Red List Criteria & the Criteria Summary Sheet

The IUCN Red List of Threatened Species™

1 Red List Criteria

Rabb’s Fringe-limbed Treefrog

Photo © Brad Wilson rabborum

Category: Critically Endangered CR A2ace;B1ab(iii)

Criteria & subcriteria

Species that are assessed as threatened are assigned a code that includes:

• The Red List Category – remember, the threatened categories are Critically Endangered, Endangered, or Vulnerable; and • Red List Criteria.

An example of an assessment code is shown on the screen: the abbreviation on the left indicates the category [CLICK] (in this case, Critically Endangered), and the letters and numbers on the right summarize the criteria and subcriteria that the species meets for that category [CLICK].

The assessment code quickly summarizes the situation for the species. In the example shown, an experienced Assessor would understand that this species is Critically Endangered because it has undergone a reduction of at least 80% over the last 10 years or 3 generations; and because its extent of occurrence is less than 100 km², it is severely fragmented or occurs in just 1 location, and there is continuing decline in habitat area or quality.

2 Red List Criteria Nature of the Criteria

CRITERIA THREATENED

Population CATEGORIES A reduction

Restricted B geographic range Critically Endangered (CR)

Small population Quantitative C size & decline thresholds Endangered (EN)

Very small or Vulnerable (VU) D restricted population E Quantitative analysis

• There are five Red List Criteria (A-E).

• Each criterion is based on a different issue related to risk.

• Each criterion has a set of quantitative thresholds that determine which (if any) of the threatened categories a species qualifies for.

• If none of the thresholds are met then the Assessor must decide which of the other Red List Categories is appropriate for that species (is it already EX or EW; or does it nearly meet the conditions for a threatened category is therefore NT; or is its current extinction risk relatively low and qualifies for LC; or is the available information insufficient to list it under any category except DD).

• The criteria are independent of each other (i.e., meeting the thresholds under criterion B does not mean that the rules for criterion E are also true for the taxon).

3 Red List Criteria Why use multiple criteria? Not all of the criteria will be suitable for all taxa.

• All taxa being assessed must be evaluated against all five criteria.

• Meeting any one of the EN B1ab(iii,iv); VU A2cd criteria qualifies a taxon C2a(i) for listing at that level of threat

• All criteria met at the ✓ highest level of threat ✓ should be listed. ✓  ?

There are five Red List criteria available. However, not all of them will be suitable for all taxa, because not all taxa have the same level or type of information available for them.

[CLICK] However, it is important to consider all of the available data against all five criteria.

It might not be immediately obvious to you that the data you have available can actually tell you enough to apply more than one criterion. [CLICK] So, if you assess a species against criterion A and it meets the thresholds for Vulnerable, you may decide to list it as Vulnerable under criterion A and just move on to assessing the next species.

However, if you take just a bit more time to consider the other Red List Criteria, [CLICK] you may well find that the species also qualifies for a higher category under one or more of the other criteria (in the example shown, the species also qualifies for EN under criterion B). If the other criteria are not considered, then this higher listing will be missed.

[TRAINER’S NOTE: in the slide, the tick means the species meets the thresholds for that criterion