Information Sources & Quality

Information Sources & Quality

The information presented in the current IUCN Red List represents an accumulation of knowledge derived from previously published Red Lists, including the 1996 IUCN Red List of Threatened Animals and The World List of Threatened Trees. Readers are therefore referred to the previous publications when checking on information sources and data quality. Many of the assessments done for the 1996 list are in the present Red List unchanged and the original sources who provided either the information or the assessments are still recognized. For every species entry, there is a name of one or more assessor or the name of an SSC Specialist Group. In some cases assessments are the product of group discussion, but often they represent the judgement of individual Specialist Group members. In order to ensure greater accuracy and transparency in the listing process, a peer review system of Red List Evaluators has been initiated. The intention of the system is that the assessments of all species on the Red List should be scrutinized and evaluated by at least two people from a designated Red List Authority. The Red List Authorities will be responsible for ensuring that all species they are responsible for are documented and re-assessed at regular intervals.

BirdLife International is the Red List Authority for birds and as such they have provided all the bird assessments used for the IUCN Red List. These assessments and the accompanying documentation reflects partially the contents of Threatened Birds of the World (BirdLife International 2000).

All mammal species (as listed in Wilson and Reeder 1993) have supposedly been assessed, but there are a number of new species which have been described in recent years which have not yet been evaluated. These are a very small fraction of the total number of mammal species, so for the purposes of the summary statistics, all mammal species have been assessed. The quality of the mammal assessments is highly variable, with many being based on relatively poor or sparse information in the case of the rodents, insectivores and insectivorous bats, although the status of many of the latter species was re-evaluated during the preparation of the microbat action plan (Hutson et al. 2001).


Where possible, standard world checklists have been used in order to promote nomenclatural stability. In a few instances Specialist Groups have used alternative systematic opinion and provided justification for doing so. All names of taxa on the Red List were checked and verified as far as was possible. In doing this, the correct authority name was included in an attempt to clarify what species concept is being followed. The names of the phyla and classes used in general follow Margulis and Schwartz (1988), but there are a number of deviations based on new evidence and thinking, particularly with regards to the plant groups. The following paragraphs note the main taxonomic sources used.


The names of mammal orders, families and contents of families follows Wilson and Reeder (1993). Species nomenclature generally also follows this source, except when a Specialist Group has expressed a very strong preference for another system, or has used nomenclature different from Wilson and Reeder and we have been unable to resolve subsequent ambiguities about the population content of the species concerned and their distribution. Principal departures from Wilson and Reeder are relatively few in number, and are found mainly in the primates and the bovids. A new treatment of primate taxonomy was recently published by Groves (2001). Much of this revised taxonomy has been adopted by the SSC Primate Specialist Group and used in the Red List, but there are still some significant differences. The recent sixth edition of Walker's Mammals of the World (Nowak 1999) proved to be very useful in clarifying various species concepts and for obtaining information for the documentation requirements.


Nomenclature for genera and families of birds generally follows Sibley and Monroe (1990, 1993). Solely to maintain uniformity with Threatened Birds of the World, we use the names of orders and families, and the species content of families of Morony et al. (1975). BirdLife International (2000) has used subfamily names to split up the larger families like the Muscicapidae, Embirizidae and Ploceidae in Threatened Birds of the World. These subfamilies are not used in the 2000 Red List.


Turtles and tortoises generally follow Iverson (1992); crocodilians follow King and Burke (1989); and tuatara systematics are after Daugherty et al. (1990). Names in common use, including those used by Specialist Groups or in national sources, have been employed for other groups of reptiles. Increasing use is being made of The EMBL Reptile Database compiled by Peter Uetz (Uetz and Etzold 1996), and made available on the World Wide Web at: This is rapidly becoming the standard global checklist for reptiles.


Nomenclature generally follows Frost (1985) as updated by Duellman (1993). The Amphibian Species of the World Database is now available on the World Wide Web and is updated regularly, so this has become the source for any recent changes: Another important web site for documentation on amphibian species, especially those in decline is the Amphibia Web Database.


The names of orders, families, and the species content of families currently follows Eschmeyer (1990), but a number have been updated to be in line with the new thinking presented in Eschmeyer (1998). Some of the fish names used are derived from national sources or from Specialist Groups. Extensive recent taxonomic changes mean that the status of many fish species on the Red List needs to be re-assessed. This was not possible for the current Red List, and the names and assessments are left as they appeared in the 1996 Red List, but it is important that this issue be resolved soon. An updated version of Eschmeyer's work is maintained as part of the comprehensive ICLARM (International Centre for Living Aquatic Resources Management) database (FishBase) or through Species 2000.


Parker (1982) has generally been followed for nomenclature at class, order and family level. There is a lack of widely accepted class-level checklists for invertebrates and in the absence of such sources no attempt has been made to standardize names for inclusion. The Integrated Taxonomic Information Service (ITIS) web site developed jointly by the US Departments of Agriculture and US Geological Survey is a useful source for a number of global and North American checklists covering a wide range of taxonomic groups including many invertebrates.


For plant families and genera Brummitt (1992) is generally followed, but for the content of genera reference is made to a wide range of taxonomic treatments including papers on individual species, monographic treatments, standard floras, global checklists (e.g., Farjon 1998) and even site-specific checklists (e.g., Cable and Cheek 1998). The taxonomy of plant families and orders is undergoing major revision at present. Until such time that some level of stability is achieved, the orders of Cronquist (1981, 1988) are followed. Specific names are frequently checked against the International Plant Names Index that incorporates Index Kewensis, the Gray Index and the Australian Plant Names Index. The author citations for species follow Brummitt and Powell (1992) and as updated on the IPNI web site.

Undescribed Species

Undescribed species are accepted on the Red List only under the following conditions:

  • There is general agreement that the undescribed taxon is in fact a good species.
  • Clear distribution information can be provided.
  • Listing the undescribed species will potentially aid in its conservation.
  • Specimen reference numbers (voucher collection details) are provided which will enable the species to be traced without confusion.
  • The museum, herbarium or other institution holding the collection and the individual responsible for the proposal can be identified.
  • Whenever possible a common name can be added.
Undescribed species are represented in the Red List by the generic name and the abbreviation sp. or sp. nov. Details of specimen numbers and institution should ideally be included in parentheses after the sp. nov. There are some instances where this has been done, but in many cases there have been requests for this information to be withheld because of fears that someone else will then describe the species concerned.

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