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Lifespan, longevity, and ageing

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Maximum longevity: 23.8 years (wild)
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Biology

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Breeding in the bristle-thighed curlew probably starts around May, when the bird can be found on the Alaskan tundra (2). They are monogamous birds, forming long-term bonds, and are not only faithful to a partner, but also to breeding and wintering sites, returning to the same place year after year (5). Generally, four eggs are laid into a simple, bare depression in mossy vegetation, and both sexes will incubate the eggs for about 25 days (2) (6). The chicks leave the nest shortly after hatching, and continue to receive parental care, initially from both parents, and then just the male as the female deserts the brood before the chicks fledge (2) (6). Whilst breeding, the adults aggressively defend the eggs and chicks, and often attack potential predators or perform displays to distract them (6). After the breeding season juveniles and adults congregate on the Yukon River delta. Here they feed on berries, insects and other foods in preparation for the migration to their wintering grounds; an impressive journey in which they fly non-stop for over 4000 kilometres (2) (6). They arrive at the oceanic islands in late August to early September, where they will undergo a moult. During this moult, over 50 percent of adults become completely flightless, for a period of two weeks (2). Whilst on their wintering grounds, the curlews are opportunistic feeders, taking crustaceans, insects, spiders, snails, small fish, scorpions and the eggs of seabirds (2) (6). They show remarkable ingenuity by using rocks to crack the thick egg shells, a rare example of tool use by birds (6). Occasionally they also feed on seabird carrion and fish regurgitated by seabirds and lizards (2).
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Conservation

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The bristle-thighed curlew occurs in a number of protected areas. Both the Yukon Delta and some of the remote Hawaiian Islands, are designated National Wildlife Refuges, which protects breeding grounds and several stop-over and wintering sites (4) (6). Wildlife and habitat is monitored in the Yukon Delta, but further specific monitoring of the curlew is recommended (4). Hawaii's Comprehensive Wildlife Conservation Strategy proposes a number of conservation actions for the bristle-thighed curlew including protecting the current habitat of the curlew in Hawaii, and protecting and restoring additional wetland habitat, especially where it can be reclaimed from abandoned urban or agricultural uses (7). However, to protect this species from further declines, it is important to tackle the primary threat of introduced mammals across its wintering range.
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Description

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This medium-sized shorebird possesses a long, down curved, touch-sensitive bill; a unifying characteristic of all curlews. The curlew's genus name Numenius means 'of the new moon' and refers to the long, crescent-shaped bill. It has plumage that is mostly flesh-coloured to pale brown, with darker brown broad stripes on the head, and the upperparts are spotted cinnamon and dark brown. The underparts are streaked buff, the belly and feathers under the tail are whitish, and the legs are a pale blue-grey (2) (4). Their name comes from the bristle-like extensions at the base of their legs, although these are generally inconspicuous and can only be seen when close up. Females are heavier than males and have longer wings and a shorter bill. Juveniles are similar to adults except for the presence of larger cinnamon-buff spots on the upperparts, and virtually unstreaked underparts (2).
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Habitat

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During the breeding season it can be found on exposed hilly tundra. Over winter, it occurs on oceanic islands, generally in the interior amongst dense vegetation, but sometimes on sandy beaches, rocky shores, tidal mudflats and exposed reefs (2) (4).
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Range

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The bristle-thighed curlew breeds on the lower Yukon River and central Seward Peninsula in western Alaska, United States. It winters on many small oceanic islands in the South Pacific, from the Marshall and Hawaiian Islands, south to Santa Cruz, Fiji, Tonga, Samoa, Marquesas, Tuamotu Island and Pitcairn Island (2).
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Status

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Classified as Vulnerable (VU) on the IUCN Red List 2007 (1) and listed on Appendix II of the Convention on the Conservation of Migratory Species (CMS) (3).
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Threats

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The fairly small population of bristle-thighed curlews is believed to be declining, primarily due to the impacts of introduced predators on their wintering grounds (1). The flightless period during the moult would have evolved during a time when there were no mammalian predators on the South Pacific islands where it spends the winter. Today, with the establishment of humans on these islands, and the subsequent introduction of mammals, moulting leaves the curlew in an extremely vulnerable position. Introduced cats, dogs and possibly pigs, prey heavily on the flightless curlews, causing a significant decline in numbers (4) (6). Hunting was a threat to this species in the past; on the Tuamotu islands it was traditionally caught for food. However, the possession and use of firearms is now restricted on these islands and therefore hunting no longer poses a significant threat (2). On their breeding grounds the curlew suffers predation by Arctic skuas, common ravens and foxes, and the expanding development of gold mines and mining roads on the Seward Peninsula is an increasing threat that could have a significant impact on this bird, due to its reliance on this small area for breeding (2) (6).
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Bristle-thighed curlew

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The bristle-thighed curlew (Numenius tahitiensis) is a medium-sized shorebird that breeds in Alaska and winters on tropical Pacific islands.

It is known in Mangareva as kivi or kivikivi and in Rakahanga as kihi; it is said to be the origin of the name for the New Zealand flightless bird kiwi[2] although some linguists like Robert Blust has proposed an alternate origin from Proto-Oceanic *kiwiwi, the Pacific golden plover, instead.[3]

Taxonomy

The bristle-thighed curlew was formally described in 1789 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Carl Linnaeus's Systema Naturae. He placed it in the genus Scolopax and coined the binomial name Scolopax tahitiensis.[4] Gmelin based his description on the "Otaheite curlew" that had been described in 1785 by the English ornithologist John Latham in his A General Synopsis of Birds. "Otaheite" is a former name of Tahiti. The specimen used by Latham was supplied by the naturalist Joseph Banks.[5] Banks had accompanied James Cook on his first voyage to the south Pacific but had also received specimens from Cook's subsequent voyages.[6] The bristle-thighed curlew is now one of nine species placed in the genus Numenius that was erected in 1760 by the French scientist Mathurin Jacques Brisson in his Ornithologie.[7][8] The name Numenius is from Ancient Greek noumenios, a bird mentioned by Hesychius. It is associated with the curlews because it appears to be derived from neos, "new" and mene "moon", referring to the crescent-shaped bill.[9] The species is considered to be monotypic: no subspecies are recognised.[8]

Description

The bristle-thighed curlew has a long, decurved bill and bristled feathers at the base of the legs. Its length is about 40–44 cm and wingspan about 84 cm (females averaging bigger than males). The size and shape are the same as the whimbrel's, and the plumage is similar, spotted brown on their upper body with a light belly and rust-colored or buffy tail. The bigger buff spots on the upper body, unmarked light belly and barely marked flanks, tail color, and pale buffy-orange rump distinguish it from the whimbrel.[10]

Distribution and habitat

Its winter habitat is tropical Oceania, and includes Micronesia, Fiji, Tuvalu, Tonga, Hawaiian Islands, Samoa, French Polynesia and Tongareva (Penrhyn atoll). There is concern over encroachment and introduced predators in their winter habitat.

Although it was described after James Cook's visits to Tahiti in the 18th century, its breeding area was not identified until 1948.[11] Nesting grounds are on the lower Yukon River and Seward Peninsula, with the birds preferring low-lying tundra near the shoreline. The bird is rarely seen near populated land masses, with only a handful of sightings in Canada, California and Oregon.

Behavior and ecology

Breeding

Nests are built in ground depressions and lined with tundra moss. Eggs are greenish with brown spots, with four to a clutch and one brood per season. Incubation lasts around 24 days, with both parents tending the nest and protecting the newly hatched chicks.[10]

Adults leave their chicks at about five weeks of age to migrate south. The chicks continue to feed until they are able to make the journey. The first leg of the migration includes a nonstop 4,000 km flight from Alaska to Laysan. They can make non-stop flights in excess of 6,000 km.[12]

Food and feeding

Bristle-thighed curlews feed on a wide variety of vegetation such as flowers and berries and on insects, sea life, and other bird's eggs, which they break open with rocks — the only tool use among shorebirds.

Gallery

References

  1. ^ BirdLife International (2020). "Numenius tahitiensis". IUCN Red List of Threatened Species. 2020: e.T22693182A181357867. doi:10.2305/IUCN.UK.2020-3.RLTS.T22693182A181357867.en. Retrieved 19 November 2021.
  2. ^ "kiwi". Polynesian Lexicon Project Online. POLLEX-Online. 2010. Archived from the original on 24 July 2011. Retrieved 7 January 2011.
  3. ^ Blust, Robert; Trussel, Stephen (2010). "*kiwiwi: shore bird - sandpiper, Pacific Golden Plover". Austronesian Comparative Dictionary. Max Planck Institute for Evolutionary Anthropology. Retrieved 8 November 2022.{{cite web}}: CS1 maint: url-status (link)
  4. ^ Gmelin, Johann Friedrich (1789). Systema naturae per regna tria naturae : secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis (in Latin). Vol. 1, Part 2 (13th ed.). Lipsiae [Leipzig]: Georg. Emanuel. Beer. p. 656.
  5. ^ Latham, John (1785). A General Synopsis of Birds. Vol. 3, Part 1. London: Printed for Leigh and Sotheby. pp. 122–123, No. 4.
  6. ^ Medway, D.G. (2009). "The fate of the bird specimens from Cook's voyages possessed by Sir Joseph Banks". Archives of Natural History. 36 (2): 231–243. doi:10.3366/E0260954109000965. PMID 20014506.
  7. ^ Brisson, Mathurin Jacques (1760). Ornithologie, ou, Méthode contenant la division des oiseaux en ordres, sections, genres, especes & leurs variétés (in French and Latin). Vol. 1. Paris: Jean-Baptiste Bauche. Vol. 1, p. 48, Vol. 5, p. 311.
  8. ^ a b Gill, Frank; Donsker, David; Rasmussen, Pamela, eds. (August 2022). "Sandpipers, snipes, coursers". IOC World Bird List Version 12.2. International Ornithologists' Union. Retrieved 3 November 2022.
  9. ^ Jobling, James A (2010). The Helm Dictionary of Scientific Bird Names. London: Christopher Helm. p. 276. ISBN 978-1-4081-2501-4.
  10. ^ a b Marks, J.S.; Tibbitts, T.L.; Gill, R.E.; McCaffery, B.J. (2020). Poole, A.F.; Gill, F.B. (eds.). "Bristle-thighed Curlew (Numenius tahitiensis), version 1.0". Birds of the World. Ithaca, NY, USA: Cornell Lab of Ornithology. doi:10.2173/bow.brtcur.01. Retrieved 3 November 2022.
  11. ^ Allen, A.A.; Kyllingstad, H. (1949). "The eggs and young of the bristle-thighed curlew" (PDF). The Auk. 66 (4): 343–350. doi:10.2307/4080277. JSTOR 4080277.
  12. ^ Marks, J.S.; Redmond, R.L. (1994). "Migration of bristle-thighed curlews on Laysan Island: timing, behavior and estimated flight range" (PDF). The Condor. 96 (2): 316–330. doi:10.2307/1369317. JSTOR 1369317.
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Bristle-thighed curlew: Brief Summary

provided by wikipedia EN

The bristle-thighed curlew (Numenius tahitiensis) is a medium-sized shorebird that breeds in Alaska and winters on tropical Pacific islands.

It is known in Mangareva as kivi or kivikivi and in Rakahanga as kihi; it is said to be the origin of the name for the New Zealand flightless bird kiwi although some linguists like Robert Blust has proposed an alternate origin from Proto-Oceanic *kiwiwi, the Pacific golden plover, instead.

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