From Cuba to New Zealand, teams of scientists around the world are looking for rare species of animals, plants and fungi. How rare? They haven't been seen by humans for at least 10 years - and in some cases, almost 200 years.
This global effort is part of the Search for Lost Species, a program run by an organization called Re:wild. In 2017, Re:wild came up with a list of its 25 Most Wanted Lost Species. It was reduced from a much larger list of more than 2,200 species in 60 countries that was made with the help of the International Union for Conservation of Nature (IUCN). IUCN tracks species around the world that are threatened with extinction.
Since the Re:wild program began, eight species have been rediscovered, surprising even the program's leaders, who weren't sure they would find any of the lost species. Among the rediscovered animals are two species in Africa: a tiny mouse-size elephant shrew called the Somali sengi in Djibouti, and the Voeltzkow's chameleon in Madagascar. Also rediscovered is a bunny-size deer, known as the silver-backed chevrotain, in southern Vietnam.
Regarding the chevrotain, "we got the first photographic evidence that the species still exists," said Andy Tilker, Re:wild's Asian species officer. An Nguyen, who led the search in the field, says that three populations of the chevrotain were found. He and Tilker will work to better protect the mammal, which may get caught in hunters' snares. Better protections are the goal of all Re:wild's efforts.
This month, eight new species were added to the lost species list to replace the ones that have been found. They include a South American fungus, a Portuguese spider and a Brazilian tree that hasn't been seen for 184 years.
Andy Gluesenkamp is director of conservation at the San Antonio Zoo in Texas. He is heading a team that's seeking the Blanco blind salamander. He says it's the rarest amphibian in North America and one that is probably a top predator - like a "tiny great white shark" - in its ecosystem.
Gluesenkamp says that the salamander hasn't really "disappeared" since the only time it was seen, 70 years ago. It lives in deep aquifers (underground places where groundwater is held). So it isn't easy for scientists to find or study them. To search for clues to the animal's whereabouts, he and his team use satellite images and DNA samples from its environment.
Inger Perkins is leading efforts to find a New Zealand bird called the South Island kokako. She says the kokako and other native birds have struggled to survive in the country since rats, stoats and possums arrived with European and other settlers beginning hundreds of years ago.
Since 2017, there have been 317 reports from people who think they've heard the bird's unique sound. According to Perkins, the kokako has a call with a "haunting melody" that she and other scientists are trying to capture with acoustic recorders. A photo or video of the kokako is also necessary, though, "to confirm that the bird still exists," Perkins said. So her team has set up trail cameras, too.
Although Perkins's team has been searching for the kokako for more than 40 years, she is optimistic that it can be rediscovered and protected.
"New Zealand has a good record of bringing birds back from the brink," she says. "We are doing all we can to find it, so it does not join the ranks of extinct species."