- Researchers compiled a database showing the number of lost species is increasing faster than rediscovered species: since 1800, more than 800 amphibian, bird, mammal and reptile species have not seen by scientists in at least a decade.
- Reptiles as well as small, nocturnal or underground species tend to stay lost longer than larger, more widespread mammals and birds.
- Once found, many lost species remain threatened with extinction as their populations are often small and fragmented due to habitat loss.
- New technologies like camera traps and environmental DNA are aiding rediscovery efforts, but the involvement of local communities is also key to finding lost species.
“We did it!” Doka Nason shouted as he stared at the screen of a camera trap in Papua New Guinea. He and his team had just captured a long-sought image: that of the black-naped pheasant-pigeon (Otidiphaps nobilis insularis). Believed to be extinct, this rare ground-dwelling bird was photographed as part of the Search for Lost Species program. Scientists hadn’t seen one in the wild for 140 years.
Lost species are those that haven’t been observed by scientists in their natural habitat for at least a decade. Yet most have been missing for around 50 years on average, according to a new study in the journal Global Change Biology.
Researchers compiled a database of 856 lost and 424 rediscovered amphibian, bird, mammal and reptile species (known collectively as tetrapods) listed since 1800. As the number of lost species globally continues to rise, they’re being lost faster than they’re being found.
“The number of lost tetrapod species is increasing decade on decade,” said Thomas Evans, a conservation scientist at the Free University of Berlin and lead author of the paper. “This means that despite many searches, we are losing tetrapod species at a faster rate than we are rediscovering them.”
The results highlight differences in which lost species are more likely to be found again based on location and type of animal. Sometimes, their natural traits like nocturnality or living underground make them difficult to find. Larger animals and those that can live in multiple habitats are more likely to be found again. But many smaller, specialized species stay lost for longer.
Others remain lost because less effort has gone into searching for them. These tend to be less charismatic species like reptiles compared to birds and mammals.
“Our results suggest that while many lost species are difficult to find, with some effort and the use of new techniques, they are likely to be rediscovered,” Evans said. “These species include those that are very small (including many lost reptile species), those that live underground, those that are nocturnal, and those living in areas that are difficult to survey.”
The findings emphasize the need for more attention to overlooked groups like reptiles and rodents, Evans said: “Our efforts tend to focus on birds and mammals.”
“A lot of resources go to high-profile, charismatic, cute and fuzzy or large mammal species,” said co-author Christina Biggs of the conservation NGO Re:wild. “It’s important those absolutely need attention, but we also need to focus on the ‘underfrogs,’ those less likely to be high-profile … we think they’re all important.”
The results also imply an underreporting of extinctions. Evans said declaring a species extinct may discourage further searches or conservation efforts. Hence, “conservation scientists are often reluctant to declare extinctions — particularly if they are not completely sure a species is extinct.”
Technologies for finding wildlife are improving. Environmental DNA (eDNA) sampling, audio recordings and camera traps have aided in many rediscoveries.
Biggs said the use of eDNA is particularly exciting. When animals move about, they shed their DNA in the environment via skin, hair and excrement. Scientists can use general water and soil samples to determine if an animal is present. For example, environmental DNA was used to detect the De Winton’s golden mole (Cryptochloris wintoni) in South Africa last year, and burrowing seabirds on a remote sub-Antarctic island.
Once found, many lost species remain threatened with extinction as their populations are often small and fragmented due to habitat loss. “It is important that we rediscover these lost species and work out ways to protect them, before they become extinct,” Evans said.
Evans said local community involvement in searches should also be encouraged, as locals can and often do provide key insights to finding lost species in their native habitat. Monitoring programs should add neglected species like rodents and reptiles alongside more popular animals. And overall, protecting whole habitats may work better than searching for some hard-to-find species.
Banner image of De Winton’s Golden Mole, found in June 2021. Photo courtesy of JP Le Roux.
Liz Kimbrough is a staff writer for Mongabay and holds a Ph.D. in ecology and evolutionary biology from Tulane University, where she studied the microbiomes of trees. View more of her reporting here.
Lost bird found: Dusky tetraka seen in Madagascar after 24-year absence
Citation:
Lindken, T., Anderson, C. V., Ariano‐Sánchez, D., Barki, G., Biggs, C., Bowles, P., … Evans, T. (2024). What factors influence the rediscovery of lost tetrapod species? Global Change Biology, 30(1). doi:10.1111/gcb.17107
