The most common question about endangered species has a specific, checkable answer — and it is almost always quoted incorrectly. As of version 2026-1 of the IUCN Red List of Threatened Species, 175,909 species have been assessed and more than 49,500 are threatened with extinction. That is 28% of everything assessed.
What "threatened" actually means
"Threatened" is not a mood or a trend. On the Red List it is the union of exactly three categories:
- Vulnerable (VU) — high risk of extinction in the wild
- Endangered (EN) — very high risk
- Critically Endangered (CR) — extremely high risk
Species listed as Near Threatened, Least Concern, Data Deficient or Not Evaluated are not counted in the 49,500. This matters, because a species can be in steep decline and still sit outside the threatened categories — and a species can be listed as Data Deficient simply because nobody has surveyed it.
Why the number is not the number
The 28% figure is the share of assessed species, not the share of all species. Science has described roughly 2 million species and estimates many millions more remain undescribed. The Red List has assessed 175,909 of them. The IUCN's own Strategic Plan for 2021–2030 targets 260,000 assessments — meaning 84,091 assessments remain outstanding against its current goal, and that goal is itself a fraction of described life.
Assessment effort is also not evenly spread. Vertebrates, and especially mammals and birds, are far better covered than invertebrates, fungi and plants. So the headline percentage is drawn disproportionately from the best-studied groups, and the groups we know least about are the ones most likely to be quietly disappearing.
Threat levels by group
The aggregate figure hides enormous variation. From the same 2026-1 release:
- Cycads — 71% threatened, the highest of any assessed group
- Reef corals — 44%
- Amphibians — 41%
- Sharks and rays — 38%
- Conifers — 34%
- Selected crustaceans — 28%
- Mammals — 26%
- Reptiles — 21%
- Birds — 11%
Birds are the most comprehensively assessed group on the list and show the lowest threatened share. That is not evidence that birds are safe — it reflects both genuine conservation success and the fact that complete assessment coverage includes the many common species that partial coverage of other groups tends to skip.
Why the Red List changes in both directions
A species moving between categories is not always bad news, and not always news about the species. Reassessments happen for three quite different reasons:
- The population genuinely changed. The giant panda moved from Endangered to Vulnerable in 2016 after decades of habitat protection.
- The evidence improved. The snow leopard was downlisted from Endangered to Vulnerable in 2017 on the basis of better survey methods, not population recovery — an important distinction that was widely misreported at the time.
- The taxonomy changed. Splitting one species into three can create two newly threatened species overnight without a single animal being lost.
This is why we treat any status change as a prompt to check the assessment rather than a headline in itself.
How WARN uses the Red List
We reconcile the conservation status published on our species guides against the current Red List, and we do it deliberately as a review step rather than an automatic overwrite. Automated matching fails in a specific and dangerous way: it matches at the wrong taxonomic rank. A naive sync would relabel our page on working donkeys with the status of the African wild ass, and replace the migratory monarch butterfly's Vulnerable listing with the Least Concern status of the species as a whole. Both would be wrong, and both would look authoritative.
Where our published status and the current Red List agree, we say so and link the assessment. Where they disagree, a person checks which is right before anything changes.
