Vulnerable

What "Vulnerable" means

Vulnerable is one of the categories on the IUCN Red List, the most widely used global assessment of extinction risk, run by the International Union for Conservation of Nature.

A species is listed as Vulnerable when the evidence shows it faces a high risk of extinction in the wild. It's the first of the three "threatened" categories:

1. Vulnerable: high risk
2. Endangered: very high risk
3. Critically Endangered: extremely high risk

Just below it is Near Threatened, for species that are close to qualifying but don't yet. Its official abbreviation is VU.

How a species qualifies

A species is assessed against five sets of measurable criteria, and it qualifies as Vulnerable if it meets any one of them. In simplified form:

• A: Rapid decline. The population has fallen, or is expected to fall, by 30% to 50% or more over 10 years or three generations, whichever is longer.
• B: Small, shrinking range. An extent of occurrence under 20,000 km², or an area of occupancy under 2,000 km², that is fragmented, declining or fluctuating.
• C: Small, declining population. Fewer than 10,000 mature individuals, and still declining.
• D: Very small or restricted population. Fewer than 1,000 mature individuals, or a range so restricted (typically under 20 km², or five or fewer locations) that a single event could push it toward extinction.
• E: Modeling. Analysis shows at least a 10% chance of extinction in the wild within 100 years.

The snow leopard is a good example: it's listed as Vulnerable because its global population is estimated at fewer than 10,000 mature individuals and is expected to keep declining.

"Vulnerable" doesn't mean rare everywhere

The category describes a species in the wild. Some Vulnerable species are common in human care, and some are still locally abundant in parts of their range. What matters is the overall trend and the measurable risk.

Vulnerable vs. the Endangered Species Act

The IUCN Red List is a global scientific assessment. The U.S. Endangered Species Act is a law that uses the terms "endangered" and "threatened," with listings decided by U.S. agencies. There's no "vulnerable" listing under the ESA, and the two systems are decided separately. On Feather & Fang, animal pages show the IUCN Red List category.

Vulnerable animals at the zoo

Many familiar zoo animals are Vulnerable, including the lion, cheetah, polar bear, hippopotamus and giant anteater. Accredited zoos manage many of these through Species Survival Plans and support field conservation in the animals' native habitats.