During their first week of life, the well-hidden baby pigeons are fed a high-fat, high-protein diet of crop milk produced by both parents. They grow very fast. They walk well at about 18 days of age and start exercising their wings about a week later. But because they have been regularly fed by the adults and haven't done much exercising, the babies are often bigger than their parents by the time they start to fly, which is on average 30 to 32 days after hatching.
Some young pigeons, or squabs, might venture away from the nest site before fledging, but most stay close to home. So we humans aren't likely to lay eyes on a juvenile pigeon until it is full-grown. maybe even temporarily a little plumper than its parents. and has taken flight and begun to scrabble for food with other city pigeons.
Look at the color of their eyes and ceres (the fleshy covering on the upper part of the beak).
Adult pigeons have orange or reddish orange eyes and juveniles that are less than six to eight months old have medium brown or grayish brown eyes.
The cere is white in adults and grayish in young pigeons.
Pigeons can live about five years in the wild. They sometimes live for more than 15 years when raised by people.
A pigeon nest usually is constructed on covered building ledges that resemble cliffs, a Rock Pigeon's natural habitat. They also nest and roost on the support structures under bridges in cities and along highways. Pigeons build their nests with small twigs. A cock brings the nesting material to his mate, one piece at a time, and she builds the nest. Sometimes they don't use much nesting material at all and lay their eggs on bare ground. Nests are usually well-hidden and hard to find. Pigeons will often re-use nests.
Pigeons usually lay two white eggs. The parents take turns keeping their eggs warm (incubating). Males usually stay on the nest during the day; females, at night. Eggs take about 18 days to hatch.
Both male and female parent pigeons produce a special substance called "pigeon milk," which they feed to their hatchlings during their first week of life. Pigeon milk is made in a special part of the bird's digestive system called the "crop." When hatchlings are about one week old, the parents start regurgitating seeds with crop milk; eventually seeds replace the pigeon milk.
Young pigeons leave the nest or fledge approximately 30 days after hatching.
Although pigeons may have long and involved courtship displays, it does not take long to actually mate. Mating (the transfer of sperm from the male to the female) is very brief and takes place by the coming together of the two birds' 'cloacas'. During the breeding season, the area around the cloaca becomes swollen and reaches its peak size when the time is just right to reproduce. Sometimes it is called a "Cloacal Kiss".