Guidelines for Using the IUCN Red List Categories and Criteria Version 14 (August 2019) Prepared by the Standards and Petitions Committee of the IUCN Species Survival Commission. Citation: IUCN Standards and Petitions Committee. 2019. Guidelines for Using the IUCN Red List Categories and Criteria. Version 14. Prepared by the Standards and Petitions Committee. Downloadable from http://www.iucnredlist.org/documents/RedListGuidelines.pdf. THE IUCN RED LIST OF THREATENED SPECIES™ Contents 1. INTRODUCTION ..................................................................................................................................... 5 2. AN OUTLINE OF THE RED LIST CATEGORIES AND CRITERIA............................................... 5 2.1 TAXONOMIC LEVEL AND SCOPE OF THE CATEGORIZATION PROCESS ........................................................ 5 2.1.1 Taxonomic scale of categorization ................................................................................................ 5 2.1.2 Geographical scale of categorization ........................................................................................... 7 2.1.3 Introduced taxa and subpopulations ............................................................................................. 8 2.1.4 Managed subpopulations .............................................................................................................. 9 2.2 NATURE OF THE CATEGORIES ................................................................................................................ 10 2.2.1 Transfer between categories ....................................................................................................... 12 2.3 NATURE OF THE CRITERIA...................................................................................................................... 14 2.3.1 The quantitative thresholds ......................................................................................................... 18 2.4 CONSERVATION PRIORITIES AND ACTIONS ............................................................................................. 19 2.5 DOCUMENTATION .................................................................................................................................. 20 3. DATA QUALITY .................................................................................................................................... 20 3.1 DATA AVAILABILITY, INFERENCE, SUSPICION AND PROJECTION............................................................. 20 3.2 UNCERTAINTY ....................................................................................................................................... 21 3.2.1 Types of uncertainty .................................................................................................................... 22 3.2.2 Representing uncertainty ............................................................................................................ 22 3.2.3 Dispute tolerance and risk tolerance .......................................................................................... 22 3.2.4 Dealing with uncertainty ............................................................................................................. 23 3.2.5 Documenting uncertainty and interpreting listings ..................................................................... 23 3.2.6 Uncertainty and the application of the categories Data Deficient and Near Threatened ........... 24 4. DEFINITIONS OF TERMS USED IN THE CRITERIA AND THEIR CALCULATION .............. 24 4.1 POPULATION AND POPULATION SIZE (CRITERIA A, C AND D) ................................................................ 24 4.2 SUBPOPULATIONS (CRITERIA B AND C) ................................................................................................. 24 4.3 MATURE INDIVIDUALS (CRITERIA A, B, C AND D) ................................................................................. 25 4.3.1 Notes on defining mature individuals .......................................................................................... 25 4.3.2 Clonal colonial organisms, such as most corals, algae, bryophytes, fungi and some vascular plants ........................................................................................................................................... 26 4.3.3 Fishes .......................................................................................................................................... 28 4.3.4 Sex-changing organisms ............................................................................................................. 28 4.3.5 Trees ............................................................................................................................................ 28 4.4 GENERATION (CRITERIA A, C1 AND E) .................................................................................................. 28 4.5 REDUCTION (CRITERION A) ................................................................................................................... 31 4.5.1 Calculating population reduction using statistical methods ....................................................... 31 4.5.2 Calculating population reduction using population models ....................................................... 36 4.5.3 Taxa with widely distributed or multiple subpopulations ........................................................... 37 4.5.4 Estimating overall reduction ....................................................................................................... 38 4.5.5 Dealing with uncertainty ............................................................................................................. 41 4.6 CONTINUING DECLINE (CRITERIA B AND C) ........................................................................................... 43 4.7 EXTREME FLUCTUATIONS (CRITERIA B AND C2) ................................................................................... 44 4.8 SEVERELY FRAGMENTED (CRITERION B) ............................................................................................... 47 4.9 EXTENT OF OCCURRENCE (CRITERIA A AND B) ...................................................................................... 48 4.10 AREA OF OCCUPANCY (CRITERIA A, B AND D) ...................................................................................... 51 4.10.1 Problems of scale ........................................................................................................................ 52 4.10.2 Methods for estimating AOO....................................................................................................... 53 4.10.3 The appropriate scale ................................................................................................................. 53 4.10.4 Scale-area relationships .............................................................................................................. 54 4.10.5 Scale correction factors .............................................................................................................. 55 4.10.6 "Linear" habitat .......................................................................................................................... 56 4.10.7 AOO and EOO based on habitat maps and models .................................................................... 57 4.10.8 Effect of sampling effort and detectability on estimates of AOO................................................. 59 4.10.9 Complementarity of AOO, EOO and number of locations .......................................................... 60 4.11 LOCATION (CRITERIA B AND D) ............................................................................................................. 60 4.12 QUANTITATIVE ANALYSIS (CRITERION E) .............................................................................................. 61 5. GUIDELINES FOR APPLYING CRITERION A ............................................................................... 61 Red List Guidelines 3 5.1 THE BASIS OF REDUCTIONS .................................................................................................................... 63 5.2 THE USE OF TIME CAPS IN CRITERION A ................................................................................................. 65 5.3 HOW TO APPLY CRITERION A4 ............................................................................................................... 65 5.4 REDUCTION FOLLOWED BY SHORT-TERM STABILIZATION OR INCREASE: THE 'SKI-JUMP' EFFECT ........... 66 5.5 HISTORICAL REDUCTION FOLLOWED BY LONG-TERM STABILIZATION: SEVERELY DEPLETED POPULATIONS......................................................................................................................................... 66 5.6 FISHERIES .............................................................................................................................................. 67 5.6.1 Fisheries management and extinction risk .................................................................................. 67 5.6.2 Technical aspects of using criterion A for fisheries .................................................................... 68 5.7 LONG-LIVED TAXA ................................................................................................................................ 68 5.8 RELATIONSHIP BETWEEN LOSS OF HABITAT AND POPULATION REDUCTION ........................................... 68 6. GUIDELINES