Taxa considered to be Endangered, Vulnerable or Rare in Great Britain but where there is not enough information to say which of the three categories (RDB 1 to 3) is appropriate.


Taxa in Great Britain that are suspected but not definitely known, to belong to any of the above categories, because of lack of information.


Taxa with small populations in Great Britain that are not at present endangered or vulnerable, but are at risk. These taxa are usually localised within restricted geographical areas or habitats or are thinly scattered over a more extensive range.


Taxa believed likely to move into the endangered category in the near future if the causal factors continue operating. Included are taxa of which most or all of the populations are decreasing because of over-exploitation, extensive destruction of habitat or other environmental disturbance; taxa with populations that have been seriously depleted and whose ultimate security is not yet assured; and taxa with populations that are still abundant but are under threat from serious adverse factors throughout their range.


Taxa in danger of extinction in Great Britain and whose survival is unlikely if the causal factors continue operating. Included are those taxa whose numbers have been reduced to a critical level or whose habitats have been so dramatically reduced that they are deemed to be in immediate danger of extinction. Also included are some taxa that are possibly extinct.


Based on records from the modern recording period, and where:

  • There is reasonable confidence that exhaustive recording would not find them in more than 100 hectads.
  • Where it is believed to occur as a breeding species within each of these hectads (i.e. discount those that are known to contain only casual immigrants).

The Ordnance Survey national grid has 2,853 hectads that overlap with Great Britain.

Legal Protection

For most species, this protection is provided through their inclusion on various schedules contained in the Wildlife and Countryside Act 1981 and the Habitats Regulations 1994. Protection is variable, ranging from killing and injuring to sale only.