Golden moles are a family of highly threatened small mammals with 10 of the 21 species listed as threatened on the IUCN Red List.
Using novel environmental DNA (eDNA) techniques and the olfactory prowess of a sniffer dog, a tenacious team of local scientists have rediscovered an enigmatic golden mole species that was presumed extinct “swimming” through the sand dunes of Port Nolloth.
The conservationists and geneticists from the Endangered Wildlife Trust (EWT) and the University of Pretoria have confirmed the mysterious existence of the little-known De Winton’s golden mole, which was last seen in 1936.
Golden moles are a family of highly threatened small mammals with 10 of the 21 species listed as threatened on the IUCN Red List. De Winton’s, which is a blind iridescent mammal with “hearing superpowers”, is classified as critically endangered and “possibly extinct”.
It was ranked 11th of the world’s most wanted lost species to be rediscovered since Re:wild, a group that protects and restores biodiversity, launched its Search for Lost Species in 2017.
The search for De Winton’s was a “very exciting project with many challenges”, said Esther Matthew, senior field officer at the EWT. “Luckily, we had a fantastic team full of enthusiasm and innovative ideas, which is exactly what you need when you have to survey up to 18km of dune habitat in a day.”
Novel technique
They used a revolutionary technique that had never been used to detect golden moles: eDNA, which is the DNA that animals shed as they move through the environment, typically in the form of skin cells, hair and bodily excretions.
De Winton’s lives in largely inaccessible underground burrows and has extremely sensitive hearing and can detect vibrations from movement above ground. This helps the tiny mammals avoid being seen from the surface.
“It just so happens that for golden moles, the eDNA technique is very good because moles are in contact with the sand the whole time,” explained Cobus Theron, senior conservation manager for EWT and a member of the search team.
“In their burrows that are close to the surface of the dunes, when they crawl in that sand, they leave skin cells and we’re able to scoop that sand and then basically extract the DNA from that and identify the DNA.”
Like other species of golden moles, they move by gliding through the sand using their wide claws as paddles. As the sand collapses behind them, they don’t leave tunnels, making it harder for scientists to find them.
Theron said there was some scepticism from the scientific community “about whether the De Winton’s golden mole even existed; whether the eDNA technique would be viable and whether or not dogs can actually do stuff like this”.
But he had “good faith” that the species had not yet gone extinct. “I was convinced it would just take the right detection method, the proper timing, and a team passionate about finding it. Now not only have we solved the riddle, but we have tapped into this eDNA frontier where there is a huge amount of opportunity not only for moles, but for other lost or imperilled species.”
Leaving no sandhill unturned
A research paper documenting the intrepid team’s quest to find the elusive subterranean insectivore was published in November in the scientific journal, Biodiversity and Conservation.
It described how golden moles are “notoriously obscure and understudied”, mostly because of the challenges associated with finding them, trapping them and/or observing their subterranean behaviour in the wild. “Environmental DNA techniques are efficient and relatively cheap and simple, non-destructive and non-invasive and can be highly effective at detecting rare, cryptic, and elusive species, even at relatively low densities,” it stated.
Extracting DNA from soil is not without its hurdles, said Samantha Mynhardt, a conservation geneticist at the EWT and Stellenbosch University. “But we have been honing our skills and refining our techniques – even before this project – and we were fairly confident that if De Winton’s golden mole was in the environment, we would be able to detect it by finding and sequencing its DNA.”
In June 2021, the researchers collected more than 100 soil samples from beaches and dunes on the northwest coast — including Port Nolloth beach, the only place where De Winton’s golden mole had ever been found.
Finding a match
After conducting a complex and comprehensive genetic analysis of each sample, the team determined that there were several species of golden mole living in the sand along the stretch of coast. Two more common species, Cape golden mole and Grant’s golden mole, were found, as well as a third, Van Zyl’s golden mole, which is rare and endangered.
The team struck gold with the fourth species they found — it was De Winton’s golden mole — but it would take almost another year to definitively prove it.
As De Winton’s golden mole is genetically very similar to Van Zyl’s golden mole, the team needed more genetic information about De Winton’s to confidently identify it using eDNA.
At the time, there was only one De Winton’s golden mole reference DNA sequence available. That DNA sequence represents a nuclear gene that has limited variation between De Winton’s and Van Zyl’s, meaning the team couldn’t confidently assign the fourth species to De Winton’s at that time.
Nearly a year later, the search team found exactly the information they needed to finally solve the case when a second gene sequence for a De Winton’s golden mole specimen — now housed at the Iziko South African Museum — became publicly available in January 2022.
It was a mitochondrial gene, from a much more variable part of the genome that has much higher levels of variation between De Winton’s and Van Zyl’s. When the team compared their eDNA sequences from Port Nolloth beach to the new reference sequence, it was a clear match to De Winton’s golden mole.
Theron said that terrestrial eDNA is poorly developed in South Africa and the EWT, through Samantha Mynhardt, is at the “forefront of developing terrestrial eDNA for use in elusive species”.
Nose for moles
In an effort that spanned more than two years, the team started their work by identifying areas on the West Coast where it was possible the species was living undetected. They, too, interviewed local residents. Theron added that a poster the team produced of the golden moles of the West Coast had produced “huge interest and reports of sightings”.
When they arrived on the beach in Port Nolloth there were fresh golden mole trails in the sand, but it can be very difficult to identify a species of golden mole from its physical characteristics alone. Despite seeing golden moles, they also collected soil samples for eDNA analysis to accurately determine the species that left the trails.
A scent-detection border collie, Jessie, had been specially trained to sniff out golden moles, and led them to trails left behind by the cryptic critters.
“It was just really looking at a pilot [project] to see if the dogs could distinguish between the different golden mole species,” Theron said. “Basically, because we didn’t know what De Winton’s looked like, we trained Jessie on a very common species, called Grant’s golden mole.”
If the team took Jessie to the mole trails and she did not indicate on that trail, then it wasn’t Grants. “Then we knew it was either Van Zyl’s golden mole, which is also an endangered golden mole, or De Wintons.”
Flagship species
Finding donors to support the work was difficult. He applied multiple times for funding unsuccessfully until Re:wild, through its Lost Species expedition project, provided the team with a small grant to do the work.
“It’s fantastic on multiple fronts because the techniques you had hoped would work, worked, and the species that you were looking for was found. The experience of the team is a phenomenal thing and the faith that the donor placed in you, is fulfilled.”
Port Nolloth is a busy area and “there’s lots of development on that beach” but that doesn’t mean that all hope is lost. “In fact, that area contains a very healthy population of golden moles,” he said.
Since the 2021 expedition, the EWT has identified four more De Winton’s golden mole populations, and further research could unearth more populations hidden in the golden sand dunes of the West Coast.
Work is now under way to protect the moles – and their habitat – from major threats including mining, agricultural expansion and residential development.
“The opportunity is to get people to be proud of their environment and to be conscious of the protection of coastal dune ecology,” he said. “De Winton’s golden mole is such a perfect flagship for that and it’s a beautiful little creature.”