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'Darwin's finches' (also known as the 'Galápagos Finches') are 13 or 14 different but closely related species of finches Charles Darwin collected on the Galápagos Islands during the voyage of the ''Beagle''. Thirteen reside on the Galápagos Islands and one on Cocos Island.
The birds are all about the same size (10–20 cm). The most important differences between species are in the size and shape of their beaks, and the beaks are highly adapted to different food sources. The birds are all brownish or black. Their behaviour differs, and they have different song melodies.

Contents

The finches and Darwin's theory

Taxonomy

Family

Species

Text from the ''Voyage of the Beagle''

References

External links

The finches and Darwin's theory

Although these birds were to play an important part in the inception of Darwin's theory of evolution by natural selection, at the time of the survey voyage of HMS ''Beagle'' Darwin had no idea of their significance. It is often assumed that when he saw the finches on the islands this inspired the theory, but this is not true: Darwin believed that they were not closely related when he encountered them; indeed he thought that most of these birds were not finches at all (Sulloway 1982).
Following his return from the voyage, Darwin presented the finches to the Geological Society of London at their meeting on 4 January 1837, along with other mammal and bird specimens he had collected. The bird specimens, including the finches, were given to John Gould, the famous English ornithologist, for identification. Gould set aside his paying work and at the next meeting on 10 January reported that birds from the Galápagos Islands which Darwin had thought were blackbirds, "gross-beaks" and finches were in fact ''"a series of ground Finches which are so peculiar"'' as to form ''"an entirely new group, containing 12 species."'' This story made the newspapers.
In March Darwin met Gould again, learning that his Galápagos "wren" was another species of finch and the mockingbirds he had labelled by island were separate species rather than just varieties, with relatives on the South American mainland. Darwin had not bothered to label his finches by island, but others on the expedition had taken more care. He now sought specimens collected by Captain Robert FitzRoy and crewmen. From them he was able to establish that the species were uniquely related to individual islands, giving him the idea that somehow in this geographical isolation these different species could have been formed from a small number of common ancestors so that each was modified to suit "different ends."
The term ''Darwin's Finches'' was first applied in 1936, and popularized in 1947 by David Lack. Later, Peter and Rosemary Grant conducted extensive research in documenting evolutionary change among the finches. Beginning in 1973, the pair spent many years tracking thousands of individual finches across several generations, showing how individual species changed in response to environmental changes. ''The Beak of the Finch'' by Jonathan Weiner is a book about the finches, highlighting the Grants' research.

Taxonomy

Family

For some decades taxonomists have placed these birds in the family Emberizidae with the New World sparrows and Old World buntings (Sulloway 1982). However, the Sibley-Ahlquist taxonomy puts Darwin's finches with the tanagers (Monroe and Sibley 1993), and at least one recent work follows that example (Burns and Skutch 2003). The American Ornithologists' Union, in its North American check-list, places the Cocos Island Finch in the Emberizidae but with an asterisk indicating that the placement is probably wrong (AOU 1998–2006); in its tentative South American check-list, the Galápagos species are ''incertae sedis'', of uncertain place (Remsen et al. 2007).

Species

★ Genus ''Geospiza''

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★ Large Cactus-finch, ''Geospiza conirostris''

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★ Sharp-beaked Ground-finch, ''Geospiza difficilis''

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★ Vampire Finch, ''Geospiza difficilis septentrionalis''

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★ Medium Ground-finch, ''Geospiza fortis''

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★ Small Ground-finch, ''Geospiza fuliginosa''

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★ Large Ground-finch, ''Geospiza magnirostris''

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★ Darwin's Large Ground-finch, ''Geospiza magnirostris magnirostris'' - possibly extinct (1957?)

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★ Common Cactus-finch, ''Geospiza scandens''

★ Genus ''Camarhynchus''

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★ Vegetarian Finch, ''Camarhynchus crassirostris'' - sometimes separated in ''Platyspiza''

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★ Large Tree-finch, ''Camarhynchus psittacula''

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★ Medium Tree-finch, ''Camarhynchus pauper''

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★ Small Tree-finch, ''Camarhynchus parvulus''

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★ Woodpecker Finch, ''Camarhynchus pallidus''

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★ Mangrove Finch, ''Camarhynchus heliobates''

★ Genus ''Certhidea''

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★ Warbler Finch, ''Certhidea olivacea''

★ Genus ''Pinaroloxias''

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★ Cocos Island Finch, ''Pinaroloxias inornata''

Text from the ''Voyage of the Beagle''

The passage in chapter 17 of ''The Voyage of the Beagle'' in which Darwin describes the finches and surmises that they may have shared a common ancestor is shown below. This was written in the months after John Gould had revealed that the birds which Darwin had thought to be unrelated were different species of finches.
:''The remaining land-birds form a most singular group of finches, related to each other in the structure of their beaks, short tails, form of body and plumage: there are thirteen species, which Mr. Gould has divided into four subgroups. All these species are peculiar to this archipelago; and so is the whole group, with the exception of one species of the sub-group ''Cactornis'', lately brought from Bow Island, in the Low Archipelago. Of ''Cactornis'', the two species may be often seen climbing about the flowers of the great cactus- trees; but all the other species of this group of finches, mingled together in flocks, feed on the dry and sterile ground of the lower districts. The males of all, or certainly of the greater number, are jet black; and the females (with perhaps one or two exceptions) are brown. The most curious fact is the perfect gradation in the size of the beaks in the different species of ''Geospiza'', from one as large as that of a hawfinch to that of a chaffinch, and (if Mr. Gould is right in including his sub-group, ''Certhidea'', in the main group) even to that of a warbler. The largest beak in the genus ''Geospiza'' is shown in Fig. 1, and the smallest in Fig. 3; but instead of there being only one intermediate species, with a beak of the size shown in Fig. 2, there are no less than six species with insensibly graduated beaks. The beak of the sub-group ''Certhidea'', is shown in Fig. 4. The beak of ''Cactornis'' is somewhat like that of a starling, and that of the fourth subgroup, ''Camarhynchus'', is slightly parrot-shaped. Seeing this gradation and diversity of structure in one small, intimately related group of birds, one might really fancy that from an original paucity of birds in this archipelago, one species had been taken and modified for different ends. In a like manner it might be fancied that a bird originally a buzzard, had been induced here to undertake the office of the carrion-feeding Polybori of the American continent.''

References

★ Check-list of North American Birds

★ The Firefly Encyclopedia of Birds, Kevin J. Burns and Alexander F. Skutch, , , Firefly Books, 2003, ISBN 1-55297-777-3 It is not clear whether this placement was made by Burns and Skutch or by Perrins.

★ Adrian Desmond and James Moore, ''Darwin''. London: Michael Joseph, the Penguin Group (1991). ISBN 0-7181-3430-3

★ Burt L. Monroe and Charles G. Sibley, ''A World Checklist of Birds''. New Haven, Conn.: Yale University Press (1993). ISBN 0-300-07083-7. Accessed 2007-04-09. Monroe and Sibley consider the tanagers to be a tribe (Thraupini) of a big family Fringillidae rather than a family of their own (Thraupidae).

★ J. V. Remsen, Jr., C. D. Cadena, A. Jaramillo, M. Nores, J. F. Pacheco, M. B. Robbins, T. S. Schulenberg, F. G. Stiles, D. F. Stotz, and K. J. Zimmer. [Version 2007-04-05.] ''A classification of the bird species of South America''. American Ornithologists' Union. Accessed 2007-04-09.

★ Frank J. Sulloway, The ''Beagle'' collections of Darwin's finches (Geospizinae) (1982), ''Bulletin of the British Museum (Natural History) Historical Series'' 43, No. 2: pp 49-94

External links

★ 'Darwin, C.R.' ''The Voyage of the Beagle'' Chapter 17 from Darwin's book ''The Voyage of the Beagle'' Chapter 17 in which he discusses the Galapagos islands and the birds

★ Sulloway, F.J. (1982): "Darwin and his finches: the evolution of a legend". ''J. Hist. Biol. 15: p.1–53

★ Different bills and song melodies

★ ''Genetics and the Origin of Birds Species'', Grant and Grant in PNAS

★ Sato ''et al'' Phylogeny of Darwin's finches as revealed by mtDNA sequences in PNAS

★ Galápagos Online's Darwin's Finches page

★ Darwin's Finches Evolve Before Scientists' Eyes: new developments reported 13 July 2006

★ Fink F.A.Q. Darwin's finches inspired the naming of the Fink project, a collaborative initiative for porting open source software to the Darwin platform to enable its use and evolution in the Apple Macintosh OS X environment. "Fink" is the German name for "finch."