IUCN 2001 Red List Categories (Version 3.1)
(Note: These criteria were also used for ratings assessed in 2002
and 2003; for Red List Categories from previous years, see 1960's,
1970's, 1980's,
1994, 1996, 2000)
2001 Categories:
- EX - Extinct. A species is Extinct when there is no
reasonable doubt that the last individual has died. A species is presumed
Extinct 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 species's life cycle and life form.
- EW -
Extinct in the Wild. A species is Extinct in the Wild when it is
known only to survive in cultivation, in captivity or as a naturalized
population (or populations) well outside the past range. A species 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 species's life
cycle and life form.
- CR - Critically Endangered. A species is Critically Endangered when the
best available evidence indicates that it meets any of the criteria A to
E for Critically Endangered (see Section V), and it is therefore
considered to be facing an extremely high risk of extinction in the
wild.
- EN - Endangered. A species is Endangered when the best
available evidence indicates that it meets any of the criteria A to E
for Endangered (see Section V), and it is therefore considered to be
facing a very high risk of extinction in the wild.
- VU - Vulnerable.
A species is Vulnerable when the best
available evidence indicates that it meets any of the criteria A to E
for Vulnerable (see Section V), and it is therefore considered to be
facing a high risk of extinction in the wild.
- NT - Near Threatened.
A species is Near Threatened when it has been
evaluated against the criteria but does not qualify for Critically
Endangered, Endangered or Vulnerable now, but is close to qualifying for
or is likely to qualify for a threatened category in the near future.
- LC - Least Concern.
A species is Least Concern when it has been
evaluated against the criteria and does not qualify for Critically
Endangered, Endangered, Vulnerable or Near Threatened. Widespread and
abundant taxa are included in this category.
- DD - Data Deficient.
A species 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
species 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. 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 a threatened status. If the range
of a species is suspected to be relatively circumscribed, and a
considerable period of time has elapsed since the last record of the species, threatened status may well be justified.
- NE - Not Evaluated.
A species is Not Evaluated when it is has not
yet been evaluated against the criteria.
Criteria for Critically Endangered, Endangered and Vulnerable:
Critically Endangered -
A species is Critically Endangered when the best available evidence
indicates that it meets any of the following criteria (A to E), and it
is therefore considered to be facing an extremely high risk of
extinction in the wild: A. Reduction in population size based on any of the following:
- 1. An observed, estimated, inferred or suspected population size
reduction of greater than or equal to 90% over the last 10 years or three generations, whichever is the
longer, where the causes of the reduction are clearly reversible AND
understood AND ceased, based on (and specifying) any of the following:
- (a) direct observation
- (b) an index of abundance appropriate to the species
- (c) a decline in area of occupancy, extent of occurrence and/or
quality of habitat
- (d) actual or potential levels of exploitation
- (e) the effects of introduced taxa, hybridization, pathogens,
pollutants, competitors or parasites.
- 2. An observed, estimated, inferred or suspected population size
reduction of greater than or equal to
80% over the
last 10 years or three generations, whichever is the longer, where
the reduction or its causes
may not have ceased OR may not be understood OR may not be
reversible, based on (and specifying)
any of (a) to (e) under A1.
- 3. A population size reduction of greater than or equal to
80%, projected or suspected to be met within the next 10
years or three generations, whichever is the longer (up to a
maximum of 100 years), based on
(and specifying) any of (b) to (e) under A1.
- 4. An observed, estimated, inferred, projected or suspected
population size reduction of greater than or equal to
80% over any 10 year or three generation period, whichever is longer
(up to a maximum of 100 years in
the future), where the time period must include both the past and
the future, and where the reduction
or its causes may not have ceased OR may not be understood OR may
not be reversible, based on
(and specifying) any of (a) to (e) under A1.
B. Geographic range in the form of either B1 (extent of
occurrence) OR B2 (area of occupancy) OR both:
- 1. Extent of occurrence estimated to be less than 100 kmē, and
estimates indicating at least two of a-c:
- a. Severely fragmented or known to exist at only a single
location.
- b. Continuing decline, observed, inferred or projected, in any of
the following:
- (i) extent of occurrence
- (ii) area of occupancy
- (iii) area, extent and/or quality of habitat
- (iv) number of locations or subpopulations
- (v) number of mature individuals.
- c. Extreme fluctuations in any of the following:
- (i) extent of occurrence
- (ii) area of occupancy
- (iii) number of locations or subpopulations
- (iv) number of mature individuals.
-
2. Area of occupancy estimated to be less than 10 kmē, and
estimates indicating at least two of a-c:
- a. Severely fragmented or known to exist at only a single
location.
-
b. Continuing decline, observed, inferred or projected, in any of
the following:
- (i) extent of occurrence
- (ii) area of occupancy
- (iii) area, extent and/or quality of habitat
- (iv) number of locations or subpopulations
- (v) number of mature individuals.
- c. Extreme fluctuations in any of the following:
- (i) extent of occurrence
- (ii) area of occupancy
- (iii) number of locations or subpopulations
- (iv) number of mature individuals.
C. Population size estimated to number fewer than 250 mature
individuals and either:
-
1. An estimated continuing decline of at least 25% within three
years or one generation, whichever is
longer, (up to a maximum of 100 years in the future) OR
-
2. A continuing decline, observed, projected, or inferred, in
numbers of mature individuals AND at least
one of the following (a-b):
- (a) Population structure in the form of one of the following:
- (i) no subpopulation estimated to contain more than 50 mature
individuals, OR
- (ii) at least 90% of mature individuals in one subpopulation.
- (b) Extreme fluctuations in number of mature individuals.
D. Population size estimated to number fewer than 50 mature
individuals.
E. Quantitative analysis showing the probability of extinction in
the wild is at least 50% within 10 years or three generations,
whichever is the longer (up to a maximum of 100 years).
Endangered
A species is Endangered when the best available evidence indicates
that it meets any of the following criteria (A to E), and it is
therefore considered to be facing a very high risk of extinction in
the wild:
A. Reduction in population size based on any of the following:
-
1. An observed, estimated, inferred or suspected population size
reduction of greater than or equal to
70% over the last 10 years
or three generations, whichever is the longer, where the causes of
the reduction are clearly reversible
AND understood AND ceased, based on (and specifying) any of the
following:
- (a) direct observation
- (b) an index of abundance appropriate to the species
- (c) a decline in area of occupancy, extent of occurrence and/or
quality of habitat
- (d) actual or potential levels of exploitation
- (e) the effects of introduced taxa, hybridization, pathogens,
pollutants, competitors or parasites.
-
2. An observed, estimated, inferred or suspected population size
reduction of greater than or equal to
50% over the last 10 years
or three generations, whichever is the longer, where the reduction
or its causes may not have
ceased OR may not be understood OR may not be reversible, based on
(and specifying) any of (a)
to (e) under A1.
-
3. A population size reduction of greater than or equal to
50%, projected or suspected to be met within the next 10 years
or three generations, whichever is the longer (up to a maximum of
100 years), based on (and specifying)
any of (b) to (e) under A1.
-
4. An observed, estimated, inferred, projected or suspected
population size reduction of greater than or equal to
50% over any 10
year or three generation period, whichever is longer (up to a
maximum of 100 years in the future),
where the time period must include both the past and the future,
and where the reduction or its
causes may not have ceased OR may not be understood OR may not be
reversible, based on (and
specifying) any of (a) to (e) under A1.
B. Geographic range in the form of either B1 (extent of
occurrence) OR B2 (area of occupancy) OR both:
-
1. Extent of occurrence estimated to be less than 5000 kmē, and
estimates indicating at least two of a-c:
- a. Severely fragmented or known to exist at no more than five
locations.
- b. Continuing decline, observed, inferred or projected, in any of
the following:
- (i) extent of occurrence
- (ii) area of occupancy
- (iii) area, extent and/or quality of habitat
- (iv) number of locations or subpopulations
- (v) number of mature individuals.
- c. Extreme fluctuations in any of the following:
- (i) extent of occurrence
- (ii) area of occupancy
- (iii) number of locations or subpopulations
- (iv) number of mature individuals.
-
2. Area of occupancy estimated to be less than 500 kmē, and
estimates indicating at least two of a-c:
- a. Severely fragmented or known to exist at no more than five
locations.
- b. Continuing decline, observed, inferred or projected, in any of
the following:
- (i) extent of occurrence
- (ii) area of occupancy
- (iii) area, extent and/or quality of habitat
- (iv) number of locations or subpopulations
- (v) number of mature individuals.
- c. Extreme fluctuations in any of the following:
- (i) extent of occurrence
- (ii) area of occupancy
- (iii) number of locations or subpopulations
- (iv) number of mature individuals.
C. Population size estimated to number fewer than 2500 mature
individuals and either:
-
1. An estimated continuing decline of at least 20% within five
years or two generations, whichever is
longer, (up to a maximum of 100 years in the future) OR
-
2. A continuing decline, observed, projected, or inferred, in
numbers of mature individuals AND at least one
of the following (a-b):
- (a) Population structure in the form of one of the following:
- (i) no subpopulation estimated to contain more than 250 mature
individuals, OR
- (ii) at least 95% of mature individuals in one subpopulation.
- (b) Extreme fluctuations in number of mature individuals.
D. Population size estimated to number fewer than 250 mature
individuals.
E. Quantitative analysis showing the probability of extinction in
the wild is at least 20% within 20 years or five generations,
whichever is the longer (up to a maximum of 100 years).
Vulnerable
A species is Vulnerable when the best available evidence indicates
that it meets any of the following criteria (A to E), and it is
therefore considered to be facing a high risk of extinction in the
wild:
A. Reduction in population size based on any of the following:
-
1. An observed, estimated, inferred or suspected population size
reduction of greater than or equal to
50% over the last 10 years
or three generations, whichever is the longer, where the causes of
the reduction are: clearly reversible
AND understood AND ceased, based on (and specifying) any of the
following:
- (a) direct observation
- (b) an index of abundance appropriate to the species
- (c) a decline in area of occupancy, extent of occurrence and/or
quality of habitat
- (d) actual or potential levels of exploitation
- (e) the effects of introduced taxa, hybridization, pathogens,
pollutants, competitors or parasites.
-
2. An observed, estimated, inferred or suspected population size
reduction of greater than or equal to
30% over the last 10 years
or three generations, whichever is the longer, where the reduction
or its causes may not
have ceased OR may not be understood OR may not be reversible,
based on (and specifying)
any of (a) to (e) under A1.
-
3. A population size reduction of greater than or equal to
30%, projected or suspected to be met within the next 10 years
or three generations, whichever is the longer (up to a maximum of
100 years), based on (and
specifying) any of (b) to (e) under A1.
-
4. An observed, estimated, inferred, projected or suspected
population size reduction of greater than or equal to
30% over any 10
year or three generation period, whichever is longer (up to a
maximum of 100 years in the future), where
the time period must include both the past and the future, and
where the reduction or its causes may not
have ceased OR may not be understood OR may not be reversible,
based on (and specifying) any of (a) to
(e) under A1.
B. Geographic range in the form of either B1 (extent of
occurrence) OR B2 (area of occupancy) OR both:
-
1. Extent of occurrence estimated to be less than 20,000 kmē, and
estimates indicating at least
two of a-c:
- a. Severely fragmented or known to exist at no more than 10
locations.
- b. Continuing decline, observed, inferred or projected, in any of
the following:
- (i) extent of occurrence
- (ii) area of occupancy
- (iii) area, extent and/or quality of habitat
- (iv) number of locations or subpopulations
- (v) number of mature individuals.
- c. Extreme fluctuations in any of the following:
- (i) extent of occurrence
- (ii) area of occupancy
- (iii) number of locations or subpopulations
- (iv) number of mature individuals.
-
2. Area of occupancy estimated to be less than 2000 kmē, and
estimates indicating at least two of a-c:
- a. Severely fragmented or known to exist at no more than 10
locations.
- b. Continuing decline, observed, inferred or projected, in any of
the following:
- (i) extent of occurrence
- (ii) area of occupancy
- (iii) area, extent and/or quality of habitat
- (iv) number of locations or subpopulations
- (v) number of mature individuals.
-
c. Extreme fluctuations in any of the following:
- (i) extent of occurrence
- (ii) area of occupancy
- (iii) number of locations or subpopulations
- (iv) number of mature individuals.
C. Population size estimated to number fewer than 10,000 mature
individuals and either:
-
1. An estimated continuing decline of at least 10% within 10 years
or three generations, whichever is
longer, (up to a maximum of 100 years in the future) OR
-
2. A continuing decline, observed, projected, or inferred, in
numbers of mature individuals AND at least
one of the following (a-b):
- (a) Population structure in the form of one of the following:
- (i) no subpopulation estimated to contain more than 1000 mature
individuals, OR
- (ii) all mature individuals are in one subpopulation.
- (b) Extreme fluctuations in number of mature individuals.
D. Population very small or restricted in the form of either of
the following:
-
1. Population size estimated to number fewer than 1000 mature
individuals.
-
2. Population with a very restricted area of occupancy (typically
less than 20 kmē) or number of locations
(typically five or fewer) such that it is prone to the effects of
human activities or
stochastic events within a very short time period in an uncertain
future, and is thus capable
of becoming Critically Endangered or even Extinct in a very short
time period.
E. Quantitative analysis showing the probability of extinction in
the wild is at least 10% within 100 years.
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