On the conservation biology of a Chinese population of the birdwing Troides aeacus (Lepidoptera: Papilionidae)

摘要

This study deals with the habitat requirements and (meta)population ecology of the Birdwing Butterfly Troides aeacus in the Xiaolongshan forest area and the Baishuijiang Natural Reserve of Gansu Province, China. The more descriptive components mainly summarize the biology and habitat requirements of the species. A detailed account is given of 3-year presence/absence dynamics in a suspected metapopulation, which consists of ten habitat patches. By means of GLM a habitat model was developed which has shown that the abundance of Troides aeacus will increase with both the number of larval host plants and adult nectar plants, while it will decrease with denser forest canopy structure. The hierarchical partitioning of the explained variance indicated that the independent effects of the number of nectar plants and the forest canopy density are the most important factors, while the explanatory power of the number of host plants was minimal. Habitat loss and degradation are the most severe threats to Troides aeacus populations in the study area. These are mainly due to continuous human activities such as destruction of forest for reclamation, grazing, mine exploitation, and cutting of firewood, but also herbicide application and sometimes even certain types of afforestation. While the availability of host plants is a clear pre-requisite for the survival of the species, conservation should be most efficient through an increase in the abundance of nectar plants as well as through the avoidance of complete forest cover (through an appropriate cutting management which would also promote growth of the host plants). As environmental threats are quite similar in the entire Southern Gansu region, we expect that the implementation of such butterfly conservation measures should have positive impacts on many other components of biodiversity.