Mar232023

Yeoncheon Imjin River Biosphere Reserve, March 13th-17th

Bird Sightings

Bird news from Nial Moores, Baek Seung-Kwang and Lee Su-Young

Baikal Teal Sibirionetta formosa 가창오리 : Birds Korea logo bird, and one of several really beautiful duck species found along the Imjin and Hantan Rivers.

Research and discussion continues in support of the internationally important Yeoncheon Imjin River Biosphere Reserve and Yeoncheon County. Birds Korea’s focus, much as last year, remains on improving understanding of habitat use by the globally Endangered Scaly-sided Merganser Mergus squamatus and additional riverine and river-side biodiversity. Reports and a paper (currently still at draft stage) will present much fuller details of this work later this year.

During this 5-day period, in unseasonally mild (warm even) conditions, we conducted three whole day counts along the length of the Imjin River in Yeoncheon County; a one day count along the Hantan River; and spent a half day in the CCZ followed by a 2.5 hour field consultation with Dr Yoo Miyeon back at the Hantan.

Field time to look at some of the links between biodiversity, wetland restoration, water quality and genuine environmental education…

In spite of massive disturbance caused by active drills (including heavy hardware in a couple of stretches of river and up to three helicopters overhead for an hour or more at a time), we again found Ramsar-defined internationally important concentrations of the very easily-disturbed Scaly-sided Merganser – with most birds in pairs and strong indications of rapid turnover (based on individual differences in plumage of some individuals, and different numbers within preferred areas during each of the three counts);  widespread Mandarin Duck; >2,000 Baikal Teal (revealing several of their behavioral “secrets”) ; good numbers of both Red-crowned and White-naped Cranes watched spiralling up high before departing northward; and decent numbers of other early spring migrants, including several large flocks of Rook with a handful of Daurian Jackdaw mixed in, several flocks of 50-100+ Rustic Bunting (and at least two Little Bunting), and a scattering of Naumman’s Thrush, Long-tailed Rosefinch and Siberian Accentor.

Scaly-sided Merganser Mergus squamatus 호사비오리 © Nial Moores. Even in these really poor digi-scope images individual differences are apparent in each of these three pairs, including in males in crest length; extent of scaling; and pattern at the base of the dark neck sock (a wide open indent on some; much reduced or even absent on others). Females also tend to show wide variation in crest length; darkness of scales and extent (with some heavily marked on the breast and others almost unmarked) ; and also in the pattern at the base of the neck sock in addition to contrasts on the “face”. Of particular note too, one pair was feeding on small items taken from the river bed in some especially shallow riffles. Up to now, we have only seen them foraging on fish here in the ROK – though they are known to feed on e.g., insect larvae in the breeding grounds
Mandarin Duck Aix galericulata 원앙 © Baek Seung-Kwang: another one of Korea’s gorgeous duck species
Baikal Teal 가창오리 © Nial Moores. Note the raised mantle and back feathers, presumably to help birds warm up in the morning sun (none appeared to be doing this in the afternoon; and no other duck species seemed to be doing this either). Is this something Baikal Teal often do? Do other duck species do this too? As an/ the archetypal duck species, Baikal Teal really seem to show an amazing range of behaviours – some perhaps unique, some obviously shared with other species.
Baikal Teal © Nial Moores. In Korea, we usually think of this species as a specialist feeder on fallen rice, consumed mostly at night. During this survey, we saw birds actively dabbling, picking at tiny items on or close to the water surface. The items were too small to see, even through a ‘scope: algae or hatching insects perhaps?
Two out of a flock of 1800 Baikal Teal, many of which were feeding on some small item near the water’s surface © Nial Moores.
In Korea in winter, Baikal Teal often form dense rafts of hundreds of thousands of birds out on open water. They are usually rather quiet. Many males in this flock gave a constant, noisy “wot-wot-wot”, though none were seen in active display. It is tempting to suggest that most of these birds are unpaired still and are also likely Second Calendar-years. Many of the males showed some blurring or reduced white foreflank stripe and seemed to lack as much black in the “super scapulars” as said to be shown by adults (see here for an article by the amazing late and great Martin Garner).
Siberian Accentor Prunella montanella 멧종다리 © Nial Moores.

Counts will continue on through March (and the rest of the year) led by Birds Korea Yeoncheon.

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