Darwin's famous finches are not true finches at all
True finches, family Fringillidae, are small to medium songbirds with stout cone-shaped bills made for cracking seeds. More than two hundred species belong, from canaries to Hawaiian honeycreepers, yet many birds called finches, including Darwin's finches of the Galápagos, sit in entirely different families.
True finches live almost everywhere except Australia and the polar regions, and most stay put rather than migrate. The family holds over two hundred species in fifty genera, including siskins, redpolls, serins, grosbeaks and euphonias. The name-sharers are a mixed crowd: the estrildid finches of the Old World tropics and Australia, some buntings and New World sparrows, and Darwin's finches, which are now grouped with the tanagers. Finches and canaries also served in British, American and Canadian coal mines from the eighteenth to the twentieth century as early warnings of carbon monoxide, a practice Britain ended only in 1986.
William Elford Leach named the family in 1819 in a guide to the British Museum's collections, and sorting it out has been messy ever since, because unrelated species in similar niches evolved similar shapes. In 1968 the ornithologist Raymond Paynter judged the cardueline finches the most confused of all songbirds, rivalled only by the waxbills. DNA studies from around 1990 reshuffled everything. Euphonias and chlorophonias, once thought tanagers, proved to be finches and got their own subfamily. The Hawaiian honeycreepers, formerly a separate family, turned out to be close kin of the Carpodacus rosefinches. The big genera Carpodacus, Carduelis and Serinus were broken up, with 37 species moved from Serinus alone. Przewalski's rosefinch, which has ten main flight feathers instead of nine, now sits in a family of its own.
Today there are three subfamilies: the chaffinches, the Carduelinae with 183 species in 49 genera, and the euphonias. Fossils are scarce, but the family seems to have arisen roughly 20 to 10 million years ago, and an unidentified finch fossil from the late Miocene was found at Polgárdi in Hungary.
Sizes run from the Andean siskin at around 9.5 centimetres and the lesser goldfinch at about 8 grams up to the collared grosbeak at 24 centimetres and 83 grams. All have nine primary wing feathers and twelve tail feathers. Plumage is usually brownish or greenish, often with black; yellow and red carotenoid pigments are common, which makes blue rare because yellow turns blue into green. In many species females lack the males' bright markings, and the Hawaiian honeycreepers are famous for bills of wildly different shapes.
Source: Finch
