Extinction-risk models are based on accounting for "randomness" and currently involve looking at two factors: 1) Accidents or chance events, such as the drowning of a rock wallaby, and 2) External or environmental variability, such as changes in...

PARIS (AFP)

Some endangered species may face an extinction risk that is up to a hundred times greater than previously thought, according to a study released Wednesday.

By overlooking random differences between individuals in a given population, researchers may have badly underestimated the perils confronting threatened wildlife, it said.

"Many larger populations previously considered relatively safe would actually be at risk," Brett Melbourne, a professor at the University of Colorado and the study's lead author, told AFP.

There are more than 16,000 species worldwide threatened with extinction, according to the International Union for Conservation of Nature (IUCN).

One in four mammals, one in eight birds and one in three amphibians are on the IUCN's endangered species "Red List".

In a study released on Wednesday by the journal Nature, Melbourne said the current models used draw up such lists typically look only at two risk factors.