Classification and Listing Processes
The first NT Threatened Species List using IUCN criteria (see below) was produced in 2003. This was reviewed in 2006, resulting in the current List. The NT Threatened Species List is reviewed every 4-5 years, and is currently under review.
Public comment is a vital component of the review process and is required under the Territory Parks and Wildlife Conservation Act. In the 2003 and 2006 review public consultation was part of the listing process, and in the 2010 review the community will again be invited to have their say.
Information from the public on distribution and abundance of native species of concern is always welcome, and should be sent to the Threatened Species Officer. Nominations of species for higher or lower threatened status can also be sent to the Threatened Species Officer, and available data will be assessed against the IUCN criteria for consideration during a review. Only in exceptional circumstances will changes be considered outside the 4-5 year review program.
Classifying the Status of Species
The Species Survival Commission of the IUCN (International Union for the Conservation of Nature) has developed a classification system and criteria for use in assessing the conservation status of species. This system has been widely adopted by conservation agencies around the world.
In the Territory the latest version of these criteria (Version 8.1, 2010) is used.
The IUCN uses criteria relating to:
- Absolute size, number of subpopulations and extent of reduction in population size;
- Extent, degree of fragmentation, and degree of fluctuation in geographic range (both the extent of occurrence and the area of occupancy); and
- Quantitative analysis of the probability of extinction
to classify the conservation status of species with different values of the above criteria applying to different categories. The IUCN categories are listed below:
-
Extinct (EX)
A taxon is Extinct when there is no reasonable doubt that the last individual has died. A taxon is presumed Extinct when exhaustive surveys in known and/or expected habitat, at appropriate times (diurnal, seasonal, annual), throughout its historic range have failed to record an individual. Surveys should be over a time frame appropriate to the taxon's life cycle and life form. -
Extinct in the Wild (EW)
A taxon is Extinct in the Wild when it is known only to survive in cultivation, in captivity or as a naturalized population (or populations) well outside the past range. A taxon is presumed Extinct in the Wild when exhaustive surveys in known and/or expected habitat, at appropriate times (diurnal, seasonal, annual), throughout its historic range have failed to record an individual. Surveys should be over a time frame appropriate to the taxon's life cycle and life form. -
Critically Endangered (CR)
A taxon is Critically Endangered when the best available evidence indicates that it meets any of the criteria A to E for Critically Endangered, and it is therefore considered to be facing an extremely high risk of extinction in the wild. In cases where a taxon may be extinct but where surveys have not been sufficient to establish the taxon’s absence, the tag “(Possibly Extinct)” may be added to this classification. -
Endangered (EN)
A taxon is Endangered when the best available evidence indicates that it meets any of the criteria A to E for Endangered, and it is therefore considered to be facing a very high risk of extinction in the wild. -
Vulnerable (VU)
A taxon is Vulnerable when the best available evidence indicates that it meets any of the criteria A to E for Vulnerable, and it is therefore considered to be facing a high risk of extinction in the wild. -
Near Threatened (NT)
A taxon is Near Threatened when it has been evaluated against the criteria but does not qualify for Critically Endangered, Endangered or Vulnerable now, but is close to qualifying for or is likely to qualify for a threatened category in the near future. -
Least Concern (LC)
A taxon is Least Concern when it has been evaluated against the criteria and does not qualify for Critically Endangered, Endangered, Vulnerable or Near Threatened. Widespread and abundant taxa are included in this category. -
Data Deficient (DD)
A taxon is Data Deficient when there is inadequate information to make a direct, or indirect, assessment of its risk of extinction based on its distribution and/or population status. A taxon in this category may be well studied, and its biology well known, but appropriate data on abundance and/or distribution are lacking. Data Deficient is therefore not a category of threat. Listing of taxa in this category indicates that more information is required and acknowledges the possibility that future research will show that threatened classification is appropriate. It is important to make positive use of whatever data are available. In many cases great care should be exercised in choosing between DD and a threatened status. If the range of a taxon is suspected to be relatively circumscribed, and a considerable period of time has elapsed since the last record of the taxon, threatened status may well be justified. -
Not Evaluated (NE)
A taxon is Not Evaluated when it is has not yet been evaluated against the criteria.
It is important to note that the classifications have been undertaken on the status of species within the Northern Territory. The status of particular species within the Northern Territory may sometimes differ to their status in other States or at the National level. A species can have a very restricted distribution within the Northern Territory and hence be classified as threatened but can be common in other parts of Australia and hence not be listed under the Commonwealth Environment Protection and Biodiversity Conservation Act as threatened at a National level. Theoretically, any species that is endemic to the Northern Territory should have the same status in the Territory and at the national level. However, often data on species, particularly the plants, have not been supplied to the Commonwealth and hence they are not listed at the national level.
Threatened Wildlife
Under the Act species that have been classified as Extinct in the Wild, Critically Endangered, Endangered or Vulnerable are considered to be threatened wildlife. These are shown in bold in the Table below. Threatened wildlife are automatically given protected wildlife status.
Summary of Classifications
The number of taxa (species and subspecies) in each category for each of the major groups are listed below.
| Group | EX | EW | CR | EN | VU | NT | LC | DD | NE | Total |
|---|---|---|---|---|---|---|---|---|---|---|
| Mammals | 14 | 1 | 3 | 7 | 12 | 18 | 64 | 26 | 2* | 147 |
| Birds | 1 | 3 | 6 | 10 | 25 | 311 | 21 | 52* | 429 | |
| Reptiles | 4 | 7 | 6 | 239 | 55 | 0 | 311 | |||
| Frogs | 1 | 1 | 41 | 6 | 0 | 49 | ||||
| Fish | 1 | 7 | 5 | 563 | 90 | >100 | 666+ | |||
| Invertebrates | 2 | 8 | 25 | 1 | 111 | 45 | >50.000 | 192+ | ||
| Plants | 2 | 16 | 47 | 381 | 3040 | 707 | 309 | 4502+ |
* All these species are vagrants or irregular visitors to the NT.