Scaly-sided Mergansers Mergus squamatus on the lower Chongchon River, central Korea.

In autumn 2003, the lower Chongchon River in central Korea supported at least 40 Scaly-sided Mergansers Mergus squamatus, significantly exceeding previous published estimates of the DPR Korean population. This is a non-breeding concentration of global significance (on currently available information) for this threatened species. Information is presented upon numbers present, sex ratio and behaviour from mid-October (when the birds were found) until late November (when observations ceased). Supplementary observations from March 2004 and autumn 2004, indicating regular use of the site, are also presented. Conservation issues related to the species at the site are reviewed.