After more than a century without anyone seeing a Fernandina giant tortoise (Chelonoidis phantasticus), the species was presumed extinct, and conservation ecologist Washington Tapia had no plans to search for it. “The probability to find a giant tortoise [was] one in one million,” says Tapia, who works at the Galápagos Conservancy. But after his colleague Jeffreys Málaga found the reptiles’ telltale poop, which is bigger, rounder, and contains more undigested seeds than that of other tortoises, Tapia changed his mind. In 2019, he led a five-day expedition to the Galápagos island of Fernandina, which the tortoises had once inhabited, in the hope of finding one.
Fernandina is the archipelago’s youngest and most volcanically active isle, and scientists hypothesize that giant tortoise populations declined following centuries of eruptions. After four grueling days of searching, the team had found only years-old scat in the same area as Málaga’s first report. Then, on the last day, a patch of vegetation caught Tapia’s eye, he recalls. After hiking to the area, the team found fresh dung, and soon Málaga exclaimed that he’d spotted a member of the lost species. At first, Tapia couldn’t believe his eyes, “but when I [had] Fernanda in my hands, I believed,” he says, adding that the team later named the female tortoise after her home island.
Finding a supposedly extinct species may seem like a happy ending, but the organisms and the scientists who rediscover them often face a long road filled with obstacles. When the joy of such discoveries dissipates, complicated questions begin piling up: Will genetic testing confirm the species’ identity? Should it be left in the wild or protected in captivity? Can researchers find others and breed them back to healthy populations? And if not, what then?
Due to her appearance, Tapia and his colleagues decided to take Fernanda into captivity. In particular, she was about half the body weight she should have been for her age, which the team judged was around 100 years old based on the fading rings of her carapace scales.
Determining her identity was less straightforward. Fernanda’s carapace lacked the saddle shape of the only other known specimen of C. phantasticus, a male tortoise preserved in 1906—which cast some doubt on her origins, explains Evelyn Jensen, a molecular ecologist at Newcastle University. She notes that at least fourteen of the Galápagos islands are thought to have unique giant tortoise species, and historically humans have transported them between the islands. Thus, it seemed quite possible that Fernanda was a member of a different, extant species from another island, says Jensen, “especially because she looks so different from the museum specimen.”
Recent genetic testing by Jensen, Tapia, and colleagues supports the idea that Fernanda is a member of the long-lost species (Commun Biol, 5:546, 2022)—although it’s unlikely to be the last word on the subject. Another group of researchers concluded the different island populations were subspecies and recommended revising their taxonomy to lump all Galápagos tortoises into a single species, something Jensen says she disagrees with.
Also grappling with complicated questions after finding a presumed-extinct species is botanist Wesley Knapp of the nonprofit NatureServe. This past May, after several days of hiking through the Chisos Mountains in Texas’s Big Bend National Park, he and colleagues found what seemed to be a lateleaf oak (Quercus tardifolia), which was thought to have been lost in 2011 when the last-known specimen in the area died. Knapp recalls his fellow expeditioner Michael Eason suddenly exclaiming, “Hey, Wes! You should get over here.” When Knapp arrived, Eason held out a small branch he’d pulled from the tree. “It was just, oh wow—I’m getting goosebumps even thinking about it,” Knapp says, adding that he thought, “That’s it.”
Eason and Knapp compared the new tree’s foliage against lateleaf leaves collected in 1997. The species’ leaves are thicker and broader than those of related oak species and have little hairlike follicles on their undersides, Knapp explains. Looking at the new leaves, “we were both taken away by how hairy this plant was,” he says. It ultimately convinced them the oak was an authentic lateleaf.
Like Tapia’s team, Knapp and colleagues are having to work to demonstrate their discovery is genuine. Genetic testing results are expected as soon as this winter, Knapp says, but it may still be difficult to ID the tree on that basis. Because oaks tend to hybridize, some researchers have maintained that the lateleaf isn’t a distinct species but rather a mixture of others. With so few specimens to capture the variation that might have occurred across the historical lateleaf population, even genetic results may not be able to resolve the debate. “When you only have a couple of individuals that you’re describing the species on,” says Knapp, “it gets hard to defend it as a species.”
Even when a species’ identity isn’t in question, it can be onerous coming back from the dead. Researchers surveying Ecuador’s Intag Valley in 2016 happened upon two male and two female longnose harlequin toads (Atelopus longirostris), which had been declared extinct back in 2004. “It was a beautiful surprise,” Andrea Terán-Valdez, a biologist at the Jambatu Amphibian Research and Conservation Center, writes in an email, because scientists had long thought that the fungal disease chytridiomycosis had wiped the toads out. But now, the deadly fungus isn’t the species’ only threat: Copper mining is planned for the toads’ native habitat, something that Terán-Valdez explains could contaminate the water and further imperil the animals in the narrow tract of rainforest they call home. “The risk for the toad is very high because, as a tadpole, it depends one hundred percent on water quality,” she says. A provincial court in Imbabura may soon decide whether the mining can proceed.
Even when a species’ identity isn’t in question, it can be onerous coming back from the dead.
The good news is that after taking the male and female toads into captivity, the Jambatu Center was able to breed the amphibians and now has about 36 adults and 200 juveniles and tadpoles. The center can’t yet risk reintroducing them to their forest home, however, says Terán-Valdez. “For that, we have to make sure that the habitat is protected in the long term.”
The future for the Fernandina giant tortoise and the lateleaf oak is perhaps even more precarious. Tapia will mount one last expedition this December to look for more of Fernanda’s species. Finding a male “would be the best [news] for me in my life,” says Tapia. If the expedition comes up empty-handed, he says that the Galápagos National Park could decide to breed Fernanda with another species, as it has for other endangered tortoises. Meanwhile, the lateleaf in Texas is fire-scarred and isn’t producing acorns that would enable it to reproduce, perhaps because of the stress it’s under, Knapp says. Specialists are working on other ways to propagate cuttings, he adds, such as by grafting small lateleaf branches onto the saplings of other oak species.
Life for the unextinct—whether it’s a tree, a tortoise, or toad—is tenuous, but “they represent hope,” says Terán-Valdez. “A species that was considered extinct comes back? You don’t get that every day.”