Sparrows are small (about 10 to 17cm/4 to 7 inches long) birds of the Passeridae and Emberizidae families. These birds are so common to every continent (except Antarctica) that in many countries they're considered pests. These birds are omnivorous (they eat both plants and insects), devouring different seeds, berries and bugs.
American sparrows breed between May and September. The female lays between four and six eggs. Both parents take part in incubating the eggs for 10 to 14 days and taking care of the young, which are born with down but develop feathers quickly.
Hatchlings are altricial (helpless) and rely on the parents for protection and warmth. Both parents feed the chicks until they're about six weeks old. Some species "push" out siblings so that only the strongest of the brood survive. Hatchlings that are featherless must be fed every 15 to 20 minutes from about sunrise to sunset (or later).
Infants reach fledgling stage around the 10th day of life. Fledglings are partially feathered birds and usually jump or fall out of the nest as they're learning to fly. The mother bird continues feeding the fledgling if it falls to the ground until it learns to fly. The fledgling period is 12 to 20 days.
Sparrows are usually able to fly by the third week of life, but the parents continue to provide food until the fifth or sixth week. This stage is important for young sparrows to gain strength and skill at flying. They are extra vulnerable to predatory animals during this learning stage as they fall frequently, exhaust themselves easily and even crash.
Sparrows are old enough to live independently by the time they're six to seven weeks old; they usually have the strength and skill to fly well by this time. It's unknown at what age these young birds are ready to seek mates; however, it is known that sparrows are monogamous. They rarely migrate (except in extremely cold or high-altitude areas) and can be spotted in winter eating seeds and nuts. They nest in pairs under the snow. In the spring, nests are made out of grass, roots and hair.