This species is listed as Least Concern as its population is now growing rapidly and has not undergone the once-predicted declines. Despite its current population trend, the species remains potentially threatened by a number of factors. It tends to congregate in very large flocks, and suffered rapid declines in many parts of its range during the twentieth century because of hunting and other threats. Its roost sites are unprotected, large numbers died in a recent disease outbreak, and most importantly, the dry rice paddies where it feeds are being converted to vegetable farms and other uses. If evidence arises in the future that these threats have begun to drive a decline, the species may warrant uplisting.
AERC TAC. 2003. AERC TAC Checklist of bird taxa occurring in Western Palearctic region, 15th Draft. Available at: http://www.aerc.eu/DOCS/Bird_taxa_of _the_WP15.xls.
AOU. 1998. Check-list of North American birds. American Ornithologists' Union, Washington, D.C.
Cramp, S.; Perrins, C. M. 1977-1994. Handbook of the birds of Europe, the Middle East and Africa. The birds of the western Palearctic. Oxford University Press, Oxford.
Sibley, C. G.; Monroe, B. L. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven, USA.
Distribution and populationAnas formosa
39-43 cm. Small dabbling duck with striking head pattern. Males have complex buff, green, white and black head pattern, dark-spotted pinkish breast, grey flanks, black undertail-coverts and long chestnut, black and whitish scapulars. Female has isolated, round, pale loral spot and broken supercilium. Eclipse male resembles female. Juvenile has less defined loral spot than female, somewhat plainer head sides and dark mottling on whitish belly. Similar spp. Female Garganey A. querquedula lacks round, white loral spot and has unbroken supercilium. Voice Males utter deep, chuckling wot-wot-wot, females a low quack.
breeds in eastern Siberia, Russia
and occurs on passage in Mongolia
and North Korea
. It winters mainly in Japan
, South Korea
, which now holds the majority of the wintering population, and mainland China,
and it is a rare winter visitor to Taiwan (China)
and Hong Kong
(China). In the early 20th century, it was one of the most numerous ducks in eastern Asia and flocks of many thousands were regularly reported, but a significant decline took place since the 1960s and 1970s. Since then however, wintering counts in South Korea have increased spectacularly from the c.20,000 located in the 1980s to a total of 658,000 recorded during simultaneous surveys in 2004, including c. 600,000 in the lower reaches of the Geum River, and a staggering total of c.1.06 million counted in January 2009 (Moores et al
. 2010, N. Moores in litt
. 2010), with concentrations of over 20,000 at six different sites (N. Moores in litt
. 2010). In support of the view that a genuine population increase has taken place in South Korea, an analysis of counts conducted at 38 sites every year since 1999 indicate an increase from a yearly average of 11,533 in 1999-2003 to a yearly average of 314,994 in 2005-2009 (N. Moores in litt
. 2010). The increase in the South Korean wintering population is believed to be linked an increase in newly reclaimed land as well as a decline in hunting pressure (Moores 1996, Moores et al
. 2010, N. Moores in litt
. 2010). In January 2006 a flock of 8,000-10,000 individuals was noted at the small Chongming Dongtan Ramsar Site in China (where the previous maximum was 300 individuals) and in 2006/2007 a flock of 50,000 was recorded at Yancheng National Nature Reserve; these represent the largest flocks recorded outside of South Korea in recent years (Zhang Kejia in litt.
2006, Zhang 2006). The total national population estimate has since been placed at 91,000 individuals (Cao et al
. in prep.). The species has continued to increase its numbers and range in China (Lei Cao and M. Barter in litt
. 2010), and a possibly slow increase in the population has been noted in Japan since the 1990s, albeit with some fluctuation in numbers (Hironobu Tajiri in litt
. 2011). Population justification
The 2004 Asian Waterbird Census estimated the population in Korea at 455,000 individuals (D. Li in litt
. 2005; Wetlands International 2006). A separate study in 2004 reported 658,000 individuals in Korea (Hansoo Lee in litt
. 2004), but this could be an over-estimate. Further to this, Brazil (2009) has estimated national population sizes at <c.100 breeding pairs and c.50-10,000 wintering individuals in China and c.10,000-1 million breeding pairs in Russia.Trend justification
Surveys conducted every January since 1999 indicate a rapid and consistent increase in the numbers wintering in South Korea (Moores et al
. 2010, N. Moores in litt
. 2010), accompanied by increases in the species's range and population in China in recent years (Lei Cao and M. Barter in litt
. 2010) and possibly a slow increase in Japan since the 1990s (Hironobu Tajiri in litt
. 2011). Ecology
It nests in open tussock meadows near water and in mossy bogs with clumps of willows Salix
and larch Larix
. It winters (in dense aggregations) on freshwater lakes, rivers, reservoirs, and farmland, often roosting on water during the day and feeding in fields during the night. It feeds on seeds and grain, water snails, algae and other water plants. The species arrives on its Korean wintering grounds from September, peaking through October and November and returning north in mid March/early April (Degtyarev et al
Hunting was probably the main reason for its decline and is still a serious threat, particularly as it concentrates in large flocks on wetlands and arable land. However, hunting itself is now thought to be in decline (Moores 1996, Moores et al
. 2010). In China and South Korea, birds are killed by poisoned grain; pesticide poisoning and pollution from agricultural and household wastes are thought to be a serious problem in the Geum River, South Korea (Degtyarev et al
. 2006). Large declines in the numbers of Anatidae have occurred in Sanjiang plain and Poyang Hu, China, as a result of habitat loss to agricultural development and hunting. Wintering sites in South Korea are largely unprotected and threatened by the development of wetlands (N. Moores in litt
. 2010); there has been a recent proposal for building the largest tourist development in northeast Asia on the Haenem reclamation site, a key site for wintering Baikal Teal (C. Moores in litt
. 2005). Also, its habit of forming dense aggregations in winter renders the species susceptible to infectious diseases; 10,000 birds were recorded dead owing to avian cholera in October, 2002 (Degtyarev et al
. 2006). The species suffers from disturbance at the Geum River with up to 12 incidences per day of disturbance from low flying aircraft (Degtyarev et al
. 2006).Conservation actions underway
CITES Appendix II, CMS Appendix II. It is legally protected in Russia, Mongolia, Japan, South Korea, Hong Kong and some provinces in China; and is listed in the Red Data Books of South Korea, Russia and Yakutia (Degtyarev et al
. 2006). Some important sites are protected areas, including Bolob lake and Khanka lake (Russia), the Geum River (South Korea [Degtyarev et al
) and Katano duck pond (Japan). Annual monitoring takes place in parts of its range (Degtyarev et al
. Conservation actions proposed
Continue to study its population trend and establish more protected areas in its breeding grounds. Research its wintering status in China. Draft and implement a management plan for the wintering population in South Korea. Regulate hunting of all Anatidae species in China. Ensure its legal protection in all range states. Carry out efforts to reduce disturbance at key sites (N. Moores in litt
. 2010). Garner the support of farmers for the conservation of this and other rice field species (N. Moores in litt
BirdLife International. 2001. Threatened birds of Asia: the BirdLife International Red Data Book. BirdLife International, Cambridge, U.K.
Degtyarev, A. G.; Germogenov, N. I.; Heui-Young Kang; Hansoo Lee. 2006. Baikal Teal wintering status and distribution in South Korea. TWSG News: 77-81.
Zhang Kejia. 2006. Survey on waterfowls at the North Lake, Chongming Island. China Crane News 10(1): 31-34.
Cao, L.; Barter, M. A.; Lei, G. in prep. Population estimates for Anatidae in eastern China: implications for flyway population sizes and the status of globally threatened species.
Further web sources of information
Detailed species accounts from the Threatened birds of Asia: the BirdLife International Red Data Book (BirdLife International 2001).
View photos and videos, and hear sounds of this species from the Internet Bird Collection
Text account compilers
Benstead, P., Bird, J., Taylor, J.
Barter, M., Chan, S., Crosby, M., Hironobu, T., Lee, H., Lei, C., Moores, N.
IUCN Red List evaluators
Butchart, S., Symes, A.
BirdLife International (2013) Species factsheet: Anas formosa. Downloaded from
http://www.birdlife.org on 21/05/2013.
Recommended citation for factsheets for more than one species: BirdLife International (2013) IUCN Red List for birds. Downloaded from
http://www.birdlife.org on 21/05/2013.
This information is based upon, and updates, the information published in BirdLife International (2000)
Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004)
Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.
To provide new information to update this factsheet or to correct any errors, please email BirdLife
To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.
Additional resources for this species