Biology
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To date, few observations of the breeding behaviour of this species have been made (4). Nests are built on the ground amongst or under vegetation, but mostly on steep slopes or cliffs (2), and clutches usually consisting of two eggs appear to be laid around September and October (4). Adult plumage is not reached for at least three years, but sexual maturity and activity may not necessarily correlate (2).
The diet consists primarily of invertebrates (80% of foraging time), but also of fruit, grass seeds, and scavenged birds and broken eggs (2).
Conservation
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Gough Island is both a Nature Reserve and World Heritage Site, and while this provides good protection from human disturbance, it does not offer the Gough bunting any protection from the mouse predation that is driving it towards extinction (2). A study of the mice conducted by The Royal Society for the Protection of Birds (RSPB) and funded by the UK government's Overseas Territories Environment Programme has shown that their eradication from the island is feasible. Unfortunately, however, until adequate funding from the UK government is supplied this will not occur (6). Gough Island is widely recognised as having one of the most diverse bird colonies in the world, including four endangered species, and every effort should therefore be made to protect it and the rich biodiversity it hosts (7).
Description
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The Gough bunting is a large, stocky, olive-coloured bunting, endemic to Gough Island in the South Atlantic Ocean. The more or less uniformly olive-green colouration of the male, which is slightly paler on its underparts, is disrupted only by the yellowish plumage of the forehead and eyebrow, and the prominent black 'bib' just below the thick-based, pointed black bill. Females lack the black bib and juveniles, by contrast, possess a buff-olive plumage, heavily streaked above and below with dark brown. The contact call consists of a keet keet sound and the song of a high, keening whistle (2).
Habitat
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Most common in tussock-grassland, wet heath and among scrub up to 800 m, occuring at lower densities in fern-bush and peat-bogs (2) (3).
Range
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Endemic to Gough Island of the Tristan da Cunha group (St Helena, UK) in the South Atlantic Ocean. The population was estimated at approximately 200 pairs in 1974 and 1,500 pairs in 1991, but recent surveys of breeding territories in 2007 suggest a population of just 400 – 500 pairs (2).
Status
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Classified as Critically Endangered (CR) on the IUCN Red List (1).
Threats
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This bird's occurrence in a restricted habitat of one very small island makes it extremely vulnerable to natural disasters like fires and hurricanes, or to introduced diseases, and especially to the accidental introduction of non-native predators (3). Indeed, the introduced house mouse Mus musculus poses the greatest present threat through competition and predation (2). Buntings are found at low density in lowland areas where mice are abundant (2), and experiments with 'dummy' eggs imply that mouse predation on their nests is very high (5). Thus, researchers think the bird may have been forced by these mice from the best nesting sites into less suitable upland regions (5). Over the last 15 years, the proportion of juveniles in the population has declined from 50% to 20%, this appears to indicate that there are now too few young surviving to reproductive age to sustain the population.
The accidental introduction of the black rat Rattus rattus from Tristan is also a huge potential threat, having caused devastation on Tristan to a number of bird species. Worryingly, a dead rat was discovered in a packing case in 1967, another was found on the Gough supply ship in 1974, and there was an unconfirmed rat sighting on the island in 1983 (2).
Gough finch
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The Gough finch (Rowettia goughensis) or Gough bunting, is a critically endangered species of songbird.
Taxonomy
The Gough finch was formally described in 1904 by the British ornithologist William Eagle Clarke from a specimen collected on Gough Island in the South Atlantic. Clarke coined the binomial name Nesospiza goughensis.[2] The Gough finch is now the only species placed in the genus Rowettia that was introduced in 1923 by the English ornithologist Percy Lowe.[3][4] The genus name was chosen to honour John Quiller Rowett, an English businessman and the sponsor of the Shackleton–Rowett Expedition.[5] The Gough finch was traditionally considered to be a bunting in the family Emberizidae,[6] but molecular phylogenetic studies have shown that it is a member of the subfamily Diglossinae in the tanager family Thraupidae and is sister to a clade containing birds in the genus Melanodera.[7] The species is monotypic: no subspecies are recognised.[4]
Another species of finch was described from Gough Island, Nesospiza jessiae, in 1904. This species was later identified as a juvenile of the Gough finch.[3]
Description
The Gough finch is 22 to 26 cm (8.7–10.2 in) in length and weighs 50–56 g (1.8–2.0 oz).[8]
Distribution and habitat
It is endemic to the remote Gough Island, part of the British overseas territory of Saint Helena, and nearby stacks, in the South Atlantic. Its natural habitats are temperate shrubland and subantarctic grassland.
The immature was described as
Nesospiza jessiae
Status and conservation
It was formerly classified as a Vulnerable species by the IUCN.[1] But new research has shown that its population has collapsed and it is on the verge of extinction due to the introduced population of house mice (Mus musculus), noted for its unusual aggressiveness,[9] competing with the birds for food and eating their eggs and nestlings. Consequently, it was uplisted to Critically Endangered in 2008.[1]
References
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^ a b c BirdLife International (2017). "Rowettia goughensis". IUCN Red List of Threatened Species. 2017: e.T22723149A119142383. doi:10.2305/IUCN.UK.2017-3.RLTS.T22723149A119142383.en. Retrieved 11 November 2021.
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^ Clarke, W. Eagle (1904). "Nesospiza goughensis, n. sp". Bulletin of the British Ornithologists' Club. 15: 18.
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^ a b Lowe, Percy R. (1923). "Notes on some land birds of the Tristan da Cunha group collected by the 'Quest' expedition". Ibis. 65 (3): 511–528 [512]. doi:10.1111/j.1474-919X.1923.tb08110.x.
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^ a b Gill, Frank; Donsker, David; Rasmussen, Pamela, eds. (July 2020). "Tanagers and allies". IOC World Bird List Version 10.2. International Ornithologists' Union. Retrieved 6 November 2020.
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^ Jobling, James A. (2010). The Helm Dictionary of Scientific Bird Names. London: Christopher Helm. p. 338. ISBN 978-1-4081-2501-4.
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^ Paynter, Raymond A. Jr, ed. (1970). Check-List of Birds of the World. Vol. 13. Cambridge, Massachusetts: Museum of Comparative Zoology. p. 112.
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^ Burns, K.J.; Shultz, A.J.; Title, P.O.; Mason, N.A.; Barker, F.K.; Klicka, J.; Lanyon, S.M.; Lovette, I.J. (2014). "Phylogenetics and diversification of tanagers (Passeriformes: Thraupidae), the largest radiation of Neotropical songbirds". Molecular Phylogenetics and Evolution. 75: 41–77. doi:10.1016/j.ympev.2014.02.006. PMID 24583021.
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^ Ryan, P. & Sharpe, C.J. (2017). Gough Finch (Rowettia goughensis). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from http://www.hbw.com/node/62039 on 28 March 2017).
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^ Wanless, R.M.; Angel, A.; Cuthbert, R.J.; Hilton, G.M.; Ryan, P.G. (2007). "Can predation by invasive mice drive seabird extinctions?" (PDF). Biology Letters. 3 (3): 241–244. doi:10.1098/rsbl.2007.0120. PMC 2464706. PMID 17412667.
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Gough finch: Brief Summary
provided by wikipedia EN
The Gough finch (Rowettia goughensis) or Gough bunting, is a critically endangered species of songbird.
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- cc-by-sa-3.0
- copyright
- Wikipedia authors and editors
