Tag Archives: Thraupidae

Geospiza magnirostris ssp. magnirostris Gould

Large Ground Finch (Geospiza magnirostris ssp. magnirostris)

The Large Ground Finch was described in 1837 based on material that was collected by Charles Darwin on the Galápagos Islands.

The species reaches a size of about 16 cm; the males are mostly blackish brown while the females are speckled dark – and light brown.

Today this species can be found on all the main islands within the archipelago, except for Darwin, Española, and San Cristóbal, where it is thought to have become extinct. 

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When Charles Darwin visited the Galápagos Islands in 1835, he collected several specimens on several of the islands; his specimens, however, don’t always bear reliable labels, and in some cases, he seems to have forgotten on which island he had collected which specimen.

Indeed, Darwin’s typespecimens have provided a considerable nightmare of taxonomic problems for subsequent ornithologists, based largely on their controversial localities. Darwin claimed, for example, that specimens of a peculiar large-beaked form of Geospiza magnirostris came from Chatham [Isla Floreana] and Charles islands [Isla San Cristóbal]. But after more than a century of subsequent collecting without finding any such large-billed specimens, ornithologists found themselves faced with a puzzle. Either this form had become extinct on Chatham and Charles islands, where no magnirostris specimens (large or small) had ever been found by other expeditions; or else Darwin’s specimens must have come from islands other than those indicated.” [1]

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This very large-billed Large Ground Finch is often treated as some kind of nominate form of the species but may in fact be nothing but a just large-billed population that is now gone for whatever reasons.

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References:  

[1] Frank J. Sulloway: The Beagle collections of Darwin’s finches (Geospizinae).- Bulletin of the British Museum of Natural History (Zoology) 43: 49-94. 1982

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Depiction from: ‘John Gould: The Zoology of the Voyage of H.M.S. Beagle, under the command of Captain Fitzroy, during the years 1832-1836. Part III, Birds. London, Smith, Elder & Co. 1838’  

(public domain)

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edited: 31.05.2021

Pyrrhulagra grandis (Lawrence)

St. Kitts Bullfinch (Pyrrhulagra grandis)

The St. Kitts Bullfinch was described in 1882, originally as a subspecies of the Puerto Rican Bullfinch (Pyrrhulagra portoricensis (Daudin)) (see photo).

… a short description: 

Similar to P. portoricensis but much larger and with the rufous markings darker (intermediate between ferruginous and vinaceous-rufous); that of the throat more restricted, scarcely extending to the chest, and that of the under tail-coverts mixed with black.” [1]

The species was endemic to the island of St. Kitts, where it was restricted to the higher slopes of Mt. Misery, the highest part of the island, it may very likely once have been found all over the island and very likely also on the neighboring islands of Nevis and St. Eustatius, which were connected with St. Kitts during the last glacial period. 

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The St. Kitts Bullfinch was originally known from nine specimens all of which had been collected in 1880 by Frederick A. Ober, an American naturalist, and the species was considered extinct since that date, however, a specimen that previously had been overlooked, was found in the collection of the National Museum of Natural History of the Smithsonian Institution in Washington, D.C., USA; this specimen was collected in 1929 or 1937. [2][3]

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References:

[1] Robert Ridgeway: The birds of North and Middle America: A descriptive catalogue of the higher groups, genera, species, and subspecies of birds known to occur in North America, from the arctic lands to the isthmus of Panama, the West Indies and other islands of the Caribbean sea, and the Galapagos Archipelago: Part I. family Fringillidae – the finches. Bulletin of the United States National Museum 1901
[2] Storrs L. Olson: The last St. Kitts Bullfinch Loxigilla portoricensis grandis (Emberizinae) and the extinction of its race. Bulletin of the British Ornithologists’ Club 104(4): 121-123. 1984
[3] Orlando H. Garrido; James W. Wiley: The taxonomic status of the Puerto Rican Bullfinch (Loxigilla portoricensis) (Emberizidae) in Puerto Rico and St. Kitts. Ornithologia Neotropical 14: 91-98. 2003

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Puerto Rican Bullfinch (Loxigilla portoricensis)
Photo: Carlos Davi Hernández

(under creative commons license (3.0))
http://creativecommons.org/licenses/by/3.0

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edited: 10.11.2020

Nesospiza sp. ‘Tristan da Cunha’

Tristan da Cunha Finch (Nesospiza sp.)

The Tristan da Cunha archipelago, which lies nearly exactly in the middle of the vast Atlantic Ocean, harbors one of the most interesting radiations known in the bird world – the Atlantic Island Finches (Nesospiza spp.).

These are at least three species, the Inaccessible Island Finch (Nesospiza acunhae Cabanis), the Nightingale Island Finch (Nesospiza questi Lowe), and Wilkin’s Finch (Nesospiza wilkinsi Lowe), which inhabit Inaccessible Island as well as Nightingale island but are absent from the island of Tristan da Cunha itself.

This, however, wasn’t always the case, since these birds were actually originally found on –  and described from that island, this population, however, disappeared sometimes around 1873, of course due to the usual reasons – habitat destruction, hunting and predation by introduced mammals. [1]

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The birds from Tristan da Cunha were not described as a distinct subspecies or whatsoever but are considered to be conspecific with the nominate form that is otherwise restricted to Inaccessible Island (see photo below). They may, however, indeed constitute a distinct form, endemic to this one island; this form is now known only from a single specimen that was collected on the island in 1817, when the species was said to be plentiful. [2]

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References:

[1] M. W. Fraser; D. J. Briggs: New information on the Nesospiza buntings at Inaccessible Island, Tristan da Cunha, and notes on their conservation. Bulletin of the British Ornithologists’ Club 112(3): 191-205. 1992 
[2] Peter G. Ryan: Taxonomic and conservation implications of ecological speciation in Nesospiza buntings on Tristan da Cunha. Bird Conservation International 18: 20-29. 2008

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Inaccessible Island Finch (Nesospiza acunhae ssp. acunhae); nominate form

Photo: Brian Gratwicke

(under creative commons license (2.0))
https://creativecommons.org/licenses/by/2.0/

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edited: 30.05.2021

Pyrrhulagra sp. ‘Barbuda’

Barbudan Bullfinch (Pyrrhulagra sp.)

This form is known from at least two subfossil remains, a quadrate and a rostrum, found on the island of Barbuda, Antigua and Barbuda, in the Lesser Antilles.

The remains were compared to other closely related forms and most agree with the bones of the largest subspecies of the Greater Antillean Bullfinch (Pyrrhulagra violacea ssp. ruficollis (J. F. Gmelin)) from Jamaica, which is about the same size as the now extinct St. Kitts Bullfinch (Pyrrhulagra grandis (Lawrence)). [1]

The Barbudan Bullfinch may have been identical with the St. Kitts species or it might have been a distinct species, I personally like to refer to it as a distinct species. [2]

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References:

[1] Gregory K. Pregill; David W. Steadman; David R. Watters: Late Quaternary vertebrate faunas of the Lesser Antilles: historical components of Caribbean biogeography. Bulletin of Carnegie Museum of Natural History 30: 1-51. 1994
[2] D. W. Steadman; R. L. Norton; M. R. Browning; W. J. Arendt: The birds of St Kitts, Lesser Antilles. Caribbean Journal of Science 33(1–2):S. 1–20. 1997

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edited: 17.02.2020