Jump to content

American goldfinch

From Wikipedia, the free encyclopedia

This is an old revision of this page, as edited by Hey jude, don't let me down (talk | contribs) at 00:14, 31 May 2007 (→‎Further reading: change ref for book.). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Eastern or American Goldfinch
Male in summer plumage
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Aves
Order:
Passeriformes
Family:
Fringillidae
Genus:
Carduelis
Species:
C. tristis
Binomial name
Carduelis tristis
(Linnaeus, 1758)
Approximate range/distribution map of the American Goldfinch; yellow indicates the summer-only range, blue indicates the winter-only range, and green indicates the year-round range of the species.

The Eastern or American Goldfinch (Carduelis tristis), also known as the Wild Canary, is a North American bird in the finch family. It is migratory, spending the summer breeding season in ranges from southern Canada to North Carolina in the United States and the in winter in ranges from just south of the Canadian border to the core Southwestern States. It is the state bird of Iowa, New Jersey, and Washington.[1]

The plumage color of the American Goldfinch changes twice a year after it undergoes a complete molt, the only species in the finch family to do this. It displays sexual dimorphism in its coloration; males are a vibrant yellow in the summer and an olive color during the winter months, while females are a dull yellow-brown shade, which brightens only slightly during the summer. It has adapted several features in order aid seedhead consumption, such as a conical beak to better remove the seeds, and agile feet with which to grip the stems of seedheads while feeding.

The American Goldfinch is granivorous, though it feeds on insects while feeding young in order to provide the chicks with protein. It is a social bird, and will gather in large flocks while feeding and migrating. It may behave territorially during nest construction, but this aggressiveness is shortlived. Its breeding season begins in late July, relatively late in the year for a finch. The late start of the breeding season is tied to the peak of the food supply, as late summer is the point at which seedheads, their main food, are most plentiful. This species is generally monogamous, and produces one brood containing four to six chicks each year.

Taxonomy

The American Goldfinch was one of the many species originally described by Linnaeus in his 18th century work, Systema Naturae.[2] The American Goldfinch was orginally included in the genus Spinus, a group containing New World goldfinches and siskins, but in 1976, Spinus was merged into the genus Carduelis and retained as a subgenus.[3] Its closest relatives are the Lesser Goldfinch (C. psaltria ), Lawrence's Goldfinch (C. lawrencei) and the siskins. Though it shares a name with the European Goldfinch, the two are in separate subgenera, and are not directly related.[4] The genus name of the American Goldfinch, carduelis is derived from carduus, the latin name for thistle, referring to feeding preferences. The species name, tristis, is from the Latin tristis, meaning sorrowful.[5]

There are four recognised subspecies of the American Goldfinch:[6]

  • C. t. tristis is the most common of the subspecies. Its summer range is from southern Canada to Colorado, and east to the Carolinas. The winter range extends as far as Florida to central Mexico.[7]
  • C. t. jewetti is smaller and darker than other subspecies. It occurs on the coastal slope of the Cascade Mountains from southern British Columbia to central California, overlapping with the range of C. t. pallidus.[7]
  • C. t. pallidus is differentiated from other subspecies by its paler body color, stronger white markings, and larger black cap of males. It is slightly larger than C. t. tristis. It ranges from British Columbia to western Ontario, south to northwest Colorado and west to Oregon. In winter, the range extends to the south, to nothern California through Mexico.[7]
  • C. t. salicamans occurs west of the Sierra Nevada range during the summer and in south and central Baja California to the Mohave and Colorado deserts in winter. In winter, the plumage of both sexes is browner than other subspecies, and in summer, the male's black cap is comparatively small relative to that of other subspecies.[7]

Description

Female American goldfinch in winter plumage.

The American Goldfinch is a small finch, 11-13 cm (4-5 in) in length, with a wingspan of 19-22 cm (7-9 in). It weighs from 11 to 20 g (0.39-0.71 ounces).[8] The bill is small and pointed, conical in shape, and pink during most of the year, though it turns to a bright orange with the spring molt in both sexes.[9] The shape and size of the beak are a result of adaptation, to aid in the extraction of seeds from the seed heads of thistles, sunflowers, and the other plants which make up its diet.[10]

The American Goldfinch undergoes a molt in the spring and autumn. The sexual dimorphism displayed in plumage coloration is especially pronounced after the spring moult, when the bright color of the males' summer plumage is needed to attract a mate.[10] It is the only finch to undergo a complete molt; other finches change plumage color by the gradual wearing-down of the feathers. In each molt, it sheds all but the wing and tail feathers, which are dark olive in the female and black in the male. The markings of these feathers remain identical in each molt, with large white bars on the wings, and white feathers at the edges of the short, notched tail.

Once the spring moult is completed, the body of the male is a brilliant lemon yellow, a color produced by carotenoid pigments from plant materials in its diet, with a striking jet black cap and white rump that is visible during flight.[11] The female is an olive yellow, with a yellow bib on the neck and breast.[12] After the autumn molt, the bright feathers of the summer with are replaced with duller plumage. The goldfinch becomes buff below and olive-brown above, with a pale yellow face and bib. The autumn plumage is almost identical in both sexes; the only markings which differentiate the sexes are the yellow shoulder patches of the male.[13] In some winter ranges, the goldfinches lose all traces of yellow, becoming a predominantly medium tan-gray color, with an olive tinge evident only on close viewing.

The immature American Goldfinch possesses different coloring to the adult during its first autumn and winter. The upperparts are dull brown, and the underside is pale yellow. The shoulders and tail are dull black with buff-colored, rather than white, markings on wings and rump. This coloration is identical regardless of gender.[13]

The song of the American Goldfinch is a series of musical warbles and twitters, often with a long note. A tsee-tsi-tsi-tsit, call is often given in flight; it may also be described as per-chic-o-ree.[9] While the female incubates the eggs she calls her returning mate with a soft continuous teeteeteeteete sound. The young begin to use a call of chick-kee or chick-wee shortly before fledging, which they use until they have left the nest entirely.[10]

Distribution and habitat

The American Goldfinch prefers open fields and meadows, flood plains, roadsides, orchards, and gardens. This habitat preference is maintained during the spring and fall migrations.[9]

The summer range, which is the breeding range as well, is bounded on the north by Saskatchewan and stretches south across the North American continent to North Carolina in the east, and northern California in the west.[9] The American Goldfinch is a short-distance migrant, moving south in response to colder weather and lessened food supply. The migration is completed in compact flocks, which travel in an erratic, wavelike flight pattern.[10]

Its winter range includes southern British Columbia, Manitoba, Ontario, New Brunswick, Nova Scotia, and the United States to parts of Mexico. In winter, in the northern part of its range, the finch may move nearer to feeders if they are available. In southern ranges, during winter, they remain in areas similar to the fields and flood plains where they live during the summer months.[14]

Conservation status

The American Goldfinch is not threatened, and is widespread throughout its geographic range.[6] The North American Breeding Bird Survey, which tracks the population of common bird species, has shown a decline in the breeding populations of American Goldfinch. In the United States, the mean rate decline is approximately 4 percent per year. This decrease is attributed to loss of breeding habitat through the commercial development of meadows and flood plains.[10]

Behaviour

Male goldfinch at a thistle feeder.

The American Goldfinch is gregarious during the nonbreeding season, when it is often found in large flocks, usually with other finches. Flocks generally fly in an undulating pattern, creating an ocean wave-shaped path.[14] During the breeding season, it lives in loose colonies. While the nest is being constructed, the male will act aggressively towards other males who intrude into his territory, driving them away, and the female reacts in the same way towards other females. This aggressiveness fades once the eggs have been laid.[15]

The American Goldfinch does not act aggressively toward predators within its territory; its only reaction is alarm calling. Predators include snakes, weasels, squirrels, and blue jays, which may destroy eggs or kill young, and hawks andcats, which pose a threat to both young and adults. The Brown-headed Cowbird may lay an egg in a goldfinch nest, and the hatched cowbird will act as a parasite. However, the cowbird chick will usually die because the seed-based diet the finches provide cannot support it.[16]

Diet

The American Goldfinch is a diurnal feeder. It is mainly granivorous, but will occasionally eat insects, which it feeds insects to its young in order to provide them with 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.[17] However, it also consumes tree buds, maple sap, and berries.[11] It will eat at bird feeders provided by humans, particularly in the winter months, preferring thistle seed in the feeders.[18]

Male goldfinch perched on a thistle plant.

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 them up with its beaks 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.[17]

Reproduction

Male (left) and female (right) Goldfinches at a thistle feeder.

The American Goldfinch begins its breeding season the latest in the year of any finch.[10] It is thought that this is related to the abundance of seeds in the late summer months, as seeds represent such a large part of their diet. [19]

The courtship rituals of 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. If a female accepts the male as a mate, the pair will fly in wide circles, as the male warbles throughout the flight.[10]

Once a male has found a mate, he selects a territory, which he marks the boundaries of by warbling as he flies from perch to perch. After encircling the perimeter, he circles and 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 often group their territories together in a loose colony, perhaps to aid in defense against predators.[10]

File:Aug 5 2006 goldfinchnest.jpg
Nest of an American Goldfinch.

The 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 m (1-30 ft). The nest building lasts approximately six days, during which time the females builds in 10 to 40-minute periods. The male frequently flies with the female as she collects nesting materials. Though the male may carry some materials back to the nest, he leaves the construction of the nest to the female. The outer shell of the nest is built of bark, weeds, vines, and grass.[20]The inside diameter of the finished nest is about 6.5 cm.[21] The rim is reinforced with bark bound by spiderweb 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.[12]

American Goldfinches lay four to six bluish-white to greenish-blue eggs, which are oval in shape and about 16 x 12 mm, or roughly the size of a peanut.[22] It is thought that they are laid during the night.[14] 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.[20]

The chicks hatch 12 to 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.[23] The mother bird feeds her young regurgitated seeds and insects as they grow.[11] The hatchings develop quickly, first opening their eyes after three days, and completing the growth of olive-brown juvenile plumage after 11 to 15 days after hatching, when they first 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.[10]

Relationship with humans

The American Goldfinch is found in residential areas throughout its range. Backyard birders may attract it using feeders containing Nyjer thistle seed,[24] or by planting grasses and perennial plants, such as zinnias, cosmos, bee balm, or globe thistle, which produce seedheads favored by finches. An increase in backyard feeding by humans has generally been beneficial to this species.[24] Some controversy surrounds bird feeding, however (see bird feeder for details).

The clearing of forests by humans, though harmful to many species, has in fact benefited the American Goldfinch. Clearing of woodlands causes declines in numbers of neotropical migrants, while favoring short- distance migrants and permanent residents.[25] 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- which produce the main food of the American Goldfinch- thrive.[12]

References

  1. ^ "Symbols of Washington State". Washington State Legislature. Retrieved 2007-03-11.
  2. ^ Template:La icon Linnaeus, C (1758). Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata. Holmiae. (Laurentii Salvii). p. 824.
  3. ^ "THIRTY-THIRD SUPPLEMENT TO THE AMERICAN ORNITHOLOGISTS' UNION CHECK-LIST OF NORTH AMERICAN BIRDS". {{cite web}}: Unknown parameter |accessmonthday= ignored (help); Unknown parameter |accessyear= ignored (|access-date= suggested) (help)
  4. ^ BayScience Foundation. "Carduelis tristis(American Goldfinch)". {{cite web}}: Unknown parameter |accessmonthday= ignored (help); Unknown parameter |accessyear= ignored (|access-date= suggested) (help)
  5. ^ William Whitaker. "Words by William Whitaker". {{cite web}}: Unknown parameter |accessmonthday= ignored (help); Unknown parameter |accessyear= ignored (|access-date= suggested) (help)
  6. ^ a b ITIS Report. "ITIS Standard Report: Carduelis tristis". {{cite web}}: Unknown parameter |accessmonthday= ignored (help); Unknown parameter |accessyear= ignored (|access-date= suggested) (help)
  7. ^ a b c d ALEX L. A. MIDDLETON. "American Goldfinch Carduelis tristis ". {{cite web}}: Unknown parameter |accessmonthday= ignored (help); Unknown parameter |accessyear= ignored (|access-date= suggested) (help); line feed character in |title= at position 19 (help)
  8. ^ The Georgia Museum of Natural History and Georgia Department of Natural Resources. "Carduelis tristis". {{cite web}}: Unknown parameter |accessmonthday= ignored (help); Unknown parameter |accessyear= ignored (|access-date= suggested) (help)
  9. ^ a b c d Cornell Lab of Ornithology. "American Goldfinch". {{cite web}}: Unknown parameter |accessmonthday= ignored (help); Unknown parameter |accessyear= ignored (|access-date= suggested) (help)
  10. ^ a b c d e f g h i E. Hayakawa. "American Goldfinch". {{cite web}}: Unknown parameter |accessmonthday= ignored (help); Unknown parameter |accessyear= ignored (|access-date= suggested) (help)
  11. ^ a b c Michigan DNR. "American Goldfinch (Carduelis tristis)". {{cite web}}: Unknown parameter |accessmonthday= ignored (help); Unknown parameter |accessyear= ignored (|access-date= suggested) (help)
  12. ^ a b c Chipper Woods Bird Observatory. "American Goldfinch". {{cite web}}: Unknown parameter |accessmonthday= ignored (help); Unknown parameter |accessyear= ignored (|access-date= suggested) (help)
  13. ^ a b Philip Unitt and Nicole Perretta. "the American, Lawrence's, and Lesser Goldfinches". {{cite web}}: Unknown parameter |accessmonthday= ignored (help); Unknown parameter |accessyear= ignored (|access-date= suggested) (help)
  14. ^ a b c Roof, J. "Carduelis Tristis". {{cite web}}: Unknown parameter |accessmonthday= ignored (help); Unknown parameter |accessyear= ignored (|access-date= suggested) (help)
  15. ^ Jerry Sullivan, Victor M. Cassidy (Editor), Bobby Sutton (Illustrator). Hunting for Frogs on Elston, and Other Tales from Field & Street. Chicago: University of Chicago Press. ISBN 0-226-77993-9. {{cite book}}: |author= has generic name (help)CS1 maint: multiple names: authors list (link)
  16. ^ Oiseaux.net. "American Goldfinch". {{cite web}}: Unknown parameter |accessmonthday= ignored (help); Unknown parameter |accessyear= ignored (|access-date= suggested) (help)
  17. ^ a b Shaw Creek Bird Supply. "American Goldfinch". {{cite web}}: Unknown parameter |accessmonthday= ignored (help); Unknown parameter |accessyear= ignored (|access-date= suggested) (help)
  18. ^ South Dakota Birds. "American Goldfinch". {{cite web}}: Unknown parameter |accessmonthday= ignored (help); Unknown parameter |accessyear= ignored (|access-date= suggested) (help)
  19. ^ http://books.google.com/books?vid=ISBN0226779939&id=2ENJUxG5cQwC&pg=PA207&lpg=PA207&ots=B2Q_MY5MJj&dq=Carduelis+tristis&sig=LBv9vlWqKtOTjsmRRSoSUsXoLDc
  20. ^ a b Bent, Arthur Cleveland and collaborators (compiled and edited by Oliver L. Austin, Jr.). "Carduelis tristis [Eastern American Goldfinch]". {{cite web}}: |author= has generic name (help); Unknown parameter |accessmonthday= ignored (help); Unknown parameter |accessyear= ignored (|access-date= suggested) (help)CS1 maint: multiple names: authors list (link)
  21. ^ CJ Wildlife. "American Goldfinch". {{cite web}}: Unknown parameter |accessmonthday= ignored (help); Unknown parameter |accessyear= ignored (|access-date= suggested) (help)
  22. ^ Dendroica. "American Goldfinch Carduelis tristis". {{cite web}}: Unknown parameter |accessmonthday= ignored (help); Unknown parameter |accessyear= ignored (|access-date= suggested) (help)
  23. ^ Paul R. Ehrlich, David S. Dobkin, and Darryl Wheye. "Precocial and Atricial". {{cite web}}: Unknown parameter |accessmonthday= ignored (help); Unknown parameter |accessyear= ignored (|access-date= suggested) (help)CS1 maint: multiple names: authors list (link)
  24. ^ a b "Backyard Birdwatching". Garden and Hearth. Retrieved 2007-05-25.
  25. ^ Sam Droege. "WBirds and Landscape Changes in Northeastern Forests". U.S. Geological Survey, Biological Resources Division. Retrieved 2007-05-26.
  • Template:IUCN2006 Database entry includes justification for why this species is of least concern
Wikimedia Commons has media related to American Goldfinch (Carduelis tristis).
Wikispecies has information related to Carduelis tristis.




Further reading

  • Middleton,, A. L. A (1993). "American Goldfinch (Carduelis tristis)". In A. Poole and F. Gill (ed.). The Birds of North America (No. 80 ed.). Philadelphia:: The Academy of Natural Sciences. doi:10.2173/bna.80. {{cite book}}: |access-date= requires |url= (help); Cite has empty unknown parameters: |accessyear=, |accessmonth=, and |coauthors= (help); External link in |chapterurl= (help); Unknown parameter |chapterurl= ignored (|chapter-url= suggested) (help)CS1 maint: extra punctuation (link)
Retrieved from "https://en.wikipedia.org/w/index.php?title=American_goldfinch&oldid=134695180"