Invasive species are sometimes referred to as ‘aliens’. They are plants, animals, fungi and microorganisms that have been moved from their home (native) range,  into a new environment. This movement of species is done by humans and can be intentional (e.g. the introduction of a new garden tree) or accidental (such as insects imported on fruit and vegetables). 

Once these aliens arrive in their new home, they begin to take over. Invasive species often share a number of characteristics which lead to them getting out of control. They adapt to their new home by eating whatever they find available. They often have lots of babies or produce lots of seeds. Also the predators and diseases that keep the invaders in check in their native range are often not found in the new range, so there is nothing to keep the population down.

For example, in the Indian and Pacific Oceans there are other fish that prey on lionfish, and the little fish that the Lionfish eat are used to hiding from them. In the Atlantic Ocean there are almost no predators that can eat a Lionfish, and our young fish do not recognize the Lionfish as a threat to them, so lots of them get gobbled up.

World-wide invasive species are one of the leading causes of biodiversity loss. Because invasive species are so successful in adapting to a new environment, they directly compete for food, water, space and other resources with the native species. This can lead to the invasives crowding out or eating the natives and even pushing endemic species to extinction.

Island environments, like Bermuda, are especially vulnerable to invasive species because our native island species are used to the conditions here, and do not adapt easily. Island species are often slow growing and found in small numbers due to the small size of the islands. Islands also have a large number of endemics.

Bermuda is particularly vulnerable to the introduction of invasive species through our importation of food and other consumer products. These shipments can inadvertently introduce dangerous species into our environment. Additionally, people smuggling plants, animals, seeds or fruit back from their vacations could accidentally introduce an invasive species that will seriously damage Bermuda’s environment.

The World Conservation Union (IUCN) maintains a list of the top 100 worst invasive species in the world. Of these top 100, 23 are found in Bermuda. They include: water hyacinth, Brazil Pepper tree, Kudzu, Wedelia, cane toad, Starling, Red-eared slider, domestic cat, mouse, rats and several kinds of ants.

Some of the other species considered invasive in Bermuda include the following:


Controlling the spread of invasives and reducing their numbers is a considerable challenge in Bermuda. To read about some of the programmes that are underway, please visit our Invasive Species Management page.

Further reading available on invasive species in our library and in the PlantFinder: Guide to Indigenous and Invasive Plants