- 社団法人 日本造園学会
- ランドスケープ研究(オンライン論文集) (ISSN:1883261X)
- vol.11, pp.32-38, 2018-05-09 (Released:2018-05-23)
We investigated the migration range of Calopteryx atrata Selys (Odonata: Calopterygidae) using the mark and recapture method in Akuwa River and Ooka River which run through the urban area of Yokohama City, Kanagawa Prefecture, Japan. 286 individuals were marked and released at four spots, and 64 marked individuals were recaptured after several days. Initial findings showed that the maximum total migrant distance was 1319 meters, and the average was 323 meters. The individuals that migrated upper stream were more than those in the lower stream, and the migration range to upper was significantly longer than to the lower. Secondly, we analyzed the factors that promote or stunt the migration of C.atrata by GLMM with random effect. Results showed that survival days from release, the area of lower riverbed and coverage of shade were positively correlated with total migration distance. Meanwhile, the coverage of three types of the aquatic plant commonly had a negative correlation with the total migration distance. Also, the coverage area ratio of forest around rivers partly promotes the migration distance of C.atrata, if values of factors were added up in a more wide range from the release spot. The study’s results showed that continuously establishing preferred riparian habitats with aquatic vegetation and a conservation of forests close to rivers enhance C.atrata’s large migration and expanded habitats.