|Title:||Waders along the coast of Thailand during November and December 1984: a ground survey|
|Author(s):||P.G. Bijlsma and F.E. de Roder|
|Publication date:||February 1985|
A survey along the eastern coast of Thailand in the period 5 November - 20 December 1984. The following areas were surveyed:
The wintering waders in Southeast-Asia and North- and East- Australia originate from breeding areas in the northern USSR, Mongolia and China. Minton & Martindale (1982) and Minton (1982) considered Northwest-Australia as the major landfall for the 1.5-2 million waders. During the flight of 8000-10 000 km from the breeding areas to the wintering quarters the waders are dependent on "refuelling"stops in tropical Asia. Besides passage migrants, a large number of waders spends the whole non-breeding season in Southeast-Asia (McClure 1974, Parish & Wells 1983, Cramp & Simmons 1983).
In visiting seven minor parts of coastal areas in Thailand we counted nearly 15.000 waders in 39 species, of which 17 species with totals less than hundred individuals (table 14). According to Lekagul, Round & Komolphalin (1985) a total of 55 species of waders has so far been recorded in Thailand, of which all but nine (Painted Snipe, Black-winged Stilt, Stone-curlew, Great Thick-knee, Oriental Pratincole, Little Ringed Plover, Malaysian Plover, River Lapwing and Red-wattled Lapwing) are represented only as winter visitors or passage migrants.
During our stay in the coastal areas of Thailand we were struck by the adaptability of waders to the use of potential feeding and resting places. The birds readily exchanged between mudflats, saltpans, fish and shrimp ponds and swamps according to the suitability of the moment.
Of the mangrove forests, as shown on maps as of 1973, hardly anything was left. These forests were transformed in fish and shrimp ponds and saltpans. The biological productivity of mangrove forests has been well researched in Malaysia (Macnae 1986, Berry 1972, Diemont & van Wijngaarden 1975). Because of the extreme conditions in the intertidal zone of mangrove forests, the bottom fauna is neither rich nor varied. Crustacea, however, can easily cope with the tidal fluctuations and the extreme chemical circumstances in mangrove forests, and were abundant at all sites visited. The existence of healthy mangroves is essential for the biological productivity of the mudflats bordering the mangrove forests. The destruction of these forests in recent years will greatly effect all organisms which depend on the biomass of the macrobenthos in the intertidal zone in the near future, among these waders.
About the organization of wader counts in Thailand: in 1984 nearly the entire coast line was surveyed by plane, which is the best method to cover areas which are hard or impossible to reach from the ground. However, it is our conviction that the extensive saltpans and fish and shrimp ponds have to be surveyed from the ground. In these areas the waders are scattered all over the place, usually in small flocks. The majority of the waders in these areas consisted of the smaller species (plovers, stints) and can be easily overlooked during aerial surveys.
The report contains: