Is there a difference between threatened and endangered species?
Endangered species and threatened species are, to many people, just different ways of describing the same thing — an at-risk plant or animal. For DOC and other scientists the terms mean two different things.
We describe our species using the New Zealand Threat Classification System, which uses nationally understood and consistent categories and criteria to assess risk of extinction.
In this system, a threatened species is an umbrella term used to describe a range of risk categories, whereas an endangered species is one specific category.
New Zealand Threat Classification System categories
'Non-resident native’ is a collective term for species in these categories:
- Migrant: species that predictably and cyclically visit New Zealand but do not breed here
- Vagrant: species that are found unexpectedly in New Zealand and whose presence is transitory, or migratory species with fewer than 15 individuals known or presumed to visit each year
- Coloniser: species that would otherwise trigger a ‘Threatened’ category because of small population size, but have arrived in New Zealand without human assistance and have been breeding here only since 1950.
'Data Deficient’ species are so poorly known that we cannot assign them to any of the categories in the system.
Criteria for New Zealand threat rankings
* Predicted and ongoing due to existing threats
Dec = Declining
NC = Nationally Critical
NE = Nationally Endangered
NT = Not Threatened
NU = Naturally Uncommon
NV = Nationally Vulnerable
Rec = Recovering
Rel = Relict
RR = Range Restricted
- Population changes are calculated over 10 years or three generations, whichever is longer.
- Where more than 1 option is available in a cell, the key distinction is whether the current population level is considered natural, or results from human impacts.
- NURR (Naturally Uncommon, Range Restricted) is triggered when the breeding range is < 100,000 ha.
Text description of primary criteria table:
- Less than 250 mature individuals (natural or unnatural); or
- Any population size with a greater than 70% population decline over 10 years or 3 generations, whichever is longer.
- 250-1000 mature individuals (natural or unnatural) with a 10-50% population decline; or
- 250-1000 mature individuals (unnatural) with a stable population; or
- 1000-5000 mature individuals with a 50-70% population decline.
- 250-1000 mature individuals (unnatural) with a population increase of more than 10%; or
- 1000-5000 mature individuals (unnatural) with a stable population; or
- 1000-5000 mature individuals with a 10-50% population decline; or
- 5000-20,000 mature individuals with a 30-70% population decline; or
- 20,000-100,000 mature individuals with a 50-70% population decline.
- 5000-20,000 mature individuals with a 10-30% population decline; or
- 20,000-100,000 mature individuals with a 10-50% population decline; or
- >100,000 mature individuals with a 10-70% population decline.
- 1000-20,000 mature individuals with a population increase of more than 10%
- 5000-20,000 mature individuals with a stable population; or
- More than 20,000 mature individuals with a stable or increasing population; or
- All Relict species occupy less than 10% of their original range.
Andrew J. Townsend, Peter J. de Lange, Clinton A.J. Duffy, Colin M. Miskelly, Janice Molloy and David A. Norton. 2008. New Zealand Threat Classification System manual, 2008.
If population size is very difficult or impossible to estimate then secondary criteria can be used to help determine a species threat ranking.
Secondary criteria can be found on page 15 of New Zealand Threat Classification System manual.