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Invasive non-native species are a particularly significant problem for the UK Oversea Territories because they comprise mostly small, isolated islands and have high levels of rare and endemic biodiversity.

Find out more about invasive species in each territory by clicking on the map below:

Biodiversity in the Oveseas Territories

The UK has 14 Overseas Territories (OTs), all of which are islands except for the British Antarctic and Gibraltar. Biodiversity in the OTs is globally significant, supporting unique species and ecosystems and a large number of rare and threatened species.
Compared to metropolitan UK, the OTs comprise (according to the 2004 IUCN Red List):

  • 80 critically endangered species (compared to 10 in metropolitan UK);
  • 73 endangered species (12 in metropolitan UK); and
  • 158 vulnerable species (37 in the metropolitan UK).

Read the JNCC report Biodiversity: the UK Overseas Territories to find out more

Impacts of Invasive Non-native Species

The impacts of invasive non-native species on small islands is often much worse than elsewhere because the native flora and fauna have evolved in isolation from predators, competitors and diseases. As a result native species are less able to compete and defend themselves in the face of new threats. Since 1500 72% of global extinctions have occurred on islands and 67% of birds on oceanic islands are threatened by invasive non-native species (Baillie et al 2004).

The impact of House Mice on the critically endangered Tristan Albatross (Gough Island, Tristan da Cunha) is just one example of how native species can be unprepared to new threats posed by non-natives. Gough Island has been described as, arguably, the most important seabird island in the world but the introduction of House Mice has driven the Tristan Albatross into serious decline.

Read the JNCC report Non-native Species in the Overseas Territories: a review to find out more.


Together with the Foreign and Commonwealth Office (FCO), the Department for International Development (DFID) and the Joint Nature Conservation Committee (JNCC), Defra has agreed a Strategy for the Conservation and Sustainable Use of Biodiversity in the UK Overseas Territories. The Strategy aims to address the needs of the OTs, and has been built upon an assessment of priorities for biodiversity conservation action carried out by the JNCC.

Read the Overseas Territories Strategy here.

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