Swan Geese and concrete in Yudo, 16 November 2020

Dr. Bernhard Seliger and Dr. Hyun-Ah Choi (Hanns Seidel Foundation, Birds Korea) with Haesu Jung (HSF)

After a hiatus of several month, the November survey in the Siam wetland and Hangang Estuary area near Yudo Islet brought positive and negative results. Starting in extremely foggy conditions, for the first few hours counting was severely limited. So, a large flock of several thousand geese, maybe attracted by feeding by the Wild Bird Society of Gimpo, could only be very insufficiently estimated instead of counted. Later, weather conditions cleared and actually became beautiful, but due to the tight schedule in the border area (we had to arrive at the last guard post by 3.30 p.m.), also counting was limited.

The most depressing sight was a huge construction project to substitute former trenches with concrete slabs – where there was formerly more or less natural growth along the trenches, now the landscape becomes devoid of any habitat. This will severely affect in particular small passerines, like finches and buntings, many of which had already arrived and now find less and less habitat. Why these new concreted trenches should be so advantageous to farmers, seems incomprehensible: they prevent frog migration and thereby reduce rice yields. Though there are no studies for Korea yet, studies elsewhere showed measurable declines of yields due to the lack of frogs, plus higher costs for pesticides once frogs cannot control pest populations. In other places in Korea (like in Yeoncheon, Baegnyeongdo, Goseong) recently “frog ladders” have been installed to allow frogs climb out of the deep trenches. But this is certainly a second-best option in places, where natural trenches are already in place. Actually, in Europe many states now reverse the concretization of landscape, at high costs. Why Korea should be doing the same mistakes, given its extensive benchmarking abroad, is not understandable…

On a positive note, among the birds seen at least 800 Swan Geese were certainly a highlight, in the same place just behind the fence at Hangang River where they had been in the past two years. Allowing for more time, maybe even a much higher count could have been possible, since a third of the potential territory could not be surveyed due to time limitations. They seem to be attracted by certain tubers there and were digging voraciously for them in the soft ground. Once that ground is frozen in mid-winter, they can be expected to be further South.

Other finds include:

  • Around 10.000 geese, of which more than 3300 Greater White Fronted and Tundra Bean Geese each, and the rest not identified
  • One Chinese Grey Shrike, a rare, but seemingly regular visitor in both the Siam and Yudo area
  • Two larger flocks of Rustic Buntings, now classified as vulnerable, with a total of 185 birds
  • One Yellow-browed Bunting
  • One Light-Vented Bulbul
A Chinese Grey Shrike Lanius sphenocercus with a late frog © Bernhard Seliger
One of the new concreted trenches © Bernhard Seliger
A natural trench … what a difference for bio-diversity! © Bernhard Seliger
Swan Geese Anser cygnoides © Bernhard Seliger
A dirty Swan Goose Anser cygnoides after digging for tubers © Bernhard Seliger
Geese flying over the border – birds don´t know borders, people do…© Bernhard Seliger
Common Kestrel Falco tinnunculus © Bernhard Seliger

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