Curlew Sandpiper (BirdLife factsheet) breeds across Arctic Siberia from the Yamal Peninsula to Kolyuchinskaya Gulf (N Chukotskiy Peninsula), and winters from sub-Saharan Africa through Middle East and S & SE Asia to Australasia (van Gils and Wiersma 1996).
Globally, it has an extremely large range in both the breeding season and in winter, and hence does not approach the thresholds for Vulnerable under the range size criteria (B and D2). Its population size is also extremely large (1,085,000–1,285,000 individuals; Wetlands International 2015), and hence does not approach the thresholds for Vulnerable under the population size criteria (C and D1). Therefore, the only potentially relevant criterion is A, which relates to reductions in population size. Until recently, the population was thought to be increasing, and therefore did not approach the threshold for listing as Vulnerable under criterion A (at least a 30% decline over ten years or three generations, whichever is longer).
The following summary is based on that in Wetlands International (2015):
|Population breeds / winters||Size (individuals)||% of total||Trend and sources|
|Central Siberia/SW Asia E & S Africa||400,000||31-37%||Long term increase, apparently short term rapid decline (Nagy et al. 2014). Treated as Declining by Wetlands International (2015)|
|Western Siberia/West Africa||350,000-450,000||30-38%||Declining (van Roomen et al. 2014)|
|S Asia (non-breeding)||200,000-300,000||17-25%||Unknown (Wetlands International 2015)|
|E, SE Asia & Australia (non-breeding)||135,000||11-12%||Extremely rapid decline (80.5% in three generations; Garnett 2015)|
Trend in SW Asia/Middle East/East and Southern African wintering population
Nagy et al. (2014) report a long term moderate increase, and short term large decline since c.2007, based on TRIM analysis of International Waterbird Census data from 1988-2012. However, the range of this population was not very well covered, particularly in the Red Sea and southern Gulf.
A wintering population of c.45,000 at Walvis Bay and Sandwich harbour (Namibia) was stable between 1990-2013 (Simmons et al. 2015).
Trend in West African wintering population
Van Roomen et al. (2014) interpret count data from this wintering population as showing a short-term decline based on wintering counts for the period of 2003-2014 and also a long-term decline for the period of 1979-2014, however the large amount of inter-annual variation make interpretation of the data difficult. Total wintering numbers were estimated at 565,402 in the 1980s, 738,503 in the 1990s and 348,079 (rounded and raised to 350,000-450,000) in the 2010s. Dodman (2014) however estimated 875,000 and proposed to maintain the previous increasing trend of this population. Using the smoothed trend line produced by van Roomen et al. (2014) produces a decline of 32.9% over three generations (23 years), however it is uncertain whether this is truly representative.
Trend in South Asian wintering population
Reported as unknown by Wetlands International (2015).
Trend in the East Asian-Australasian Flyway population
c.11-12% of the global population uses the flyway. BirdLife Australia’s Threatened Species Committee, which applies the IUCN Categories and Criteria at the national level, recently recommended uplisting to Critically Endangered (under criterion A2bc+3bc+4bc) in Australia (Garnett 2015), and the recommendation was subsequently accepted by the BirdLife Australia Research and Conservation Committee. The proposal was based on a detailed analysis of all monitoring data collected on shorebirds around Australia and New Zealand in the last 30 years (Studds et al. in prep) – see extract here:
|Annual rate of decline||Generation time||Loss over three generations||Action Plan status 2010||Recommended status 2015|
|-0.075||7.6||-80.5||Endangered (Vulnerable)||Critically Endangered|
The analysis used Bayesian binomial mixture models of non-breeding count data throughout Australia and New Zealand to estimate trends for subpopulations thought to follow different migration routes and summarized these estimates to yield flyway-level trends. Count data for each taxon were acquired from local and national databases in Australia and New Zealand. Many counts began in the early 1980s, but several key sites initiated counts in the 1990s.
For shorebirds of the East Asian-Australasian Flyway there is considerable concern that loss of intertidal stopover habitat in the Yellow Sea region of East Asia is driving population declines (Amano et al. 2010; Yang et al. 2011). Up to 65 percent of intertidal habitat in the Yellow Sea has been lost over the past 50 years, and habitat is currently disappearing at a rate of >1 percent annually owing to reclamation for agriculture, aquaculture, and other development (Murray et al. 2014). Current rates of Yellow Sea habitat loss seem likely to continue or accelerate owing to projected human population growth, much of it concentrated along the margins of the Yellow Sea.
Declines in count data in Australia from c.85,000 in 1993 to c22,000 in 2012 (Studds et al. in prep) imply that if this decline is representative of flyway population, and if the 2007-2009 estimate of 135,000 individuals for whole EAAF flyway was correct, there would have been 382,500 birds in the flyway in 1993. This is far higher than previous estimates, suggesting either that the flyway population was previously underestimated, or that the Australian data are not representative of the whole flyway trend. Since the key threat is assumed to be loss of habitat at Yellow Sea stopover sites, and this species is one of the most dependent on these sites, the Australian declines may well be representative of the flyway. However, Amano et al. (2010) found no clear trend in Japan between 1978-2008.
Due to uncertainties over the population trend in much of the range the overall trend is very difficult to determine. However, even if the Middle East/East and South African population is assumed to be stable (despite recent indications of a rapid decline), and the South Asian population is also assumed to be stable, if the EAAF population is declining as fast as Australian data suggest, and the large West African population has declined in the manner implied by van Roomen et al. (2014), an overall decline of 32-40% in three generations may have taken place. This would imply that the species could warrant listing as Vulnerable. However, given the uncertainties outlined above, it may be appropriate to infer a more conservative rate of decline. Conversely, if there is evidence for decline in populations currently assumed to be stable, the overall rate of decline may be even higher.
Comments on all population size and trend estimates and threats to the species are welcomed, in particular from parts of the range where data are limited.
Amano, T., T. Szekely, K. Koyama, H. Amano, and W. J. Sutherland. 2010. A framework for monitoring the status of populations: An example from wader populations in the East Asian-Australasian flyway. Biological Conservation 143:2238-2247.
Bamford, M.; Watkins, D.; Bancroft, W.; Tischler, G.; Wahl, J. 2008. Migratory shorebirds of the East Asian-Australasian flyway: population estimates and internationally important sites. Wetlands International – Oceania, Canberra.
Delany, S.; Scott, D.; Dodman, T.; Stroud, D. 2009. An atlas of wader populations in Africa and Western Eurasia. Wetlands International, Wageningen, The Netherlands.
Dodman, T. 2014. Status, Estimates and Trends of Waterbird Populations in Africa: AEWA-listed African populations. Wetlands International. Consultation draft. http://www.wetlands.org/Portals/0/CSR6%20Africa%20populations%20DRAFT%20140928.pdf
Garnett, S. T. 2015. BirdLife Australia Threatened Species Committee report to RACC. 23rd January 2015. Unpublished report.
Moores N., Rogers D., Kim R-H., Hassell C., Gosbell K., Kim S-A & Park M-N. 2008. The 2006-2008 Saemangeum Shorebird Monitoring Program Report. Birds Korea publication, Busan. http://www.awsg.org.au/pdfs/Saemangeum-Report.pdf
Murray, N. J., R. S. Clemens, S. R. Phinn, H. P. Possingham, and R. A. Fuller. 2014. Tracking the rapid loss of tidal wetlands in the Yellow Sea. Frontiers in Ecology and the Environment 12:267-272 http://www.fullerlab.org/wp-content/uploads/2014/05/Murray-et-al-2014.pdf
Nagy, S., Flink, S., Langendoen, T. (2014) Waterbird trends 1988-2012: Results of trend analyses of data from the International Waterbird Census in the African-Eurasian Flyway. Wetlands International, Ede. www.wetlands.org/Portals/0/TRIM Report 2014_10_05.pdf
Simmons, R.E.; Kolberg, H.; Braby, R.; Erni, B. 2015. Declines in migrant shorebird populations from a winter-quarter perspective. Conservation Biology 29(3): 877-887.
Studds, C. E. et al. in prep. Dependence on the Yellow Sea predicts population collapse in a migratory flyway.
Van Gils, J. & Wiersma, P. (1996). Curlew Sandpiper (Calidris ferruginea). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.) (2014). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from http://www.hbw.com/node/53935 on 23 July 2015).
van Roomen, M., van Winden, E. & Langendoen, T. (2014) The assessment of trends and population sizes of a selection of waterbird species and populations from the coastal East Atlantic Flyway for Conservation Status Report 6 of The African Eurasian Waterbird Agreement. http://www.wetlands.org/Portals/0/EAF_selection%20of%20species2014_2.doc.pdf
Wetlands International (2015). “Waterbird Population Estimates” . Retrieved from wpe.wetlands.org on Wednesday 22 Jul 2015
Yang, H. Y., B. Chen, M. Barter, T. Piersma, C. F. Zhou, F. S. Li, and Z. W. Zhang. 2011. Impacts of tidal land reclamation in Bohai Bay, China: ongoing losses of critical Yellow Sea waterbird staging and wintering sites. Bird Conservation International 21: 241-259