Bird of the Month: House Finch
By Andy McCormick
Scientific Name: Haemorhous mexicanus
Length 5.7 in
Wingspan 10 in
Weight 0.74 oz
AOU Band code HOFI
The House Finch is one of the most abundant birds in North America and it has shown a remarkable adaptability to a variety of habitats. It evolved over 500,000 years as a bird of the semi-arid Southwest where it remains common. It has expanded its range to cover almost the entire continent of North America. In 1939 pet shop owners who had illegally captured House Finches in Santa Barbara, CA released them on Long Island, NY to avoid prosecution (Kaufman). These eastern House Finches have spread westward and today now overlap the western birds. The accompanying map shows how quickly and extensively the House Finch has expanded its range. Eleven subspecies have been identified.
The House Finch is almost exclusively a seed eater and its spread has undoubtedly been aided by humans putting out bird feeders. They will feed on the ground or hang onto weeds and eat the seeds from them. Their jaw has a specialized groove at the side in which the bird guides seeds so the shells can be crunched and the hulled seed eaten. They will feed their young regurgitated seeds and sometimes aphids.
The female House Finch builds an open cup nest in a variety of sites such as in conifers, in ivy on buildings, in cavities in cactus or human-made structures, and sometimes in hanging planters. Usually 4-5 pale blue eggs are deposited. Incubation lasts about two weeks and the young fledge in another two weeks. House Finches can have up to three broods per year (Kaufman).
The House Finch is one of three Haemorhous (formerly Carpodacus) finches including the Purple Finch and Cassin’s Finch which can be challenging to identify. The House Finch is the most common. It has a curved upper bill (culmen), a longer, rounded tail with longer primary projection (the distance between the end of the wing and tip of the tail). The Purple and Cassin’s Finches have straight bills and forked tails.
The red coloration of the House Finch depends on the carotenoids in the bird’s diet and can vary from a deep red to yellow. Specifically, the color depends on the diet eaten during their annual molt when new feathers are growing. Western House Finches eat a wide variety of seeds from Napa thistle, black and wild mustards, knotweed, amaranth, and about 20 other plant species. Chicks are fed mostly weed seeds from sunflower, milk thistle, burweed and poison oak (Badyaev, et al). In the Southwest it will eat desert fruits from saquaros and fishhook cacti, and flowers of ocotillo and creosote.
House Finch populations are abundant and except for some local subspecies, there is little need for conservation efforts. The species is threatened by the spread of Mycoplasmal Conjunctivitis, an eye infection characterized by swelling and a watery discharge leading to mortality in some birds as the disease spreads to their internal organs. Project Feederwatch participants are asked to look for symptoms of this disease in House Finches at their feeders and include this information in their regular reports on their feeder birds.