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. We 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 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 and naturalists 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.

The Syr Darya Shovelnose Sturgeon was last seen in the 1960s in Kazakhstan. (Photo by Bernard R. Kuhajda)

The Syr Darya Shovelnose Sturgeon was last seen in the 1960s in Kazakhstan. (Photo by Bernard R. Kuhajda)

Q. What do you consider proof of a rediscovery?

While we may come across evidence that our top 25 “most wanted” species are still out there in marketplaces selling animal parts, we will only confirm the rediscovery of a species if scientists, geneticists, experienced naturalists or other reliable sources 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, would suffice as proof of a rediscovery. 


Our goal with the Search for Lost Species is to elevate our top 25 most wanted 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 any and all risks 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.


GWC will certainly go out looking for some of these species ourselves and will support partners in looking for others, 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. GWC is working with teams and individuals the world over the publicize their stories of rediscovery and adventure as part of this shared campaign of hope and celebration. 

Q. How did you select the top 25 “most wanted” species?

We wanted to ensure that our top 25 “most wanted” species spanned taxa and represented ecosystems across the planet, including land- and water-dwelling species. Our top 25 “most wanted” species includes 10 mammals, three birds, three reptiles, two amphibians, three fish, one insect, one crustacean, one coral and even one plant, and are found in 18 countries. The top 25 “most wanted” species also includes at least seven species that are associated with unverified reports in the last 20 years suggesting they may still be out there (Miss Waldron’s Red Colobus, New Zealand Greater Short-tailed Bat, Attenborough’s Long-beaked Echidna, Ilin Island Cloudrunner, Omiltemi Cottontail Rabbit, Pink-headed Duck, Scarlet Harlequin Frog). In some cases, the rediscovery of one of the top 25 species could have tremendous scientific significance (the rediscovery of the Scarlet Harlequin Frog, for example, could help scientists better understand resistance to chytrid, the fungal pathogen killing frogs worldwide) or cultural significance.

Most importantly, our top 25 “most wanted” 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” 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.

Q. Do you think you’ll find most of the species on your top 25 list?

We really don’t know what to expect. So far the Jackson’s Climbing Salamander, Wallace’s Giant Bee and Fernandina Galapagos Tortoise have been rediscovered. Some of these species are known only from a single individual (Wondiwoi Tree Kangaroo, Namdapha Flying Squirrel, Attenborough’s Long-beaked Echidna, Ilin Island Cloudrunner, Velvet Pitcher Plant). The Bullneck Seahorse has actually never been seen in the wild. However, there is unsubstantiated evidence from local communities that some of these species may still be out there. And if there’s any one theme for this initiative, it’s hope. Hope that maybe, by some chance, these species are still out there. Hope that once we rediscover them, we’ll be able towork with partners to conserve them, along with the species that share their habitats. Most conservationists will say that hope is what drives them, against all odds. That’s what this initiative is all about.

One of the only-known specimens of the Wallace’s Giant Bee, last seen in 1981 in Indonesia. (Photo by Clay Bolt)

One of the only-known specimens of the Wallace’s Giant Bee, last seen in 1981 in Indonesia. (Photo by Clay Bolt)

Q. What happens if you don’t find one of the top 25 most wanted species during an expedition?

As we embark on these expeditions, we’ll be learning about the habitats these species once called home and will be looking for conservation opportunities even if we discover that the flagship species is no longer there. The top 25 flagship species represent only a fraction of the more than 1,200 species that scientists, naturalists and conservationists from around the world nominated, and for now, are the targets of our continued fundraising efforts. However, as this initiative grows, we will be adding expeditions and working with partners to find additional lost species. In some cases, the flagship species actually share habitat with other nominated lost species, so we’ll be looking for those animals or plants, too, and reporting back. For some of our target species, we may launch additional expeditions, for others we may 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 on developing the best conservation strategies for this species, its habitat, and the species it shares its home with. This could involve working with communities to protect it, when appropriate establishing a new protected area, 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 will depend on the natural history of the species, its habitat and the threats causing it harm. 

Following the rediscovery of our first top 25 “most wanted” 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.

Q. How can I learn about the outcome of an expedition? 

The easiest way is to sign up to received our Search for Lost Species e-mails and e-newsletter. We’ll announce when an expedition launches, the results of that expedition, and other important or interesting Lost Species news.

Q. As you rediscover species on the current top 25 list, will you replace those with others?

We will! We have a long list to pick from—scientists, naturalists and conservationists from around the world nominated more than 1,200 lost species, and will announce new additions as we go. The new additions will 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 Namdapha Flying Squirrel was last seen in 1981 in India.

The Namdapha Flying Squirrel was last seen in 1981 in India.

Q. Has any organization ever done anything like this before?

In 2010, our conservation scientists launched a global Search for Lost Frogs, a joint GWC partnership with Conservation International. GWC Communications Director Robin Moore, then at Conservation International, was leading the team, which included GWC President Dr. Don Church, GWC Associate Scientist Nikki Roach, and other GWC team members. The project was supported by various sources such as the US Fish & Wildlife Service, and GWC scientists participated in expeditions. The team developed a list of lost frog 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 BirdLife International, have ongoing expeditions to look for specific 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. Become an institutional partner or a corporate sponsor. 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 1,200 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 to receive updates on all things lost species.