Shorebirds of the Yellow Sea

Importance, threats and conservation status
Mark Barter
Wetlands International, 2002
ISBN 90 5882 009 2

4. Shorebirds occuring in internationally important numbers at Yellow Sea sites

4.1 Organisation of species accounts

Accounts have been prepared for all species that occur in internationally important numbers at one or more sites in the coastal regions of the Yellow Sea. Species are listed according to the taxonomic order given in Christidis & Boles (1994), with guidance from Hayman et al. (1986) for species which have not been recorded in Australia.

Each species account contains:

  1. Sections on:
  • Subspecies - worldwide and for the Yellow Sea. Recently, there has been much discussion about the taxonomy of a number of species that occur in the East Asian-Australasian Flyway (see, for example, Engelmoer & Roselaar 1998 and Tomkovich & Serra 1999). However, it has been decided to adopt a conservative approach to taxonomy and employ the widely recognized subspecies nomenclature used in major reference works, such as Higgins & Davies (1996), Cramp & Simmons (1983), Rose & Scott (1997) and del Hoyo et al. (1996). For two species (Red Knot and Dunlin) mention is made of potential additional subspecies where these seem to be gaining wider acceptance.
  • Distribution:
    • Breeding - core areas.
    • Non-breeding - main regions.
  • Usage and importance of the Yellow Sea:
    • Occurrence - habitat used in the Yellow Sea, most important regions for the species during the breeding season (B), northward migration (NM), southward migration (SM) and non-breeding (NB) season, and comment on the accuracy of species number estimates.
    • Movements - timing of passage and information, where it is available from banding data, on the non-breeding locations of populations passing through the Yellow Sea.
    • Significance of the Yellow Sea - an estimate of the proportion of flyway population passing through the Yellow Sea on northward migration is given when sufficient information is available. This estimate is mainly based on the China and South Korea data, but some allowance is made for North Korea where it is believed to be appropriate. Where possible, comments are also made on numbers during southward migration and at other times of the year.
    • Key sites - number of sites of international importance in the Yellow Sea, total and by country, listings of sites which are important in more than one period (i.e. northward migration, southward migration and the non-breeding season), and of those sites which support >5% of the estimated species flyway population.
    • Status of key sites - number of sites in Protected Areas. Protected Areas comprise National (NNR) and Provincial (PNR) Nature Reserves in China, a Migratory Bird Wetland Reserve (MBWR) in North Korea and the Dongjin Shorebird Network Site in South Korea. The fact that a site lies within a Protected Areas does not necessarily imply that shorebirds and their habitats are effectively conserved (see Section 7 for more information on shorebird conservation status in Protected Areas).
    • Major gaps in knowledge
  1. Tables listing internationally important sites and maximum counts at these sites during the northward and southward migration periods, and in the non-breeding season. Maps show locations of the sites and a list of references for the counts is provided at the end of each account. N.B. With the exception of Common Redshank and Oriental Pratincole, maps are not given for important breeding locations as these are covered in the relevant species text under Occurrence.
  1. A box containing key summary information - conservation status (if the species is threatened or near-threatened), flyway population estimate, status of the species in the Yellow Sea, estimates of minimum numbers occurring in South Korea and China, and information on the number of internationally important sites and their Protected Area status. The South Korean number estimates have been taken from Yi & Kim (in prep.); those for China are for northward migration only, as there are insufficient count data to make estimates for other periods.

The individual species accounts have been mostly compiled from the sources listed below. In order to simplify the text, these sources are not cited within the Species Accounts. Less frequently used references have been included within the text.

4.2 Major sources of information for the species accounts

4.2.1 Subspecies and distribution

Higgins & Davies 1996.
Cramp & Simmons 1983.
Rose & Scott 1997.
del Hoyo et al. 1996.
P.S. Tomkovich in litt.

4.2.2 Yellow Sea count and migration information

China count data

Jiu Duan Sha: J.J. Lu in litt.

Chongming Dao PNR: Wang & Tang 1990a, 1990b Barter et al. 1997a, 1998a; J.J. Lu in litt.

Dong Sha: Wang & Barter 1998

Yancheng NNR: Wang & Liu 1994; Wang 1997 Barter et al. in prep.

Huang He NNR: Wang et al. 1991, 1992; Barter et al. 1999; Zhu et al. 2000

Tianjin Municipality: Barter et al. 2001; S.P. Zhang in litt.

Shi Jiu Tuo: J. Kriegs, G. Carey, C. Doughty, F. Heintzenberg, J. Hornskov, Regulus Travel, all in litt.

Linghekou: Barter et al. 2000b

Shuangtaizihekou NNR: Brazil 1992; Barter et al. 2000d; Y.X. Li in litt.

Yalu Jiang NNR: Barter et al. 2000c, 2000i

South Korea count data

Yi & Kim in prep., plus additional data for 1999 supplied by the authors.

Moores 1999a

Japan count data

JAWAN 1998, 1999

Banding data

Australia - Australian Bird and Bat Banding Scheme unpub. data.

New Zealand - Riegen 1999; A.C. Riegen in litt.

4.3 Species accounts summary

4.3.1 Introduction

A total of 36 shorebird species has so far been found to occur in internationally important numbers at one or more sites in the Yellow Sea. This number represents 60% of the migratory shorebird species in the East Asian-Australasian Flyway. Two of the species are classified as globally threatened, the Spotted Greenshank (Endangered) and Spoon-billed Sandpiper (Vulnerable), whilst two are near-threatened, the Eastern Curlew and Asian Dowitcher (BirdLife International 2001).

The shorebirds using the Yellow Sea have breeding ranges which are spread across a wide area ranging from the Taimyr Peninsula, in central north Siberia, eastwards to the Russian Far East and Alaska, and southwards to Mongolia, northern China and the Yellow Sea, itself. Their non-breeding distributions occur within the region stretching from Bangladesh through Indochina and southern China to Japan, and southwards through South East Asia to Australasia.

Most of the shorebirds using the Yellow Sea feed on the vast intertidal flats, but many birds also use near-coastal non-tidal wetlands, particularly mariculture ponds and saltpans. These inland areas also provide particularly important roosting sites in locations where reclamation has resulted in the removal of typical roosting habitat on spits, saltmarsh and mudflats. A few species are found in grassland and arable areas.

It is highly probable that numbers of some species have been significantly underestimated. Potential reasons for this include:

  • dispersed distribution of shorebirds over tidal flats and mariculture ponds;
  • inadequate surveying of non-tidal wetlands, grasslands and arable areas;
  • timing of surveys may not have coincided with the occurrence of maximum numbers during the migration periods or the non-breeding season;
  • identification problems.

It is very likely that more thorough surveying would result in a significant increase in the estimated abundances of many species and in the identification of additional internationally important sites.

4.3.2 Usage of the Yellow Sea

Table 3 lists the 36 shorebird species recorded in internationally important numbers at sites in the Yellow Sea. It also gives details on the number of sites at which they occur in significant numbers during the migration and non-breeding periods, and the breeding season. The locations of the internationally important sites are shown in Figure 6 (see 5.2).

Thirty-five species (i.e. all except the Oriental Pratincole) use the Yellow Sea wetlands in internationally important concentrations during the migration periods, with 20 of these occurring at more sites during northward migration than on southward passage - however this could be an artefact caused by the relative lack of information from China during southward migration. Despite this potential bias, some species have been found to occur at more sites during southward migration than northward (Kentish Plover, Eurasian Curlew, Terek Sandpiper and Common Greenshank). Significant proportions of some species, such as Bar-tailed Godwit, Whimbrel, Great Knot and Grey Plover, appear to bypass the region during southward migration and fly across the Pacific directly to their non-breeding grounds, but it is possible that high numbers of these species may yet be found at Yellow Sea sites not yet surveyed during southward passage.

Seven species occur in internationally important concentrations in the southern part of the Yellow Sea during the non-breeding season (Eurasian Curlew, Spotted Redshank, Common Greenshank, Sanderling, Eurasian Oystercatcher, Pied Avocet and Kentish Plover). The great majority of the estimated flyway population of the Eurasian Oystercatcher appears to spend the non-breeding season in the Yellow Sea, and more than 50% of the population occurs at one site on the west coast of South Korea (Geum Gang Hagu).

Five species breed at Yellow Sea sites in internationally important numbers, i.e. Common Redshank, Eurasian Oystercatcher, Black-winged Stilt, Kentish Plover and Oriental Pratincole. Table 4 lists sites at which species counts have exceeded 5%, 10% or 20% of their estimated flyway population during northward migration, southward migration or the non-breeding season. It can be seen that many species occur in site concentrations that greatly exceed the 1% threshold used for determining international importance. These sites are of prime conservation significance.

Table 3. Species ranked according to the number of sites at which they occur in internationally important numbers, with details on seasonality
  Number of sites of international importance
Species Total Northward migration Southward migration Non-breeding season Breeding season
Kentish Plover 21 11 16 4 2
Eurasian Curlew 15 7 11 6 -
Terek Sandpiper 14 9 13 - -
Eastern Curlew 13 12 7 - -
Grey Plover 13 12 7 - -
 
Great Knot 12 11 3 - -
Black-tailed Godwit 12 7 6 - -
Dunlin 11 10 5 - -
Lesser Sand Plover 11 10 7 - -
Common Greenshank 11 4 8 1 -
 
Whimbrel 9 9 - - -
Spotted Greenshank 9 4 6 - -
Bar-tailed Godwit 8 8 1 - -
Eurasian Oystercatcher 7 3 4 2 2
Red-necked Stint 5 5 2 - -
 

Black-winged Stilt

5 4 3 - 2
Marsh Sandpiper 5 3 4 - -
Red Knot 5 3 2 - -
Broad-billed Sandpiper 5 2 4 - -
Asian Dowitcher 4 4 3 - -
 
Spotted Redshank 4 4 2 1 -
Little Ringed Plover 4 4 2 - -
Ruddy Turnstone 3 3 1 - -
Sanderling 3 1 3 1 -
Common Redshank 2 2 1 - 2
 
Sharp-tailed Sandpiper 2 2 1 - -
Curlew Sandpiper 2 2   - -
Northern Lapwing 2 1 2 - -
Grey-tailed Tattler 2 1 1 - -
Pied Avocet 2 1   1  
 
Spoon-billed Sandpiper 2 - 2 - -
Grey-headed Lapwing 2 - 2 - -
Little Curlew 1 1 - - -
Oriental Plover 1 1 - - -
Red-necked Phalarope 1 - 1 - -
Oriental Pratincole 1 - - - 1
Table 4 Species occurring in concentrations >20%, >10% and >5% of their estimated flyway population and the sites at which they occur on a seasonal basis
Species >20% >10% >5%
Black-tailed Godwit   Asan Man (NM) Mangyeung Gang Hagu (SM)
Bar-tailed Godwit   Yalu Jiang NNR (NM)  
Little Curlew   Huang He NNR (NM)  
Eurasian Curlew Huang He (NM)
Shi Jiu Tuo (SM)
  Tianjin Municipality (NM, SM & NB)
Shi Jiu Tuo (NM)
Namyang Man (NM & SM)
Geum Gang Hagu (SM)
Eastern Curlew    

Yalu Jiang NNR (NM)
Ganghwa Do (NM)

Spotted Redshank   Yancheng NNR (SM) Yancheng NNR (NM)
Marsh Sandpiper   Yancheng NNR (NM) Yancheng NNR (SM)
Spotted Greenshank     Namyang Man (NM)
Mangyeung Gang Hagu (SM)
Dongjin Gang Hagu (SM)
Asian Dowitcher     Dong Sha (SM)
Great Knot   Dongjin Gang Hagu (NM)
Mangyeung Gang Hagu (NM)
Yalu Jiang NNR (NM)
Asan Man (NM)
Shuangtaizihekou NNR (NM)
Namyang Man (NM)
Red Knot     Tianjin Municipality (NM)
Sanderling   Yancheng NNR (NM) Yancheng NNR (NB)
Dunlin     Yancheng NNR (NM)
Mangyeung Gang Hagu (NM)
Curlew Sandpiper     Tianjin Municipality (NM)
Eurasian Oystercatcher Geum Gang Hagu (NB) Geum Gang Hagu (SM)  
Black-winged Stilt   Tianjin Municipality (NM) Shi Jiu Tuo (SM)
Grey-headed Lapwing     Shi Jiu Tuo (SM)
Northern Lapwing     Shi Jiu Tuo (SM)
Grey Plover   Huang He NNR (NM) Yalu Jiang NNR (NM)
Tianjin Municipality (NM)
Kentish Plover Huang He NNR (NM) Mangyeung Gang Hagu (SM) Chongming Dao (NM)
Dongjin Gang Hagu (SM)
Shi Jiu Tuo (SM)
Yancheng NNR (SM)
Little Ringed Plover   Yancheng NNR (SM)  
Lesser Sand Plover     Dongjin Gang Hagu (NM & SM)
Mangyeung Gang Hagu (NM & SM)

(Key: For site location see Figure 6. NM = northward migration, SM = southward migration, NB = non-breeding season)

Shorebirds employ a wide variety of strategies in their use of the Yellow Sea. Some, such as Great Knot, Spotted Redshank and Asian Dowitcher, occur in high concentrations at a relatively limited number of sites, whilst others, such as Terek Sandpiper and Dunlin, spread themselves over a large number of sites with few major concentrations. The strategies of many species lie in between these extremes and they can occur in high numbers at a limited number of sites, whilst still having a generally widespread distribution (e.g. Eurasian Curlew, Eastern Curlew, Grey Plover and Kentish Plover). Conservation management of the different species will need to take into account the varying ways in which they use the Yellow Sea wetlands.

4.3.3 Importance of the Yellow Sea

Table 5 provides a summary of the estimated numbers using the Chinese and South Korean portions of the Yellow Sea during northward migration for those species for which sufficient count data are available. An estimate is also given of the proportion of the flyway breeding populations being supported at this time of the year. See Section 3.5 for information on how northward migration numbers and the size of flyway breeding populations have been calculated.

The very great importance of the Yellow Sea for shorebirds during northward migration is demonstrated by the fact that it supports 30% or more of the flyway breeding populations of 18 species; for six of these species the region supports almost their whole flyway breeding population.

Table 5 Proportion of the breeding populations supported by the Yellow Sea during northward migration
Species Population estimate % breeding pop.
Great Knot 290 000 >90
Bar-tailed Godwit 230 000 >90
Grey Plover 110 000 >90
Kentish Plover 90 000 >90
Eastern Curlew 32 000 >90
Eurasian Curlew 32 000 >90
Dunlin 660 000 70
Whimbrel 33 000 70
Lesser Sand Plover 32 000 65
Spotted Redshank 20 000 60
Asian Dowitcher 9 300 50
Red Knot 67 000 40
Marsh Sandpiper 39 000 40
Red-necked Stint 87 000 35
Common Greenshank 15 000 35
Terek Sandpiper 14 000 35
Broad-billed Sandpiper 5 100 35
Black-tailed Godwit 48 000 30
Ruddy Turnstone 4 500 20
Little Curlew >>17 000 >10
Sharp-tailed Sandpiper 17 000 10
Curlew Sandpiper 18 000 <10

The Yellow Sea is particularly important for four species of special concern, i.e. the endangered Spotted Greenshank and vulnerable Spoon-billed Sandpiper, and the near-threatened Eastern Curlew and Asian Dowitcher, which are all endemic to the East Asian-Australasian Flyway.

It is highly likely that the great majority of Spotted Greenshank and Spoon-billed Sandpiper use the Yellow Sea during both northward and southward migrations. Both these species are difficult to separate from their congeners and many birds are probably missed. Nonetheless, eight internationally important sites have been identified for the Spotted Greenshank and two for the Spoon-billed Sandpiper.

Approximately 80% of the estimated flyway population of the Eastern Curlew uses the Yellow Sea on northward migration and 40% of the Asian Dowitcher. These percentages rise to >90% and about 50%, respectively, when only the breeding portions of the flyway populations are considered.

In total, it is estimated that a minimum of 2 000 000 shorebirds use the Yellow Sea wetlands during northward migration, i.e. approximately 40% of the estimated flyway population of migratory shorebirds. Perhaps 1 000 000 shorebirds pass through the region on southward migration.

4.3.4 "Missing" and undercounted species

Only small numbers have been recorded of a number of species that could be expected to occur in significant concentrations in the Yellow Sea. Examples of such "missing" species are Ruddy Turnstone, Red Knot, Sanderling, Red-necked Stint, Sharp-tailed Sandpiper, Curlew Sandpiper and Broad-billed Sandpiper. It is possible that some of these species occur in large numbers in parts of the Yellow Sea that have not yet been surveyed. However, the evidence to date indicates that many Red-necked Stint, Sharp-tailed Sandpiper and Curlew Sandpiper are using inland routes through China (see individual Species Accounts). The Red Knot is an obligate coastal species which traditionally uses a very small number of staging sites during migration and it is probable that it is occurring in high numbers in some of the intertidal areas yet to be visited.

There are other species that almost certainly occur in the Yellow Sea in significant concentrations, e.g. Pin-tailed Snipe, Swinhoe's Snipe, Common Snipe, Green Sandpiper, Wood Sandpiper, Common Sandpiper, Temminck's Stint and Long-toed Stint. It is likely that intensive surveying of suitable habitat would lead to some of these species being recorded in internationally important numbers.

It is important to survey intensively for breeding shorebirds such as Common Redshank, Eurasian Oystercatcher, Black-winged Stilt, Kentish Plover and Oriental Pratincole. Important breeding concentrations of these species have already been identified and it is very probable that more exist.