Protecting threatened Over-seas biodiversity

Invasive alien species in metropolitan France and overseas territories

What is an invasive alien species?

An IAS is a species introduced by humans, voluntarily or involuntarily, outside of its natural range, which reproduces and extends its range over the territory of introduction. The population or populations of this species then threaten the ecosystems, habitats or native species with ecological, economic or health consequences.

The Coypu Myocastor coypus © Gzen92

Did you know?

  • In metropolitan France, 509 invasive alien species have been introduced.
  • Invasive alien species have contributed to 40% of the extinctions recorded in the last 400 years (CBD, 2006).
  • IAS are involved in 53% of the extinctions of species recorded in the Overseas Territories.
  • 370 invasive alien species are present in overseas France.
  • 60 species appearing on the list established by the IUCN of the 100 most invasive species in the world are present in French communities overseas (ONB 2016).

Cases of voluntary introduction of species in metropolitan France

  • The coypu

Native to South America, the species was introduced voluntarily in Asia, East Africa, North America and Europe for the exploitation of its fur. The individuals are believed to have come from the base of voluntary escape or release. Present in more than 70 departments in France, the coypu digs burrows which degrade the banks and accelerate the filling of ditches and canals. It is also responsible for overconsumption of aquatic plants, the destruction of aquatic bird nests and damage to crops.

  • The red swamp crayfish

Native to southern Mexico and the United States, this species was introduced in 1976 in Europe for commercial purposes. Aggressive and robust, it attacks many invertebrates and can also transmit certain fungi to crayfish such as the white-legged crayfish, which saw its population drop by 68% between 1978 and 2006 in the Poitou-Charentes area.

  • The red-eared slider

Native to the eastern United States and northern Mexico, the species was introduced to Europe for pet stores in the 1970s. From 1989 to 1994, more than 4 million turtles were allegedly imported and sold alone in France. Released in the wild, this naturally voracious species attacks the species of amphibians and plants present in the ponds and threatens the European pond turtle. Finally, the species is also a vector and reservoir of salmonellosis.

The red swamp crayfish Procambarus clarkii © MikeMurphy
The red-eared slider Trachemys scripta elegans










Cases of involuntary introduction of cash in metropolitan France

  • The Asian hornet

The Asian hornet was probably introduced by the ceramic trade originating in the Chinese province in 2004. In 2020, the hornet would have colonized almost all of France, and reached Portugal, Spain, Italy, Germany, the Belgium, Great Britain and the Netherlands. This hornet particularly attacks worker bees and destroys beehives.

  • The Floating primrose-willow

Originally from South America, this aquatic herb was accidentally introduced into Australia and Europe. In France, it was reported from 1820-1830 and is today considered one of the most problematic invasive plants in France. It competes with the submerged aquatic flora by preventing the penetration of light towards the bottom and causes a reduction in the oxygen level in the water, thus limiting the survival of most animal species.

The Asian hornet Vespa velutina © Nicolas Y. D. TIREL
The Floating primrose-willow Ludwigia peploides © Père Igor









And Overseas?

Island environments are strongly impacted by IAS because they have small areas, high rates of endemism and geographic isolation.

  • The Black Rat on different islands

Native to tropical Asia, the species would have colonized the Near East in Roman times before invading Europe in the 8th century using boats. Present on many overseas islands, it threatens certain bird species in particular by consuming eggs and chicks. The rat is also a vector or reservoir of certain diseases such as leptospirosis, plague or bilharziasis.

  • The Hiptage on Reunion Island

Native to India and Southeast Asia, this lianescent bramble was introduced around 1915 and now invades the semi-dry forests of the island. She suffocates the canopy by surrounding herself around the trees.

Black rat Rattus rattus © CSIRO
Hiptage Hiptage benghalensis © Forestowlet










  • The red lionfish in the Caribbean

Originally found in the Pacific Ocean and the eastern Indian Ocean, the species was introduced in 1992 in the West Atlantic Ocean, probably by releases from aquarium animals. The species creates an imbalance within the Caribbean reefs because it is very voracious and consumes the juveniles of many species while having no predator in this region.

  • The Swamp harrier in French Polynesia

Diurnal raptor native to the western Pacific (New Zealand, Australia, New Guinea), the species was introduced to Tahiti in 1885 by the German Consul with the intention of limiting the number of rats. It then colonized many islands in French Polynesia and caused significant damage to the avifauna of these territories.

The red lionfish Pterois volitans © Jens Petersen
The Swamp harrier Circus approximans © Jude











One of the priorities of the LIFE BIODIV’OM is to put in place actions to manage these invasive alien species that threaten the biodiversity of the overseas territories.

  • In Reunion island, Mayotte and Martinique, rat management methods will be deployed in order to reduce their population in the territory of the Tuit-tuit, the Madagascar pond-heron and the White breasted trasher.
  • In Martinique, methods will also be implemented to limit the impact of mongooses on the White breasted trasher.
  • In French Guyana, management techniques will be implemented to reduce the area of Acacia mangium on the Guyana savannas and tests will be carried out on the Niaouli, a species also threatening the Guyana savannas.