Terms & Definitions - Threats and impact

Click on any of the following for some background and an explanation of the technical terms used in the species factsheets and additional data tables:

Threats, stresses and impact

In the species factsheets, details of the threats affecting the species are given, and in some cases past threats are described, including all threats that contribute to the species's status. In BirdLife's World Bird Database, threat types have been coded against the IUCN-Conservation Measures Partnership (CMP) Unified Classification of Direct Threats for analytical purposes. These codes are listed in the 'additional data' tables, along with codes for their timing, scope, severity and impact (see below). The threat types used are listed below, and are the standard terms used in the IUCN-CMP Unified Classification of Direct Threats. Updates to this scheme will be posted at: www.iucn.org/themes/ssc/sis/authority.htm.

Threat classification

1. Residential & commercial development
1.1. Housing & urban areas; 1.2. Commercial & industrial areas; 1.3. Tourism & recreation areas.

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/artisinal 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.

5. Biological resource use
5.1. Hunting & trapping terrestrial animals; 5.1.1. Intentional mortality (human use); 5.1.2. Incidental or accidental mortality (bycatch); 5.1.3. Persecution/control; 5.1.4. Motivation Unknown/Unrecorded; 5.2. Gathering terrestrial plants; 5.2.1. Intentional mortality (human use); 5.2.2. Incidental or accidental mortality (bycatch); 5.2.3. Persecution/control; 5.2.4. Motivation Unknown/Unrecorded; 5.3. Logging & wood harvesting; 5.3.1. Intentional mortality (human use - subsistence/small scale); 5.3.2. Intentional mortality (human use - large scale); 5.3.3. Incidental or accidental mortality (bycatch - subsistence/small scale); 5.3.4. Incidental or accidental mortality (bycatch - large scale); 5.3.5. Motivation Unknown/Unrecorded; 5.4. Fishing & harvesting aquatic resources; 5.4.1. Intentional mortality (human use - subsistence/small scale); 5.4.2. Intentional mortality (human use - large scale); 5.4.3. Incidental or accidental mortality (bycatch - subsistence/small scale); 5.4.4. Incidental or accidental mortality (bycatch - large scale); 5.4.5. Persecution/control; 5.4.6. Motivation Unknown/Unrecorded.

6. Human intrusions & disturbance
6.1. Recreational activities; 6.2. War, civil unrest & military exercises; 6.3. Work & other activities.

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.

8. Invasive & other problematic species & genes
8.1. Invasive non-native/alien species; 8.1.1. Unspecified species; 8.1.2. Named species; 8.2. Problematic native species; 8.3. Introduced genetic material.

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 and 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.

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.

12. Other

Threat impact - For each threat, BirdLife assigns the timing (ongoing or future), the scope (i.e. the proportion of the total population affected) and the severity (the overall declines caused by the threat) an "impact score" (0-3). Severity is scored within the scope of the particular threat. For example, if hunting 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.

The overall impact of the threat is determined by adding these separate impact scores (see table below).

Thus all threats are recorded without any initial (unrecorded) pre-judgement, but only those with a High/Medium/Low/Unknown impact are included as relevant in relation to current IUCN Red List status (i.e. excluding those with Negligible impact or Past impact where the threat is unlikely to return).

Timing and impact score

Description Impact score
Ongoing 3
Future (long term) 1


Scope and impact score

Description Impact score
Affects the whole (>90%) population 3
Affects the majority (50-90%) of the population 2
Affects the minority (<50%) of the population 1
Affects a negligible proportion of the population 0
Unknown special case 2 (see "calculating overall impact")


Severity and impact scores

Description Impact score
Causing or likely to cause very rapid declines (>30% over 10 years or three generations) 3
Causing or likely to cause rapid declines (20-30% over 10 years or three generations) 2
Causing or likely to cause relatively slow, but significant, declines (<20% over 10 years or three generations) 1
Causing or likely to cause fluctuations 1
Causing or likely to cause negligible declines 0
No decline 0
Unknown  special case 2


Calculating overall impact -The overall impact of the threat is calculated by adding the individual scores for Timing, Scope and Severity as follows:

  • High impact - score 8,9
  • Medium impact - score 6,7
  • Low impact - score 3,4,5
  • No/negligible impact - score 0,1,2

Stresses - In addition to the direct threats identified as actual or potential drivers of population change, accompanying non-exclusive stresses are coded with each threat to highlight how a threat impacts upon a population. Thus, for example, in 7. Natural System Modifications, we have listed the human activity fire suppression rather than the stress lack of fire. Multiple stresses can be ticked with each threat coded, chosen from the following list:

Ecosystem stresses  
Ecosystem conversion, Ecosystem degradation, Indirect ecosystem effects

Species stresses
Direct mortality, Species disturbance, Hybridisation, Competition, Loss of a mutualism, Inbreeding, Skewed sex ratio, Reduced reproductive success, Other