Slender-billed Curlew
Encyclopedia
The Slender-billed Curlew, Numenius tenuirostris, is a bird
in the wader
family Scolopacidae
. It breeds in marshes and peat bogs in the taiga
of Siberia
, and is migratory
, formerly wintering in shallow freshwater habitats around the Mediterranean. This species has occurred as a vagrant in western Europe
, the Canary Islands
, the Azores
, Oman
, Canada
and Japan
.
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The Slender-billed Curlew is a medium-sized curlew
, 36–41 cm in length with a 77–88 cm wingspan. It is therefore about the same size as a Whimbrel
, but it is more like the Eurasian Curlew
in plumage. The breeding adult is mainly greyish brown above, with a whitish rump and lower back. The underparts are whitish, heavily streaked with dark brown. The flanks have round or heart-shaped spots. The non-breeding plumage is similar, but with fewer flank spots. Male and female are alike in plumage, but females are longer-billed than males, an adaptation in curlew species that avoids direct competition for food between the sexes. The juvenile plumage is very similar to the adult, but the flank are marked with brown streaking, the heart-shaped spots only appearing towards the end of the first winter.
Compared to the Eurasian Curlew, the Slender-billed Curlew is whiter on the breast, tail and underwing, and the bill is shorter, more slender, and slightly straighter at the base. The arrowhead-shaped flank spots of the Eurasian Curlew are also different from the round or heart-shaped spots of the Slender-billed. The head pattern, with a dark cap and whitish supercilium
, recalls that of the Whimbrel, but that species also has a central crown stripe and a more clearly marked pattern overall; the pattern of the Slender-billed Curlew would be hard to make out in the field.
This species shows more white than other curlews, and the white underwings, along with the distinctive flank markings, are key identification criteria.
Slender-billed Curlews feed by using their bill
s to probe soft mud for small invertebrate
s, but will also pick other small items off the surface if the opportunity arises. It used to be highly gregarious outside the breeding season, associating with related species, particularly Eurasian Curlews.
. It is actually the first European bird species highly likely to become entirely extinct since the last Great Auk
died over 150 years ago.
The primary cause of the decline is thought to be excessive hunting
on the Mediterranean wintering grounds. Habitat loss, particularly in the wintering grounds, may also have played a part, but huge areas of forest bogs suitable for breeding still exist in Siberia. It is unknown to what extent the birds still reproduce successfully, and how much gene flow
still exists in what may once have been a large and widely dispersed population undergoing little purging of deleterious recessive allele
s and consequently with a high MVP
. Furthermore, although there is evidence that birds in winter quarters were more numerous once and in general not a very rare sight in Western Europe
in the 19th century and were hunted with some regularity - and later on also threatened by pollution
, e.g. oil spill
s -, there is no data how these threats endanger the species today exist. Theoretically they might have retreated to all but inaccessible areas, but then, a single hunter might unwittingly wipe out enough of the few remaining birds to doom the species.
The only well documented nest was found in 1924, near Tara
in Omsk
oblast
, Siberia
(57°N 74°E).
Its nesting grounds since then remain unknown, despite several intensive searches (not surprising, with over 100,000 square kilometres to search). The extent of its decline is also reflected in the absence of wintering birds at previously regular Moroccan
sites.
More recently, 20 birds were recorded in Italy
in 1995. Remarkably, there is also a single recent (4–7 May 1998) record of an immature (one year old) at Druridge Pools in Northumberland
, England
,
for details of which see the Druridge Bay curlew
.
Slender-billed Curlews have been reported in various Western Palearctic
locations on a number of occasions since the Druridge bird, including claimed, but unverified, sightings of single birds from Italy and Greece
; none have been documented with conclusive photographs and at least one claimed bird, at RSPB Minsmere
, Suffolk
, England
in 2004, is now widely believed to have been a Eurasian Curlew.
Further sourced reports of the species were published in 2007, in British Birds magazine
; the article stated, quoting from Zhmud:
A sighting of a single bird was reported from Albania
in 2006 by a team including ornithologists from the environmental organization EuroNatur.
Thus, though hard proof is lacking but given the extent of possible habitat and the precautionary principle
, it is believed to be extant for the time being. Apparently at least the wintering range has starkly contracted; it appears that the handful of family or neighbor groups that are left retreat to remote habitat in southeastern Europe in winter. The IUCN classifies it as Critically Endangered
(CR) C2a(ii); D. This means that an estimated 50 mature birds or less are believed to exist, with numbers declining, and that there is probably only one subpopulation.
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
in the wader
Wader
Waders, called shorebirds in North America , are members of the order Charadriiformes, excluding the more marine web-footed seabird groups. The latter are the skuas , gulls , terns , skimmers , and auks...
family Scolopacidae
Scolopacidae
The sandpipers are a large family, Scolopacidae, of waders or shorebirds. They include many species called sandpipers, as well as those called by names such as curlew and snipe. The majority of these species eat small invertebrates picked out of the mud or soil...
. It breeds in marshes and peat bogs in the taiga
Taiga
Taiga , also known as the boreal forest, is a biome characterized by coniferous forests.Taiga is the world's largest terrestrial biome. In North America it covers most of inland Canada and Alaska as well as parts of the extreme northern continental United States and is known as the Northwoods...
of Siberia
Siberia
Siberia is an extensive region constituting almost all of Northern Asia. Comprising the central and eastern portion of the Russian Federation, it was part of the Soviet Union from its beginning, as its predecessor states, the Tsardom of Russia and the Russian Empire, conquered it during the 16th...
, and is migratory
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
, formerly wintering in shallow freshwater habitats around the Mediterranean. This species has occurred as a vagrant in western Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, the Canary Islands
Canary Islands
The Canary Islands , also known as the Canaries , is a Spanish archipelago located just off the northwest coast of mainland Africa, 100 km west of the border between Morocco and the Western Sahara. The Canaries are a Spanish autonomous community and an outermost region of the European Union...
, the Azores
Azores
The Archipelago of the Azores is composed of nine volcanic islands situated in the middle of the North Atlantic Ocean, and is located about west from Lisbon and about east from the east coast of North America. The islands, and their economic exclusion zone, form the Autonomous Region of the...
, Oman
Oman
Oman , officially called the Sultanate of Oman , is an Arab state in southwest Asia on the southeast coast of the Arabian Peninsula. It is bordered by the United Arab Emirates to the northwest, Saudi Arabia to the west, and Yemen to the southwest. The coast is formed by the Arabian Sea on the...
, Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
and Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
.
Appearance
Curlew
The curlews , genus Numenius, are a group of eight species of birds, characterised by long, slender, downcurved bills and mottled brown plumage. They are one of the most ancient lineages of scolopacid waders, together with the godwits which look similar but have straight bills...
, 36–41 cm in length with a 77–88 cm wingspan. It is therefore about the same size as a Whimbrel
Whimbrel
The Whimbrel Numenius phaeopus, is a wader in the large family Scolopacidae. It is one of the mostwidespread of the curlews, breeding across much of subarctic North America, Europe and Asia as far south as Scotland....
, but it is more like the Eurasian Curlew
Eurasian Curlew
The Eurasian Curlew, Numenius arquata, is a wader in the large family Scolopacidae. It is one of the most widespread of the curlews, breeding across temperate Europe and Asia...
in plumage. The breeding adult is mainly greyish brown above, with a whitish rump and lower back. The underparts are whitish, heavily streaked with dark brown. The flanks have round or heart-shaped spots. The non-breeding plumage is similar, but with fewer flank spots. Male and female are alike in plumage, but females are longer-billed than males, an adaptation in curlew species that avoids direct competition for food between the sexes. The juvenile plumage is very similar to the adult, but the flank are marked with brown streaking, the heart-shaped spots only appearing towards the end of the first winter.
Compared to the Eurasian Curlew, the Slender-billed Curlew is whiter on the breast, tail and underwing, and the bill is shorter, more slender, and slightly straighter at the base. The arrowhead-shaped flank spots of the Eurasian Curlew are also different from the round or heart-shaped spots of the Slender-billed. The head pattern, with a dark cap and whitish supercilium
Supercilium
The supercilium is a plumage feature found on the heads of some bird species. It is a stripe which runs from the base of the bird's beak above its eye, finishing somewhere towards the rear of the bird's head. Also known as an "eyebrow", it is distinct from the eyestripe, which is a line which runs...
, recalls that of the Whimbrel, but that species also has a central crown stripe and a more clearly marked pattern overall; the pattern of the Slender-billed Curlew would be hard to make out in the field.
This species shows more white than other curlews, and the white underwings, along with the distinctive flank markings, are key identification criteria.
Vocalisations
The call is a cour-lee, similar to that of the Eurasian Curlew but higher-pitched, more melodic and shorter. The alarm call is a fast cu-ee.Behavior
Little is known about the breeding biology, but the few nests observed had on average four eggs.Slender-billed Curlews feed by using their bill
Beak
The beak, bill or rostrum is an external anatomical structure of birds which is used for eating and for grooming, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young...
s to probe soft mud for small invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s, but will also pick other small items off the surface if the opportunity arises. It used to be highly gregarious outside the breeding season, associating with related species, particularly Eurasian Curlews.
Status
After a long period of steady decline, the Slender-billed Curlew is extremely rare, with only a minute and still declining population. This is thought to be under 50 adult birds, with no more than two or three verified sightings in any year in the last five . As a result it is now listed as critically endangeredCritically endangered
Version 2010.3 of the IUCN Red List of Threatened Species identified 3744 Critically Endangered species, subspecies and varieties, stocks and subpopulations.Critically Endangered by kingdom:*1993 Animalia*2 Fungi*1745 Plantae*4 Protista-References:...
. It is actually the first European bird species highly likely to become entirely extinct since the last Great Auk
Great Auk
The Great Auk, Pinguinus impennis, formerly of the genus Alca, was a large, flightless alcid that became extinct in the mid-19th century. It was the only modern species in the genus Pinguinus, a group of birds that formerly included one other species of flightless giant auk from the Atlantic Ocean...
died over 150 years ago.
The primary cause of the decline is thought to be excessive hunting
Hunting
Hunting is the practice of pursuing any living thing, usually wildlife, for food, recreation, or trade. In present-day use, the term refers to lawful hunting, as distinguished from poaching, which is the killing, trapping or capture of the hunted species contrary to applicable law...
on the Mediterranean wintering grounds. Habitat loss, particularly in the wintering grounds, may also have played a part, but huge areas of forest bogs suitable for breeding still exist in Siberia. It is unknown to what extent the birds still reproduce successfully, and how much gene flow
Gene flow
In population genetics, gene flow is the transfer of alleles of genes from one population to another.Migration into or out of a population may be responsible for a marked change in allele frequencies...
still exists in what may once have been a large and widely dispersed population undergoing little purging of deleterious recessive allele
Allele
An allele is one of two or more forms of a gene or a genetic locus . "Allel" is an abbreviation of allelomorph. Sometimes, different alleles can result in different observable phenotypic traits, such as different pigmentation...
s and consequently with a high MVP
Minimum Viable Population
Minimum viable population is a lower bound on the population of a species, such that it can survive in the wild. This term is used in the fields of biology, ecology, and conservation biology...
. Furthermore, although there is evidence that birds in winter quarters were more numerous once and in general not a very rare sight in Western Europe
Western Europe
Western Europe is a loose term for the collection of countries in the western most region of the European continents, though this definition is context-dependent and carries cultural and political connotations. One definition describes Western Europe as a geographic entity—the region lying in the...
in the 19th century and were hunted with some regularity - and later on also threatened by pollution
Pollution
Pollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat or light...
, e.g. oil spill
Oil spill
An oil spill is the release of a liquid petroleum hydrocarbon into the environment, especially marine areas, due to human activity, and is a form of pollution. The term is mostly used to describe marine oil spills, where oil is released into the ocean or coastal waters...
s -, there is no data how these threats endanger the species today exist. Theoretically they might have retreated to all but inaccessible areas, but then, a single hunter might unwittingly wipe out enough of the few remaining birds to doom the species.
The only well documented nest was found in 1924, near Tara
Tara, Russia
Tara is a town in Omsk Oblast, Russia, located about north of Omsk, at the confluence of the Tara and Irtysh Rivers at a point where the forested country merges into the steppe. It serves as the administrative center of Tarsky District, although it is not administratively a part of it...
in Omsk
Omsk
-History:The wooden fort of Omsk was erected in 1716 to protect the expanding Russian frontier along the Ishim and the Irtysh rivers against the Kyrgyz nomads of the Steppes...
oblast
Oblast
Oblast is a type of administrative division in Slavic countries, including some countries of the former Soviet Union. The word "oblast" is a loanword in English, but it is nevertheless often translated as "area", "zone", "province", or "region"...
, Siberia
Siberia
Siberia is an extensive region constituting almost all of Northern Asia. Comprising the central and eastern portion of the Russian Federation, it was part of the Soviet Union from its beginning, as its predecessor states, the Tsardom of Russia and the Russian Empire, conquered it during the 16th...
(57°N 74°E).
Its nesting grounds since then remain unknown, despite several intensive searches (not surprising, with over 100,000 square kilometres to search). The extent of its decline is also reflected in the absence of wintering birds at previously regular Moroccan
Morocco
Morocco , officially the Kingdom of Morocco , is a country located in North Africa. It has a population of more than 32 million and an area of 710,850 km², and also primarily administers the disputed region of the Western Sahara...
sites.
More recently, 20 birds were recorded in Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
in 1995. Remarkably, there is also a single recent (4–7 May 1998) record of an immature (one year old) at Druridge Pools in Northumberland
Northumberland
Northumberland is the northernmost ceremonial county and a unitary district in North East England. For Eurostat purposes Northumberland is a NUTS 3 region and is one of three boroughs or unitary districts that comprise the "Northumberland and Tyne and Wear" NUTS 2 region...
, England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
,
for details of which see the Druridge Bay curlew
The Druridge Bay curlew
The Druridge Bay curlew was a curlew which was present in Druridge Bay, Northumberland in May 1998, whose species identification proved to be controversial. The bird was identified by its finder, and most others who saw it, as a first-summer Slender-billed Curlew, one of the rarest birds in the...
.
Slender-billed Curlews have been reported in various Western Palearctic
Palearctic
The Palearctic or Palaearctic is one of the eight ecozones dividing the Earth's surface.Physically, the Palearctic is the largest ecozone...
locations on a number of occasions since the Druridge bird, including claimed, but unverified, sightings of single birds from Italy and Greece
Greece
Greece , officially the Hellenic Republic , and historically Hellas or the Republic of Greece in English, is a country in southeastern Europe....
; none have been documented with conclusive photographs and at least one claimed bird, at RSPB Minsmere
RSPB Minsmere
Minsmere RSPB reserve is a nature reserve owned and run by the Royal Society for the Protection of Birds in Suffolk, England. It lies on the Suffolk coast to the south of Southwold and north of Aldeburgh within the Suffolk Coast and Heaths Area of Outstanding Natural Beauty and the Suffolk...
, Suffolk
Suffolk
Suffolk is a non-metropolitan county of historic origin in East Anglia, England. It has borders with Norfolk to the north, Cambridgeshire to the west and Essex to the south. The North Sea lies to the east...
, England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
in 2004, is now widely believed to have been a Eurasian Curlew.
Further sourced reports of the species were published in 2007, in British Birds magazine
British Birds (magazine)
British Birds is a monthly ornithology magazine that was established in 1907. It is now published by BB 2000 Ltd, which is wholly owned by The British Birds Charitable Trust , established for the benefit of British ornithology...
; the article stated, quoting from Zhmud:
During the last few years, small groups of birds have been found in the northern coastal areas [of the Danube DeltaDanube DeltaThe Danube Delta is the second largest river delta in Europe, after the Volga Delta, and is the best preserved on the continent. The greater part of the Danube Delta lies in Romania , while its northern part, on the left bank of the Chilia arm, is situated in Ukraine . The approximate surface is...
], frequenting low-lying islands, bays and sand-spits covered with Common Glasswort Salicornia europaea [...] Four birds were present from 25th July to 21st August 2003, six were seen on 11th August 2004, and another on 12th August 2004.
A sighting of a single bird was reported from Albania
Albania
Albania , officially known as the Republic of Albania , is a country in Southeastern Europe, in the Balkans region. It is bordered by Montenegro to the northwest, Kosovo to the northeast, the Republic of Macedonia to the east and Greece to the south and southeast. It has a coast on the Adriatic Sea...
in 2006 by a team including ornithologists from the environmental organization EuroNatur.
Thus, though hard proof is lacking but given the extent of possible habitat and the precautionary principle
Precautionary principle
The precautionary principle or precautionary approach states that if an action or policy has a suspected risk of causing harm to the public or to the environment, in the absence of scientific consensus that the action or policy is harmful, the burden of proof that it is not harmful falls on those...
, it is believed to be extant for the time being. Apparently at least the wintering range has starkly contracted; it appears that the handful of family or neighbor groups that are left retreat to remote habitat in southeastern Europe in winter. The IUCN classifies it as Critically Endangered
Critically Endangered
Critically Endangered is the highest risk category assigned by the IUCN Red List for wild species. Critically Endangered means that a species' numbers have decreased, or will decrease, by 80% within three generations....
(CR) C2a(ii); D. This means that an estimated 50 mature birds or less are believed to exist, with numbers declining, and that there is probably only one subpopulation.
General references
- Hayman, Peter; Marchant, John & Prater, Tony (1986): Shorebirds: an identification guide to the waders of the world. Houghton Mifflin, Boston. ISBN 0-395-60237-8
- Svensson, Lars; Zetterström, Dan; Mullarney, Killian & Grant, P. J. (1999): Collins bird guide. Harper & Collins, London. ISBN 0-00-219728-6
Identification
- Identification of Slender-billed Curlew, John Marchant, British Birds 77: 135-140.
- Slender-billed Curlew studies, Richard Porter, British Birds 77: 581-586.
- Habitat of Slender-billed Curlews in Morocco, Arnoud van den Berg, British Birds 83: 1-7.
- Slender-billed Curlew in Tunisia in Feb 1984, Eddy Wijmengs & Klaas van Dijk, Dutch Birding 7: 67-68.
- Slender-billed Curlews in Morocco in Feb 1979, Peter Ewins, Dutch Birding 11: 119-120.
- Identification of Slender-billed Curlew and its occurrence in Morocco in winter 1987/88, Arnoud van den Berg, Dutch Birding 10: 45-53.
- Slender-billed Curlew on Sicily in March 1996, Andrea Corso, Dutch Birding 18: 302.
- Slender-billed Curlew collected at Canis-vliet in September 1896, Gunter De Smet, Dutch Birding 19: 230-232.
- The identification of the Slender-billed Curlew, British Birds Vol 56 No8 1963
External links
- ARKive: Photographs of Slender-billed Curlew (Numenius tenuirostris). Retrieved 2007-APR-06.
- BirdLife International: Species factsheet. Retrieved 2007-APR-06.
- BirdLife International: Additional data. Retrieved 2007-APR-06.
- British Ornithologists' Union Records Committee: Slender-billed Curlew at Druridge Pools accepted as first for Britain (with photo). Retrieved 2007-APR-06.
- Photos from Morocco. Retrieved 2007-APR-06.
- The RSPB project: Slender-billed Curlew.
- Surfbirds.com: The Slender-billed Curlew in Northumberland, 1998 - 'plate 164' - response by the British Birds Rarities CommitteeBritish Birds Rarities CommitteeThe British Birds Rarities Committee , established in 1959, is the national bird rarities committee for Britain. It assesses claimed sightings of bird species that are rarely seen in Britain, based on descriptions, photographs and video recordings submitted by observers...
and more photos of the "Druridge Bay curlew". Retrieved 2007-APR-06. - Convention on Migratory Species: Slender-billed Curlew Memorandum of Understanding
- CIC - International Council for Game and Wildlife Conservation: CIC Species Conservation: Slender-billed Curlew