‘Lost’ deer species rediscovered after 30 years

The Vietnam mouse-deer (which also goes by the name of silver-backed chevrotain, or more technically, Tragulus versicolor) was first described in 1910, based on specimens near the city of Nha Trang, Vietnam. This bordering area between Vietnam and Laos hosts one of the richest biodiversities in the world. However, as of 1990, it was believed that the mouse-deer was no longer a part of that biodiversity.

High levels of hunting (particularly with snares) and habitat loss led the numbers of these deer to decline, with no official sightings being reported throughout the 1990s. Researchers feared that the species had gone extinct, which seemed to be more and more likely as years passed on.

But An Nguyen from the Leibniz Institute for Zoo and Wildlife Research wasn't so sure. Along with Andrew Tilker and other colleagues, Nguyen set up a plan to find out whether the chevrotain is still around or it actually went extinct. They spoke to locals around the Greater Annamites Ecoregion of Vietnam and Laos who claimed to have seen the species. Their stories seemed consistent, but there was a problem: the silver-backed chevrotain looks a lot like other mouse-deer which inhabited the area.

So the research team set up 30 motion-activated cameras in the Nha Trang area to see whether they could find evidence of this critter.

"We had no idea what to expect, so I was surprised and overjoyed when we checked the camera traps and saw photographs of a chevrotain with silver flanks. For so long this species has seemingly only existed as part of our imagination."

After six months of camera observations, the researchers confirmed over 200 detections (although it's not clear how many individuals were observed). The locals were right in their claims that the species never went extinct, leaving researchers overjoyed.

" In an age of mass extinctions, confirming the survival of lost species provides rare second chances for biodiversity conservation," researchers write. "The silver-backed chevrotain Tragulus versicolor, a diminutive species of ungulate known only from Vietnam, has been lost to science for almost three decades. Here, we provide evidence that the silver-backed chevrotain still exists and the first photographs of the species in the wild, and urge immediate conservation actions to ensure its survival."

While it's always exciting to rediscover a species once thought to be lost, the fate of the silver-backed chevrotain is not yet certain. At best, the species still hosts a small but healthy population. At worst, only a few individuals survive in the area, and the species is still on the brink of extinction.

Researchers have developed a mitigation plan dealing with the two main threats to the species: habitat alteration and poaching. Poaching is probably the more pressing issue of the to, so reducing snares is the first and very critical step in ensuring that we don't lose the species again.

The study has been published in Nature.