낙동강하류 교량간격에 따른 큰고니(Cygnus cygnus) 월동개체수 차이 연구

The purpose of this was to examine the differences of large whopper swan (Cygnus cygnus) in wintering habitat preference among bridge sections of the lower Nakdong River of the Nakdong River Estuary, the largest whopper swan’s wintering habitat in Korea. This species is designated and protected as Natural Monument in Korea. The survey was conducted in six time-series during the 2018~2019 wintering season, and it found up to 500 whopper swans were wintering in the lower Nakdong River. For the survey, a seven sections were set up based on the bridges across the river. Whopper swans were rarely observed in five narrow sections where the distance between bridges was less than 2 ㎞. The stable population of the whopper swan was observed only in two broader sections where the distance between bridges was is over 4 ㎞. As these sections were relatively little affected by artificial interference, the distance from the mouth of the Nakdong River was not a factor. Securing a stable space is considered as one of the most important factors for wintering of whopper swans, which are an endangered species. The survey results indicate that the distance between bridges should be at least 4 ㎞ to secure the whopper swan’s stable habitat. These results are expected to be a reference to the development or restoration of the river ecosystems, especially bridge construction.