A species 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:
- 1. An observed, estimated, inferred or suspected reduction of at least 20% over the least 10 years or
three generations, whichever is the longer, based on (and specifying) any of the following:
- a) direct observation,
- b) an index of abundance appropriate for the taxon,
- c) a decline in area of occupancy, extent of occurrence and/or quality of habitat,
- d) actual or potential levels of exploitation,
- e) the effects of introduced taxa, hybridization, pathogens, pollutants, competitors or parasites.
- 2. 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 (b), (c), (d) or (e) above.
- B. Extent of occurrence estimated to be less than 20,000 km2 or area of occupancy estimated
to be less than 2000 km2, and estimates indicating any two of the following:
- 1. Severely fragmented or known to exist at no more than ten locations.
- 2. Continuing decline, inferred, observed or projected, in any of the following:
- a) extent of occurrence,
- b) area of occupancy,
- c) area, extent and/or quality of habitat,
- d) number of locations or subpopulations,
- e) number of mature individuals.
- 3. Extreme fluctuations in any of the following:
- a) extent of occurrence,
- b) area of occupancy,
- c) number of locations or subpopulations,
- d) number of mature individuals.
- C. Population estimated to number less than 10,000 mature individuals and either:
- 1. An estimated continuing decline of at least 10% within 10 years or 3 generations, whichever is longer, or
- 2. A continuing decline, observed, projected, or inferred, in numbers of mature individuals and population structure in the form of either
- a) severely fragmented (i.e., no subpopulation estimated to contain more than 1,000 mature individuals),
- b) all individuals are in a single subpopulation.
D. Population very small or restricted in the form of either of the following:
- 1. Population estimated to number less than 1,000 mature individuals.
- 2. Population is characterized by an acute restriction in its area of occupancy (typically less than
100 km2) or in the number of locations (typically less than 5). Such a taxon would thus be prone to the
effects of 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.
