IUCN Red List Guidelines - The IUCN Red List of Threatened Species

Contents
1. INTRODUCTION ..................................................................................................................................... 4
2. AN OUTLINE OF THE RED LIST CATEGORIES AND CRITERIA ............................................... 4
2.1 TAXONOMIC LEVEL AND SCOPE OF THE CATEGORIZATION PROCESS ......................................................... 4
2.1.1 Taxonomic scale of categorization ................................................................................................ 4
2.1.2 Geographical scale of categorization ........................................................................................... 6
2.1.3 Introduced taxa ............................................................................................................................. 7
2.2 NATURE OF THE CATEGORIES ................................................................................................................... 7
2.2.1 Transfer between categories ....................................................................................................... 10
2.3 NATURE OF THE CRITERIA ...................................................................................................................... 12
2.4 CONSERVATION PRIORITIES AND ACTIONS .............................................................................................. 15
2.5 DOCUMENTATION .................................................................................................................................. 15
3. DATA QUALITY .................................................................................................................................... 15
3.1 DATA AVAILABILITY, INFERENCE AND PROJECTION ................................................................................ 15
3.2 UNCERTAINTY ....................................................................................................................................... 17
3.2.1 Types of uncertainty .................................................................................................................... 17
3.2.2 Representing uncertainty ............................................................................................................ 17
3.2.3 Dispute tolerance and risk tolerance .......................................................................................... 18
3.2.4 Dealing with uncertainty ............................................................................................................. 18
3.2.5 Documenting uncertainty and interpreting listings ..................................................................... 18
3.2.6 Uncertainty and the application of the categories Data Deficient and Near Threatened ........... 19
4. GUIDELINES FOR THE DEFINITIONS OF TERMS USED IN THE CRITERIA ........................ 19
4.1 POPULATION AND POPULATION SIZE (CRITERIA A, C AND D) ................................................................. 19
4.2 SUBPOPULATIONS (CRITERIA B AND C) .................................................................................................. 19
4.3 MATURE INDIVIDUALS (CRITERIA A, B, C AND D).................................................................................. 20
4.3.1 Notes on defining mature individuals.......................................................................................... 20
4.3.2 Colonial or modular organisms .................................................................................................. 21
4.3.3 Fishes .......................................................................................................................................... 22
4.3.4 Sex-changing organisms ............................................................................................................. 22
4.3.5 Trees ............................................................................................................................................ 23
4.4 GENERATION (CRITERIA A, C1 AND E) ................................................................................................... 23
4.5 REDUCTION (CRITERION A) .................................................................................................................... 25
4.5.1 Estimating reduction ................................................................................................................... 25
4.5.2 Inferring or projecting population reduction .............................................................................. 26
4.6 CONTINUING DECLINE (CRITERIA B AND C) ........................................................................................... 26
4.7 EXTREME FLUCTUATIONS (CRITERIA B AND C2) .................................................................................... 28
4.8 SEVERELY FRAGMENTED (CRITERION B)................................................................................................ 30
4.9 EXTENT OF OCCURRENCE (CRITERIA A AND B) ...................................................................................... 31
4.10 AREA OF OCCUPANCY (CRITERIA A, B AND D) ....................................................................................... 34
4.10.1 Problems of scale ................................................................................................................... 35
4.10.2 Methods for estimating AOO .................................................................................................. 35
4.10.3 The appropriate scale ............................................................................................................. 36
4.10.4 Scale-area relationships ......................................................................................................... 36
4.10.5 Scale correction factors .......................................................................................................... 37
4.10.6 "Linear" habitat ..................................................................................................................... 39
4.10.7 AOO based on habitat maps and models ............................................................................... 40
4.11 LOCATION (CRITERIA B AND D) ............................................................................................................. 41
4.12 QUANTITATIVE ANALYSIS (CRITERION E) ............................................................................................... 42
5. GUIDELINES FOR APPLYING CRITERION A ............................................................................... 42
5.1 THE USE OF TIME CAPS IN CRITERION A ................................................................................................. 44
5.2 HOW TO APPLY CRITERION A4 ............................................................................................................... 45
5.3 THE SKI-JUMP EFFECT ............................................................................................................................ 45
5.4 SEVERELY DEPLETED POPULATIONS ....................................................................................................... 46
5.5 FISHERIES .............................................................................................................................................. 46
5.6 TREES .................................................................................................................................................... 46
5.7 RELATIONSHIP BETWEEN LOSS OF HABITAT AND POPULATION REDUCTION ............................................. 47