The Species Black List

Species nobody has seen for a very long time

2,120 species that have not been recorded in years, in some cases in centuries, and that nobody has been able to declare extinct. They are not gone. They are unaccounted for, which is a different thing, and the difference is where the work is.

Where they were last seen

Countries are shaded by how many lost species have their range recorded there, darker for more. A circle marks a place that is not a country, an island like Luzon or a region like Lake Victoria, and it sits at the country's center point rather than at a locality. It is not a sighting, not a range map, and not a search area: large countries accumulate large circles partly because they are large. Hover or tap either for the breakdown.

Where we lose them is not where we find them

This site carries two maps: species that have gone missing, and species being described for the first time. Set side by side they disagree, and the disagreement is the argument. Brazil has lost the most and is still describing plenty. China is describing more new species than anywhere on earth and carries almost no backlog. The United States is the reverse: a long list of losses and very few new descriptions.

The longest wait in each group

The groups are nothing like each other, though: a bird goes missing for a decade and it is news, while a snail can go missing for a century before anyone notices it has. These are the record holders, the species in each group whose last confirmed record is the oldest of all.

Counting is not the same as rate

Why some species come back and others never do

Rediscovery is not random, and it is not simply a matter of looking harder. Lindken and colleagues examined every lost tetrapod they could trace and found that the species which come back share a profile: they tend to be large, conspicuous mammals and birds, tolerant of a range of habitats, living near people, in countries with money for fieldwork.

The species that stay lost are the mirror image. Narrow range. Small, cryptic, nocturnal, or underground. And, the finding that matters most here, living somewhere that is hard or dangerous to reach, so nobody has searched. A species can remain "lost" for a century without any evidence that it has declined at all. It can simply be that no qualified person has been to the right ridge in the right month.

Their overall estimate is that roughly a quarter of lost species are probably already extinct. Which is a bleak number read one way, and an extraordinary one read the other: it implies that most of the species on this map are still out there.

They also found that tetrapods are being lost faster than they are being found again. Rediscovery is slowing for amphibians, birds and mammals, while reptiles are being lost quickly. The gap is widening, and it will not be closed by the kind of survey that finds large animals near roads.

Plenty do come back. Of the tetrapods Lindken and colleagues traced, 424 of 1,280, a third of them, had already been found again by the time they published. This page carries the ones still missing, so a rediscovery is a species leaving it. The longest documented wait on record here is a Sierra Leone freshwater crab, Afrithelphusa afzelii, refound after 225 years. Recent finds are collected on the Rediscoveries page.

What The Biodiversity Group does about it

The Biodiversity Group works in the places the profile above predicts will be overlooked: steep, wet, unglamorous forest, a long way from a field station, looking for small animals at night. Three of those records are on this map.

The list is not a finished thing

Two open questions sit on it, and both need a taxonomist rather than a spreadsheet. Fifteen names are treated by one authority as valid species and by another as synonyms of something else. When a narrow endemic is absorbed into a widespread species, it leaves conservation attention by clerical means rather than by evidence. A further 149 were removed from the source list by IUCN SSC specialists for reasons that were never recorded per species: some because they had been found, some because nobody had ever looked. Those two reasons point in opposite directions, and the difference is the whole argument.

Species from this list that have turned up again in the news are collected on the Rediscoveries page.

Another list, counting something else

Recently Extinct Plants and Animals is the most thorough catalog of its kind we know of, with 12,859 taxa, painstakingly sourced and with a citation behind almost every entry. It is worth your time, and it is worth saying exactly how it differs from this page, because the two look like the same subject and are not.

Its rediscoveries section counts species that disappeared from a country and were later refound there, such as a plant gone from the British flora for ninety years, turning up on one roadside. This page counts species missing from science, everywhere, at once. Both are real losses and both matter; they are simply different questions.

The gap is measurable. We compared the two: of 1,063 species in their rediscoveries listing, exactly one also appears among the 2,120 here: Amphilophus lyonsi, a Costa Rican cichlid, and it has indeed been found again. That near-total absence is not a disagreement between the lists. It is the two definitions doing their jobs.