Although most introduction of species are a result of man’s intervention, some can be attributed to natural causes as well. This is accounts for very little of exotic species.

Due to rapid industrialization, forest and natural habitats are quickly being exterminated to make way for urban developments. The wildlife that used to live in these habitats are now homeless and are forced to find other places to live. Although most species die as their habitat are being destroyed, some species venture to different regions to call it their home. This is especially so for birds, which are able to fly to different regions to reside in.