The common pigeon is one of the most versatile birds I can think of in that they have been used for centuries for food, messages, racing and hobbies.
Almost every large city has pigeons that inhabit its parks, bridges and tall buildings. These are domestic pigeons, but are not owned by anyone. The truly wild ones are called rock doves and are aptly named as they seem to prefer rocky cliffs where they make their nests on the ledges and cracks of the rocks. Their plumage is the same as most of the city-dwelling pigeons. Domestic pigeons come in various sizes and colors, however.
The large white ones are raised for food where their squabs are sold as a delicacy in the most fashionable restaurants. Other pigeons have been used in wartime to carry messages across battlefields. Some breeds are raised as hobbies for their ability to tumble and roll as acrobats in the sky. I had a flock of these rollers when I was a teenager and I had to protect them from hawks and the neighbors’ cats. I sold several of my best performers to adults who paid me as much as 5 dollars for a pair of them. That was a lot of money back in the 1930s. I had to sell them all when I left home to take a job in Alaska after high school.
The big city pigeons got most of their food from people at the parks who fed them peanuts and bread crumbs. The ones in the country, including the wild rock doves, got their food from the spillage at grain elevators and along railroad tracks. Quite often, both wild and domestic pigeons will take up living in the rafters of large hay barns where they are considered a nuisance bird just as many of the city pigeons are.
One thing of interest is that the formerly endangered peregrine falcons have started making their nests under the large bridges in the cities. And guess what their main food source is? You guessed it ... they are feeding their nestlings on a diet of pigeon meat. So the balance of nature can even occur in non-natural habitats.