Photo: Joel Sartore/Photo Ark.
Rare flat-headed cats were declared “lost” before the species was rediscovered in 1995.
Lady Macbeth says, “What’s done cannot be undone.” Similarly, when a species is truly extinct, it’s done, never mind random talk of bringing back a wooly mammoth from its DNA. What is more feasible is bringing back to its former range a species that is merely extinct in that region.
Remember our post on the tiger quoll, thought to be extinct in southern Australia? And how about that gray whale, thought to be extinct in the Atlantic Ocean? It just showed up, although that was probably a sign of melting ice that could have opened a passage from the Pacific.
You might like Daniel Shailer’s related story at Scienific American on species that scientists think may yet be found. He explains how researchers will go about prioritizing their searches.
“Gison Morib was home lying in bed, sick from exhaustion after a month-long jungle expedition, when his phone buzzed and a black-and-white photograph appeared. Morib ran outside, jumped on his motorbike and sped through the city of Sentani on Indonesian New Guinea to his colleagues’ expedition and research base — where he broke down in tears.
“ ‘I cannot believe we found it,’ was all he could say, over and over. The photograph showed the first recorded sighting in more than 60 years of an Attenborough’s long-beaked echidna, an egg-laying mammal. After the researchers had spent three years of research and four weeks of trekking through the island’s remote Cyclops Mountains … the team’s camera trap had finally captured an image of the echidna. ‘Even now I can’t describe the feeling,’ … says Morib, a biology undergraduate student at nearby Cenderawasih University. …
“It can be painful for scientists to conclude that an entire species is gone forever. So after at least a decade without recorded sightings, local researchers sometimes simply declare a species temporarily ‘lost’ — hoping it may eventually be found again — instead of giving up entirely. In 2023 that hope led to rediscoveries of animals that included Attenborough’s echidna, De Winton’s golden mole in South Africa and the Victorian grassland earless dragon, a type of Australian lizard that went unseen for half a century. Such hope also fuels ongoing, decades-long searches for species such as the American Ivory-billed Woodpecker, which was last seen in 1944.
“Now an international study published [in] Global Change Biology aims to ‘bring a bit of science back to the search’ for all mammals, amphibians, reptiles and birds playing hide-and-seek, according to senior study author Thomas Evans, a conservation scientist at the Free University of Berlin. In a span of two years, Evans and a team of researchers across the globe — from the U.S. to China, Ecuador and South Africa — compiled what they call the most exhaustive catalog ever of four-limbed creatures that were considered lost to science and those among these animals that were later rediscovered. …
“Although there has been plenty of research into lost species, the study authors say that rediscoveries haven’t been thoroughly assessed since 2011. Analysis tallying losses and rediscoveries across animal groups is even rarer, Evans says.
“His team’s catalog suggests that 856 species are currently missing and that the number of lost species is growing around the world faster than expedition parties can keep up. And this is occurring even though researchers are finding animals through the use of increasingly sophisticated technology, including systems that detect environmental DNA (eDNA) traces of burrowing birds near the South Pole, software that disentangles the noises of different nocturnal species, and even techniques used to spot microscopic traces of rare frogs in ship rats’ stomachs.
“Adding up losses and rediscoveries also suggests that roughly a quarter of lost species are likely already extinct. … Analysis shows that many rediscovered species fit a certain profile: they are big, charismatic mammals or birds that tend to live across a range of habitats, often near humans and in more-developed countries. So, Evans says, if an animal fits the bill for the kind of species that is usually found more easily but continues to evade researchers after long searches, it is probably gone forever. The thylacine, or Tasmanian tiger, is a good example: since the last captive thylacine died in a zoo in 1936, the wolflike species has taken on huge cultural significance across Australia and inspired decades of searching, but it remains lost. The paper argues that precisely because the thylacine is a perfect candidate for rediscovery, the fact it remains lost strongly suggests that it is actually extinct. The same goes for more than 200 other lost species that have been thoroughly searched for as well, Evans says.
“On the other hand, creatures that don’t fit the profile for easy rediscovery, especially reptiles, could still be out there. Because they’re often hard to find and inspire less search effort, small, uncharismatic species are more likely to genuinely be lost but still alive, Evans says. His optimism is backed up by the numbers: new species of small reptiles continue to be discovered at a steady rate, and rediscoveries have boomed, with more than twice as many lost reptiles found between 2011 and 2020 than in the decade before.
“The thylacine has acquired a Bigfoot-like status, complete with amateur hunters and highly questionable sightings. Meanwhile reptiles such as the Fito leaf chameleon of Madagascar are probably sitting pretty and waiting to be found. …
“A probability analysis of some factors also rang ‘alarm bells’ in different ways for different classifications of lost species, Evans says. Mammals classified as lost on islands, such as the Bramble Cay melomys, a rat lost in 2009 and declared extinct in 2016, are disproportionately likely to be gone for good, compared with mammals in other environments. There’s also a sweet spot for finding birds after they’ve been lost: 66 years, on average. This time span is long enough to raise interest in search expeditions but not so long that the animals are considered extremely likely to be extinct. So the odds are not good for the more than a dozen bird species that were lost more than a century ago.
“Evans hopes such details about what may be simply unseen versus what is more likely extinct will help conservationists.”
More at Scientific American, here.
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