While it's fun to feed pigeons at parks and courtyards, pigeons and similar pest birds can create all sorts of problems. They cause millions of dollars in damage to buildings, facades and mechanical structures--like air conditioning units, telephone, electrical and lighting systems. Pigeons can also create a health hazard. Because their poop, besides being corrosive, can carry any of 60 known diseases. Fortunately, man has devised all sorts of clever pigeon and pest-bird deterrents. And unlike the days of old when property owners used poisons or shotguns to cull down pest bird populations, today's methods are far more humane. One way to discourage pest birds from "taking over" an area is to exploit their natural fear of predators. And few predators are as despised among pigeons and most pest birds as the Red-tail Hawk.