동물은 그들의 필요와 외부 자극, 그리고 주변 환경에 반응하면서 특정한 행동과 이동 패턴을 보이며, 생활하면서 대부분의 시간을 보내는 일정한 영역인 행동권(home range)을 가진다. 행동권은 종의 존속과 보전에 매우 중요한 영역이라는 점에 기반하여 해외에서는 행동권 추정 방법론 개발 및 정책 반영이 활발하게 이루어지고 있다. 원격 추적 기술의 발전으로 인해 좌표간 시간 간격이 줄어들며 정밀해진 동물 추적 데이터는 기존 행동권 방법론에 한계점을 드러냈으며, 이를 보완하기 위하여 다양한 새로운 방법론이 개발되었다. 하지만, 국내 행동권 연구는 아직 더딘 편이며 새로이 개발된 방법론 도입도 전혀 이루어지지 않고 있는 상태이다. 본 연구는 동물 행동권의 더욱 정확한 추정을 목적으로 꾸준하게 개발되어 온 해외의 방법론들을 정리 및 소개하여 국내 도입을 촉진하는 것을 목적으로 한다. 먼저 크게 기하학적 그리고 통계적 추정 방법론으로 나눈 후 좌표들이 독립일 때와 자기상관성이 존재할 때의 경우로 나누어 총 7가지의 행동권 추정 방법론을 비교 및 고찰하였다. 실제 전남 신안군 불무기도에 번식하는 괭이갈매기(Larus Crassirostris)의 6월 한 달간 GPS 위치 추적 정보를 사용해 본 연구에서 소개한 방법론을 적용하여 행동권을 도출하였 다. 행동권 결과를 비교분석 함으로써 각 방법론의 특징 및 한계점을 논의하였으며, 향후 동물 행동권을 분석하고자 하는 연구자가 본인이 가지고 있는 데이터 특성과 분석 목적에 알맞는 방법론을 선택할 수 있도록 행동권 분석 방법론 선택 의사결정 가이드라인을 제시하였다.

In this study, total mercury (THg) variations of Black-tailed Gull (Larus crassirostris) eggs laid on Baengnyeongdo, West Sea of Korea were compared between within- and among clutch in order to ensure statistical representativeness of an egg sampling method. In the ANOVA analysis, the THg variation (59%) among clutches was much higher than within-clutch (27%). This means that the mercury variation of sampled eggs was significantly influenced by the mercury variation among female individuals occupying different nests. In spite of relatively smaller variation of THg in the within-clutch, the THg concentration depending on an egg-laying sequence within a clutch significantly appeared higher in the first-laid eggs rather than the second-laid eggs. Therefore, it is necessary to take one egg from one nest in order to sample more nests in terms of better sampling representativeness. Also, one egg selection from one nest should be consistently applied in order to ensure comparability of mercury concentrations among monitoring sites and monitoring years.

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.