Environment Australia, 1999
ISBN 0 642 2546 363
Structure and Definitions of the IUCN (1994) Red List Categories
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 only to survive 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 historic 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 defined by any of the criteria A to E in the table below.
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 to E in the table below.
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 to E in the table below.
Lower Risk (LR)
A taxon is Lower Risk when it has been evaluated, does not satisfy the criteria for any of the categories Critically Endangered, Endangered or Vulnerable. Taxa included in the Lower Risk category can be separated into three subcategories:
- Conservation Dependent (cd). Taxa which are the focus of a continuing taxon-specific or habitat-specific conservation program targeted towards the taxon in question, the cessation of which would result in the taxon qualifying for one of the threatened categories above within a period of five years.
- Near Threatened (nt). Taxa which do not qualify for Conservation Dependent, but which are close to qualifying for Vulnerable. This Action Plan outlines four criteria for allocation of taxa to this category which were agreed upon by participants at the December 1995 workshop.
- Least Concern (lc). Taxa which do not qualify for Conservation Dependent or Near Threatened.
Data Deficient (DD)
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 is 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 threatened classification is appropriate. It is important to make positive use of whatever data are available. In many cases great care should be exercised in choosing between DD and threatened status. If the range of the taxon is suspected to be relatively circumscribed, if a considerable period of time has elapsed since the last record of the taxon, threatened status may well be justified.
Not Evaluated (NE)
A taxon is Not Evaluated when it has not yet been assessed against the criteria.
|A) Population reduction in the form of either:|
|1) Observed, estimated, inferred or suspected reduction of at least ______, based on (and specifying) ANY OF the following:
||…80% during the last 10 years or three generations, whichever is the longer…||…50% during the last 10 years or three generations, whichever is the longer…||…20% during the last 10 years or three generations, whichever is the longer…|
|2) A reduction of at least the rate specified in A1, projected or suspected to be met, based on (and specifying) and of (b), (c), (d) or (e) above.|
|B) Extent of occurrence estimated to be less than ______
|…100 km²||…5000 km²||…20 000 km²|
|Area of occupancy estimated to be less than ______
and estimates indicating any two of:
|…10 km²||…500 km²||…2000 km²|
|1) Severely fragmented OR known to exist at ______ location(s).||…only a single location||…no more than five locations||…no more than ten locations|
|2) Continuing decline, observed, inferred or projected, in ANY OF the following:
|3) Extreme fluctuations in ANY OF the following:
|C) Population estimated to number less than ______ mature individuals AND EITHER:||…250…||…2500…||…10 000…|
|1) An estimated continuing decline of at least ______, whichever is longer OR||…25% within three years or one generation…||…20% within five years or two generations…||…10% within ten years or three generations…|
|2) A continuing decline, observed, projected, or inferred, in numbers of mature individuals AND population structure in the form of EITHER
|D) Population estimated to number less than ______ mature individuals. OR||…50…||…250…||…1000…|
|(VU only) Population is characterised by an acute restriction in its area of occupancy (typically less than 100 km²) or in the number of locations (typically less than five).
Such a taxon would thus be prone to the effects of human activities (or stochastic events whose impact is increased by human activities) within a very short period of time in an unforeseeable future, and is thus capable of becoming Critically Endangered or even Extinct in a very short period.
|not applicable||not applicable||applies|
|E) Quantitative analysis showing probability of extinction in the wild is at least ______||…50% within ten years or three generations, whichever is the longer||…20% within 20 years or five generations, whichever is the longer||…10% within 100 years|