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The First Record of Over-Summering Spoon-billed Sandpiper Eurynorhynchus pygmeus in Thailand

By Krairat Eiam-Ampai, Somchai Nimnuan, Thiti Sonsa, Smith Sutibut & Philip D. Round
 
Note: This article was originally published in Stilt 60 (2011) the journal for the Australasian Wader Studies Group and was kindly submitted by Philip D. Round.

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During routine monthly surveys of over-summering shorebirds and other waterbirds conducted by the Wildlife Research Division of the Department of National Parks, Wildlife and Plants Conservation of the Thai government, a single Spoon-billed Sandpiper Eurynorhynchus pygmeus was found feeding among Red-necked Stints Calidris ruficollis on newly accreting intertidal mudflats at Khok Kham, Samut Sakhon Province, Thailand (c. 13° 31’ N; 100° 19’ E) on 19 July 2010. Many shorebirds display delayed maturity, not returning to natal sites until their second or third year (Loftin 1962, Summers et al. 1995, Rogers et al. 2006) and it has long been assumed that first-year Spoon-billed Sandpipers do likewise (Tomkovich 1995, Zöckler et al. 2010a). This appears to be the first documented record of a Spoon-billed Sandpiper over-summering in the non-breeding grounds. Given the critically endangered status and ongoing rapid population decline of Spoon-billed Sandpipers (Zöckler et al. 2010a, b), this over-summering record is highly significant.

The same individual was photographed by SS almost one month later, on 16 August 2010, when it roosted on saltpans. Its primaries were in active moult, with score being “555554[1 or 2] 000” and the tertials had been dropped or were growing. A few black-centred, breeding plumage feathers were visible in the mantle and scapulars, but the bird was otherwise in grey, non-breeding plumage (Figures 1 and 2).

The outermost three (unmoulted) primaries were extremely bleached, brownish and pointed, supporting the supposition that this was a first-summer bird. Although firstyear shorebirds frequently renew a few outer primaries in a partial post-juvenile moult, some do not, and there are many species in which only a proportion of the population undergoes such a moult (Higgins & Davies 1996, Marchant & Higgins 1993, D. Rogers, in litt.). While the detailed ontogeny of the moult of Spoon-billed Sandpiper appears to be unreported, the extreme wear and bleaching of the outer primaries of the present individual was thought typical among unmoulted first-summer shorebirds. Additionally, the primary moult (more than 50% completed by mid-August) was too advanced to indicate normal post-breeding moult of an adult (C.D.T. Minton, in litt., D. Rogers, in litt.).

What was thought to be the same bird was seen on 17 and 21 September when its stage of moult had progressed to the extent that it more or less resembled “typical” nonbreeding adults (S. Daengphayon, pers. comm.). The latter sightings still pre-dated the arrival of non-breeding Spoonbilled Sandpipers in the Thai Gulf, usually occurring in October (Round & Gardner 2008).


Figure 1. Over-summering Spoon-billed Sandpiper with wing extended, enabling determination of primary moult status. Khok Kham, Samut Sakhon Province, Thailand, 16 August 2010 (Photo: Smith Sutibut)

Figure 2. Over-summing Spoon-billed Sandpiper showing upperparts feathering. Khok Kham, Samut Sakhon Province, Thailand, 16 August 2010 (Photo: Smith Sutibut).
Khok Kham and nearby sites in Samut Sakhon Province constitute one of two major clusters of sites in the Thai Inner Gulf where about 10–20 Spoon-billed Sandpipers regularly winter (Nimnuan & Daengphayon 2008, Round & Gardner 2008). The initial sighting, on newly accreting mudflats, may be highly relevant to the habitat preference of Spoon-billed Sandpipers which, in some parts of their non-breeding range (especially the Meghna Delta of Bangladesh), appear to favour accreting shorelines. (Enam ul-Haque, in litt.). The observation was made at the site of a conservation project which is successfully reversing coastal erosion using traditional methods (bamboo stakes) instead of intrusive concrete sea-walls, administered by the Department of Marine and Coastal Resources, in collaboration with the local community. Such accreting sites may be a valuable though highly transient resource for Spoon-billed Sandpipers. Experience in Bangladesh shows that as the substrate stabilises and compacts, Spoon-billed Sandpipers are among the first shorebirds to disappear, presumably moving elsewhere (Enam ul-Haque, in litt.). In Thailand, more coastline is eroding rather than accreting, and erosion is worsened by subsidence (caused by the unregulated extraction of ground water), reduced sediment inflow due to dam construction on rivers, and unzoned developments in the coastal zone. At least 130 sq km in 18 Thai coastal provinces were planted with mangroves during 1998–2003 (Round & Gardner 2008) to offset erosion. Since provincial and national authorities frequently choose to plant mangrove seedlings on mudflats, overtaking the process of natural succession, this could further deprive Spoon-billed Sandpipers and other shorebirds of key intertidal feeding areas. Integrated management and zoning of the both onshore and offshore habitats along the Inner Gulf coast should be adopted so as to restrict inappropriate developments, reduce erosion, and rehabilitate both onshore and offshore habitats. This would safeguard both shorebirds and other biodiversity values, and sustain the traditional (salt-farming and inshore fishing) lifestyles of the human inhabitants.
ACKNOWLEDGEMENTS
We thank Enam ul-Haque, David Melville, Clive Minton, Danny Rogers and Christoph Zöckler for their comments on drafts of this manuscript, and Suchart Daengphayon for sharing details of his Spoon-billed Sandpiper sightings. We also thank an anonymous reviewer for comments on an earlier version of this manuscript. Philip Round is supported by The Wetland Trust.
REFERENCES
Higgins, P.J. & S.J.J.F. Davies. (Eds.). 1996. Handbook of Australian, New Zealand and Antarctic Birds. Volume 3. Snipe to Pigeons. Oxford University Press, Melbourne.

Loftin, H. 1962. A study of boreal shorebirds summering on Apolachee Bay, Florida. Bird-Banding 33: 21–42.

Marchant, S, & P.J. Higgins. (Eds.). 1993. Handbook of Australian, New Zealand and Antarctic Birds. Volume 2. Raptors to Lapwings. Oxford University Press, Melbourne.

Nimnuan, S. & S. Daengphayon. 2008. The survey of population, distribution and habitat of Spoon-billed Sandpiper in the Inner Gulf of Thailand. Bird Conservation Society of Thailand Bulletin 25(4): 35–36. (Thai language).

Rogers, D.I., C.D.T. Minton, A.N. Boyle, C.J. Hassell & A. Silcocks. 2006. 'Growing up slowly by the sea-side: Age of first northwards migration of shorebirds from Australian nonbreeding grounds'. Chapter 10 in Rogers, D.I. Hidden costs: challenges faced by migratory shorebirds living on intertidal flats. PhD thesis, Charles Sturt University, Albury, Australia.

Round, P.D. & D. Gardner. 2008. Birds of the Bangkok Area. White Lotus, Bangkok.

Summers, R.W., L.G. Underhill, & R.P. Prys-Jones. 1995. Why do young waders in southern Africa delay their first return migration to the breeding grounds? Ardea 83: 351–357.

Tomkovich, P. S. 1995. Breeding biology and breeding success of the Spoon-billed Sandpiper Eurynorhynchus pygmeus. Russian Journal of Ornithology 4: 77–91. (In Russian.)

Zöckler, C., E.E. Syroechkovskiy & P.W. Atkinson. 2010a. Rapid and continued population decline in the Spoon-billed Sandpiper Eurynorhynchus pygmeus indicates imminent extinction unless conservation action is taken. Bird Conservation International 20: 95–111.

Zöckler, C., E.E. Syroechkovskiy, Jr. & G. Bunting. 2010b. International Single Species Action Plan for the Conservation of the Spoon-billed Sandpiper (Eurynorhynchus pygmeus). Technical Report Series 23. BirdLife International Asia Division, Tokyo and CMS Secretariat, Bonn.

Kindly submitted by:

Philip D. ROUND, Department of Biology, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400 Email: philip.rou@mahidol.ac.th

Krairat EIAM-AMPAI, Wildlife Research Division, Department of National Parks, Wildlife and Plants Conservation, Phaholyothin Road,
Chatuchak, Bangkok 10900

Somchai NIMNUAN, Wildlife Research Division, Department of National Parks, Wildlife and Plants Conservation, Phaholyothin Road,
Chatuchak, Bangkok 10900

Thiti SONSA, Wildlife Research Division, Department of National Parks, Wildlife and Plants Conservation, Phaholyothin Road,
Chatuchak, Bangkok 10900.

Smith SUTIBUT, Bird Conservation Society of Thailand, 221, Mu 2, Soi Ngamwongwan 2, Bangkhen, Muang District, Nonthaburi 11000.

   
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