Ever heard of the silver-backed chevrotain? We’d be surprised if you have. Until recently, scientists had only recorded five specimens of these deer-like mammals – all of them already dead. Shy, elusive, and only about the size of a rabbit, silver-backed chevrotains have been dodging scientists for almost 30 years. The last verifiable record dates back to 1990, when a research expedition to Vietnam’s Gia Lai province collected one that had been killed by a hunter.

But just because a species hasn’t been documented for a while, doesn’t mean it’s disappeared completely. Photos and footage captured on camera traps recently reveal that, in at least one pocket of forest in southern Vietnam, silver-backed chevrotains are alive and well.

The rediscovery, reported last week in the journal Nature Ecology & Evolution, was made by a team of researchers from Global Wildlife Conservation in partnership with the Southern Institute of Ecology and the Leibniz Institute for Zoo and Wildlife Research.

Silver-backed chevrotains (Tragulus versicolor), or Vietnamese mouse-deer as they are sometimes called, are distinguished from the more common lesser chevrotain (Tragulus kanchil) by a silver sheen on their rumps. They are one of the smallest members of a diverse group of mammals called ungulates, which are characterised by the presence of hooves. Chevrotains lack antlers or horns, but make up for it with tusk-like incisors which scientists speculate may be used by males when battling for territory.

To find the secretive ungulate, the team began their search in the dry coastal forests of southern Vietnam where the first four scientific specimens were discovered over 100 years earlier. These drier forests are not common in the country, but camera-trap surveys in Vietnam’s tropical forests had failed to turn up any evidence of silver-backed chevrotains, so the team theorised that the animals prefer to hang out in patches of thorn scrub.

Vietnamese researchers interviewed local residents and government forest rangers in the area about whether they had recently seen silver-backed chevrotains – a task that proved tricky as some community members were found to be involved in illegal hunting and were reluctant to chat about the local wildlife. Poaching using snares is widespread in Vietnam and is one of the reasons that the nation's forests have become drastically depleted.

The research team setting up camera traps in search of the "lost" silver-backed chevrotain. Photo by Andrew Tilker © An Nguyen/Global Wildlife Conservation 

Scientists call it “empty forest syndrome” when nearly all of the animal life has been eradicated and the forest falls silent. According to expedition leader An Nguyen, the poachers are aware of the dangerous effects of overhunting and everyone they spoke to expressed concerns about the dwindling animal populations. After spending some time gaining the trust of local villagers, the team were eventually able to establish the best spots to survey for the “lost” species.

In a five month period starting in November 2017 researchers set up three motion-activated cameras and collected 275 photos of the species. After almost three decades they had confirmation that silver-backed chevrotains were still hiding out in the dense forests. Another 29 cameras were set up in the same area and, over the next five months, they captured 1,881 photos of the species. Although most local residents would be unsurprised by the visuals, they mark the first time that the animals have been recorded alive.

© Southern Institute of Ecology/Global Wildlife Conservation/Leibniz Institute for Zoo and Wildlife Research/NCNP

Researchers hope that the rediscovery will help ramp up protection for the species as well as for other forest-dwelling animals suffering at the hands of poachers. But while it may help draw attention to the threats facing these rarely seen creatures, it could also pique the interest of those looking to exploit Vietnam’s natural resources. Although the research team did not pinpoint where they found the ungulates, it’s possible that they’ve already said too much.

“I think the most important point it raises is whether authors should in fact be publicising the rediscovery of a critically endangered species,” Diana Bell, a professor of conservation biology at the University of East Anglia whose research team has also worked with rare wildife in Vietnam, told the New York Times.

Of course, it’s difficult to protect a species if you don’t know if it stills exists, so it’s a dilemma that any researcher working with elusive species is forced to face. Do you shout your discovery from the rooftops and risk putting animals in danger, or do you keep it on the down-low and potentially watch a species fade away in silence?

© Southern Institute of Ecology/Global Wildlife Conservation/Leibniz Institute for Zoo and Wildlife Research/NCNP