This nonmigratory bird from the American southeast was last spotted in 1944 — or, that’s when the last universally agreed-upon spotting occurred. The U.S. Fish & Wildlife Service proposed to deem this bird extinct in 2021, but delayed this decision. Though we haven’t definitively seen it for decades, the U.S. Fish & Wildlife Service still classifies it as critically endangered, recognizing that there may be a few lone survivors. A cadre of researchers look for these stragglers. Steven Latta, director of conservation and field research at the National Aviary in Pittsburgh, published a paper in May 2023 describing evidence for the bird’s continued existence in Louisiana, such as visual observations, over 70,000 hours of audio recordings, and over 1,000 hours of footage from over 3,200 drones. From this material, Latta and his team glean there could be as many as three ivory-bills in the state. Paper co-author and research ornithologist John Trochet at the University of California, Davis Museum of Wildlife and Fish Biology has spent over 10 years gathering data on these woodpeckers, assisting on the annual survey for them. Both Latta and Trochet are part of Project Principalis, a collaboration between the National Aviary and independent researchers to find evidence for this elusive bird.

This elusive amphibian native to Mexico is considered critically endangered with 50 to 1,000 mature individuals in the wild. They reside exclusively in two freshwater lakes in Mexico. Scientists are fascinated with this salamander’s ability to regenerate limbs, tissues, and organs, which makes its conservation crucial for further understanding. We may never know if there’s a truly wild Axolotle anymore thanks to ecologist Luis Zambrano. He began tracking wild axolotl populations in the early 2000s for the Mexican government and has since lead to restoring urban wetlands where released, lab-raised axolotls can try to thrive in the wild once again. So if you are near Mexico City and see an axolotl, it could be wild or a product of Zambrano’s good work.

After a single specimen’s discovery in 1906, this charismatic reptile was believed extinct. But then, a 2019 research expedition on Fernandina Island in the Galapagos found what they thought was another specimen of this giant tortoise, whom they called Fernanda. A genome test confirmed that she was closely related to the 1906 tortoise, casting doubt on the true number of these gentle giants left. A 2022 paper on Fernanda’s sequenced genome speculates that Fernanda could face either an opportunity to respawn her species, or the same fate as Lonesome George, another giant tortoise who went extinct. In December 2023 the Galapagos Conservancy wrote that it’s increasingly likely that Fernanda is the last of her kind. More explorations of this island, conducted by the Conservancy and Galapagos National Park Directorate to find another Fernandina giant tortoise, “so far have been fruitless.” The Conservancy writes that this species’ current status is still unknown.

Since its last official sighting in 1937, this blind mole went 87 years without making an appearance, leading the world to conclude it was extinct. Conservation biologist Samantha Mynhardt at Endangered Wildlife Trust spent years searching for this sand-dwelling creature. By tracing the animal’s residual DNA in the environment, she and a team of researchers in South Africa rediscovered it, publishing their findings in a 2023 paper. While this little nugget isn’t widespread, this research at least confirms its persistence on the west coast of southern Africa. Mynhardt and her colleagues emphasize that though they’ve confirmed its existence, the next great challenge will be protecting them from destructive diamond mining that threatens their habitats.

Named after famed biologist Sir David Attenborough, this mammal is the only one besides the duck-billed platypus known to lay eggs. After a single specimen’s discovery in 1961 in Indonesia’s Cyclops Mountains, this monotreme was thought gone. A 2009 paper by researchers from Zoological Society of London describes efforts involving local residents to find traces of this echidna. While this trip saw actual live echidnas, this critical paper offered evidence for their continued existence. Then, in 2023, an international research group finally captured footage of one in Papua. Oxford University biologist James Kempton spearheaded the Cyclops Expedition and claims to have found the echidna on their final day in Papua.

This has been one slippery whitefish. A paper from 2005 argued that it had been globally extinct since 1940, though a 2006 paper countered this claim with genetic monitoring of the fish’s only remaining indigenous population. Declared extinct in 2008 by the International Union for Conservation of Nature (IUCN), this salmonid inspired researchers to continue pursuing it. A 2019 paper by biologists in Denmark describes the animal’s migratory behavior to inform conservation planning. It wasn’t until 2023 that this creature officially resurfaced. Using mitochondrial DNA, researchers in Amsterdam and London performed phylogenetic analysis on living whitefish and a 1754 museum specimen. They concluded that C. oxyrinchus is phylogenetically the same as a living houting species, C. lavaretus. In this case, the North Sea houting reappeared after phylogenetic re-evaluation rather than discovery of a missing school.

This living fossil of a fish had been believed extinct for 66 million years — until 1938, when it reared its ancient head off the east coast of South Africa. Now, researchers investigate these geezer fish to understand how they’ve persisted since the dinosaur age, how other tetrapods have evolved, and how they’re able to live for so long. A paper published in 2021 found that they may live as long as a century, which is five times longer than previous studies had suggested.

We’d thought this large rodent had gone the way of the Incas that once prized it, but in 2009 a park ranger found what he believed was a live specimen. A team led by Horacio Zeballos from the Museum de Arequipa and Gerardo Ceballos from the Instituto de Ecología of the Universidad Nacional Autónoma de México visited the site in 2012. Indeed, they were able to spot the large rodent. In 2016, the IUCN updated the chinchilla rat’s status from “extinct” to “data deficient.” Today, ecologists like Jose Ochoa keep tabs on the cat-sized rodent with cameras. His 2020 paper — co-authored by the ranger who found the first chinchilla rat back in 2009 — describes 67 photographs of these scamps between April 2018 and 2019.

Also known as the Somali sengi, this little guy hadn’t been seen since 1970, and our current knowledge of it comes from 39 museum specimens. In 2019 a team of scientists, including phylogenetic biologist Steven Heritage, set off to the Republic of Djibouti where they conducted interviews with locals to confirm these animals’ presence. Their 2020 paper argues that the Somali sengi is not only extant, but has expanded from Somalia into the so-called Horn of Africa.

This lizard species is native to the Île of Pins off the coast of New Caledonia. It was first described in 1876, but wasn’t found alive again until 1993. Two specimens were collected in 2003 and 2005 from New Caledonia. Researchers like Stephane Caut continue to investigate this rare lizard. His 2013 paper claims to be the first to study this skink’s diet, food web position, and the extent of genetic variation in the only known extant population on the Isle. Biologist Michael Jowers also studies this creature, with his 2022 paper exploring the biomechanics behind a terror skink bite.

What is the sasquatch? It’s not something that scientists stake their reputations on, that’s for sure, but it does make its way into respectable tomes nonetheless. The obsession with this never confirmed creature is probably best captures by the obsession of the great novelist and American naturalist Peter Matthiessen. In his brilliant non-fiction work The Snow Leopard, he hikes the mountains of Nepal and waxes on the possibility — unspoken among researchers — of Bigfoot’s existence. The flesh and blood animal he and his companion zoologist George Schaller are actually after, the snow leopard, much like Bigfoot never makes an appearance in the book. “Isn’t that wonderful?” writer Matthiessen. In a Buddhist sense, maybe. But for the researchers hoping delisting a Lazarus taxa is far better.