Image via WikipediaPigeons that you see hanging out under bridges and on statues are the feral descendants of domesticated Rock Pigeons introduced to North America by early settlers.
In their native land of southern Europe, North Africa, and into South Asia, the Rock Pigeons nest along coastal cliff faces.
In their non-native land, pigeons have adapted to nesting under bridges and artificial cliff faces created by tall buildings with accessible overhangs and perching on giant sculptures that serve as substitutes for natural ledges.
Rock Pigeons are a large, highly variably colored dove also called the Domestic Pigeon, Homing Pigeon, or Rock Dove.
Now the Rock Pigeon is a year-round resident across the United States, seen in the city area, in parks, and in some backyards. They are ground feeders and will feed from bird feeders if possible.
Parent birds feed the young regurgitated liquid known as crop-milk for the first few days of life just like the Mourning Dove. A group of pigeons has many collective nouns, including a "band", "dropping", "loft", "passel" and "school" of pigeons.