괭이갈매기는 국내에서 서식하는 대표적인 바닷새로, 서해와 남해뿐만 아니라 동해까지 집단 번식지가 존재하고 있다. 하지만 현재 괭이갈매기에 대한 연구의 대부분이 서해와 남해에서 번식하는 개체에 집중되고 있어, 동해 지역에 대한 연구가 상대적으로 부족한 상황이다. 이에 본 연구에서는 동해 울릉도에서 번식하는 괭이갈매기 4개체를 대상으로 2021년과 2022년 5월에 야생동물 위치추적기(WT-300)를 부착하여 이동경로와 행동권 분석을 실시하였다. 괭이갈매기는 번식기간에 울릉도 주변 또는 강릉에서 울진에 이르는 동해 연안까지 활동범위로 삼았고, 번식기 이후에는 일본의 중남부 지역으로 이동하여 서식하는 것으로 나타났다. 국내에서 번식기간 MCP 분석에서 행동권 평균면적은 9,476± 10,066㎢로 확인되었고, KDE 분석에서는 95%일 때 3,574±3,378㎢, 50%일 때 289±200㎢로 나타났다. 번식기간 이후 일본에서의 MCP 행동권 평균면적은 1,899±3,127㎢이었고, KDE 95%는 2,844±4,787㎢, KDE 50%는 385±635㎢ 의 행동권을 보여주었다. 본 연구는 동해와 일본 연안을 이동하며 서식하는 괭이갈매기의 행동권을 제공함으로써, 괭이갈매기의 보전과 관리를 위한 기초자료로 사용될 수 있을 것으로 생각된다.

Nando Island is reported as one of the biggest breeding colonies of seabirds in South Korea, and is protected as a Natural Monument. This study was conducted between July to November 2015, to investigate the breeding population of Black-tailed gulls and their habitat on Nando Island. We estimated the breeding population of Black-tailed gulls (Larus crassirostris) using nest density. The mean nest density of Black-tailed gulls was 0.51 per 1 m2 (0.51 m-2), and the breeding population was approximately 26,760 individuals. The dominant vegetation was Echinochloa crusgalli and Agropyron tsukushiense var. transiens, which served as shelter and nest sites to Black-tailed gulls. The diet of Black-tailed gulls was mainly the fish, Japanese Anchovy Engraulis japonicas (48%). Other species which were found to breed on Nando Island were Streaked Sheawater (Calonectris leucomelas), Temminck’s Cormorant (Phalacrocorax capillatus), and Swinhoe’s storm petrels (Oceanodroma monorhis).

Sea gulls are high trophic level consumers in the coastal environment, and thus, which have been widely used to monitor contamination biomagnified through a food web. However, such monitoring studies using sea gulls have been rare in the Korean literature. The National Environmental Specimen Bank chose eggs of a black-tailed gulls (Larus crassirostris) to serve as an environmental specimen for the long-term monitoring of the coastal ecosystem affected by terrestrial pollutants. Black-tailed gull eggs were collected from Baengnyeongdo, Hongdo and Uleungdo, and their DDTs and total mercury content were determined. The highest concentration of ΣDDTs was 231.6±106.1 μg/kg wet in Baengnyeongdo, followed by 230.0±123.8 μg/kg wet in Ulleungdo, and 117.7±18.3 μg/kg wet in Hongdo. In addition, total mercury was detected at 414.5±97.6 μg/kg wet in Ulleungdo, 363.9±123.6 μg/kg wet in Hongdo, and 237.5±42.3 μg/kg wet in Baengnyeongdo. Relatively high concentrations of the target pollutants were recorded in specimens from Ulleungdo. Additional comprehensive and prolonged studies are required to elucidate spatial and temporal patterns of contamination in black-tailed gull eggs with regard to monitoring contaminant trends in eggs and prey.