Hawks Versa Pigeons

Pigeons are the natural prey of hawks. They know very well that the appearance of a hawk means their death. This is an interesting story I’ve read recently.
In Warsaw, Capital of Poland authorities tried to keep its metro free of pigeon droppings by tapping the killer instinct of birds of prey to deal with this universal urban scourge. Pigeon droppings mar walls, cover the metro's granite floors and plop onto passengers heads. Just the presence of hawks inside or at the entrance of a station happened to be enough to act as a deterrent to solve their pigeon problem.
They hired the handler of two hawks to do the trick. Pigeons are the natural prey of hawks. They know very well that the appearance of a hawk means their death. Before the hawks appearance metro station was plagued by hundreds of pigeons. Within days after that, the number dwindled to a very few. Hawks perched on handler’s arm clad in a thick leather glove.
The chirps of baby pigeons draw hawk's attention. As soon as an adult pigeon appears, hawks take a flight in pursuit if allowed by their trainer. He does for a brief chase then calls them back.
They are not allowed to kill pigeons! It’s against the law. Beside the low, it would be too dangerous for hawks because urban pigeons carry many diseases. They are worse than rats. With hawk worth from $20 and up, the risk is too high. The cost of their services is also high but not as much. It won't take long to recoup investment. The costs of cleaning the stations, the maintenance products and above all renovation work on the walls and ceilings drops dramatically. Authorities battled against the pigeons for years, without any success. Now they can breath easy.