Biology
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الإنجليزية
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المقدمة من Arkive
The large cactus-finch generally feeds on seeds, arthropods and, as its name suggests, various parts of the prickly pear cactus (Opuntia helleri) (5) (7). During the dry season when competition for food is most intense, it exercises different skills to obtain four main food items. This includes cracking hard Opuntia seeds, extracting seeds from Opuntia fruit and eating the arils, stripping bark to find arthropods, and opening decomposing Opuntia pads to obtain insect larvae (7).
Darwin's finches generally breed opportunistically, with egg-laying being most profuse when rainfall is high and food abundant (2). Pairs are typically monogamous and maintain small territories within which they build a small dome-shaped nest in a bush or cactus. On average each clutch comprises three eggs that are incubated for around 12 days before hatching. The nestlings are mostly raised on insects and leave the nest after about two weeks (4).
During the breeding season, competition for resources between different species of finch can be extremely intense. In promoting ever increasing levels of specialisation, competition for resources has been the driving force behind the evolution of Darwin's finches. This is exemplified by the widely divergent beak sizes of different finch species co-inhabiting one island, compared with much more convergent beak sizes when the same species are isolated from each other on separate islands (4).
Conservation
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الإنجليزية
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المقدمة من Arkive
For their unique biological diversity and significance, the Galapagos Islands are designated both a National Park and a World Heritage Site. As a consequence, conservation of the islands' native fauna and flora is a high priority (10). Furthermore,scientists from the Charles Darwin Foundation continue to conduct further research on Darwin's finches in order to ensure their long-term conservation (8).
Description
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الإنجليزية
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المقدمة من Arkive
Ever since they were first collected during the voyage of the Beagle, Darwin's finches have inspired a plethora of evolutionary research (3). Descending from an ancestral flock that colonised the Galapagos archipelago several millennia ago, each species famously possesses a beak specialised according to its individual dietary niche (2) (4). The large cactus-finch is one of the most variable of Darwin's finches, with individuals in a single population exhibiting a relatively wide array of beak dimensions (5). Like the other ground finches (Geospiza sp.), the adult male plumage of the large cactus-finch is completely black while the female is brown and streaked (2).
Habitat
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الإنجليزية
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المقدمة من Arkive
Occurs mainly in the arid lowland zone (6).
Range
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الإنجليزية
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المقدمة من Arkive
The large ground-finch is endemic to the Galapagos where it occurs on the islands of Española and Genovesa (2).
Status
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الإنجليزية
)
المقدمة من Arkive
Classified as Least Concern (LC) on the IUCN Red List (1).
Threats
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الإنجليزية
)
المقدمة من Arkive
In common with much of the Galapagos' endemic fauna and flora, Darwin's finches are under threat from habitat destruction, introduced diseases, and invasive predatory species such as rats and cats (8). However, there aren't known to be any substantial threats to the large cactus-finch in particular and its population is thought to be stable (9).
Española cactus finch
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الإنجليزية
)
المقدمة من wikipedia EN
The Española cactus finch (Geospiza conirostris), is a species of bird in the tanager family Thraupidae. It is one of Darwin's finches, and is endemic to the Galápagos islands, where it is restricted to Española, Genovesa, and the Darwin and Wolf Islands. This rather dark bird resembles the smaller and finer-beaked common cactus finch, but the two species do not co-inhabit any island.
Its natural habitat is dry shrubland and it is commonly seen on the ground. Its main food source is the cactus Opuntia.
Taxonomy
The Española cactus finch is one of Darwin's finches, a group of closely related birds that evolved on the Galápagos Islands. The group is related to the Tiaris grassquits, which are found in South America and the Caribbean.[2] An ancestral relative of those grassquits arrived on the Galápagos Islands some 2–3 million years ago, and the Española cactus finch is one of the species that evolved from that ancestor.[3]
From a study done in 2015, the Española cactus finch (G. conirostris) of Española was found to be a sister to the large ground finch, not to the Genovesa cactus finch.[4] The International Ornithologists' Union has changed the taxonomy based on the study. Other taxonomic authorities have kept the large cactus finch and the Genovesa cactus finch conspecific.
Genetic speciation
The Española cactus finch (G. conirostris) first arrived in Daphne Major in 1981, when it was observed to be a newcomer by Peter and Rosemary Grant. This has enabled scientists to trace changes in its genome: it originally interbred with local finches (G. fortis) but has ceased to do so in later generations. The new descendants have become a distinct species. It is the first example of speciation to be directly observed by scientists in the field.[5] Subsequent genetic research suggests that genes for beak shape (ALX1) and beak size (HMGA2) may be crucial in separating the hybridized species from local finches. Genes relating to the finches' song may also be involved.[6][7]
Description
The Española cactus finch is among the largest of the Darwin's finches, measuring 15 cm (5.9 in) in length. The male is black, with white-tipped undertail coverts. Female and immature birds range in color from dull gray to matte black, and frequently show white edges to the feathers of their underparts.[8]
References
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^ BirdLife International (2020). "Geospiza conirostris". IUCN Red List of Threatened Species. 2020: e.T103815509A182514440. doi:10.2305/IUCN.UK.2020-3.RLTS.T103815509A182514440.en. Retrieved 12 November 2021.
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^ Newton, Ian (2003). Speciation and Biogeography of Birds. San Diego, CA, USA: Academic Press. p. 78. ISBN 978-0-12-517375-9.
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^ Grant & Grant (2008), p. 25.
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^ Lamichhaney, Sangeet; Berglund, Jonas; Almén, Markus Sällman; Maqbool, Khurram; Grabherr, Manfred; Martinez-Barrio, Alvaro; Promerová, Marta; Rubin, Carl-Johan; Wang, Chao; Zamani, Neda; Grant, B. Rosemary; Grant, Peter R.; Webster, Matthew T.; Andersson, Leif (February 2015). "Evolution of Darwin's finches and their beaks revealed by genome sequencing". Nature. 518 (7539): 371–375. doi:10.1038/nature14181. ISSN 1476-4687. PMID 25686609. S2CID 4462253. Retrieved 14 February 2022.
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^ Galloway, Rory (23 November 2017). "Galapagos finches caught in act of becoming new species". BBC News. Retrieved 14 February 2022.
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^ Holmes, Bob (10 February 2022). "Learning about birds from their genomes". Knowable Magazine. doi:10.1146/knowable-021022-1. Retrieved 11 February 2022.
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^ Lamichhaney, Sangeet; Han, Fan; Webster, Matthew T.; Andersson, Leif; Grant, B. Rosemary; Grant, Peter R. (12 January 2018). "Rapid hybrid speciation in Darwin's finches". Science. 359 (6372): 224–228. doi:10.1126/science.aao4593. PMID 29170277. S2CID 206663426. Retrieved 14 February 2022.
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^ Swash, Andy; Still, Rob (2005). Birds, Mammals, and Reptiles of the Galápagos Islands: An Identification Guide (2nd ed.). London, UK: Christopher Helm. p. 104. ISBN 978-0-300-11532-1.
Cited works
Española cactus finch: Brief Summary
(
الإنجليزية
)
المقدمة من wikipedia EN
The Española cactus finch (Geospiza conirostris), is a species of bird in the tanager family Thraupidae. It is one of Darwin's finches, and is endemic to the Galápagos islands, where it is restricted to Española, Genovesa, and the Darwin and Wolf Islands. This rather dark bird resembles the smaller and finer-beaked common cactus finch, but the two species do not co-inhabit any island.
Its natural habitat is dry shrubland and it is commonly seen on the ground. Its main food source is the cactus Opuntia.
