Baby sparrows need abundant protein to help them grow, so their parents feed them grasshoppers, crickets, spiders, ants, sawflies, beetles and whatever other insects are available. Once they are adults, sparrows switch to a diet of mainly seeds.
Sparrows typically mate for life and are monogamous, though some males have several mates. A male finds a nesting site and initiates nest building as a prelude to finding a mate. Later, the female assists in nest construction, but the task is predominantly accomplished by the male. Nests may be in the eaves and crevices of buildings, on tree branches, in the hollows of trees, in sandy banks or in the sides of cliffs. Nest building is a year-round process, and once the nest is established, sparrows defend it aggressively.
A Female sparrow lays clutches of four to five eggs four to seven times a year. She incubates the eggs for 10 to 15 days before they hatch. The fledglings are ready to fly and leave the nest 15 to 17 days after hatching. The male continues to feed them until they are able to take care of themselves completely after another seven to 10 days. The mortality rate of sparrows is high, and only about 25 percent of the fledglings live to their first breeding season. The main predators of sparrows are cats and other birds.