Introduction to the IUCN Red Listing Process

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Introduction to the IUCN Red Listing Process
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The IUCN Red List assessment estimates risk of
extinction
What is the likelihood of a species
becoming extinct in the near future, given
current knowledge about population trends,
range, and recent, current or projected threats?
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The IUCN Red List Categories Criteria
All materials are freely available on IUCN Red
List web site www.iucnredlist.org
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Scope of Application
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The IUCN Categories
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A taxon is threatened when the best available
evidence indicates that it meets any of the
criteria A to E for the thresholds stated in one
of the three threatened categories Critically
Endangered, Endangered or Vulnerable.
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Data Deficient (DD)
Not Evaluated (NE)
Although DD and NE are not threatened categories,
taxa classed as DD or NE should NOT be treated as
not threatened
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Types of data required for IUCN Red List
assessments
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Dealing with a lack of high quality data

• The threatened categories use quantitative
  thresholds
• BUT a lack of high quality data should not deter
  assessors from applying the IUCN criteria.

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Acceptable types of data quality
Observed
Estimated
Projected
Inferred
Suspected
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Concepts and definitions underlying the IUCN Red
List Categories and Criteria
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Key terms used in the IUCN Red List criteria
Population and Population Size
Subpopulations
Mature Individuals
Generation Length
Reduction
Continuing Decline
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Key terms used in the IUCN Red List criteria
Extreme Fluctuations
Severely Fragmented
Extent of Occurrence
Area of Occupancy
Location
Quantitative Analysis
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Population and Population Size
Population is the total number of individuals of
a given taxon across its global range. Population
size is measured as the number of mature
individuals only.
Subpopulations
Subpopulations are geographically or otherwise
distinct groups in the population between which
there is little demographic exchange (e.g., 1
successful migrant individual or gamete per year).
Mature Individuals
Mature Individuals are individuals that are
known, estimated or inferred to be capable of
reproduction.
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Population
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• Greater than the age at first breeding and less
  than the oldest breeding individual, except in
  taxa that breed only once.
• Reflects turnover rate of breeding individuals in
  a population.
• Scales all time-based measurements in the
  criteria to account for different rates at which
  taxa survive and reproduce.
• Where generation length varies under threat, use
  the more natural (i.e. pre-disturbance)
  generation length.

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Reduction
Reduction is a decline in population size of at
least the stated in criterion A over the
specified time period.
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Extreme Fluctuations
Extreme Fluctuations occur in a number of taxa
where population size or distribution area varies
widely, rapidly and frequently, typically with a
variation greater than one order of magnitude
(i.e., a tenfold increase of decrease).
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Extreme Fluctuations
Natural seasonal fluctuations flux of
individuals between different life stages. Not
real changes in total population size, therefore
not extreme fluctuation
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Extreme Fluctuations
Natural seasonal fluctuations, with threatening
events also causing very large population size
variations during reproductive seasons (e.g.,
dormant eggs/seeds damaged or lost). Real changes
in total population size, therefore extreme
fluctuation
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Severely Fragmented
Severely Fragmented refers to the situation in
which increased extinction risks to the taxon
result from the fact that most of its individuals
are found in relatively isolated subpopulations.
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Severely Fragmented
The existence of small and isolated habitat
patches alone is not enough to consider a taxon
to be severely fragmented there should also be
knowledge about the taxons dispersal ability.
Taxa with highly mobile adult stages or producing
large numbers of small, mobile diaspores can
disperse more easily and are not so vulnerable to
isolation through fragmented habitats.
Taxa producing small numbers of diaspores (or
none at all), or only large ones are less able to
disperse over wide areas and are more easily
isolated.
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Extent of Occurrence
Area of Occupancy
Extent of Occurrence is the area contained within
the shortest continuous imaginary boundary which
can be drawn to encompass all known, inferred, or
projected sites presently occupied by the taxon.
Area of Occupancy is the area within the extent
of occurrence which is actually occupied by the
taxon (measured by overlaying a grid and counting
number of occupied cells).
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Extent of Occurrence
Comparison of taxa with same AOO but different
EOO a single threatening event is more likely
to rapidly have a major impact on the taxon with
the smaller EOO than the taxon with the larger
EOO
AOO 10x4 40 km2 EOO 34 km²
AOO 10x4 40 km2 EOO 105 km²
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Extent of Occurrence
Comparison of taxa with same AOO but different
EOO a single threatening event is more likely
to rapidly have a major impact on the taxon with
the smaller EOO than the taxon with the larger
EOO
One major threatening event caused 20 decline
in AOO, 22 decline in EOO, lt20 decline in
population size
One major threatening event caused 50 decline
in AOO, 76 decline in EOO, gt60 decline in
population size
AOO 5x4 20 km2 EOO 8 km²
AOO 8x4 32 km2 EOO 82 km²
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Area of Occupancy
Problems of Scale
In many cases, a grid size of 2 km (i.e., cell
area 4 km²) is an appropriate scale.
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Location
Location is a geographically or ecologically
distinct area in which a single threatening event
can rapidly affect all individuals of the taxon.
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Location
2 locations
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Location
4 locations
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Location
4-5 locations
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Quantitative Analysis
Quantitative Analysis is any form of analysis
which estimates the extinction probability of a
taxon based on known life history, habitat
requirements, threats and any specified
management options (e.g., Population Viability
Analysis (PVA)).
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The IUCN Red List Criteria
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Nature of the Criteria
CRITERIA
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Why use multiple criteria?
Not all the criteria are appropriate to all taxa.

• All taxa being assessed must be evaluated against
  each criterion.
• Meeting any one of the criteria qualifies a taxon
  for listing at that level of threat
• All criteria met at the highest level of threat
  should be listed.

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Criterion A
Past, present or future population reduction
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Criterion A
Based on any of four criteria A1 Population
reduction in past and causes of decline now
ceased A2 Population reduction in past and
causes of decline ongoing A3 Population
reduction expected in future A4 Population
reduction in past AND future
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Criterion A1past reduction causes understood
ceased reduction is reversible
Criterion A2past reduction causes may not be
understood or may not have ceased or reduction
may not be reversible
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Sub-criterion A3future decline
Sub-criterion A4past future
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Sub-criterion A4past future shifting time
window
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• For ALL the criteria (A1A4), rate of population
  reduction should be based on any of
• (a) Direct observation (not for sub-criterion
  A3 future reduction)
• (b) An index of abundance appropriate to the
  taxon.
• (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

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Criterion A

• Points to remember
• Reduction in population size may be a one-off
  event, or may be continuing.
• Sub-criterion A1 has higher thresholds than the
  other sub-criteria.
• For sub-criterion A1, causes of population
  decline must be understood AND must have ceased
  AND the reduction is reversible.
• Sub-criterion A3 based on declines projected into
  the FUTURE, therefore it cannot be based on
  direct observation.
• Sub-criterion A4 (the shifting time window)
  must include some time in the past AND some time
  in the future.
• All time measurements are based on ten years OR 3
  generations whichever is the longer time period
  (100 year time cap in future).

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Criterion B
Restricted geographic range and fragmentation,
continuing decline or extreme fluctuations
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Criterion B
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Criterion B
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Criterion B
Subcriterion B1 Extent of occurrence estimated
to be
Subcriterion B2 Area of occupancy estimated to
be
lt 100 km²
CR
lt 5,000 km²
EN
lt 20,000 km²
VU
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Criterion B
AND at least TWO of a, b or c
a. Severely fragmented or locations
? 5
EN
? 10
VU
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Criterion B

• Points to remember
• Subcriterion B1 is based on extent of occurrence,
  while subcriterion B2 is based on area of
  occupancy.
• Either subcriteria B1 or B2, or both may apply.
• To fully qualify for a listing under criterion B,
  the taxon must meet at least two of the
  subcriteria a, b or c.
• Subcriterion B1a / B2a may be based on either
  severe fragmentation OR number of locations
  please remember the definitions of these terms
  when applying them.

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Criterion C
Small population size and continuing decline
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Criterion C
Based on small population size AND either C1 or
C2
C1 Continuing decline in population size at a
specified rate OR
C2 Continuing decline in population size at
any, unspecified rate AND either C2a or C2b
C2a (i) very small subpopulations, OR (ii) most
mature individuals are in one subpopulation C2b e
xtreme fluctuations in number of mature
individuals
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Criterion C
Thresholds for criterion C Population size is
estimated at
EN
VU
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Criterion C
Subcriterion C1 Observed, projected or inferred
continuing decline of
? 20 within 5 years or 2 generations
EN
? 10 within 10 years or 3 generations
VU
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Criterion C
Subcriterion C2 Observed, projected or inferred
continuing decline at any rate
AND at least one of the following
C2a(i). All subpopulations have
lt 50 mature individuals
? 90 of the mature individuals
CR
lt 250 mature individuals
? 95 of the mature individuals
EN
100 of the mature individuals
lt 1,000 mature individuals
VU
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Criterion C

• Points to remember
• The population size threshold must be met before
  considering the thresholds for subcriteria C1 or
  C2.
• Subcriterion C1 is based on continuing decline at
  a specified rate and over a very specific time
  period.
• Subcriterion C2 is based on continuing decline at
  any, unspecified rate, but the taxon must also
  meet the requirements for subcriteria C2a or C2b.

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Criterion D
Very small or restricted population
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Criterion D
Criterion D is split into D for the CR and EN
categories and D1 and D2 for the VU category.
D. Total current population size estimated as
NOTE for the VU D2, there should be a plausible
threat that is likely to rapidly affect the
population.
lt 250 mature individuals
EN
D2. The population has a very restricted AOO
(typically lt20 km²) or is known from very few
locations (typically 5).
lt 1,000 mature individuals
VU
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Criterion D

• Points to remember
• Criterion D has population size thresholds that
  apply to categories CR and EN only.
• Subcriteria D1 and D2 apply to the VU category
  only.
• Subcriterion D2 should be used when a population
  has a very restricted range such that it is prone
  to the effects of human activities or stochastic
  events within a very short time period.
• When using subcriterion D2, the most serious
  plausible threat to the species should be stated
  in the assessment.
• In subcriterion D2, the values for AOO and number
  of locations are given as examples only.

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Criterion E
Quantitative analysis
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Criterion E
Based on quantitative analysis showing a
probability of extinction in the wild is at least
Within 10 years or 3 generations
Within 20 years or 5 generations
Within 100 years
Up to a maximum of 100 years in the future