Abstract: Biological invasion is recognized as one of the greatest threats to the global biodiversity because invasive exotic species not only alter the local environments but also have serious ecological effects on native species. Birds are positioned at high trophic level within the food web in the ecosystem, and thus any changes within the system can affect the birds in one way or another. The ecological effects of different exotic taxa like mammals, birds, invertebrates and plants on native birds are reviewed in this paper. In summary, the exotic species can affect native bird species in four main ways, 1) predation of birds or eggs by the exotic mammals; 2) competition for habitats and foods with exotic birds, and loss of genetic diversity by hybridization with the closely-related exotic species; 3) direct and indirect alterations of native habitats and food resources, and predation by the exotic invertebrates; and 4) loss and fragmentation of habitats for native birds through altering species composition and structure of native plant communities by exotic plants. The unsolved questions and future research directions in this field are also addressed.