The importance of the Territories for biodiversity and geodiversity


Globally threatened species

Of globally threatened species identified in the 2004 IUCN Red List, 74 critically endangered species occur in the UK Overseas Territories (compared to 10 in mainland UK) along with 49 endangered species (12 in mainland UK) and 117 vulnerable species (37 in the mainland UK).  Many of these species are endemic and so are found nowhere else in the world.  In addition, and as an indication of the threat to island biodiversity, there are 39 recorded extinctions in the UK Overseas Territories and two species are extinct in the wild, compared with only a single extinction from the metropolitan UK (namely the great auk).  The latest extinction in the Overseas Territories, the St Helena olive Nesiota elliptica, occurred in 2003 when the last tree in cultivation died (the last wild individual died in 1994).  It is likely that these figures are under-estimates; new studies invariably report the occurrence of additional species or populations, especially amongst the less well known taxa, such as invertebrates.

Globally/regionally important concentrations of species

Green turtle Chelonia mydas on Ascension Island © Anselmo PelembeIn addition to numbers of globally threatened species, the Overseas Territories also hold regionally or globally important concentrations or assemblages of species.  For example, Ascension Island supports the second largest green turtle rookery in the Atlantic; Gough Island (Tristan da Cunha) has been described as, arguably, the most important seabird island in the world; and the reefs of the Chagos Archipelago (British Indian Ocean Territory) are some of the most pristine and best protected in the Indian Ocean (and account for some 1.3% of the world resource).  The importance to nature conservation of parts of the Territories is recognised through the designation of Gough Island & Inaccessible Islands (Tristan) and Henderson Island (Pitcairn) as World Heritage Sites for their insular natural heritage interests.

Crown Dependencies

The Crown Dependencies have greater biogeographical similarities with the mainland UK but are notable, for:
  • a range of species found in the Channel Islands whose range does not extend to mainland Britain;
  • insular forms of some species (such as the Guernsey vole);
  • populations of breeding birds (e.g. seabirds, chough and hen harrier on the Isle of Man);
  • and for a range of marine and terrestrial habitats which are significant in a UK and regional context. 

Geomorphological features

Volcanic coastline of St Helena island © Emma BennettThere has been no overall review of the importance of the Territories to geodiversity but they contain geological and geomorphological features, such as active volcanoes, glaciers and coral reefs that are almost certainly significant in a regional or global context.

Threats to biodiversity

Threats to the biodiversity of the Territories include non-native species, climate change and the impacts of development. Threats also come from fisheries, and tourism. Various conservation projects have been set up in the territories to attempt to start to address some of these threats.