Shorebirds of the Yellow Sea
Importance, threats and conservation status
Wetlands International, 2002
ISBN 90 5882 009 2
At the height of migration they arrive in flocks that at times seem to fill the sky. They spread out as they land, bills probing almost before their feet touch the ground. They stitch the mud again and again at each low tide, turning the seemingly inexhaustible invertebrate inventory into shorebird tissue. They refuel for some days and then, swaddled in sustaining fat, are on their way again to north or south.
Dennis Paulson (1993)
Shorebirds, or waders, are small- to medium-sized birds of the water's edge. They have a variety of bill shapes and sizes, and legs which vary from short to very long. Typically, they are gregarious and often occur together in very large numbers. Shorebirds have two important characteristics that provide significant conservation challenges.
Firstly, most shorebirds are highly dependent on wetlands, both coastal and inland, for their food - shellfish, crabs, shrimps, and worms. Unfortunately, much wetland habitat has already been destroyed on a worldwide scale and a high proportion of the remaining area is under serious threat from a wide variety of human activities (Finlayson & Spiers 1999).
Secondly, many species of shorebird undertake annual migrations of thousands of kilometres between their breeding and non-breeding areas, often stretching from the coasts and islands of the high arctic to the southernmost wetlands of the globe. Northward migration to the breeding grounds typically takes place from March to early June, whilst the return migration to the non-breeding areas occurs between July and October. During their migrations, shorebirds move through networks of wetland sites, spread across many countries, at which they prepare for the next stage of their journey by building up stores of fat to fuel their onward flight.
The international nature of shorebird migrations and the ubiquitous threats to wetlands requires that any effective conservation programme will need coordinated multinational support that is based on good knowledge and understanding of shorebird annual life cycles and of the important habitats that are used during the breeding, migration and non-breeding periods (Davidson et al. 1998; Rose 1998).
The need for international action in the Asia Pacific region has been recognized in the development of a conservation strategy for migratory water birds (Asia-Pacific Migratory Waterbird Conservation Committee 2001), which includes a shorebird action plan that calls for the building of an extensive network of well-managed shorebird sites of international importance, improved knowledge of migration routes and identification of key staging areas (www.ea.gov.au/water/wetlands/mwp/infosrn1.html).
There are eight shorebird flyways around the world, each of which consists of a geographical grouping of similar routes used by many individual species. The East Asian-Australasian Flyway, stretching from Siberia and Alaska, southwards through east and south-east Asia, to Australia and New Zealand (Figure 1), supports over 7 million shorebirds, of which some 5 million are migratory (Bamford et al. in prep.).
Shorebirds share the East Asian-Australasian Flyway with more than 45% of the world's human population, many of whom live in countries that have some of the fastest developing economies in the world. The resulting economic and social pressures are posing major threats to wetlands, with more than 80% of the significant wetlands in east and south-east Asia being classified as threatened in some way; 51% of these are under serious threat (Scott & Poole 1989). Within the East Asian-Australasian Flyway, only Mongolia and Papua New Guinea have less than 20% of their wetlands moderately or seriously threatened. It is estimated that China and South Korea have already reclaimed 37% and 43%, respectively, of their intertidal areas (Yuan et al. 2001; Moores et al. 2001; MOMAF 1998).
Much has been learnt about the breeding and non-breeding portions of shorebirds' lives within the Flyway, with considerable work on their breeding biology and distribution having been carried out, especially in Russia and Alaska (e.g. Rogacheva 1992; Tomkovich 1996; Gill 1996), and a substantial counting and banding programme being conducted in Australia, New Zealand and Japan during the last 20 years which has provided much information on flyway population sizes, non-breeding distributions and biometrics (e.g. Lane 1987; Watkins 1993; Higgins & Davies 1996; Robertson 1999; JAWAN 1998, 1999). However, relatively little is known of the migration strategies of the individual species - a deficiency which is particularly serious given that the key wetlands used during migration in east and south-east Asia are the most threatened in the Flyway (Melville 1997).
The need for greatly improved information on important shorebird staging sites has led to extensive survey and counting activity during the last 10 years, particularly along the coastline of the Yellow Sea. Since 1996, Wetlands International, building on earlier work by East China Normal University (Wang & Tang 1990a, 1990b; Wang et al. 1991, 1992), has been active around the Yellow Sea coastline of China (Chen et al. 1998, 1999, 2000a, 2000b). In South Korea, following a preliminary survey by the East Anglia and Kyung Hee Universities in 1988 (Long et al. 1988), staff of the Avian Laboratory, Ministry of Environment, have been conducting intensive counts of important Yellow Sea sites on both northward and southward migration since 1993 (Yi & Kim in prep.). Non-government organisations in South Korea have also made a major contribution in recent years (Moores 1999a, 1999b).
The information collected has significantly improved our understanding of shorebird abundance and distribution in the Yellow Sea and of how the different species use the region. The results to date show clearly that the coastal regions of the Yellow Sea provide key migration staging sites for many shorebird species and also support important concentrations of some species during the non-breeding season. Some species also breed in significant numbers. The Yellow Sea staging sites are particularly important during northward migration, as birds are preparing for their final flights into the breeding grounds, when it is essential that they depart from the Yellow Sea in good condition so that they can withstand the often adverse weather conditions after arrival and then breed successfully.
The purpose of this monograph is to provide up-to-date information from the Yellow Sea on:
- its importance for migratory shorebirds;
- key shorebird sites; and
- threats to shorebird habitat;
in order to assist governments and non-government organisations to develop effective conservation policies and plans for shorebirds and their habitats.
- describes the physical geography of the Yellow Sea and its shorebird habitats;
- provides detailed information on the abundance and distribution of those shorebird species which occur at Yellow Sea sites in internationally important numbers;
- identifies the sites currently known to support internationally important shorebird concentrations;
- lists the threats to, and discusses the conservation status of, shorebirds and their habitats in the Yellow Sea;
- in addition to a list of cited references, also provides a selected listing of shorebird-related papers which are based on work carried out in the Yellow Sea.
East Asian-Australasian Flyway