Each year, the Species Survival Commission (SSC) of IUCN-The World Conservation Union receives hundreds of emails from people around the world seeking more information about the IUCN Red List. SSC is delighted with the level of interest that the Red List generates. We are particularly pleased to see the broad spectrum of users of the Red List web site and the wide variety of questions being asked.

In response to this tide of interest, SSC has compiled the following list of "Frequently Asked Questions" (FAQs) and their answers, which it hopes will help broaden knowledge of issues such as how the Red List is compiled, and what information is available from the Red List.

To help users more easily find the answers they are looking for, we have grouped questions into the following categories:

1. Technical issues involving use of the Red List web site, in particular the use of the search function.
   • Why can't I get any results using the search functions on the web site?
   • Why do the search results differ between different versions of the Red List?
   • Why is the Red List not available as a hardcopy?
   • Is it possible to use the web site to search for species in certain areas within countries, for example, all species occurring in the Canary Islands rather than all species recorded as occurring in Spain?
   • How do I search the IUCN Red List for a list of species in a specific region?

2. Scientific issues such as those concerning the Red List criteria.
   • What criteria are used for listing species on the Red List?
   • What are the criteria for classifying a species as Extinct?
   • Why do certain groups of plants not appear on the IUCN Red List of Threatened Species?

3. Trends, facts and figures e.g., how many Critically Endangered species are on the list?
   • How many Critically Endangered species are there?
   • Is it possible to determine the changes between different versions of the Red List?
   • What are the five most threatened animal species in the world? Can you describe their situation and what is being done the protect them?
   • In which countries or continents is the threatened species situation worst?
   • Can you give examples of a few species that have moved to the brink of extinction since the 1996 Red List was published?
   • Can you give some examples of species that have been listed as Extinct and have subsequently been discovered to still exist?
   • Is the situation improving or getting worse?

4. Miscellaneous
   • How often is the Red List updated?
   • Do you have photographs of species included in the Red List?
   • How should the Red List be cited?

Further information on the IUCN Red List is available from this site on the Introduction and Red List Programme pages and also from the IUCN web site.

A. If a search does not produce any results, you should receive a message telling you what search criteria you specified. Please check these very carefully. If you are not sure how to use the search criteria, read the Help file (click on help on the Search page). If your search criteria are correct and you get no results, this means that the species you looked for is not in the database. Any species listed as Not Evaluated (NE) do not appear on the Red List. If you searched for a plant, the species you are looking for may have been assessed in 1997 but has not yet been reassessed for inclusion in the current Red List and you should consult the 1997 IUCN Red List of Threatened Plants (please see the Introduction page on this web site for an explanation of this).

Return to top of page

A. Search results will differ from year-to-year because of the annual changes that are made to the underlying data. A key feature of the web site is that searches produce a list of species only as the default option, whereas earlier versions searched for all taxa (species, subspecies, varieties and subpopulations). To search for subspecies, varieties and/or subpopulations the user must specify this in the Search page (in the section What taxa would you like to see?). Similarly, Least Concern species have been included in the web site since the 2003 update; however, prior to 2006, the default search option was set to 'All evaluated (excluding Least Concern)'. In 2006, the default is set to the option 'All evaluated (including Least Concern)' (see options in the Red List Categories list box on the Search page).

Return to top of page

A. The amount of extra documentation that appears with each species assessment means that the IUCN Red List would run to several large volumes if printed as a book. In addition, the Red List is updated annually, and the costs of producing an annual hardcopy version would be too prohibitive. For the 2000 and 2004 versions of the Red List, analyses of the Red List data were published. The 2000 book included a CD-ROM version of what appeared on the 2000 IUCN Red List of Threatened Species web site. There are plans to produce a new CD-ROM version in future (funds permitting).

Return to top of page

A. The Red List web site does not allow searches to be carried out at the sub-country level. This is mainly because we still have to check the data stored in the database to ensure all taxa included on the list have their distributions recorded at the sub-country level. This information has been recorded for many of the species held on the database, but not for all taxa. Searches at the sub-country level therefore will currently give an incomplete picture.

Return to top of page

A. The Search page allows users to tailor their searches so that only certain parts of the database are selected. To find a list of species for a specific region or country, follow the steps below:

1. The Text Search box can be used to specify which taxonomic group you would like to find. For example, if you want a list of animals, type in the word ANIMALIA or ANIMALS (this will restrict your search to animals only this includes mammals, birds, reptiles, amphibians, fishes, and invertebrates); if you want a list of threatened plants, type in the word PLANTAE or PLANTS; if a list of all species is required, leave the 'Text Search' box empty.
2. The default setting on the Search page is set at species only. To open your search to include subspecies, varieties and subpopulations, check the appropriate boxes in the What taxa would you like to see? section.
3. Use the Red List Categories list box to indicate which categories you want to include in your list. For example, if you are looking for a list of threatened species only, highlight all three of the threatened categories (Critically Endangered, Endangered and Vulnerable) by clicking on "CR - Critically Endangered", then hold down the Ctrl key on your keyboard and click on "EN - Endangered" and "VU - Vulnerable".
4. Use the Regions of the World list box to search for a list of species occurring within a specific region. For example, highlight Sub-Saharan Africa to find African species occurring south of the Sahara. Alternatively, a list of species occurring in only part of a region can be obtained using the Select one or more countries list box. For example, highlight Kenya, Tanzania, Uganda, Burundi and Malawi to find a list of species occurring in Eastern Africa.
5. Other options on the search screen can help to restrict searches further (e.g., to find all freshwater species only in your region, ensure the 'Freshwater' box is checked in the section What system is the species found in?
6. Click on Search.

If you have problems using the Search page, please refer to the Help page, which should guide you through most of the searches. If you still have problems using the Search page, contact the IUCN Red List office (either through the feedback form at the bottom of the Search page, or contact us at redlist@iucn.org).

Return to top of page

A. All assessments in the 2000 IUCN Red List of Threatened Species and the 1996 IUCN Red List of Threatened Animals used a system of categories and criteria adopted by IUCN in 1994 (for a full explanation of these see the Categories and Criteria page on this web site). While this was developed to make the assessment process more objective and easier to apply consistently to a wide range of species, there was some debate over their effectiveness when assessing certain taxonomic groups (such as fisheries species, long-lived species, and some invertebrates with very narrow distributions). In 1997, an extensive consultation was initiated to review the IUCN Red List assessment system and this resulted in some changes to the categories and criteria. The revised categories and criteria (version 3.1) were adopted by IUCN in February 2000 and they provide a more robust system. Copies of the IUCN Red List Categories and Criteria version 3.1 (in English, French and Spanish) can be downloaded from the Species Survival Commission web site; the English version is also available from the Categories & Criteria page on this web site. All new or updated assessments added to the IUCN Red List follow this revised system, and these assessments are noted as "ver 3.1 (2001)" on the Search Results page, while the assessments based on the older system are noted as "ver 2.3 (1994)".

Return to top of page

A. To declare a species as Extinct, there must be no reasonable doubt that the last individual has died. This means that exhaustive surveys for the species must have been carried out in its known and/or expected habitat at appropriate times throughout its known historic range, and that such searches have failed to record the species. These surveys should cover a period appropriate to the species' life-cycle and life-form. For the Red List, IUCN only records "recent" extinctions, meaning those species known to have become Extinct since 1500 AD.

Return to top of page

A. While the IUCN Red List of Threatened Species is designed to combine both animal and plant assessments in one list, including all species assessed for the World List of Threatened Trees, many of the plant taxa previously assessed for the 1997 IUCN Red List of Threatened Plants are not included on this Red List. This is because most of the plants are still assessed using the older categories (pre-1994). As more plants are reassessed using the most recent Red List assessment system they will be added to the Red List in future updates.

Return to top of page

A. This answer can be obtained by using the search function (in the Search page, highlight the "CR – Critically Endangered" option in the Red List Categories list box then click on Search). However, tables of Summary Statistics have also been prepared to help save time.

Return to top of page

A. In some cases this is fairly straightforward to answer especially when there has been a genuine deterioration or improvement in the status of a species, or if new information has come to light. However, listings frequently change as a result of taxonomic revisions. In such cases, the Red List assessments are not directly comparable because although the taxon may have the same name, the circumscription of the taxon may be different. So effectively they are different entities that have been assessed and are therefore not comparable in time. Teasing out all these issues, is very complex, but hopefully the possibility to track such changes will be included in a future upgrade of the Red List.

Changes in numbers of threatened species between 1996 and the current Red List can be found in summary statistics tables 1 and 2. The summary tables show changes between years as a result of any of the reasons given above. When analysing changes in numbers of threatened species, it is very important to take into account changes for genuine reasons only. Identifying genuine changes in Red List category is an important tool for monitoring the changing status of biodiversity. Although it is not possible to identify genuine changes for all species on the current Red List, one group (birds) does have sufficient data to do so. Based on genuine changes in Red List status of birds between 1988 and 2004, a Red List Index has been developed and was published in PloS Biology (Public Library of Science: Biology). The Red List is being developed to identify reasons for change in status for all species on the list, and at some time in the future it should be possible to highlight genuine changes only.

Return to top of page

A. It is impossible to provide such a list. Critically Endangered is the highest threatened category. All species assessed at this level face an extremely high risk of extinction in the wild unless the pressures on them are relieved. To find five species currently listed as Critically Endangered you can either search the Red List web site and select species from the list. Alternatively, the following examples selected from the list can be used:

Chinese Alligator Alligator sinensis. This is one of the most endangered of all the crocodilian species. It is a relatively small reptile, growing up to 2m and is found in the lower parts of the Yangtzee River in wetland habitats that have dense human populations and are intensively cultivated. This species is very secretive and spends a large part of the year hibernating in burrows. The greatest threats to the alligator are habitat destruction and killing by local farmers because its burrows damage agricultural land.

Bonin Fruit Bat Pteropus pselaphon. This species was listed as Vulnerable in 1996 and was uplisted to Critically Endangered in 2000. It is found in small numbers on only five small and remote Japanese islands. The status change was partly due to better information about the species, but is also attributed to hunting and increasing habitat loss through deforestation on the islands.

Brazilian Guitarfish Rhinobatos horkelii. This is a species of ray found along the coast of southern Brazil. Its numbers have declined by 96% between 1984 and 1994 due to over-fishing. The species is extremely vulnerable to over-exploitation because the inshore areas where pregnant females and adult males congregate, and where juveniles remain, are heavily fished. Juveniles are often taken two to three years before they reach maturity, which has severe consequences for the population. Fisheries in the area target several other species and are not dependent on the guitarfish, therefore the near-extinction of this species alone will not have much effect on the fishery industry. It is therefore likely that this species could be driven to extinction in the near future.

Philippine Eagle Pithecophaga jefferyi. Since the 1960s there have been strong and repeated predictions of the impending extinction of this eagle because of its small and rapidly declining population. It faces numerous threats including loss of old-growth forest habitat, and it is estimated that there may be as few as 226 mature individuals, with the total population, including immatures, estimated at c.350-670 birds. Various conservation initiatives have been launched and include passing legislation prohibiting persecution of the birds, protecting their nests, population surveys, public awareness campaigns, and captive breeding efforts. The future of the species will only be secured by full implementation of a forest conservation programme that will also benefit a further 27 other threatened forest bird species occurring in the same areas.

Kouprey Bos sauveli. The total population of this species is estimated at less than 250 individuals. Hunting, both for subsistence and for trade (meat and body parts, especially horns and skulls), is the major threat throughout the Kouprey’s range. Diseases from domestic and/or feral livestock could have disastrous consequences given the already severely reduced Kouprey population. Habitat loss as a result of the increase in areas under permanent cultivation and logging, as well as increasing levels of other human-created disturbances are also threats, but are insignificant compared to hunting. Land mines also pose a threat to the Kouprey both by directly killing animals and by hampering conservation efforts.

Other examples of Critically Endangered species on the Photo Gallery pages, and in press releases for previous Red List updates (see the list of previous Red Lists on the SSC web site). Please note that some of the species highlighted in previous Red List updates may now have been reassessed; the current Red List should be checked to confirm the current assessment.

Return to top of page

A. It is difficult to compare all taxa assessed in each country because some areas, and some taxa, have been more widely studied. Some regions also have a greater natural biodiversity than others – some have higher concentrations of mammals while others have many more bird species.

The Global Species Assessment (Baillie et al. 2004) analysed data from taxonomic groups with the most complete coverage on the 2004 IUCN Red List (birds, amphibians, mammals, turtles, conifers and cycads). In this analysis, certain "hotspots" appear. Most threatened species occur in the tropical continents (the Neotropical, Afrotropical and Indo-Malayan regions), especially on mountains and islands. Countries holding particularly large numbers of threatened species and endemics are Australia, Brazil, China, Indonesia and Mexico. However, patterns differ remarkably between taxonomic groups.

For more information on the geography of the Red List, see the Global Species Assessment.

Return to top of page

Many species have moved into the Critically Endangered category since 1996, stepping closer to extinction. Examples of these are:

Common Sawfish Pristis pristis. This species moved from Endangered to Critically Endangered in 2000. This large, inshore marine and freshwater sawfish was once common in the Mediterranean and Eastern Atlantic, but has now, along with all other sawfishes, disappeared from Europe and the Mediterranean. Its status in West Africa is unknown, but it is extremely vulnerable to bycatch (accidental catch in fisheries) and is believed to be severely depleted in Africa. Without timely intervention, there is a high probability that this sawfish will become extinct.

Fragile Tree Snail Samoana fragilis. This snail was uplisted from Endangered to Critically Endangered in 2000. The species was originally known to be widespread but uncommon on Guam and Rota. Currently, one population on Rota supports about 100 individuals. The Fragile Tree Snail has not been seen on Guam since 1996 and may be extinct on the island.

Iberian Lynx Lynx pardinus. With the population reduced to less than half of the 1,200 in the early 1990s, the Iberian Lynx is close to becoming the first wild cat species to go extinct for at least 2,000 years. The total population size is estimated at 250 mature breeding individuals and is continuing to decline due to loss of habitat and prey base, and persecution. Assessed as Endangered in 1996, this cat was uplisted to Critically Endangered in 2002.

Giant Hispaniolan Galliwasp Celestus warreni. This lizard moved from a Near Threatened listing to Critically Endangered in 2004. The population has declined by at least 80% over the last 20 years. It is threatened by habitat loss, especially deforestation for agricultural activities (planting crops and creating pastures). The galliwasp is also killed by by dogs, cats and mongooses, and by people who mistakenly consider it to be venomous.

Central American River Turtle Dermatemys mawii. This freshwater turtle was uplisted from Endangered to Critically Endangered in 2006. The species is hunted for its meat and in the 1970s, 1,000-2,000 turtles were harvested annually in Mexico. By the 1980s, no large populations remained and hunters began to travel further afield to find animals to harvest. In 2005, the only viable populations existing in Mexico occurrend in inaccessible areas. At recent harvest rates, the species is expected to be driven inevitably to extinction.

For additional examples see the Photo Gallery pages, or see examples from previous Red Lists on the SSC web site.

Return to top of page

A. Even when searches for a taxon have failed to produce evidence of its presence over many years and it has been pronounced Extinct, there are still cases of species being rediscovered. These are sometimes referred to as 'Lazarus species'. Some examples of these are:

The Madeiran Land Snail Discus guerinianus was listed as Extinct in 1996 because it had not been recorded since the 1860s despite regular surveys being carried out since 1983. However, in 1999 the species was recorded as existing on a part of the Island not previously surveyed because it was not known to be part of the snail's historic range. Its rediscovery has resulted in the species being reclassified as Endangered.

The Fernandina Rice Rat Nesoryzomys fernandinae from the Galapagos Islands was listed Extinct in 1996 because it had previously only been described by skeletal fragments found in owl pellets in 1980 - no living specimens were collected until the late 1990s when the species was found to exist on the island of Fernandina, mainly around the rim of the island's volcano. The species is now listed as Vulnerable.

The Ivory-billed Woodpecker Campephilus principalis was assessed as Extinct in 1996, has now been reclassified as Critically Endangered after a recorded sighting of the bird in 1999. The species was again recorded in eastern Arkansas in 2004.

The Lord Howe Island Stick Insect Dryococelus australis was thought to have become Extinct around 1920 after the introduction of rats to Lord Howe Island. However, in 2001 the species was rediscovered on Balls Pyramid, a rocky outcrop 23 km from Lord Howe Island. It is now listed as Critically Endangered.

The Bavarian Pine Vole Microtus bavaricus was known previously from only one location which was later drastically altered by the construction of a hospital on the site. No specimens of this rodent have been recorded at this location since 1962. However, in 2001 a population apparently belonging to this taxon was discovered in Northern Tyrol, just across the German-Austrian border. It is now listed as Data Deficient.

The Philippines Bare-backed Fruit Bat Dobsonia chapmani is known only from the islands of Cebu and Negros where it was previously considered to be Extinct after no records of the species since 1964. However, it was rediscovered on Cebu in 2000, and then on Negros in 2003. It is now listed as Critically Endangered.

Return to top of page

A. Looking only at changes in numbers of threatened species since 1996, the overall number of threatened species has increased in nearly all taxonomic groups, which suggests that the situation is deteriorating for many species. However, as mentioned in the “Trends, Facts and Figures” section above, when analyzing trend data, it is important to look only at genuine changes between categories and not at changes occurring as a result of improved knowledge about the species, or changes caused by taxonomic revisions. Analysis of genuine status changes in birds (Red List Index) supports the suggestion above by clearly showing that their overall threat status has continued to deteriorate since 1988, with particularly steep declines for Indomalayan birds, and for albatrosses and petrels.

For more information on trends in the status of biodiversity, see the Global Species Assessment and the Red List Index paper published in PloS Biology.

Return to top of page

A. Whenever possible, information on the Red List is updated on the web site annually (production of an updated CD-ROM will depend on the availability of funds). A full analysis of the data held on the Red List is published once every four years.

Return to top of page

A. SSC does not have a photo library of all species included on the Red List. However, there are photos available for some species highlighted during the annual updates (see Photo Gallery), and electronic copies of the photos included on the Red List web site are available for non-commercial purposes. For copies of these please e-mail the SSC Communications team: Anna Knee (alk@iucn.org) or Andrew McMullin (Andrew.McMullin@iucn.org).

Each species account includes links to allow direct searches for images of the taxon on the world wide web. SSC is also collaborating with ARKive as they are developing an electronic archive of photographs, moving images and sounds of threatened species and habitats.

Return to top of page

A. To cite the Red List generally use the following format, changing the dates where appropriate:

IUCN 2006. 2006 IUCN Red List of Threatened Species. <http://www.iucnredlist.org>. Downloaded on 4 May 2006.

To cite a specific assessment, use the assessor/s name/s, the assessment date, and the taxon name followed by the above citation. For example:

Australasian Marsupial & Monotreme Specialist Group 1996. Zaglossus bruijni. In: IUCN 2006. 2006 IUCN Red List of Threatened Species. <http://www.iucnredlist.org>. Downloaded on 4 May 2006.

Hedges, S. 2000. Bos suaveli . In: IUCN 2006. 2006 IUCN Red List of Threatened Species. <http://www.iucnredlist.org>. Downloaded on 4 May 2006.

Sotomayor, M.M., Arredondo, A.G., Sánchez, B., Dicht, R.F. & Lüthy, A.D. 2002. Coryphantha maiz-tablasensis. In: IUCN 2006. 2006 IUCN Red List of Threatened Species. <http://www.iucnredlist.org>. Downloaded on 4 May 2006.

Return to top of page