Baby pigeons are kept in the nest until they are about a month old, so by the time they leave, they are full-sized and have adult feathers. Fledgling pigeons do no't look all that different from adult birds, and it can be hard to spot them in a crowd.
The common pigeon is a feral bird, meaning that it derives from domesticated pigeons that escaped and returned to the wild. Both domestic and feral pigeons derive from the wild rock dove, a bird that nests on high sea cliffs. City birds nest in abandoned buildings, under bridges, on rooftops and even on window ledges. They are highly gregarious and form flocks of 50 to 500 birds.
Both parents incubate the eggs and care for the chicks for about 30 days. By then, the fledglings are ready to leave the nest and begin foraging for themselves. While the month-old bird looks nearly identical to the adult bird, there are several tricks for spotting the younger ones. Pigeons have gray-brown eyes for the first six months of their lives, at which point they turn orange or red, and the flesh directly above the beak, called the "cere", is grey on a younger bird, but white on an adult.