The system was developed because the IUCN Red List, a similar conservation status system, had some shortcomings for the unique requirements of conservation ranking in New Zealand. As of 2011,[update]plants, animals, and fungi are evaluated, though the lattermost has yet to be published.[2]Algae were assessed in 2005 but not reassessed since.[2] Other protists have not been evaluated.[2]
Categories
Species that are ranked are assigned categories:[3]
Threatened
This category has three major divisions:
Nationally Critical - equivalent to the IUCN category of Critically endangered
Nationally Endangered - equivalent to the IUCN category of Endangered
Nationally Vulnerable - equivalent to the IUCN category of Vulnerable
At Risk
This has four categories:
Declining
Recovering
Relict
Naturally Uncommon
Other categories
Introduced and Naturalised
These are any species that are deliberately or accidentally introduced into New Zealand.
Migrant
Migrant species are those that visit New Zealand as part of their life cycle.
Vagrant
Vagrants are taxa that are rare in New Zealand that have made their own way and do not breed successfully.
Coloniser
These taxa have arrived in New Zealand without human help and reproduce successfully.
Data Deficient
This category lists taxa for which insufficient information is available to make as assessment on conservation status.
Extinct
Taxa for which there is no reasonable doubt that no individuals exist are ranked as extinct. For these lists only species that have become extinct since 1840 are listed.
Not Threatened
If taxa fit into none of the other categories they are listed in the Not Threatened category.
Qualifiers
A series of qualifiers are used to give additional information on the threat classification:[1][3]
Qualifier
Definition
CD
Conservation Dependent
Likely to move to a higher threat category if current management ceases
DP
Data Poor
Confidence in the listing is low due to the poor data available for assessment
De
Designated
The criteria does not completely apply to the taxa
EW
Extinct in the Wild
Exists only in cultivation or in captivity
EF
Extreme Fluctuations
Extreme unnatural population fluctuations, or natural fluctuations overlaying human-induced declines, that increase the threat of extinction
Inc
Increasing
Population thought to increase 10% over 3 generations or 10 years
IE
Island Endemic
Endemic only to a single archipelago and not the main islands
OL
One Location
Found at one location (geographically or ecologically distinct area) in which a single event (such as a predator irruption) could soon affect all individuals of the taxon
PD
Partial Decline
Taxa has one or more secure populations but otherwise is declining
RR
Range Restricted
taxa confined to less than 1,000 km2 (390 sq mi)
RF
Recruitment Failure
Current population may appear stable but the age structure is such that catastrophic declines are likely in the future
SO
Secure Overseas
Secure in other parts of its natural range outside New Zealand
Sp
Sparse
Taxa in small, scattered populations
ST
Stable
Total population stable
TO
Threatened Overseas
Threatened in those parts of its natural range outside New Zealand
^ abTownsend, Andrew J.; de Lange, Peter J.; Duffy, Clinton A.J.; Miskelly, Colin M.; Molloy, Janice; Norton, David A. (January 2008). New Zealand Threat Classification System manual(PDF). Wellington, New Zealand: Science & Technical Publishing Department of Conservation. ISBN9780478143645. Retrieved 2 February 2018.