant paint all our windows black and I am worried that someone might get fed up enough to shoot them.