Yellow Finch

by Nava Thompson

Title

Yellow Finch

Artist

Nava Thompson

Medium

Photograph - Photography

Description

A Yellow Finch on a green leaf. The American Goldfinch is a diurnal feeder. According to the Cornell Lab of Ornithology, the species is one of the strictest vegetarians in the bird world. It is mainly granivorous, but will occasionally eat insects, which are also fed to its young to provide protein. Its diet consists of the seeds from a wide variety of annual plants, often those of weeds grasses and trees, such as thistle, teasel, dandelion, ragweed, mullein, cosmos, goatsbeard, sunflower, and alder. However, it also consumes tree buds, maple sap, and berries. It will eat at bird feeders provided by humans, particularly in the winter months, preferring Niger seed (commonly and erroneously called thistle seed). Unlike some finch species, the American Goldfinch uses its feet extensively in feeding. It frequently hangs from seedheads while feeding in order to reach the seeds more easily. In the spring, the American Goldfinch feeds on the catkins hanging from birches and alders by pulling one up with its beak and using its toes to hold the catkin still against the branch. This dexterity enables it to take advantage of food sources relatively inaccessible to potential competitors, increasing its chances of survival. ReproductionThe American Goldfinch begins its breeding season later in the year than any other finch and later than any other native North American bird, besides occasionally the Sedge Wren. This may be related to the abundance of seeds in the late summer months, as seeds represent the majority of their diet. The courtship rituals of the American Goldfinch include aerial maneuvers and singing by males, who begin courtship in late July. The flight displays begin as the male pursues the female, who flies in zigzagging evasive patterns. The male is able to signal his quality and fitness, both in the short term (current body condition) and long term (genes), through ornamentation (bill color and plumage).[27] 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. Nest of an American GoldfinchThe nest is built in late summer by the female in the branches of a deciduous shrub or tree at a height of up to 10 meters (33 ft). The nest-building lasts approximately six days, during which time the female works in 10�40 minute increments. The male frequently flies with the female as she collects nesting materials, and though he may carry some materials back to the nest, he leaves its construction to the female. The outer shell of the nest is built of bark, weeds, vines, and grass.[21] The inside diameter of the finished nest is about 6.5 centimeters (2.6 in).[20] The rim is reinforced with bark bound by spiderwebs 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 eggs, which are oval in shape and about 16 by 12 millimeters (0.63 in � 0.47 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.[28] The mother bird feeds her young regurgitated seeds and insects as they grow.[17] 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. 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. Relationship with humansThe American Goldfinch is found in residential areas throughout its range. Backyard birders attract it using feeders containing Nyjer thistle seed,[26] 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 , an increase in backyard feeding by humans has generally been beneficial to this species. The American Goldfinch is not threatened by human activity, and is widespread throughout its range. 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. 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 produce the primary food source of the American Goldfinch. The American Goldfinch, or Eastern Goldfinch, is also the state bird of Iowa, New Jersey, and Washington.

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July 20th, 2012

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