Half a year of surveys at the Han River Estuary around Yudo Island

Bird News Dr. Bernhard Seliger with Dr. Choi Hyun-Ah and Dr. Nial Moores

Rice-fields and hills with mixed forests, few human settlements, a fence and then the river – this is the situation along the Han River from the estuary almost stretching to Seoul. The fence, interrupted by frequent military structures like guard houses and artillery bunkers, separates sometimes considerable strips of reed bed and along the East side of the Han River even large rice field areas from the other side, the so-called “civilian control zone”. In this area, the area from Yudo Island, a small islet in the Han River to Siam wetland , is part of Gimpo city, bordered by Gangwha Island in the West.

Between late November 2018 and April 2019, Dr. Choi Hyun-Ah and Dr. Bernhard Seliger of Hanns-Seidel-Foundation (both also members of Birds Korea) carried out ten bird and ecological surveys in this area to document its importance, in particular that of Yudo Island, for migratory birds and develop ideas for protection of the area under changing political circumstances (for a discussion of these options see the contribution in the environment section). For three surveys, they were joined by Dr. Nial Moores of Birds Korea, who also continuously served as a consultant to the project.

The survey resulted in a confirmation of the importance of the area, in particular Yudo island, on the number of grounds:
Yudo Island itself is one of the most important breeding areas for Great Cormorant, with around 580 occupied nests counted, but also Grey Herons, Great Egrets, and probably Black-crowned Night Heron and Black-Faced Spoonbill. For the latter species, a positive proof of nesting was difficult, since due to the military restrictions no survey on the island itself could be done. But observations from the mainland strongly suggest this possibility. Definitely, the area is regularly visited by Black-faced Spoonbills, a fact not only confirmed by our own records, but also by satellite tagged birds and by past records of breeding there in substantial numbers. Tags show that birds staying in the Yudo area frequently visit the opposite coast of South Hwanghae province in North Korea, confirming the truth that “birds do not know borders”.

The rice field areas around Yudo, the coastline as well as Siam wetland (on the East of the main survey area) are important wintering grounds for goose species. The most surprising finding was the use of the area during November and December of just over 1,000 Swan Geese, considered to be the largest flock seen in South Korea in more than ten years. Also, internationally important concentration of Tundra Bean Goose and Greater White-fronted Goose were recorded throughout the winter. Siam wetland is also known as a stopover spot for White-Naped cranes.

The area was also throughout the winter visited by White-tailed Eagles, with up to 15 eagles counted along the Han River and in the adjacent forests. Once, also a Golden Eagle was recorded. Other raptors included Merlin, Peregrine Falcon, Cinereous Vulture, Hen Harrier and Northern Goshawk. At least one Chinese Grey Shrike (potentially more) was seen in the survey area throughout the winter, a beautiful winter visitor today very scarce in the South with the exception of the border area. Additionally, the slowly maturing riparian forests on the soft hills along the Han River were home to at least three territories of the uncommon Grey-capped Woodpecker, a species recently making a comeback.

During the spring migration, the area becomes an important staging area and stopover for a number of species, including thousands of geese, ducks and gulls (among them surprisingly many Black-tailed Gulls usually more thought of as a coastal species). Notable species include Far Eastern Curlew, Mandarin Duck, Baikal Teal, Grey-faced Buzzard and Upland Buzzard, While there are still many places, where also small passerines can winter in ditches, along small waterways, and along the forests, the attempts by the Rural Administration to “beautify” the landscape by concrete trenches with steep walls – a death trap for many animals ending up in these concrete structures – can unfortunately be seen in many places. It makes one wonder if ever a cost-benefit-analysis of these structures, taking into account environmental costs, has been made. Among others, the empty landscapes with concrete trenches and cleaned-out fields, which partly is already found in the hinterland of Siam wetland, also probably adds up to fine dust problems: water rapidly moves along the trenches and disappears, and in the dry winter days the dust can be seen spread widely by the wind, with too few natural barriers like bushes, forests, natural trenches collecting it.

The future of this area important for bird migration and bird wintering is open – while hopefully, rapprochement and ultimately peace will make the border obsolete, new plans for development will have to be balanced with the protection of birds in the area. Already today, independently from plans for future use, habitat improvements can be introduced on a small scale, like the re-naturation of trenches, in particular through re-introduction of vegetation like reed into the cleared and sterile trenches, frog ladders to alleviate the problem of deep concrete structures, better water management and, possible, the planting of wind-breaking hedges rich in biodiversity. To achieve this, a dialogue among all stakeholders – land-owners, administrations, military, national and international environmental NGO – should take place. This is a big challenge in a society where this kind of cooperation is rather unusual… but it is the only way, the beauty and riches of Yudo and the Han River Estuary can be preserved and even improved.

Yudo Islet seen from the slopes of the riverside mountains – in the background the coastline of South Hwanghae Province. © Bernhard Seliger

Swan Geese through the fence. Anser cygnoides © Bernhard Seliger
Geese overflying the border fence – “Birds don´t know borders.” © Bernhard Seliger
The main survey team: Dr. Choi Hyun-Ah, Dr. Bernhard Seliger (both HFS, Birds Korea) © Mr Park Kung Man
Grey-capped Pygmy Woodpecker Dendrocopos canicapillus © Bernhard Seliger
Chinese Grey Shrike Lanius sphenocercus © Bernhard Seliger
Intermediate Egret Egretta Intermedia © Bernhard Seliger

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