Factors affecting population abundance of three sympatric mynas – case study in Riparian Zones of Taipei City
Date Issued
2015
Date
2015
Author(s)
Chang, Chun-I
Abstract
Invasive species threaten native biodiversity, they have been considered as one of the reasons that make native species extinct. However, there is no enough statistical evidence could prove the decreased population of native species was due to the threat from invasive species. In addition, environmental disruption and habitat loss has also been considered as one of the reasons that make the population of native species declined. In the 1970s, Acridotheres tristis and Acridotheres javanicus were introduced into Taiwan. Meanwhile, populations of the native myna species Acridotheres cristatellus continue to decline after 2000. It is generally considered that the decreasing of A. cristatellus was due to competition with the invasive mynas. However, direct evidence of competition between these mynas has not yet been recorded. Furthermore, recent research and observations suggested that large scale habitat preferences may differ between native and invasive mynas. The difference in large scale habitat requirement between these three myna species was proposed to be a crucial point to explain the different population densities between the native and invasive mynas species. In this study, Taipei riverside was chosen as the study sites and the previous bird investigation data of Taipei riverside bird survey was used to analyze. Eventually, this study aimed to answer the following two questions: (1) Do native species and invasive species have different large scale habitat preference? (2) Will presence of invasive species impact on native species’ population? According to the results of this research, compared to invasive mynas, the native myna especially prefer grass in breeding season. Moreover, the population of native myna doesn’t decrease with the other two invasive mynas. These results implied the decreasing of grass habitat may be an important factor to provide an explanation of the decreasing native myna population. Moreover, this study could be an important reference for the conservation work of A. cristatellus, which has been classified as an endangered species in Taiwan.
Subjects
invasive species
protected species
habitat destruction
competition exclusion
Type
thesis
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