Slender-billed Curlew Numenius tenuirostris Scientific name definitions

36–41 cm; 255–360 g (two specimens); wingspan 80–92 cm. Very pale curlew , with shortish, slim, pointed bill; white or pale buff ground colour of head, neck and breast; lower back, rump, undertail and underwing white; uppertail-coverts white with sparse brown markings; typically has rounded or heart-shaped dark markings on breast and flanks (1 Corso, A., Jansen, J. and Kókay, S. (2014). A review of the identification criteria and variability of the Slender-billed Curlew. British Birds. 107(6): 339–370. Close ). Similar to N. phaeopus, but paler; lacks dark crown-stripe. It is now appreciated that separation from N. arquata can also be difficult (especially versus N. a. orientalis and N. a. suschkini) and many features show some degree of overlap, but the following are now considered particularly critical for identification: colour and pattern of underside of outer primaries, pattern and extent of the tibial feathering and length of exposed tibia, leg colour, pattern of tail feathers, and shape of dark flank markings (1 Corso, A., Jansen, J. and Kókay, S. (2014). A review of the identification criteria and variability of the Slender-billed Curlew. British Birds. 107(6): 339–370. Close ). Female ave­rages larger with longer bill. Non-breeding adult has fewer marks on flanks. Juvenile like adult, but flanks streaked brown.

SW Siberia; precise breeding range virtually unknown (the only confirmed breeding site, during first quarter of 20th century, was near Tara, N of Omsk) (2 Gretton, A. (1991). The Ecology and Conservation of the Slender-billed Curlew (Numenius tenuirostris). ICBP Monograph 6. Cambridge, UK. Close ). Winters in N Africa and E to Iraq and Persian Gulf. No verified records since 2001; increasingly likely to be extinct.

Breeds in extensive peat bogs with some small willow (Salix) and birch (Betula) trees, in habitat transitional from bog to forest, using small islands of dry habitat within large marshes (3 Gretton, A., Yurlov, A.K. and Boere, G.C. (2002). Where does the Slender-billed Curlew nest, and what future does it have? British Birds. 95(7): 334–344. Close ). On migration, occurs in coastal lagoons and adjoining saltmarshes, estuaries, inland soda- or saltlakes or (drained) fishponds in steppe area. Winters in coastal bays and lagoons with saltmarshes and temporary inland marshes. Few birds observed in Morocco appear to be habitat generalists, occurring on seashore, in saline and brackish lagoons and estuaries, in temporary and permanent lakes with adjoining marshes, on mudflats, and in sandy grassland and arable fields.

SW–WSW migration towards Mediterranean, mainly terminating in Atlantic Morocco and in Tunisia, but perhaps formerly also wintered in very small numbers in Netherlands (particularly in the Zuiderzee area) (4 De Smet, G. (1997). Dunbekwulp verzameld in Canisvliet in september 1896. Dutch Birding. 19(5): 230–232. Close , 5 Jukema, J. and Piersma, T. (2004). Were Slender-billed Curlews Numenius tenuirostris once common in The Netherlands, and do they have patches of powder feathers? Ibis. 146(1): 165–167. Close , 6 Jansen, J.J.F.J. (2012). Dunbekwulp verzameld te Zierikzee in december 1888. Dutch Birding. 34(5): 314–315. Close ); chiefly via Turkmenistan, Caspian steppes, Ukraine, Bulgaria (where more recorded in spring, 20 Mar–18 May, versus autumn, 19 Sept–9 Nov) (7 Nankinov, D.N. (1994). Bulgaria is of great importance for the conservation of Siender-billed Curlew Numenius tenuirostris. Journal of Ornithology. 135(1): 223. Close ), Romania, former Yugoslavia, S Hungary, Greece and Italy; a second migration route may lead from breeding grounds to Middle East, where wintered in Iraq and also reported to occur in Iran (8 Scott, D.A. (2008). Rare birds in Iran in the late 19647s and 19747s. Podoces. 3(1–2): 1–30. Close ), Saudi Arabia, Oman and Yemen (9 Porter, R. (2004). An encounter with a Slender-billed Curlew in Yemen. Birding World. 17(10): 437–439. Close ), with unconfirmed records even further E, in coastal Pakistan and NW India (10 Crockford, N. (2009). Is the Slender-billed Curlew Numenius tenuirostris in Asia? BirdingASIA. 12: 116–120. Close ). However, many of the published records from the Middle East, especially those from Iran and Turkey, as well as adjacent Greece, are either unquestionably erroneous or, at least, might not survive modern levels of scrutiny (11 Kirwan, G.M., Porter, R. and Scott, D. (2015). Chronicle of an extinction? A review of Slender-billed Curlew records in the Middle East. British Birds. 108(11): 669–682. Close ). Records from Morocco  mainly Nov–Mar, but first birds typically arrived late Aug/early Sept (exceptionally late Jul), with last departing as late as mid May (12 Thévenot, M., R. Vernon, and P. Bergier (2003). The Birds of Morocco: An Annotated Check-list. British Ornithologists’ Union Check-list 20. British Ornithologists’ Union, Tring, UK. Close ); formerly irregular migrant in NE Africa late Jul to Aug and Apr–May. Status in Turkey uncertain, as some records of N. arquata orientalis have been erroneously attributed to present species, while other records never listed as definite were subsequently treated (erroneously) as such (13 Kirwan, G. M., K. A. Boyla, P. Castell, B. Demirci, M. Özen, H. Welch, and T. Marlow (2008). The Birds of Turkey: The Distribution, Taxonomy and Breeding of Turkish Birds. Christopher Helm, London, UK. Close ); six skins exist of birds shot in Istanbul area between mid 19th and perhaps early 20th century (14 Kirwan, G.M. (1997). A list of bird specimens held in the Robert’s College, Bebek (Istanbul, Turkey) collection, with some comments on Mathey-Dupraz (192138–24). Sandgrouse. 19(1): 30–38. Close , 15 Corso, A., Jansen, J.J.F.J. and Kirwan, G.M. (2015). Two overlooked specimens of Slender-billed Curlew Numenius tenuirostris from Turkey. Sandgrouse. 37(1): 25. Close ). Status in Azerbaijan also uncertain; definite record of bird shot in Aug 1988, and species said to pass through regularly in very small numbers, but no documented records anywhere in C Asia since 1980 and several older records have recently re-evaluated and deemed unacceptable, especially from Kazakhstan (16 Wassink, A. (2016). Status of Slender-billed Curlew in Central Asia. Dutch Birding. 38(4): 235–237. Close ). Vagrants recorded astonishingly wildly, as far afield as the Azores (Mar 1979, Jan 1981) (17 Clarke, T. (2006). Birds of the Atlantic Islands. Christopher Helm, London, UK. Close ), Canada (c. 1925) and Japan (in or prior to 1913, on Honshu) (18 Brazil, M. (1991). The Birds of Japan. Christopher Helm, London, UK. Close ), but some such records have proven to be erroneous (e.g. in Czech Republic (19 Hudeček, J.J. (2014). [What about the Slender-billed Curlew (Numenius tenuirostris)?]. Acrocephalus 29: 54–55. (In Czech with English summary.). Close , 20 Hudeček, J.J. (2016). Slender-billed Curlew (Numenius tenuirostris) in the Czech Republic: the historical occurrence of this species in Bohemia and its return on the checklist. Acta Museum Siles. Sci. Natur. 65: 71–73. Close ), Myanmar (21 Mlíkovský, J. (2004). Remarks on some records of the Slender-billed Curlew (Numenius tenuirostris). Sylvia. 40: 125–130. Close ), Seychelles (22 Skerrett, A. (2011). Slender-billed Curlew has not occurred in Seychelles. Bull. African Bird Club. 18(1): 117. Close ) ) and others are unconfirmed (Djibouti (11 Kirwan, G.M., Porter, R. and Scott, D. (2015). Chronicle of an extinction? A review of Slender-billed Curlew records in the Middle East. British Birds. 108(11): 669–682. Close ), L Chad basin) (23 Borrow, N., and R. Demey (2001). Birds of Western Africa. Christopher Helm, London, UK. Close ).

Outside breeding season, takes annelids, molluscs, snails, crustaceans and small insects, such as grasshoppers, earwigs and beetles. Probes in soft mud and soil or pecks from surface; observed taking insects from scrubby bushes. In winter, in Morocco, birds fed for 2–4 hours after dawn, then roosted at a lagoon, before feedingagain from mid-afternoon until near dusk, when they again roosted in the lagoon.

Very limited data. Gives a “cour-lee” similar to the call of N. arquata, but has been considered higher-pitched, shorter and more repeated, and sometimes followed by 5–7 very short “ti-ti-ti...” notes, which sounds like a laughing trill. The only known sound recording (flight call of a male  ) matches this description. A sweet, high-pitched and monosyllabic “kwee” has been heard from birds either taking off or landing (perhaps in alarm?). Also described is a hollow vibrating whistle (“sirrr-virrr”) or loud, high-pitched “be-be-be-be...”, given when the birds mobbed intruders on breeding territories (3 Gretton, A., Yurlov, A.K. and Boere, G.C. (2002). Where does the Slender-billed Curlew nest, and what future does it have? British Birds. 95(7): 334–344. Close ).

Very little known. Eggs found in May and species was said to arrive on breeding grounds no earlier than c. 10 May (3 Gretton, A., Yurlov, A.K. and Boere, G.C. (2002). Where does the Slender-billed Curlew nest, and what future does it have? British Birds. 95(7): 334–344. Close ); may apparently breed in small colonies, with nests 2–3 m apart, up to 10–15 m apart; nest in dense growth on dry areas within bogs, constructed of dry grass and sited in shallow hollows. Four eggs (variation unknown), colour dark olive or yellowish green, with even dark brown or red-brown markings (3 Gretton, A., Yurlov, A.K. and Boere, G.C. (2002). Where does the Slender-billed Curlew nest, and what future does it have? British Birds. 95(7): 334–344. Close , 24 McGhie, H.A. (2002). The egg of the Slender-billed Curlew at The Manchester Museum: a unique specimen? British Birds. 95(7): 359–360. Close ), size variously reported as c. 52·5–54·5 mm × 38–40·1 mm and 64–65·6 mm × 45–47·1 mm (3 Gretton, A., Yurlov, A.K. and Boere, G.C. (2002). Where does the Slender-billed Curlew nest, and what future does it have? British Birds. 95(7): 334–344. Close ). Few other data, but young said to fledge in early Jul and species was thought to depart breeding grounds in second half of Aug (3 Gretton, A., Yurlov, A.K. and Boere, G.C. (2002). Where does the Slender-billed Curlew nest, and what future does it have? British Birds. 95(7): 334–344. Close ).

CRITICALLY ENDANGERED. CITES I. Has only been definitely recorded breeding in Tara region N of Omsk in SW Siberia (although also claimed in Iran), but no nesting records since 1925 and species was known to have been already declining around Omsk by first decade of 20th century (3 Gretton, A., Yurlov, A.K. and Boere, G.C. (2002). Where does the Slender-billed Curlew nest, and what future does it have? British Birds. 95(7): 334–344. Close ). Until early 1890s probably very abundant on wintering areas in Morocco, Algeria and Tunisia, but since then numbers have declined dramatically and species is seriously threatened. Only regularly used wintering site was Merja Zerga , NW Morocco, but none recorded there since 1995 (perhaps 1998), while only recent claim from W Siberia involved a bird seen only in flight in Jul 1996 (3 Gretton, A., Yurlov, A.K. and Boere, G.C. (2002). Where does the Slender-billed Curlew nest, and what future does it have? British Birds. 95(7): 334–344. Close ). In 1964, as many as 500–800 birds were counted in SW Morocco (12 Thévenot, M., R. Vernon, and P. Bergier (2003). The Birds of Morocco: An Annotated Check-list. British Ornithologists’ Union Check-list 20. British Ornithologists’ Union, Tring, UK. Close ). During 1980–1990, there were only 103 records globally, involving 316–326 birds BirdLife International (2015) Species factsheet: Numenius tenuirostris. Downloaded from http://www.birdlife.org on 16/01/2015. , in 1990–1999, declining to 74 records involving 148–152 birds BirdLife International (2015) Species factsheet: Numenius tenuirostris. Downloaded from http://www.birdlife.org on 16/01/2015. . Between 1980 and 1995, some 25% of observations on record were made in Greece, of which 80% were at two localities (Evros Delta and Porto Lagos) (25 Vangeluwe, D., Handrinos, G. and Bulteau, V. (1998). Le point sur le Courlis à bec grêle Numenius tenuirostris. Où l’observer, comment l’identifier? [Slender-billed Curlew: its history, current status and identification]. Ornithos. 5(1): 22–35. (In French with English summary.). Close ), but it has been suggested that at least some of these records should be critically reassessed, given the lack of photo-documentation for many of these sightings and the paucity of records in the same period elsewhere within the species’ known range involving huge flocks as in Greece (11 Kirwan, G.M., Porter, R. and Scott, D. (2015). Chronicle of an extinction? A review of Slender-billed Curlew records in the Middle East. British Birds. 108(11): 669–682. Close ). Timeline to extinction may therefore have been much earlier than usually envisaged (the species was only admitted to list of globally threatened birds in 1980s). Although there have been reports from Bulgaria, Ukraine and Uzbekistan of larger groups, almost all recent sightings in entire non-breeding range usually involve only 1–5 birds; in S Italy, c. 20 birds reported in Jan–Mar 1995 (26 Serra, L., Baccetti, N. and Zenatello, M. (1995). Slender-billed Curlews wintering in Italy in 1995. Birding World. 8(8): 295–299. Close ); surprising report of 50 birds from Iran in 1994, but these not now generally accepted (see Movements). Last nationally accepted record is from Hungary in Apr 2001 (27 Oláh, J. and Pigniczk, C. (2010). The first XXIst century record of Slender-billed Curlew (Numenius tenuirostris) in Hungary. Aquila. 116/117: 49–53. Close ), but British record from May 1998, originally accepted, now rejected (28 Cleeves, T. (1998). The Slender-billed Curlew in Northumberland – a new British bird. Birding World. 11(5): 181–191. Close , 29 Cleeves, T. (2002). Slender-billed Curlew in Northumberland: new to Britain and Ireland. British Birds. 95(6): 272–278. Close , 30 Steele, J. and Vangeluwe, D. (2002). From the Rarities Committee’s files: the Slender-billed Curlew at Druridge Bay, Northumberland, in 1998. British Birds. 95(6): 279–299. Close , 31 Collinson, J.M., Rowlands, A., Steele, J.G., McInerny, C.J. and Hudson, N. (2014). The review of the record of Slender-billed Curlew at Druridge Bay, Northumberland. British Birds. 107(7): 389–404. Close ). Population estimated at 50–270 birds in 1994, but the extreme paucity of recent confirmed records suggests it is now fewer than 50 birds BirdLife International (2015) Species factsheet: Numenius tenuirostris. Downloaded from http://www.birdlife.org on 16/01/2015. and there has been intense speculation that species is already extinct (32 Wassink, A. (2013). Comments on a recently published checklist of the birds of Kazakhstan. Sandgrouse. 35(1): 87–89. Close ). A Slender-billed Curlew Working Group was established in 1997 and relaunched in Dec 2008; its principal aim is to locate any surviving individuals, protect them and their habitats and, if a bird is found, to fit it with a satellite transmitter, in an effort to rediscover the species’ breeding grounds (10 Crockford, N. (2009). Is the Slender-billed Curlew Numenius tenuirostris in Asia? BirdingASIA. 12: 116–120. Close , 33 Buchanan, G., Crockford, N. and Gretton, A. (2010). The Slender-billed Curlew Numenius tenuirostris in Africa. Bull. African Bird Club. 17(2): 202–206. Close ). However, targeted surveys (e.g. in Iran (34 van Diek, H., R. Felix, M. Hornman, P. L. Meininger, F. Willems, and M. Zekhuis (2004). Bird counting in Iran in January 2004. Dutch Birding 26(6):287–296. Close ), Kazakhstan (32 Wassink, A. (2013). Comments on a recently published checklist of the birds of Kazakhstan. Sandgrouse. 35(1): 87–89. Close ), Saudi Arabia (35 Ahmed, R. (2012). Slender-billed Curlew survey in Saudi Arabia January 25811. Phoenix. 28: 24. Close ), Tunisia) (36 Azafzaf, H., Gretton, A., Kiss, J.B., Smart, M., Zenatello, M. and Feltrup-Azafzaf, C. (2007). Search for the Slender-billed Curlew (Numenius tenuirostris) in Tunisia in January 297973. Ostrich. 78(2): 505. Close ), organized by the Working Group, have all failed to find any evidence for its survival. Species used to stage in steppes, and its decline may be due to massive loss of this particular habitat; also hunting, particularly on migration, and drainage of staging areas may have been significant. Breakdown of social behaviour patterns in a species that formerly migrated in large flocks may also constrain recovery. It has recently been suggested that the main breeding areas were not located in W Siberia but in steppe zone, which has been cultivated on a large scale, thus perhaps explaining rapid decline of species. Area N of Caspian Sea, between R Volga and R Ural, has been suggested as potential breeding location.