A quest for gold – the rediscovery of De Winton’s Golden Mole
by Samantha Mynhardt
On 29 November 2023, the Endangered Wildlife Trust (EWT) and Re:wild announced the re-discovery of De Winton’s Golden Mole (Cryptochloris wintoni), and the story was received with great excitement all over the world as it steadily became one of the biggest conservation stories for 2023. This small mammal had eluded detection for over 80 years, was listed on the International Union for the Conservation of Nature (IUCN) Red List as “Critically Endangered; Possibly Extinct”, and on Re:wild’s list of Top 25 Most Wanted “Lost” Species, until its rediscovery last year. The research findings were published in Biodiversity and Conservation on 24 November 2023 and can be read here.
Golden moles are elusive little animals that spend nearly their entire lives underground, thus they are very seldom seen by humans. Some species will occasionally come to the surface to forage, typically only at night. In most cases, the only sign of golden mole activity or presence is a raised ridge on the surface of the ground, representing their shallow underground foraging tunnels. However, for the sand-dwelling species, such as De Winton’s golden mole, even these ridges are hard to spot, since the subsurface tunnels collapse in the soft sand.
De Winton’s golden mole has been severely impacted by mining activities and other threats on the South African west coast. We suspect that the population has experienced a substantial decline over the past century. The species was last detected at the type locality (the origin of the specimen from which the species was described), Port Nolloth, in 1937, and since then has eluded scientists, likely due to difficulties in locating and trapping these animals and/or the presence of the similar-looking and more abundant Grant’s golden mole, Eremitalpa granti.
As a postdoctoral fellow at the University of Pretoria at the time, working alongside Profs. Nigel Bennet and Paulette Bloomer on small mammal genetics research, I had been looking into alternative non-invasive means of studying golden moles, having faced the immense challenge of finding them in the wild, and trapping them to collect genetic samples. The Drylands Conservation Program (DCP) of the EWT received funding from Re:wild to go in search of De Winton’s Golden Mole, and invited me to join them on their quest, despite the views of many, including experts, that the species was extinct.
In 2020 we conducted a pilot study at Lambert’s Bay, the type locality of the sister species, van Zyl’s golden mole, Cryptochloris zyli (also Endangered), to trial some novel approaches for detecting golden moles, including thermal imaging drones, a scent-detection dog, and environmental DNA (eDNA). The pilot study was very successful. The thermal imaging showed some promise in facilitating our search for golden mole presence, although this was perhaps overshadowed by our scent-detection dog’s remarkable ability to sniff out the moles, and the unmatched power of eDNA technology to identify the species present, once the burrows had been located.
In July of the following year, we began our expedition along the west coast to Port Nolloth. We surveyed multiple sites along a 300km stretch of coastline, from the Groen River mouth northwards to Alexander Bay. Our team of five, including myself, Cobus Theron, JP le Roux, Esther Matthew and her trained scent-detection border collie, Jessie, conducted surveys on foot for a week, exploring, on average, 18km of dune habitat per day. Jessie had obviously never encountered a De Winton’s golden mole before, and therefore she was not trained on the scent of this species. However, she had been trained on the scent of the two more common species in the area, Grant’s- and Cape golden mole. She therefore assisted us in finding golden mole tracks, and we knew she would indicate to us if she found the more common species. When she didn’t indicate, we had a good idea that we had found something “new”.
We collected over 100 soil samples on the expedition. Wherever we found signs of golden mole activity, we collected small soil samples from the inner linings of their subsurface tunnels. Animals shed their DNA into their environment, typically in the form of skin cells, hair, and excretions and secretions. This is known as environmental DNA (eDNA) and is present at a molecular level and therefore completely invisible. We were essentially collecting eDNA samples from the soil in the underground burrows. This eDNA would later be extracted in the lab, and a particular fragment of DNA, called a DNA barcode, would enable us to identify the species.
We found evidence of De Winton’s golden mole, not only at Port Nolloth, but at multiple additional sites, indicating that the species may be more widespread than previously thought. Golden mole activity was particularly abundant on the beach at McDougal’s Bay, Port Nolloth, indicating that there is likely a healthy population persisting there. Unfortunately, we are not able to estimate the population size at this stage, however future research should aim to do so.
While we aim to conduct further surveys for this Critically Endangered species to better understand its distribution, it is important that we protect the populations we do know of. We are therefore working towards improved habitat protection and management for the population at McDougal’s Bay, as well as nearby sites where the species has been detected, and to identify additional suitable sites for protection.