There are animals and plants living on Montserrat today which were brought here by people. They are called introduced species. Some were introduced on purpose, but others were brought to Montserrat by accident.
Some introduced species are very useful to us, such as crop plants like bananas. Some can spread quickly without natural predators, and harm native wildlife, like Red Imported Fire Ants. These species are called invasive species. Scientists also call them invasive non-native species, or INNS.