An expedition team with Endangered Wildlife Trust is using eDNA and a scent-detection dog to confirm which species are living in the dunes of Port Nolloth in South Africa
By Devin Murphy on July 15, 2021
The weather in Port Nolloth on the northwest coast of South Africa wasn’t exactly beach weather. A bitterly cold rain had soaked the beaches where a team with South Africa’s Endangered Wildlife Trust (EWT) had arrived in search of the De Winton’s Golden Mole, one of the top 25 most wanted on Re:wild’s lost species list. But the rain didn’t put a damper on the search party.
“The timing couldn’t have been better really because we had lots of nice rain,” explains Esther Matthew, senior field officer with the Endangered Wildlife Trust.
The rain made it easier to see fresh tracks and burrows of golden moles--exactly what the search team had been hoping for. And much to their delight, there were plenty of signs of the sand-burrowing mammals. The big question is, were any of those tracks made by De Winton’s Golden Mole?
There are 21 species of golden moles and many of those species are only found in South Africa. De Winton’s Golden Mole has only ever been found once near Port Nolloth, but that was back in 1936. It hasn’t been seen since. There are no photos of the species, no definitive description of it and scant information about its behavior and ecology.
However, the expedition team isn’t trying to find De Winton’s Golden Mole by sight because it’s incredibly difficult to spot any species of golden mole, even for more common species like Grant’s Golden Mole or Cape Golden Mole.
“You have to stand there and stare at the sand for ages,” says Samanth Mynhardt post-doctoral researcher at the University of Pretoria and associate researcher with EWT. “Their hearing is so good. If you’re standing around or moving around and you’re talking to each other, they actually just stop moving, and then you won’t see any activity.”
Instead, the search team is using forensic science to determine which species of golden mole left the fresh tracks on the beach. They collected more than 100 soil samples from different sites to test for environmental DNA (eDNA), or hair cells, skin cells or scat left behind by golden moles as they swim through the sand.
“When we find the burrow, we open up the burrow and we scrape the lining on the inside,” explains Mynhardt. “We’re collecting the soil that’s right on the inner surface of the burrow lining. The soil that’s directly in contact with the moles.”
At an especially active search site, the team raked the wet sand, flattening any bulges made by burrowing moles. If the bulges reappeared, it meant that a mole had moved through the area and left eDNA.
Since golden moles are so efficient at avoiding detection and at moving through the sand--they can dig 15 feet (5 meters) in 10 minutes--the expedition team also relied on Jessie, a scent-detection dog to help them find tunnels and burrows. Her sensitive nose can pick up the scent left by a golden mole, even buried in sand five to 10 centimeters deep. But it can be difficult to train a dog to find the scent of a mole that no one has seen in 85 years. So, the expedition team did the next best thing.
“At the moment, we don’t have [the] scent for De Winton’s specifically,” says Matthew, who is also Jessie’s trainer. “We conditioned Jessie on the mole we found on the previous expedition and that turned out to be Grant’s Golden Mole.”
When Jessie picks up the scent of a golden mole she recognizes, like Grant’s or Cape Golden Mole, she heads toward it and lies down to indicate where her human team should scrape for eDNA. As a reward, the team throws her favorite toy, a tennis ball, to chase.
However, at the site near Port Nolloth that had lots of visible golden mole activity, Jessie’s nose didn’t seem to pick up any familiar scents.
“[W]e basically on this trip used Jessie to help us also find fresh trails,” says Matthew. “What was interesting to us is that when we went to that beach site that had so much activity, Jessie did not show any interest. That immediately told me the chances that it’s Grant Golden Mole, the same one we found last time, is very unlikely.”
The golden moles that had been digging tunnels and burrows and feeding on insects near the waterline was likely not a species Jessie had ever encountered before.
“[S]he’s actually helping us distinguish between species without actually having to sample for the one we’re looking for...which is exciting,” says Matthew. “I was very happy to hear the results from the labs because my gut feeling said...that is not the species she was exposed to previously.”
Mynhardt’s analysis of the samples back at the University of Pretoria have so far confirmed that there is a species of golden mole living at the site near Port Nolloth whose genetics do not match any other known species of golden mole. But is it De Winton’s Golden Mole?
The eDNA analysis is focusing on three different genes, two mitochondrial genes and one nucleotide gene. The four known species of golden moles that live at the sites the team visited each have different sequences for those three genes.
“We’ll be able to use the DNA sequences to identify the golden mole species,” says Mynhardt. “We’re grouping them into their locations, so that...once we have species identifications, we can see from which site that species came or that sample came.”
The expedition team won’t have final results until all of their eDNA samples are analyzed, which will likely take several more weeks. Then, they’ll know if De Winton’s Golden Mole is living in one of the sites or if an entirely new species of golden mole, unknown to science, has been discovered.
If one of the search sites does contain a De Winton’s Golden Mole lurking beneath its sand, then the EWT team and others will have to act quickly to protect it from threats, like mining, that could push it toward extinction.
“We want to find these moles, so that the next step is, obviously, to then look at where they are and how we secure that environment for them” explains Cobus Theron, program manager for EWT’s Drylands Conservation Program. “Or how do we enhance the protection at whichever site they are at?”
Many of the sites the team surveyed were also active diamond mines. Habitat destruction from mines and human development have caused the places where golden moles live to become isolated from one another, which is a threat to their survival.
“That fragmentation is actually one of the major threats that golden moles face,” says Matthew. “When populations become fragmented, the genetic diversity drops and that drop in genetic diversity can make a population very susceptible to any environmental pressures, and the whole population can die out as a result.”
But the EWT team is hopeful that if they do find De Winton’s Golden Mole, or even Van Zyl’s Golden Mole, a Critically Endangered species, it will ignite public interest in them and help protect them.
“From a broad conservation perspective,” says Theron, “I think that the west coast is not getting the conservation attention it needs. I think that this project is going to help us to turn that around.”
Devin Murphy is Re:wilds’s senior communications specialist and helps Re:wild and its partners tell stories about the work they do to protect wildlife and wildlands around the planet. Her favorite stories about conservation include fascinating and little-known species and the dedicated humans protecting them.