As the saying goes: “.” The list of extinct animals, like , and , is depressing. And , extinction seems final.
But when does extinction start? That would seem like an easy question to answer. In the dry prose of the , extinction has occurred when “.”
And as we know from watching courtroom dramas, the concept of “no reasonable doubt” is a high bar, meant to protect the innocent in society. In conservation, it is to guard against crying wolf.
No longer extinct
In the 1980s, it was suggested that an extinction should be declared if a species was not observed for 50 years. That seems like a long time, but it wasn’t long enough. Many species have been rediscovered decades or even centuries after their last observation.
For example, the black-browed babbler was recently recorded in the jungles of Borneo !
And indeed, extinction need not technically be forever: some rediscovered species had been formally declared extinct. These species are referred to as Lazarus species — for instance, the Miles’ robber frog was after it was located in a Honduran cloud forest in 2008.
Premature declarations
Incorrectly declaring a species extinct can have serious consequences. Potentially urgent conservation actions for the species in question stop, and in some cases, those conservation actions can help protect entire ecosystems.
Perhaps more importantly, crying wolf undermines the credibility of extinction as a label.
Beyond reasonable doubt is a conservative position, but it leaves us in a bit of a pickle. With our colleague, Andrew Fairbairn, we that surprisingly many species have not been seen in over 50 years, and remain in a sort of limbo between and extinct.
Putting species in limbo is not helpful. A 2019 report by the United Nations suggested that (roughly 12 per cent of all species). The actual number of species that have been declared extinct by the IUCN seems, on the face of it, much less dramatic: or less than 2 per cent of that group, for instance.
Such a mismatch can, to put it mildly, . And because more and more species are , discrepancies between the number of “going extinct” and the number of “gone extinct” species may become more of a problem.
In our study, we found that 562 terrestrial vertebrates — mammals, birds, amphibians and reptiles — are currently stuck in lost species limbo, almost twice as many as the number declared extinct.
None of these have been declared extinct, but none have been reliably observed for at least 50 years. The famous was last seen in 1944, although . And the , was in 1963.
While most of these lost species are (or were) found in the tropics, they also hail from the United States, China, Australia and Canada, and include everything from tiny shrews and salamanders to dolphins and wild cattle.
Searching for proof
So what should be done about the confusing problem of lost species? Clearly, the answer is to go looking for them.
That is, of course, easier said than done. Many lost species live in remote ecosystems that are difficult to reach, like inaccessible rainforests or vast tundras. There are plenty of skilled field scientists who would love nothing more than to spend their time in under-studied ecosystems searching for lost animals, but funding to support such fieldwork .
Securing funding sources to support searches for lost species is therefore important. This could perhaps be helped by better awareness of and management of lost species as a group. While 50 years is an arbitrary measure, it might help focus attention by defining a clear list of candidate species.
We envision a scorecard of lost species, updated as time passes and species go on and come off when rediscovered or declared extinct.
We end with the full and depressing formal definition of extinct:
“a taxon is presumed Extinct when exhaustive surveys in known and/or expected habitat, at appropriate times (diurnal, seasonal, annual), .”
We believe many lost species are not extinct, and so will be rediscovered. Each rediscovery will be cause for minor celebration and, , renewed attention and interest. But we really need to know, one way or the other.
Arne Mooers is a member of the Committee on the Status of Endangered Wildlife in Canada, an independent federal body that makes recommendations to the Government as outlined in the Federal Species at Risk Act.
Tom Martin, a conservation scientist with the Wild Planet Trust, and Gareth Bennett, an undergraduate student in biological sciences at Simon Fraser University, co-authored this article.
