American goldfinch

The American goldfinch (Spinus tristis) is a small North American bird in the finch family. It is migratory, ranging from mid-Alberta to North Carolina during the breeding season, and from just south of the Canada–United States border to Mexico during the winter.

The only finch in its subfamily to undergo a complete molt, the American goldfinch displays sexual dichromatism: the male is a vibrant yellow in the summer and an olive color during the winter, while the female is a dull yellow-brown shade which brightens only slightly during the summer. The male displays brightly colored plumage during the breeding season to attract a mate.

The American goldfinch is a granivore and adapted for the consumption of seedheads, with a conical beak to remove the seeds and agile feet to grip the stems of seedheads while feeding. It is a social bird and will gather in large flocks while feeding and migrating. It may behave territorially during nest construction, but this aggression is short-lived. Its breeding season is tied to the peak of food supply, beginning in late July, which is relatively late in the year for a finch. This species is generally monogamous and produces one brood each year.

Human activity has generally benefited the American goldfinch. It is often found in residential areas because it is attracted to bird feeders, which increase its survival rate in these areas. Deforestation also creates open meadow areas, which are its preferred habitat.

Taxonomy

The American goldfinch was one of the many species originally described by Carl Linnaeus in the landmark 1758 10th edition of his work, Systema Naturae, where he classified it in the genus Fringilla. It was later placed in the genus Spinus, a group containing New World goldfinches and siskins. In 1976, Spinus was merged into the genus Carduelis as a subgenus. Recent studies have resurrected the genus Spinus. Its closest relatives are the lesser goldfinch (S. psaltria), Lawrence's goldfinch (S. lawrencei), and the siskins. Although it shares a name with the European goldfinch, the two are in separate genera and are not closely related. Carduelis is derived from carduus, the Latin word for 'thistle'; the species name tristis is Latin for 'sorrowful'. There are four recognized subspecies of the American goldfinch:

The pale goldfinch (S. t. pallidus) is differentiated from other subspecies by its paler body color, stronger white markings and, in males, a larger black cap. It is slightly larger than S. t. tristis. The summer range is from British Columbia to western Ontario, south to Colorado and west to Oregon. In winter, the range extends from southern Canada and northern California, south to Mexico. (S. t. salicamans) occurs west of the Sierra Nevada range during the summer and in the central and southern Baja California Peninsula to the Mojave Desert and the Colorado Desert in the winter. In winter, the plumage of both sexes is browner than the other subspecies and in summer, the male's black cap is smaller than that of the other subspecies. Among standard measurements, the wing chord is , the tail is , the culmen is and the tarsus is . The beak is small, conical, and pink for most of the year, but turns bright orange with the spring molt in both sexes. with a striking jet black cap and white rump that is visible during flight. The female is mostly brown, lighter on the underside with a yellow bib. After the autumn molt, the bright summer feathers are replaced by duller plumage, becoming buff below and olive-brown above, with a pale yellow face and bib. The autumn plumage is almost identical in both sexes, but the male has yellow shoulder patches.

The song 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.

Distribution and habitat

right|thumb|American goldfinch call

The American goldfinch prefers open country where weeds thrive, such as fields, meadows, flood plains, as well as roadsides, orchards, and gardens. It may also be found in open deciduous and riparian woodlands and areas of secondary growth. This habitat preference continues during the spring and autumn migrations. The American goldfinch is a short-distance migrant, moving south in response to colder weather and lessened food supply. According to ornithologist Marc Parnell, this responsive, southerly migratory pattern is thought to begin to occur as daily low temperatures approach freezing, and particularly as these temperatures near 0 °F. The migration is completed in compact flocks, which travel in an erratic, wavelike flight pattern.

Attempts were made to introduce the American goldfinch into Bermuda in the 19th century and Tahiti in 1938, but the species failed to become established in either place.

Behavior

thumb|right|Male (left) and female (right) at a [[thistle feeder]]

thumb|thumbtime=48|right|Eating [[Echinacea|coneflower seeds and taking flight, including slow motion.]]

thumb|right|Eating [[hyssop seed]]

The American goldfinch flies in a distinctive undulating pattern, creating a wave-shaped path. This normally consists of a series of wing beats to lift the bird, then folding in the wings and gliding in an arc before repeating the pattern. Birds often vocalize during the flapping phase of the pattern and then go silent during the coasting phase. The call made during flight is "per-twee-twee-twee", or "ti-di-di-di", punctuated by the silent periods. They communicate with several distinct vocalizations, including one that sounds like "po-ta-to-chip" to the listener.

Birds do not act aggressively toward predators within their territory; their only reaction is alarm calling. Predators include snakes, weasels, squirrels, and blue jays, which may destroy eggs or kill young, and hawks and cats, which pose a threat to both young and adults. The oldest known American goldfinch was 10 years and 5 months old.

Sociality

The American goldfinch is gregarious during the nonbreeding season when it is often found in large flocks, usually with other finches. During the breeding season, this finch lives in loose colonies. While the nest is being constructed, the male will act aggressively toward other males who intrude into his territory, driving them away, and the female reacts in the same way toward other females. This aggressiveness subsides once the eggs have been laid. The social hierarchy in the breeding season generally has the female dominant over the male.

Birds indicate their level of aggression through a range of displays. The head-up display, where the neck and legs are slightly extended, shows mild aggression and is often performed by the victor of an encounter. The carpals-raised display has the neck retracted and the carpals raised; displayers are likely to attack their opponent. The head-forward display is where the legs are flexed, the neck extended, and the beak closed. At higher intensities, the neck is lowered, the beak is pointed at the opponent, and one or both wings are raised. In extreme cases, the neck is retracted, the bill opened, the body feathers sleeked, and the tail is fanned and raised slightly. Aggression is also displayed by showing the front of the body to another individual. Attacks include pecking at feathers, supplanting the opponent by landing next to it, and flying vertically with legs and feet extended, beaks open, and necks extended. Avoidance behaviors include showing only the side of the body to an aggressor, leaning away, and flexing the legs, retracting the neck, and pointing the beak down. If a female accepts the male as a mate, the pair will fly in wide circles, as the male warbles throughout the flight. The inside diameter of the finished nest is about . The mother bird feeds her young regurgitated seeds and insects as they grow. It likely evades parasitism partly because of its late breeding season. The American goldfinch also makes a very poor host for brood parasites, with studies showing low hatching rates of brown-headed cowbird eggs and no fledging success. This is despite the lack of known behavioral adaptations against brood parasites in this finch. 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.

Feeding

thumb|Feeding|alt=Three goldfinches feeding

thumb|right|Feeding from sunflower heads|alt=Two feeding from sunflower heads

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.

Status

The American goldfinch has a large range, with an estimated global extent of about , though its population (42–47 million mature individuals) is expected to be decreasing. The species is evaluated as least concern on the 2025 IUCN Red List.

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 because it is 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. It was chosen by schoolchildren in Washington in 1951.