The House Finch (Carpodacus mexicanus), is a species of finch of the Rosefinch genus. Originally only a resident of Mexico and the southwestern United States, they were introduced to eastern North America in the 1940s. These birds are mainly permanent residents, though some eastern birds migrate south. Their breeding habitat is urban and suburban areas in the East as well as various semi-open areas in the West from southern Canada to northern Florida and the Mexican state of Oaxaca. The population in central Chiapas may be descended from escaped cage birds.
Adults have a long, square-tipped brown tail and are a brown or dull-brown color across the back with some shading into deep gray on the wing feathers. Breast and belly feathers may be streaked. In most cases, adult males’ heads, necks and shoulders are reddish. This color sometimes extends to the stomach and down the back, between the wings. The male coloration varies in intensity with the seasons and is derived from the berries and fruits in its diet. As a result, the colors range from pale straw-yellow through bright orange (both rare) to deep, intense red. Adult females have brown upperparts and streaked underparts. Their song is a rapid, cheery warble or a variety of chirps.
House Finches forage on the ground or in vegetation. They primarily eat grains, seeds and berries, being voracious consumers of weed seeds such as nettle and dandelion. They also take incidental small insects such as aphids. They are frequent visitors to feeders throughout the year, particularly if stocked with sunflower or niger seed, and will congregate at hanging niger sock feeders. The House Finch is known to damage orchard fruit and consume commercially grown grain, but is generally not considered a significant pest, rather an annoyance.
Nests are made in cavities, including openings in buildings, and also on various kinds of vegetation; sometimes nests abandoned by other birds are used. Nests may be re-used for subsequent broods or in following years. The nest is built by the female, sometimes in as little as two days. It is well made of twigs and debris, forming a cup shape, usually 60 to 80 inches above the ground. Eggs are laid from February through August, two or more broods per year with 2 to 6 eggs per brood. The eggs are a pale bluish green with few black spots and a smooth, somewhat glossy surface. The female incubates the eggs for 12 to 14 days and the young leave the nest about 11 to 19 days after hatching. Dandelion seeds are among the preferred seeds fed to the young.
During courtship, the male may present the female with choice bits of food and, if she imitates the posture of a hungry chick, he may actually feed her. The male may also feed the female during the breeding and incubation period. House Finches are one of the few birds that are aggressive enough to keep House Sparrows out of their birdhouse and evict them.