Great Knot (BirdLife factsheet) breeds in north-east Siberia, Russia, wintering mainly in Australia, but also throughout the coastline of South-East Asia and on the coasts of India, Bangladesh, Pakistan, and the eastern coast of the Arabian Peninsula (Van Gils et al. 2015). The Yellow Sea of North Korea, South Korea and China is a particularly important stop-over site on migration in both spring and autumn. The global population has been estimated at 292,000-295,000 individuals in 2007 (Wetlands International 2015), after the disappearance of c.90,000 individuals following reclamation of tidal flats at Saemangeum in the South Korean Yellow Sea in 2006 (Moores et al. 2008). The vast majority of these winter in Australia, with much smaller numbers in Southeast Asia, and just 2,000-5,000 individuals in South Asia and the Middle East.
It is currently listed as Vulnerable as it is undergoing a rapid population decline which is suspected to have been primarily driven by habitat loss and deterioration.
BirdLife Australia’s Threatened Species Committee, which applies the IUCN Categories and Criteria at the national level, recently recommended its uplisting from Vulnerable to 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|
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.
Since the species is almost entirely restricted (>98% of global population) to this flyway, and loss of habitat at critical stopover sites in the Yellow Sea is suspected to be the key threat to the species, trends in the Australasian population in the non-breeding season are thought to be representative of the overall global trend, thus it is proposed that the species be listed as Endangered or Critically Endangered globally.
However, the possibility that there has been a shift in the wintering range rather than a genuine decline should also be considered.
Further evidence of genuine very rapid recent decline comes from a study of adult survival in this species, Red Knot and Bar-tailed Godwit along the East Asian-Australasian Flyway. Whereas the survival in NW Australia in late winter remained constantly high, the survival during the time away from Australia started to decline in 2011. With an annual survival rate for Great Knot during 2011-2012 of 0.63 and annual breeding output of 0.15, the study predicts that the global population of Great Knot will halve within four years, and that only the immediate protection and safeguard of suitable staging grounds in the Yellow Sea region, during both northward and southward migration, may now help to prevent extinction (Piersma et al. submitted). If these data are representative of the whole population, the species would be undergoing extremely rapid population declines and would warrant uplisting to Critically Endangered.
Comments on the proposal to uplist to Endangered or Critically Endangered, including trends from elsewhere in the range, threats to the species and the likely representativeness of the Australasian data, are welcomed.
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.
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
Piersma, T. et al. submitted. Simultaneous declines in summer survival of three shorebird species signals a flyway at risk. PLOS Biology
Studds, C. E. et al. in prep. Dependence on the Yellow Sea predicts population collapse in a migratory flyway.
Van Gils, J., Wiersma, P. & Sharpe, C.J. (2015). Great Knot (Calidris tenuirostris). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.) (2015). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from http://www.hbw.com/node/53921 on 22 July 2015).
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