As temperatures edge higher through April, tens of thousands of shorebirds start to arrive in South Korea, crowding the tide-line and high tide roosts at a number of sites along the west and south coasts, including the internationally important shorebird sites of Ganghwa and Yeongjong Islands, Namyang and Asan Bays, the Geum estuary, Saemangeum, Aphae Do and the southwest flats in Hampyeong Bay and Shinnan Gun, Suncheon Bay and the Nakdong estuary (Moores, 1999a).
Extensive banding and flagging programs (backed up by satellite tracking) have proved that many of the larger shorebird species arriving in Korea at this time are undertaking some of the most spectacular migrations of any species: non-stop flights from Australia and Southeast Asia direct to key staging sites in the Yellow Sea, from where they then undertake (typically in May) a second massive flight up into Siberian breeding grounds.
Photo © Clive Minton.
In South Korea the most numerous of these 'extreme' migrants is the Great Knot, a species which is all but confined to the East Asian-Australasian Flyway, and which depends almost entirely on Yellow Sea tidal flats during northward migration.
The Yellow Sea (one of the world's most threatened major ecosystems due to massive reclamation schemes, over-harvesting of natural resources and pollution) supports an estimated 80% of the total world population of Great Knot in spring, with ca 176 000 staging in South Korea alone, and the very highest flyway counts being made at Saemangeum. Barter (2002) gives peak counts of 60 000 and 59 000 respectively at the Dongjin and Mangyeung estuaries: the two estuaries due to be closed off by the 33-km long Saemangeum seawall in 2006. On southward migration, numbers are rather lower, but still ca 20 000 are present, again at Saemangeum and Yeongjong island.
Identification of Great Knot in spring is straightforward, even at very long range. Birds on the edge of the densely-packed, grey-washed flocks (which at 2-3 sites can contain up to 40 000 individuals) simply look dull and dark-fronted. As the dark mass fans out across the tidal-flat, consuming small shells revealed by the receding tide, most move slowly and methodically in long lines, heads seldom lifting: a feeding behaviour much less energetic than the smaller, brighter Dunlin. Closer up, Great Knots look powerful and far more attractive: rather long-billed and long-bodied, showing a striking contrast between the dark head and blackish breast and the whiter belly, vent, rump and underwings, while the upperparts look variegated, with deep rust and chestnut patches across the scapulars.
On their return in the autumn, and after departure to their mid-winter non-breeding grounds (mainly in Viet Nam south into Australia) separation from Red Knot can be a little more problematical, but remains straightforward, based largely on overall structure (Red Knot looking rather more rotund and “cute” facially, with a shorter bill) and subtle differences in bare parts and plumage.
Thailand, January.
Photos © Chaiyan KASORNDORKBUA.
Great Knot tend to look greenish- or grayish-legged and show a faintly paler (often green-toned) base to the lower mandible, while Red Knot often have yellowish toned legs and an invariably all-dark bill. Plumage-wise, most Great Knot show less solidly dark lores, a diffuse supercilium (combined meaning the eye often stands out), variegated and pale-fringed upperparts, a more heavily streaked crown and nape than Red Knot and more obvious darker pectoral patches.
Whilst the Great Knot still remains a numerous species in South Korea, what of the future? Tragically, all of its preferred sites nationally are either undergoing partial or complete reclamation, and it is feared that the species will soon join the lengthening list of threatened waterbirds in the East Asian-Australasian flyway – perhaps even within this decade.
To conserve the Great Knot and the tidal-flats that support the species and the economic needs of large numbers of people, there is clearly an urgent need for South Korea and its neighbors to honor obligations to international conventions, and “to review and modify existing policies that adversely affect intertidal wetlands, to seek to introduce measures for the long-term conservation of these areas” (Ramsar, Resolution 7.21). Birders can help this process. Please keep media and government officials wherever you are informed of the progress of the Saemangeum and other reclamation projects outlined on this site, and please send in any shorebird count data and flag/banding observations made here in South Korea. All such records will then be posted on the site and passed onto the relevant organizations, supporting the positive steps being taken nationally for conservation, led of course by the national Ministry of Environment and the Ministry of Maritime Affairs and Fisheries.
References
- Barter, M.A. 2002. Shorebirds and The Yellow Sea: Importance, threats and conservation status. Wetlands International Global Series 9, International Wader Studies 12, Canberra, Australia.
- Moores, N. 1999. A survey of the distribution and abundance of shorebirds in South Korea during 1998-1999. Stilt 34: 18-29.
Many thanks to Dr. Clive Minton who generously provided several of the slides and who coordinates data on Australian shorebird banding/flagging along the flyway; and to Chaiyan, for his images from Thailand's Khokkarm salt-pans.
Also see : magma.nationalgeographic.com/ngm/0302/resources_cre.html.