Pigeons and humans have lived together for thousands of years. There are very many different types of pigeons in the world, and only some species give people trouble. This mainly concerns those species that live in cities and towns. They can occur in large numbers and multiply very rapidly. The city pigeons today are actually feral domestic pigeons that have been bred for centuries and originally stem from the rock dove. The pigeon droppings look awful on your roof and the uric acid in the droppings can damage your house. In addition, the droppings contain bacteria and fungi that can be dangerous to humans.