Lost Species: Frequently Asked Questions

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Q. WHAT MAKES A SPECIES “LOST?”

There is no international standard that defines what constitutes a “lost” species, or a rediscovery, and the criteria varies by taxa. In 2017 and every year since, we have relied on experts from more than 100 IUCN Species Survival Commission specialist groups to nominate species they considered lost based on criteria they proposed for the taxa. At minimum, a species had to have been lost to science (unseen by scientists) for at least a decade and cannot be in captivity anywhere for it to make it on our full list of nominations.

Q. HOW DID THESE SPECIES BECOME LOST?

Species become lost for a variety of reasons. In some cases, species that once existed in healthy populations are now possibly extinct as the result of any number of threats, including emerging disease, habitat destruction, invasive species introduction, poaching and human-wildlife conflict. In some cases, scientists haven’t had access to the species because they are in hard-to-reach wilderness or conflict-ridden regions. And in some cases, these species were very rare to begin with, existing in small numbers in small geographical areas where a single disturbance could easily wipe out the entire population. In addition, some species are incredibly cryptic, either due to their behavior or life history.

Photo ©Lucas Bustamante (@luksth)

Q. WHAT DO YOU CONSIDER PROOF OF A REDISCOVERY?

While we may come across evidence that our top 25 most wanted lost species are still out there in marketplaces selling animal parts, we will only confirm the rediscovery of a species if scientists, naturalists or other experts have verified—and have evidence—that it is still alive in the wild. Ideally the scientists or naturalists would see the animal themselves and get photo and video, or a photograph verified by DNA or eDNA evidence from the rediscovery site, would suffice as proof of a rediscovery.

Q. HOW DID YOU SELECT THE TOP 25 “MOST WANTED” SPECIES?

After launching in 2017, we are now on the second iteration of our top 25 most wanted lost species list. In 2022, we rotated the eight lost species that had been rediscovered—Jackson’s Climbing Salamander in Guatemala, Wallace’s Giant Bee in Indonesia, Velvet Pitcher Plant in Indonesia, Silver-backed Chevrotain in Vietnam, Somali Sengi in Djibouti, Fernandina Galápagos Tortoise in the Galápagos, Sierra Leone Crab in Sierra Leone, and Voeltzkow’s Chameleon in Madagascar—and rotated eight new lost species onto the list. With more than 2,200 to pick from, there is no shortage of forgotten species that need our help or of stories of hope and whimsy.

We try to ensure that our top 25 most wanted lost species span taxa and represent ecosystems across the planet, including land- and water-dwelling species. Currently our list includes 10 mammals, four birds, four fishes, two amphibians, one coral, one tree species, one arachnid, one fungus, and one reptile, and span at least 17 countries.

Most importantly, our top 25 most wanted lost species are flagships for conservation and represent genuine opportunities for conservation action with local partners on the ground (or in the water, as the case may be).

Q. HOW DID YOU SELECT YOUR TOP “MOST WANTED” LISTS BY GROUPS OF SPECIES? 

Our top “most wanted” lists by groups of species include those species that have been lost to science for at least a decade (and often for much longer!) and, like our top 25 most wanted lost species, may be lost for a variety of reasons. We worked with various IUCN Species Survival Commission specialist groups and other partners to determine these lists of flagship species. In some cases, biologists may be actively out searching—or interested in going out to search—for these species. In other cases, these species represent the kinds of compelling stories that can help raise their group’s public profile, even if nobody is out actively looking. They represent a broad geographical reach and may present opportunities for inspiring conservation action.

Two of our lists—lost birds and lost freshwater fishes—represent more comprehensive partnerships under the broader Search for Lost Species program. For lost birds, we have teamed up with American Bird Conservancy and BirdLife International, with data support from Cornell’s Lab of Ornithology to identify the 10 most wanted lost birds and to together fund and implement expeditions around the world to identify these birds, while also calling on the international community of birdwatchers to help find them. In the case of lost freshwater fishes, we’re working with Shoal to find funds and experts to scour the planet in search of the 10 most wanted lost fishes.

Q. HOW ARE LOST LEGENDS DIFFERENT FROM OTHER LOST SPECIES?

Our lost legends are those that are, in all likelihood, extinct (and are often declared as such on the IUCN Red List of Threatened Species) and are considered long-shots for rediscovery, but they live on in our collective imagination. Think Tasmanian Tiger and Ivory-billed Woodpecker—species that we hear about every few years when rumors of sightings make the headlines. Unlike the legends list, our top 25 most wanted lost species list doesn’t include any species that have been classified Extinct by the IUCN Red List of Threatened Species.

Q. IS RE:WILD REALLY GOING OUT AND LOOKING FOR ALL OF THESE SPECIES?

Because Re:wild has a local partner-based model, we support and encourage partners to look for many lost species. But the Search for Lost Species is primarily meant to be a call for action, spurring individuals and teams to go out searching for the lost species of most interest to them. We see this as a global movement to inject hope into the stale doom-and-gloom narrative of species extinction, and as a way for conservationists to raise the profile of some long-forgotten species to flagship status for conservation action. Re:wild is working with teams and individuals the world over to publicize their stories of rediscovery and adventure as part of this shared campaign of hope and celebration.

Q. ARE YOU AT ALL WORRIED THAT ANNOUNCING REDISCOVERIES COULD PUT THESE SPECIES IN MORE DANGER?

Our goal with the Search for Lost Species is to elevate our top 25 most wanted lost species to flagships for conservation to catalyze action on the ground with local partners. The only way for those species to become flagships, however, is if we tell their stories and reveal to the world that they do, indeed, still exist. That said, we try to be as strategic as possible with these announcements to ensure that we reduce all risk to the species. Sometimes we might hold off on an announcement until strong protections for the species can be put in place. Sometimes we’ll use these announcements themselves to encourage protection at various levels of government in the species’ native country or to argue for stronger trade policy. And we never reveal the exact locations where these animals are rediscovered.

Q. WHAT HAPPENS IF YOU DON’T FIND ONE OF THE TOP 25 MOST WANTED SPECIES DURING AN EXPEDITION?

We don’t expect to find these species on the first try and know that it will usually take multiple searches (these are lost species for a reason, after all!). Sometimes we start with local interviews, then searches, then place camera traps, then try to collect eDNA as we refine our methods, and our knowledge grows.

As we embark on these expeditions, we also learn about the habitats these species once called home and look for conservation opportunities even if we discover that the most wanted lost species is no longer there. The top 25 flagship species represent only a fraction of the more than 2,200 species that scientists and conservationists from around the world nominated, and for now, are the targets of our continued fundraising efforts. In some cases, the flagship species share habitat with other nominated lost species, so we look for those animals or plants, too. For some of our target species, we support additional expeditions, while for others we rely on partners to continue the search in different areas.

Q. AFTER A SPECIES IS REDISCOVERED, THEN WHAT?

First, we celebrate. Then we get to work with local and international partners to help catalyze conservation action for the species, including developing the best conservation strategies for the species, its habitat, and the species it shares its home with. This could mean our partners working with communities to protect it, establishing a new protected area when appropriate, understanding how a species has survived and applying that knowledge to help other species, working with local governments to enact laws that protect species, etc. The conservation strategy depends on the natural history of the species, its habitat and the threats causing it harm.

For example, following the first rediscovery of our original top 25 most wanted lost species, the Jackson's Climbing Salamander, in Guatemala, we ran a successful fundraising campaign—helped by the publicity generated from the rediscovery—to expand the reserve within which the salamander was found, ensuring that its cloud forest habitat is safeguarded. In the case of the Silver-backed Chevrotain, our partners have been able to find two other populations of the lost species with our support and are now working to determine how large and stable these populations are, the wider distribution of the species, and the threats to its survival. All of this information will help with the development and implementation of a conservation action plan for the species to ensure it does not become lost again.

Q. HOW CAN I LEARN ABOUT THE OUTCOME OF AN EXPEDITION?

The easiest way to learn about all new things lost species is to sign up for Your Weekly Wild and follow us on Facebook, Twitter and Instagram.

Q. AS YOU REDISCOVER SPECIES ON THE CURRENT TOP 25 LIST, WILL YOU REPLACE THOSE WITH OTHERS?

We will! And we have! We’ve already rotated eight of our original top 25 most wanted lost species off our list because they were rediscovered and rotated on a new batch of eight. We have a long list to pick from—scientists and conservationists from around the world have nominated more than 2,200 lost species and counting. The new additions always follow the same criteria for the original most wanted list—span taxa, represent various ecosystems, have cultural or scientific value, represent opportunities for conservation action, and have an interesting story for us to tell.

The first-ever photo of a live Somali Sengi for scientific documentation. (Photo by Steven Heritage, Duke University Lemur Center)

Q. HAS ANY ORGANIZATION EVER DONE ANYTHING LIKE THIS BEFORE?

In 2010, our conservation scientists launched a global Search for Lost Frogs, a joint Re:wild partnership with Conservation International. Re:wild Vice President of Communications and Marketing Dr. Robin Moore, then at Conservation International, was leading the team, which included Re:wild President Dr. Don Church, Re:wild Associate Scientist Nikki Roach, and other members of Team Re:wild. The project was supported by various sources such as the US Fish & Wildlife Service, and Re:wild scientists participated in expeditions. The team developed a list of lost amphibians that developed into an entire campaign that involved sending groups of scientists out into various habitats around the world to try to find the “most wanted” frog species. We’re replicating the success of that project across taxa in the Search for Lost Species. Other groups, such as American Bird Conservancy and BirdLife International, have ongoing expeditions to look for specific lost bird species, but no other organization has launched an initiative to look for this many lost species across taxa throughout such a wide geographical range of ecosystems.

Q. HOW CAN I GET INVOLVED?

There are lots of ways to get involved! We welcome donations to send these expeditions in search of lost species, but there are so many other ways for you to get involved. Get out in the field on your own quest and report an observation on our Lost Species iNaturalist page. Check out our full list of 2,200 lost species nominations and let us know if you have any additions or changes. We also work with artists who want to lend their skills to capture the beauty of our world’s lost species. Follow the search on Facebook, Twitter and Instagram and then share our stories. And be sure to sign up for Your Weekly Wild for all the latest on lost species and more!

One of the first images of a living Wallace’s giant bee. Megachile pluto is the world’s largest bee, which is approximately four times larger than a European honeybee.© Clay Bolt : claybolt.com