American Goldfinch

] If a female accepts the male as a mate, the pair will fly in wide circles, as the male warbles throughout the flight.

Once a male has found a mate, he selects a territory, marking the boundaries by warbling as he flies from perch to perch. After circling the perimeter, he performs two flight displays, first repeating a low, flat flight, then flying in an exaggerated version of normal flight, tucking his wings close to his body, plummeting earthwards and catching himself as he spreads his wings to glide upward in a series of loops. Two or three pairs may group their territories together in a loose colony, perhaps to aid in defense against predators.

s and caterpillar silk, and the cup is lined with plant down from milkweed, thistle, or cattail. The nest is so tightly woven that it can hold water, and it is possible for nestlings to drown following a rainstorm if the parents do not cover the nest.

American Goldfinches lay four to six bluish-white to greenish-blue eggs, which are oval in shape and about 16 x 12 millimeters (.6 x .45 in), roughly the size of a peanut. It is thought that they are laid during the night. The eggs are incubated by the female alone, though the male brings her food as she nests, and most mating pairs raise only one brood each year. The chicks hatch 12–14 days after incubation begins. Like all passerines, the chicks are altricial; they are born naked, with reddish bodies, pale grey down, and closed eyes.cite paper | author=Ehrlich, P.R.; D.S. Dobkin; D. Wheye | title=Precocial and Atricial | publisher=Birds of Stanford | url=http://www.stanford.edu/group/stanfordbirds/text/essays/Precocial_and_Altricial.html | date=1988 | format=.HTML | accessdate=2008-02-04] The mother bird feeds her young regurgitated seeds and insects as they grow. The hatchlings develop quickly, opening their eyes after three days, and completing the growth of olive-brown juvenile plumage after 11–15 days, at which time they begin to practice short flights close to the nest. For up to three weeks after fledging, they are still fed by the male, who locates them by listening for their fledging call. The chicks stop giving this call when they become entirely independent.

American Goldfinches are occasionally victims of brood parasites, particularly Brown-headed Cowbirds. One study found that 9% of nests had Brown-headed Cowbird eggs in them. [cite journal | last=Middleton | first=Alex L. | title=Effect of cowbird parasitism on American Goldfinch nesting | journal=Auk | volume=2 | issue=94 | pages=304–307 | year=1977 | url=http://elibrary.unm.edu/sora/Auk/v094n02/p0304-p0307.pdf | accessdate=2008-02-04] American Goldfinches make very poor hosts for brood parasites, with studies showing low hatching rates of Brown-headed Cowbird eggs and no fledging success. This is despite the fact that the American Goldfinch has no known behavioral adaptations against brood parasites. It is thought that the inability of Brown-headed Cowbird chicks to survive is due to a failure to get enough nutrition; the seed-rich diet of American Goldfinch chicks varies from the usual insect-rich diet of other hosts. [cite journal | last=Middleton | first=Alex L. | title=Failure of Brown-headed Cowbird parasitism in the nests of the American Goldfinch | journal=Journal of Field Ornithology | volume=2 | issue=62 | pages=200–203 | year=1991 | url=http://elibrary.unm.edu/sora/JFO/v062n02/p0200-p0203.pdf | accessdate=2008-02-04 | doi=10.1016/j.anbehav.2004.05.018]

Relationship with humans

The American Goldfinch is found in residential areas throughout its range. Backyard birders attract it using feeders containing Nyjer thistle seed, or by planting grasses and perennial plants, such as zinnias, cosmos, bee balm, or globe thistle, which produce seedheads favored by finches. Although some controversy surrounds bird feeding (see bird feeder for details), an increase in backyard feeding by humans has generally been beneficial to this species. cite web | author=Hollis, Elece | title=Backyard Birdwatching: The American Goldfinch | work=Garden and Hearth | url=http://www.gardenandhearth.com/Bird-Watching/American-Goldfinch.htm | accessdate=2008-02-04]

The American Goldfinch is not threatened by human activity, and is widespread throughout its range.cite web | url=http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=179236 | publisher=ITIS-North America | work=Integrated Taxonomic Information System | title="Carduelis tristis" (Linnaeus, 1758) | accessdate=2008-02-04] IUCN2006 | assessors=BirdLife International | year=2004 | id=53442 | title=Carduelis tristis | downloaded=12 May 2006] The clearing of forests by humans, though harmful to many species, has benefited the American Goldfinch. Clearing of woodlands causes declines in numbers of neotropical migrants, while favoring short-distance migrants and permanent residents. [cite web | author=Droege, Sam | title=Birds and Landscape Changes in Northeastern Forests | publisher=U.S. Geological Survey, Biological Resources Division | url=http://biology.usgs.gov/s+t/SNT/noframe/ne120.htm | date=2000 | archiveurl=http://web.archive.org/web/20060927144731/http://biology.usgs.gov/s+t/SNT/noframe/ne120.htm | archivedate=2006-09-07 | accessdate=2008-02-04] This benefits the American Goldfinch both as a short-distance migrant, and because the created open areas are the preferred environment of the bird, where weeds thrive which producing the primary food source of the American Goldfinch.

The American Goldfinch is also the state bird of Iowa, New Jersey, and Washington.

References

External links

* [http://ibc.hbw.com/ibc/phtml/especie.phtml?idEspecie=8850 American Goldfinch videos on the Internet Bird Collection]
* [http://lakecounty.typepad.com/life_in_lake_county/2006/09/carduelis_trist.html The American Goldfinch Show] - Informative but non-scholarly essay on the American Goldfinch.