Construction and monitoring of the crabs underpass on Green Island, Taiwan
Wei-Ting Liu, Quen-Dian Zhon, Yu-Bo Hwang, Wei-Ling Su, Chia-Yung Lu
(本公司發表成員：劉威廷 鍾昆典 黃于玻 蘇維翎 呂嘉耘)
Observer Ecological Consultant Co., Ltd., Taiwan (R.O.C)
The current crab conservation project aims to balance ecological concern for crab habitats3,4, economic development, and the local government plans for Green Island in Taiwan. In Green Island, recreation-related coastal development brings both good and bad consequences to the local community. The significant outcome of the round-the-island road is not only shown by the mass of tourists amusing themselves by the beach, but has also encroached on the migration route of land crabs to sea for spawning. To decrease the habitat fragmentation effect of crabs, several underpasses were constructed, with the combined efforts of the Green Island tourism and environmental education, which not only involved ecological experts and the local government, but also the local tourism businessmen.
Since 2006, to determine the ecological pattern of crab road kill during the breeding season, the local government conducted several projects to study the crab ecology on the island, including crab species, activity pattern1. Those studies2,3,4 also systematically collected crab road kill data such as numbers, locations, and hotspots. Based on these studies, our project sifted 2 sites from several road kill hotspots on the round-the-island road to build an underpass at the end of 2008 and in mid-2009. However, a construction project for the crabs on the only road in Green Island was not easy because the local people and tourists only perceived the construction as annoying. In an effort to reach an understanding with the local communities, several meetings held between the scientists, officers, environmental NGOs, and the local residents to ensure that the crab underpass construction adds more value of tourism rather than trouble.
After the crab passages were completed, we used direct observation and track identification methods to monitor and evaluate the effects of the crab underpass. During our study, hermit crabs used the tunnels most frequently; up to 79.2% of the total number of observed individuals. Cardisoma spp. accounted for approximately 8.3%; other crabs such as the coconut crab (Birgus latro), Metasesarma obesum, and Gecarcoidea lalandii represented 6.9%. The monitoring result shows that the road sections with the underpass had fewer crab road kills. Surprisingly, some snakes (mostly Oligodon formosanus) and mammals (Shrews and the protected Formosan gem-faced civets, Paguma larvata taivana) used the tunnels very well.
The project also involved local inhabitants who are interested in ecological tourism. While some of the residants helped monitor the utility rate of underpasses and crab behavior regularly, the tour directors started to value the crab ecology as a good scenic spot. The “crab ecology tourism” became one of most popular ecological tourism event on Green Island.
Considering the increasing awareness regarding ecology and conservation among the Taiwanese local government, this study proposed a complete protocol that includes an ecological survey, a hotspot analysis, and construction guides to improve the environmental and ecological conditions in Taiwan.
Key Words: wildlife passage, underpass, roadkill, hermit crab, coconut crab, crab, Green Island
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