Guidelines & Brochures — Global

Threats Classification Scheme (Version 3.3)

The full hierarchical structure of threat types displayed in IUCN Red List assessments is shown below.

Direct threats are the proximate human activities or processes that have impacted, are impacting, or may impact the status of the taxon being assessed (e.g., unsustainable fishing or logging, agriculture, housing developments, etc.) Direct threats are synonymous with sources of stress and proximate pressures.

In using this hierarchical classification of the drivers of species decline, Assessors are asked to indicate the threats that triggered the listing of the taxon concerned at the lowest level possible. These threats may have occured in the past ("historical, unlikely to return" or "historical, likely to return"); or may be "ongoing"; or may be likely to occur in the "future", using a time frame of three generations or ten years (whichever is the longer, up to a maximum of 100 years in the future), as required by the IUCN Red List Criteria. The 'Major Threats' referred to in the 'Required and Recommended Supporting Information for IUCN Red List Assessments', are threats coded as having High or Medium impacts (see threat impact scoring below).

The attached working document provides a list of the threat types with definitions, examples of the threats and guidance notes on using the scheme. Comments on the Threats Classification Scheme are welcome.

• 1 Residential & commercial development
  • 1.1 Housing & urban areas
  • 1.2 Commercial & industrial areas
  • 1.3 Tourism & recreation areas
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• 2 Agriculture & aquaculture
  • 2.1 Annual & perennial non-timber crops
    • 2.1.1 Shifting agriculture
    • 2.1.2 Small-holder farming
    • 2.1.3 Agro-industry farming
    • 2.1.4 Scale Unknown/Unrecorded
  • 2.2 Wood & pulp plantations
    • 2.2.1 Small-holder plantations
    • 2.2.2 Agro-industry plantations
    • 2.2.3 Scale Unknown/Unrecorded
  • 2.3 Livestock farming & ranching
    • 2.3.1 Nomadic grazing
    • 2.3.2 Small-holder grazing, ranching or farming
    • 2.3.3 Agro-industry grazing, ranching or farming
    • 2.3.4 Scale Unknown/Unrecorded
  • 2.4 Marine & freshwater aquaculture
    • 2.4.1 Subsistence/artisanal aquaculture
    • 2.4.2 Industrial aquaculture
    • 2.4.3 Scale Unknown/Unrecorded
    •  
• 3 Energy production & mining
  • 3.1 Oil & gas drilling
  • 3.2 Mining & quarrying
  • 3.3 Renewable energy
  •  

• 4 Transportation & service corridors
  • 4.1 Roads & railroads
  • 4.2 Utility & service lines
  • 4.3 Shipping lanes
  • 4.4 Flight paths
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• 5 Biological resource use
  • 5.1 Hunting & collecting terrestrial animals
    • 5.1.1 Intentional use (species being assessed is the target)
    • 5.1.2 Unintentional effects (species being assessed is not the target)
    • 5.1.3 Persecution/control
    • 5.1.4 Motivation Unknown/Unrecorded
  • 5.2 Gathering terrestrial plants
    • 5.2.1 Intentional use (species being assessed is the target)
    • 5.2.2 Unintentional effects (species being assessed is not the target)
    • 5.2.3 Persecution/control
    • 5.2.4 Motivation Unknown/Unrecorded
  • 5.3 Logging & wood harvesting
    • 5.3.1 Intentional use: subsistence/small scale (species being assessed is the target [harvest]
    • 5.3.2 Intentional use: large scale (species being assessed is the target)[harvest]
    • 5.3.3 Unintentional effects: subsistence/small scale (species being assessed is not the target)[harvest]
    • 5.3.4 Unintentional effects: large scale (species being assessed is not the target)[harvest]
    • 5.3.5 Motivation Unknown/Unrecorded
  • 5.4 Fishing & harvesting aquatic resources
    • 5.4.1 Intentional use: subsistence/small scale (species being assessed is the target)[harvest]
    • 5.4.2 Intentional use: large scale (species being assessed is the target)[harvest]
    • 5.4.3 Unintentional effects: subsistence/small scale (species being assessed is not the target)[harvest]
    • 5.4.4 Unintentional effects: large scale (species being assessed is not the target)[harvest]
    • 5.4.5 Persecution/control
    • 5.4.6 Motivation Unknown/Unrecorded
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• 6 Human intrusions & disturbance
  • 6.1 Recreational activities
  • 6.2 War, civil unrest & military exercises
  • 6.3 Work & other activities
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• 7 Natural system modifications
  • 7.1 Fire & fire suppression
    • 7.1.1 Increase in fire frequency/intensity
    • 7.1.2 Suppression in fire frequency/intensity
    • 7.1.3 Trend Unknown/Unrecorded
  • 7.2 Dams & water management/use
    • 7.2.1 Abstraction of surface water (domestic use)
    • 7.2.2 Abstraction of surface water (commercial use)
    • 7.2.3 Abstraction of surface water (agricultural use)
    • 7.2.4 Abstraction of surface water (unknown use)
    • 7.2.5 Abstraction of ground water (domestic use)
    • 7.2.6 Abstraction of ground water (commercial use)
    • 7.2.7 Abstraction of ground water (agricultural use)
    • 7.2.8 Abstraction of ground water (unknown use)
    • 7.2.9 Small dams
    • 7.2.10 Large dams
    • 7.2.11 Dams (size unknown)
  • 7.3 Other ecosystem modifications
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• 8 Invasive & other problematic species, genes & diseases
  • 8.1 Invasive non-native/alien species/diseases
    • 8.1.1 Unspecified species
    • 8.1.2 Named species
  • 8.2 Problematic native species/diseases
    • 8.2.1 Unspecified species
    • 8.2.2 Named species
  • 8.3 Introduced genetic material
  • 8.4 Problematic species/diseases of unknown origin
    • 8.4.1 Unspecified species
    • 8.4.2 Named species
  • 8.5 Viral/prion-induced diseases
    • 8.5.1 Unspecified "species" (disease)
    • 8.5.2 Named "species" (disease)
  • 8.6 Diseases of unknown cause 
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  • 9 Pollution
    • 9.1 Domestic & urban waste water
      • 9.1.1 Sewage
      • 9.1.2 Run-off
      • 9.1.3 Type Unknown/Unrecorded
    • 9.2 Industrial & military effluents
      • 9.2.1 Oil spills
      • 9.2.2 Seepage from mining
      • 9.2.3 Type Unknown/Unrecorded
    • 9.3 Agricultural & forestry effluents
      • 9.3.1 Nutrient loads
      • 9.3.2 Soil erosion, sedimentation
      • 9.3.3 Herbicides & pesticides
      • 9.3.4 Type Unknown/Unrecorded
    • 9.4 Garbage & solid waste
    • 9.5 Air-borne pollutants
      • 9.5.1 Acid rain
      • 9.5.2 Smog
      • 9.5.3 Ozone
      • 9.5.4 Type Unknown/Unrecorded
    • 9.6 Excess energy
      • 9.6.1 Light pollution
      • 9.6.2 Thermal pollution
      • 9.6.3 Noise pollution
      • 9.6.4 Type Unknown/Unrecorded
        •  
  • 10 Geological events
    • 10.1 Volcanoes
    • 10.2 Earthquakes/tsunamis
    • 10.3 Avalanches/landslides
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  • 11 Climate change & severe weather
    • 11.1 Habitat shifting & alteration
    • 11.2 Droughts
    • 11.3 Temperature extremes
    • 11.4 Storms & flooding
    • 11.5 Other impacts
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  • 12 Other options
    • 12.1 Other threat
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  Threat Impact

  For each threat, it is recommended that the timing of the threat (i.e., past, ongoing or future), its scope (i.e., the proportion of the total population affected) and severity (i.e., the overall declines caused by the threat) should be recorded. Severity should be scored within the scope of the particular threat. For example, if hunting (i.e., threat code 5.1.1) is identified as a threat within one particular region only, the severity is scored as the % rate of decline to the population within that region only.

  Timing options are:

  • Only in the past and unlikely to return
  • In the past but now suspended and likely to return
  • Ongoing
  • Only in the future
  • Unknown

   

  Scope options are:

  • Affects the whole population (>90%)
  • Affects the majority of the population (50–90%)
  • Affects the minority of the population (<50%)
  • Unknown

   

  Severity options are:

  • Causing or likely to cause very rapid declines (>30% over 10 years or three generations; whichever is the longer)
  • Causing or likely to cause rapid declines (20–30% over 10 years or three generations; whichever is the longer)
  • Causing or likely to cause relatively slow but significant declines (<20% over 10 years or three generations; whichever is the longer)
  • Causing or likely to cause fluctuations
  • Causing or likely to cause negligible declines
  • No declines
  • Unknown

   

  Any analysis of the threats should preferably take into account the timing, scope and severity of the threats. Threats marked with timing as “ongoing”, severity as “rapid” or “very rapid” declines and scopes of “majority” or “whole” are typically considered major threats to a species. Prior to Red List version 2022-2, IUCN used a scoring scheme to quantify the impact of these variables and reported them in the Threats section of each assessment. Recognizing the underdeveloped scientific basis for these impact scores, IUCN temporarily stopped providing them beginning with Red List version 2022-2 while the technical basis for assigning threats and calculating threat impact scores is under review. Users interested in these scores can generate them using this scoring table.