IUCN conservation category
A
vulnerable species
is a
species
which has been
categorized
by the
International Union for Conservation of Nature
as being
threatened
with
extinction
unless the circumstances that are
threatening
its survival and
reproduction
improve.
Vulnerability is mainly caused by
habitat loss
or destruction of the species' home. Vulnerable habitat or species are monitored and can become increasingly threatened. Some species listed as "vulnerable" may be common in
captivity
, an example being the
military macaw
.
There are currently 5,196
animals
and 6,789
plants
classified as Vulnerable, compared with 1998 levels of 2,815 and 3,222, respectively.
[1]
Practices such as
cryoconservation of animal genetic resources
have been enforced in efforts to conserve vulnerable breeds of livestock specifically.
Criteria
[
edit
]
The
International Union for Conservation of Nature
uses several criteria to enter species in this category. A
taxon
is Vulnerable when it is not
critically endangered
or Endangered but is facing a high risk of extinction in the wild in the medium-term future, as defined by any of the following criteria (A to E):
A) Population reduction in the form of either of the following:
- An observed, estimated, inferred or suspected population size reduction of ≥ 50% over the last 10 years or three generations, whichever is the longer, provided the causes of the reduction are clearly reversible AND understood AND ceased.
[2]
This measurement is based on (and specifying) any of the following:
- direct observation
- an index of abundance appropriate for the taxon
- a decline in area of occupancy, extent of occurrence or quality of habitat
- actual or potential levels of exploitation
- the effects of
introduced taxa
,
hybridisation
, pathogens,
pollutants
, competitors or
parasites
.
- A reduction of at least 20%, projected or suspected to be met within the next ten years or three generations, whichever is the longer, based on (and specifying) any of (2), (3), (4) or (5) above.
B) Extent of occurrence estimated to be less than 20,000 km
2
or area of occupancy estimated to be less than 2,000 km
2
, and estimates indicating any two of the following:
- Severely
fragmented
or known to exist at no more than ten locations.
- Continuing decline, inferred, observed or projected, in any of the following:
- extent of occurrence
- area of occupancy
- area, extent or quality of habitat
- number of locations or subpopulations
- number of mature individuals
- Extreme fluctuations in any of the following:
- extent of occurrence
- area of occupancy
- number of locations or subpopulations
- number of mature individuals
C) Population estimated to number fewer than 10,000 mature individuals and either:
- An estimated continuing decline of at least 10% within 10 years or three generations, whichever is longer, or
- A continuing decline, observed, projected, or inferred, in numbers of mature individuals and population structure in the form of either:
- severely fragmented (i.e. no subpopulation estimated to contain more than 1,000 mature individuals)
- all mature individuals are in a single subpopulation
D) Population very small or restricted in the form of either of the following:
- Population estimated to number less than 1,000 mature individuals.
- Population is characterised by an acute restriction in its area of occupancy (typically less than 20 km
2
)
[2]
or in the number of locations (typically less than five). Such a taxon would thus be prone to the effects of human activities (or stochastic events whose impact is increased by human activities) within a very short period of time in an unforeseeable future, and is thus capable of becoming Critically Endangered or even Extinct in a very short period.
E) Quantitative analysis showing the probability of extinction in the wild is at least 10% within 100 years.
The examples of vulnerable animal species are
hyacinth macaw
,
mountain zebra
,
gaur
,
black crowned crane
and
blue crane
See also
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Notes and references
[
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External links
[
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