Ten Years of Monitoring the Nesting Ecology of the Green Turtle, Chelonia mydas, on Lanyu (Orchid Island), Taiwan

Abstract

I-Jiunn Cheng, Cheng-Ting Huang, Po-Yen Hung, Bo-Zong Ke, Chao-Wei Kuo, and Chia-Ling Fong (2009) Ten years of monitoring the nesting ecology of the green turtle, Chelonia mydas, on Lanyu (Orchid I.), Taiwan. Zoological Studies 48(1): 83-94. We report on the nesting ecology and environmental parameters of one of the largest green turtle, Chelonia mydas, rookery nesting site in Taiwan: Lanyu (Orchid I.), Taitung County, southeastern Taiwan. The site was studied from 1997 to 2006. Results showed that although turtles nest year-round, the main nesting season occurs in the warm and dry summer. Green turtles were forced to nest on the smallest beach, where anthropogenic disturbances were relatively low. The warm surface-water temperature tends to result in shorter inter-nesting intervals. Fewer nesters in poor nesting years were found to lay fewer clutches. The relatively wet and cooler weather and firm sand on Lanyu tends to increase the substratum compactness, resulting in relatively shallow nests. Larger females tended to deposit larger clutch sizes. Precipitation may be responsible for increased hatching mortality. The morphological characters of the hatchlings were found to be influenced by the egg characters. Although the population size of the study area is small, studies of the nesting ecology and conservation measures are still important to the regional population status, especially in the Asian region where most populations are either severely depleted and/or poorly understood.