Hierarchy of
Lists
The Species Status Project covers all species 'of conservation
concern'. These are currently listed in the SoCC list (Species of
Conservation Concern). This list pre-dates the SSA and will be
modified as the SSA progresses, so that areas of weakness are
strengthened and all species included are assessed to an agreed
standard.
The SoCC list is compiled according to a number of criteria: Red
List status, international threat/importance, decline, localisation
and occurrence on international directives. Thus, Red Lists and
legislative lists nest inside the SoCC list. The following diagram
illustrates how the various components nest within one
another.
Futher explanation of categories included in SoCC
list
Red List categories
Definitions of IUCN threat categories (World Conservation
Union 1994) (a)
| IUCN threat category |
Definition of taxon |
| Extinct (EX) |
A taxon is Extinct when there is no reasonable doubt
that the last individual has died. |
| Extinct in the Wild (EW) |
A taxon is Extinct in the Wild when it is known to
survive only in cultivation, in captivity or as a naturalised
population (or populations) well outside the past range. A taxon is
presumed Extinct in the Wild when exhaustive surveys in
known and/or expected habitat, at appropriate times (diurnal,
seasonal, annual) throughout its range have failed to record an
individual. Surveys should be over a time frame appropriate to the
taxon's life cycle and life form. |
| Critically Endangered (CR) |
A taxon is Critically Endangered when it is facing an
extremely high risk of extinction in the wild in the immediate
future, as detailed by any of the criteria A– E.
(a) |
| Endangered (EN) |
A taxon is Endangered when it is not Critically
Endangered but is facing a very high risk of extinction in the
wild in the near future, as defined by any of the criteria A–E.
(a) |
| Vulnerable (VU) |
A taxon is Vulnerable when it is not Critically
Endangered or Endangered but is facing a high risk of
extinction in the wild in the medium-term future, as defined by any
of the criteria A–D. (a) |
Summary of the thresholds of the IUCN criteria
| Criterion |
|
Main thresholds |
|
| |
Critically Endangered |
Endangered |
Vulnerable |
| A rapid decline |
>80% over 10 yrs or 3 generations in past or future |
>50% over 10 yrs or 3 generations in past or future |
>50% over 20 yrs or 5 generations in past or future |
| B small range —fragmented, declining or
fluctuating |
extent of occurrence <100 km2 or area of occupancy <10
km2 + single locality, decline or fluctuation |
extent of occurrence <5,000 km2 or area of occupancy <500
km2 + 2–5 localities, decline or fluctuation |
extent of occurrence 20,000 km2 or area of occupancy <2,000
km2 + 6–10 localities, decline or fluctuation |
| C small population and declining |
<250 mature individuals, population declining |
<2,500 mature individuals, population declining |
<10,000 mature individuals, population declining |
| D1 very small population |
<50 mature individuals |
<250 mature individuals |
<1,000 mature individuals |
| D2 very small range |
|
|
<100 km2 or < 5 locations |
| E probability of extinction |
>50% within 5 years |
>20% within 20 years |
>10% within 100 years |
Near Threatened
This category includes:
- All species in 1-15 10 km squares not in the Red List (on the
basis that anything this rare is de facto at least close
to being threatened).
- All species that have declined/are declining severely, but are
not yet on the Red List (existing SoCC criteria state a rate of
decline of >1% per annum).
- A subset of the species now listed as Nationally
Scarce that are genuinely rare but not in the Red List or
listed as Near Threatened (precise criteria yet to be
devised).
International responsibility
This category includes:
- All species of global concern (i.e. on IUCN global Red Lists)
or possibly of global concern.
- All species of unfavourable conservation status in Europe.
- Endemic species.
- Species with >25% world population and/or range estimated to
be in UK.
Legislation
This category includes all species listed on:
- Schedules 1, 5 & 8 of the Wildlife & Countryside Act
1981
- EC Birds Directive I (native species only)
- EC Habitats Directive Annex II and/or IV (native species
only)
- Bern Convention Appendices I & II (native species
only)
- Bonn Convention Appendices I & II (native species
only)
Priority species (='BAP species')
These are species for which a national (UK) Action Plan (or in
some cases a 'species statement') has been written. They correspond
to the old 'short list' and 'middle list' produced by the UK
Biodiversity Group. They are species which are (a) globally
threatened and (b) rapidly declining in the UK (i.e. by an
estimated >50% in the last 25 years).
Other categories and lists
Data Deficient
"A taxon is Data Deficient when there is inadequate
information to make a direct or indirect assessment of its risk of
extinction based on its distribution and/or population status. A
taxon in this category may be well studied, and its biology well
known, but appropriate data on abundance and/or distribution are
lacking. Data Deficient is therefore not a category of
threat or Lower Risk. Listing of taxa in this category
indicates that more information is required and acknowledges the
possibility that future research will show that a threatened
category is appropriate." (IUCN 1994). The fact that a species
might have a status of Data Deficient does not imply that
it is consigned to a 'dustbin'. Indeed, if it is listed as Data
Deficient, new survey work should be a high priority for that
species. There is therefore an argument for including Data
Deficient species in the SoCC list.
Nationally Scarce
A category of frequency, not threat, applied to any species
occurring in 16-100 hectads (10 km squares) throughout GB. Includes
the now unused old Invertebrate Site Register categories of:
'Notable A' = 30 or fewer hectads
'Notable B' = 31-100.
This category currently includes some species that will move
into Near Threatened when the criteria for that category
are finalised.
Rare
A category of frequency, not threat, used in old Red Lists but
now discontinued. It used to be defined in GB as species occurring
in 15 or fewer hectads. The term 'rare' is now used more loosely.
Many of the species in the old Rare category are now in
the Near Threatened category.
Local Red
Lists
Numerous 'Red Lists' have been produced by many different
organisations and individuals covering geographical sub-units of
GB/UK: regions, counties, districts and even parishes. These follow
widely varying criteria and are not produced to a common standard.
The SSA project does not cover or endorse these. However, those
involved in conservation practice covering a specific area of GB/UK
may wish to use these local lists in determining conservation
priorities locally. They should always be viewed in a national and
international context.