“The beauty and genius of a work of art may be reconceived, though its first material expression be destroyed; a vanished harmony may yet again inspire the composer; but when the last individual of a race of living beings breathes no more, another heaven and another earth must pass before such a one can be again”
William Beebe (1906)
Numenius of the World in Decline
There are eight species of curlew around the globe of which only three are considered ‘Least Concern’ on the International Union for Conservation of Nature (IUCN) Red List (Whimbrel, Long-billed Curlew and Little Curlew). One species is considered ‘Near Threatened’ (Eurasian Curlew), one is assessed as being ‘Vulnerable’ (Bristle-thighed Curlew), one is considered ‘Endangered’ (Far Eastern Curlew,) and two are ‘Critically Endangered’ (Slender-billed Curlew and Eskimo Curlew).
Species in Decline…
Eurasian Curlew – Near Threatened
The Eurasian Curlew breeds in upper middle latitudes, extending north as far as the subarctic, but otherwise in boreal, temperate, and steppe zones preferring damp or wet terrain with dry patches; especially near water. Characteristically an upland bird in Britain, with most breeding up to 550m above sea level (although a few as high as 760m), but also in the lowlands, preferring open landscapes with wide visibility unbroken by forest, woodland, or ravines and other features permitting the surprise approach by predators.
After the breeding season Eurasian Curlews shift to coastal habitats, especially mudflats and sands extensively exposed at low tide, resting on adjoining saltmarshes and foreshores as intertidal areas are covered. Rocky beaches with many pools and mangroves (in the tropics) are also favoured, as are muddy estuaries and comparable habitats beside large inland waters, including riversides and swamp edges. They are omnivorous, although feed principally on invertebrates.
Worrying declines are apparent in the UK with a reduction of 82% in Northern Ireland (1985-2013), 81% in Wales (1993-2006), 55% in Scotland (1995-2012) and 30% in England (1995-2012), and. It is thought that around 136,000 individuals breed in the UK, equating to 19-27% of the global population.
Bristle-thighed Curlew – Vulnerable
This species breeds on the lower Yukon River and central Seward Peninsula in western Alaska, wintering on oceanic islands (including Hawaii, the central pacific atolls, reaching the Solomon Islands and Easter Island). The most recent (2001) breeding population estimate is of 7,000 birds, with an additional 3,000 non-breeding immatures resulting in a total population of just 10,000 birds.
Classed as ‘Vulnerable’ due to its small and declining population. The decline is thought to be largely a consequence of predation and hunting on its wintering grounds (when around 50% of adults are flightless during autumn moult), with introduced predators (dogs, cats and possibly pigs) thought to be having the greatest effect. Habitat degradation is also thought to be another key factor in the decline.
Far Eastern Curlew – EndangeredFar Eastern Curlews breed in eastern Russia and winter predominantly in Australia, with the Yellow Sea, China, an important stopover site on migration. In 2006 the population was considered to be around 38,000 birds, with an estimate in 2015 suggesting that the population had reduced to 32,000 birds.
Classed as ‘Endangered’ as it is thought to be undergoing a very rapid population decline, which is suspected to be being driven by habitat loss/deterioration, particularly in the Yellow Sea staging area, where it is estimated that 65% of the intertidal habitat has been lost over the last 50 years through land reclamation.
Eskimo Curlew – Critically Endangered
The Eskimo Curlew was once one of the most abundant shorebirds across Canada and Alaska. This species was migratory, following a route between the Yukon and Northwest Territories to South America.
Towards the end of the 19th Century it is thought around 2 million birds were being killed each year. The last confirmed sightings were in 1962 on Galveston Island, Texas and on Barbados in 1963, with unconfirmed, possible sightings in 1981 (Texas), 1987 (Texas), 1990 (Argentina) and in 2006 (Nova Scotia). Large-scale spring hunting partially explains the species decline, however, hunting was outlawed in c.1916 and no recovery occurred. A further reason is undoubtedly the near total loss of prairies to agriculture. The depressing reality is that this species is now probably no longer extant.
Slender-billed Curlew – Critically Endangered
A migratory species, breeding within the marshes and bogs of Siberia and wintering in the shallow freshwater and brackish habitats around the Mediterranean and Arabian Peninsula. Although little information is available, it is thought that this species bred in small colonies and occurred in large flocks on migration and in winter. It was regarded as very common in the early 19th Century, but by the 20th Century had become rare. The last accepted observation occurred in Hungary in 2001.
Since 2008 the RSPB have been co-ordinating a search across the Western Palearctic for this species. Although the results have not yet been published, it seems likely that no birds have been found and that Slender-billed Curlew is now extinct.
Investigating the Causes in the Decline of Eurasian CurlewThe decline in the population of this species in the UK is not a recently identified issue. The ‘Red Data Birds in Britain’ published in 1990 (essentially the first ‘Birds of Conservation Concern’) identified the majority of the issues that are currently suspected to be causing the decline and noted that ‘Following a general spread in Europe in the first half of the 20th Century, there have been decreases reported subsequently from many countries, although the scale of the decrease in Britain in uncertain’.
However, it is not until relatively recently that decline has been the topic of research efforts and there are no clear answers emerging; hopefully this conservation effort did not commence too late to halt the downward trend. Nest monitoring has suggested that the decline in the population is largely due to poor breeding success which may be related to a deterioration in the availability and quality of breeding habitats as a consequence of changes in farming practices (both in upland and lowland habitats). Predation is also likely to have played a significant role, with possible other causes including the afforestation of marginal upland areas, and climate change. During the winter it is thought that it has suffered as a result of hunting, disturbance of intertidal habitats (e.g. from construction work and foot-traffic), development of high-tide roosting sites, pollution, and the flooding of estuarine mudflats and saltmarshes as a result of tidal barrage construction. Eurasian Curlew is also thought to be susceptible to avian influenza, so may be further threatened by outbreaks of the virus should this occur.
It is highly likely that the reason for the decline is not a simple one, with the cause likely relating to all these factors to a greater or lesser extent. Untangling the knot of threats to the Eurasian Curlew, and assisting this species in its recovery is therefore a complicated and difficult task; in the UK there are a variety of initiatives that are attempting to provide at least some of the answers.
The RSPB has implemented a Curlew Recovery Project, which includes the trial management of six breeding sites with the aim of improving breeding success and abundance from autumn 2015. The aim of this management will be to develop best practice management advice. The British Trust for Ornithology has launched a project which will use previously collected data to investigate patterns of local extinctions and colonisations in the UK and Europe, investigate home range use and habitat use during the breeding season and habitat use in winter.
A relatively large local population of Eurasian Curlew occur within the pastoral farmland along the Shropshire/Wales border, with 47 breeding pairs present in 2014. In 2015 a detailed monitoring programme was completed including locating 13 nests, camera-trapping of nests and radio-tracking of juveniles. The results were depressing; 38 eggs laid, six nests predated (Fox (one confirmed, four probable), Badger (one), avian (one) and unknown (one)). Nine eggs hatched, none of which survived. This monitoring scheme is scheduled to be completed again in 2016, although requires funding.
With two likely Numenius extinctions in the last 60 years, and three of the remaining six species in decline (and rapid decline in some cases) the outlook for this genus appears bleak. All species are ground-nesters, feed predominantly on invertebrates, are migratory (to a greater or lesser extent) and face similar threats – habitat loss and degradation, predation and hunting.
In his excellent book ‘Last of the Curlews’, Fred Bosworth described the fictional plight of the last Eskimo Curlew written from the birds’ perspective in 1955. This is a depressing, although thought provoking tale of a lone male bird looking for a mate, only to find one which is then shot while displaying rendering him the last Eskimo Curlew on the planet
‘The thunder burst upon them out of the clear and vivid sky…a violent but invisible blow blasted two of the biggest feathers from one of her extended wings…At dawn he hovered high in the grey sky, his lungs swelling with the cadence of his mating song. Now she didn’t respond to the offer of courtship feeding. The tundra call was irresistible. He flew again and called once more. Then he levelled off, the rising sun glinted pinkly on his feathers, and headed north in silence, alone’.
Evidence from other likely Numenius extinctions indicates that populations can plummet with alarming speed. Without dedicated and comprehensive research in both breeding and wintering areas combined with an urgent and concerted conservation effort, it may not be too long before the last remaining bird of next threatened species in the genus faces a lonely migration.
What You Can Do…
Make an effort to monitor local populations by logging all sightings of Curlew with BirdTrack, ebird or county recorders, using the relevant breeding codes, including as much information in relation to habitats as possible and providing accurate grid references. Also, carefully check all birds for colour rings, and pass on details of the colour combinations.
Take part in the ‘BTO Breeding Waders of English Upland Farmland 2016’ monitoring project. 1,000 selected 2-km squares (tetrads) throughout England (located in upland areas) require survey by volunteers. The survey method involves two morning visits between 1st April and 15th July, during which all breeding waders and other upland farmland species are be recorded as well as habitat information –
- Financially contribute to the BTO Curlew appeal .
- Financially contribute to the monitoring of Curlew in Shropshire.
- Financially contribute to the BirdWatch Ireland ‘Cry of the Curlew’ appeal
Beebe, W (1906). The Bird, its form and function. Holt (New York)
Bodsworth, F. (1955). Last of the Curlews. The New Canadian Library
Cramp, S and Simmons, K E L (eds.) (2004) BWPi: Birds of the Western Palearctic interactive (DVD-ROM). BirdGuides Ltd, Sheffield
Eaton, M., Aebischer, N., Brown, A., Hearn, R., Lock, L., Musgrove, A., Noble, D., Stroud, D., & Gregory, R. (2015). Birds of Conservation Concern 4: the population status of birds in the UK, Channel Islands and Isle of Man. British Birds 108, December 2015, 708-746
The IUCN Red List of Threatened Species [available at: http://www.iucnredlist.org/]