Elusive Deer-Like Species Which Had Been Lost to Science for Three Decades 'Rediscovered' by Researchers

Researchers have rediscovered an elusive deer-like animal species which had been lost to science for almost three decades.

The silver-backed chevrotain (Tragulus versicolor) is a small species of ungulate—a diverse group of mammals with hooves which includes deer, horses, camels, cows, sheep, goats, pigs, giraffes, hippos, rhinos and many others—that is only known to live in Vietnam.

Prior to the latest findings, the last recorded silver-backed chevrotain was a specimen killed by a hunter in 1990. However, a team of scientists has now photographed a living individual of the species in the wild, proving that that the long lost animal has not been wiped out, according to a study published in the journal Nature Ecology & Evolution.

The finding is a rare piece of welcome news for conservationists in an age when species around the world are going extinct at an alarming rate. However, the researchers—led by An Nguyen from non-profit Global Wildlife Conservation (GWC)—say that urgent action is needed to ensure the survival of the silver-backed chevrotain.

The species lives in the so-called Greater Annamites Ecoregion which stretches across a mountainous, forested area of Vietnam and Laos. This region is spectacularly biodiverse, containing one of the highest concentrations of endemic mammal species anywhere in Asia. Notably, it is home to a particularly diverse range of unique ungulates.

However, human activities have contributed to a significant decline in the populations of these ungulates over time. Habitat loss is a major factor and intensive hunting is also a serious problem. Ungulates in the region are often trapped using wire snares and sold in the regional wildlife trade.

The silver-backed chevrotain was first discovered in 1910 after four specimens were found near the city of Nha Trang in Vietnam. The deer-like species is notable for its characteristic two-tone fur coloration and throat markings.

"It is herbivorous and probably also eats fruit," Andrew Tilker, another author of the study from GWC, told Newsweek. "It is a small animal—approximately the size of a toy poodle or house cat—you could easily hold it in one hand. The silver-backed chevrotain differs from the more common lesser chevrotain (Tragulus kanchil) in a few ways."

"Perhaps most obvious is the fact that it has two distinct colors: The first one-third is reddish-brown, and the back two-thirds is silvery-gray. It is almost like someone took a lesser chevrotain and dunked its backside into a bucket of gray paint," he said. "Another minor, but important, detail is that the throat stripings on the silver-backed chevrotain do not have a cross-stripe, so that the white runs uninterrupted from the throat to the bell."

Since the initial discovery of the silver-backed chevrotain, the only other scientifically validated sighting was the hunter-killed specimen from 1990. Due to this lack of sightings, some feared that widespread snare hunting had wiped out the species.

In their attempt to track down the elusive animal, Nguyen and colleagues decided to search the Nha Trang area and speak to local people in three Vietnamese provinces.

"We decided to search in the Nha Trang area for three reasons: (i) the area has a very different habitat than the wet evergreen tropical rainforest habitat that predominates throughout much of the Greater Annamites Ecoregion, (ii) not many surveys have been done in this area for ground-dwelling mammals, and (iii) we obtained a photograph of a dead juvenile chevrotain from this region that we believe was likely a silver-backed chevrotain," Tilker said.

"But we still had a large potential search area to cover—so we had to try to find ways to narrow this down. To do this, we conducted rapid interview surveys across three Vietnamese provinces," he said. "We talked to local people, especially people who have experience in the forest and would have information about the animals that lived there."

Locals reported the existence of the animal in two of the four forested areas where the team conducted interviews. However, the researchers needed concrete proof, so they deployed motion-activated camera traps in strategic locations.

"After the end of the interviews, the team set three camera-trap units opportunistically in one of the areas where local people reported seeing a gray-colored chevrotain," Tilker said. "Local people helped direct where exactly to place the cameras. The team then left, planning to come back later with more cameras to conduct a more intensive survey.

"When the team returned to the area to conduct the follow-up survey, they checked the three camera-traps that were opportunistically set, and found that all had images of a gray-colored chevrotain," he said. "Based on morphological features—distinct bi-coloration, non-converging throat striping patterns—we identified the animals as the silver-backed chevrotain. Success!"

After these sightings, the team set up more camera traps, which captured more than 1,800 photos of the animal. These pieces of evidence were enough for the team to declare that the species had been "rediscovered" to science, although it is not currently clear how many individuals the photos represent.

silver-backed chevrotain
Camera-trap photo of the silver-backed chevrotain. SIE/GWC/Leibniz-IZW/NCNP/Andrew Tilker

The researchers also point out that while the photos represent the first scientific proof of the animal in decades, local people living in the area did not consider the species to be "lost."

The team are now planning to conduct further surveys to try and determine the size of the population before conservation efforts are put in place.

"Confirming the existence of the silver-backed chevrotain was only the first step," Tilker said. "Now, the real work begins. First, we need to make sure that the single known population is secure. Protection efforts have already begun in the site where we recorded the species, but more is needed. Second, we need to try to locate additional populations, and then assess how healthy these populations are. Once we know the species' distribution, and how common or rare it is in places where it occurs, we can begin to develop an evidence-based conservation strategy to protect it."

"Third, we need to assess the major threats to the species. It is likely that populations of silver-backed chevrotain will have been negatively affected by snaring, but even then, we need to how severe this specific threat is to silver-backed chevrotain populations," he said. "The world needs to know about this remarkable species. I can only believe that, the more people who know about the silver-backed chevrotain, the less likely it is that the species will once again become lost."

Tilker says that the rediscovery of the species is significant locally, and it also has wider implications for the conservation of species around the world.

"The species is an important part of Vietnam's biodiversity heritage. This is a heritage that millions of Vietnamese people cherish—and I do too—and it is worth safeguarding for future generations," he said. "But this is also a story that goes beyond a single country or a single species. It is a story about how species that have fallen off the scientific radar should not be written off. When we come together to try to find these species, we can be successful. And these successes can provide us with rare second chances to protect global biodiversity."