Essex Red Data List - criteria for inclusion
The following criteria for listing are considered to be the key ones:
- in the national Red Data List (where one exists), irrespective of the frequency in Essex
- Nationally Scarce/Notable (where there is an available definition and list), again irrespective of the frequency in Essex. A small number of exceptions include situations where the national status has clearly become out of date and no longer applicable either nationally or within the county.
- for species which are not in either of the above categories, those which are rare/scarce in Essex.
- recorded in few modern sites (X or fewer sites, since 19XX)
- species with restricted distribution occurring in habitats under a high degree of threat nationally and/or within the county
- more widespread species which have undergone a substantial decline in number or distribution since 19XX. The values of X will differ for different taxonomic groups;
- species which are extinct in Essex, and for which there is significant potential for re-establishment, either naturally or through intervention.
The County Recorders and other county specialists have made judgments on which species have been included in the list, based on their specialist knowledge about the threshold values as applied to any particular taxonomic group in Essex.
The traditional county of Essex is approx. 395800ha in size. It includes 57 whole and part 10km squares (some with a very small area included in Essex) and 3958 monads or 1km squares.