In the 1970s, Acridotheres tristis and Acridotheres javanicus were introduced into Taiwan. Meanwhile, populations of the native myna species Acridotheres cristatellus, which is an endangered species in Taiwan, continue to decline after 2000. It is generally considered that the decrease of A. cristatellus is due to competition with the alien mynas. However, direct evidence of competition between these mynas has not yet been determined. Recent observations at Taipei metropolitan area suggest that habitat preferences on a large scale may differ between native and alien mynas.

In this study, I used the bird investigation data of Taipei riverbank parks to answer the following two questions: (1)Do native species and alien species have different habitat preference? (2)Will presence of alien species impact on native species’ population? According to the results of this research, we can realize native myna prefers grass in breeding season. In addition, the number of native myna isn’t influenced negatively by the other two alien mynas.

Research results verify declining of grass habitat may be another important factor causing the decline of the native myna. Moreover, it will be an important reference for conservation of A. cristatellus.