House Sparrows are the most abundant songbirds in North America and the most widely distributed birds on the planet. House Sparrows are not actually sparrows, but are Old World Weaver Finches, a family of birds noted for their ingenious nest-building abilities.
House Sparrows were introduced into North America from England in the 1850s on the mistaken premise that they would help reduce crop insect pests. At first, the new immigrants welcomed this little bird of their homeland. Within 25 years, however, they realized the seriousness of their mistake: the House Sparrow population had increased at an explosive and alarming rate, and the birds were causing extensive damage to crops and fruit trees. They were also taking over the nesting sites of native cavity-nesting birds.
The breeding season for House Sparrows begins early in the spring or even in midwinter, and each pair may produce up to four broods a season. The male House Sparrow's bond with his nest site is stronger than his bond with a mate he may lose a mate, but he won't give up his nest site. Although they usually prefer to nest in a cavity, House Sparrows will settle for any nook or cranny they can find. They will also occasionally nest in coniferous trees and in the nests of Cliff Swallows and Northern Orioles.