Rabbit-sized, deer-like species of fanged ungulate rediscovered in Vietnam

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  • The silver-backed chevrotain is about the size of a rabbit and was first described to science in 1910 based on four specimens. A joint Vietnamese-Russian expedition to central Vietnam undertaken in 1990 collected a fifth specimen, which had been killed by a hunter. That was the last any scientist saw of the species.
  • However, local villagers and government forest rangers reported seeing a gray chevrotain in the vicinity of Nha Trang, a city in southern Vietnam. The gray coloring was the key, because that’s what distinguishes the silver-backed chevrotain (Tragulus versicolor), also known as the Vietnamese mouse-deer, from the far more common lesser chevrotain (T. kanchil).
  • Based on those survey results, a team of researchers set up three camera traps in the most promising locations and ended up recording the first evidence that a species not seen in nearly 30 years is still very much in existence.

Local villagers and government forest rangers reported seeing a gray chevrotain in the vicinity of Nha Trang, a city in southern Vietnam.

Based on those survey results, a team of researchers set up three camera traps in the most promising locations and ended up recording the first evidence that a species not seen in nearly 30 years is still very much in existence.

The gray coloring was the key, because that’s what distinguishes the silver-backed chevrotain (Tragulus versicolor), also known as the Vietnamese mouse-deer, from the far more common lesser chevrotain (T. kanchil). The white-tipped gray fur on the flanks of T. versicolor gives the species its silvery appearance and common name.

By April 2018, five months after they were deployed, the camera traps had captured 275 images of the elusive silver-backed chevrotain, last seen in 1990. The researchers then set out 29 additional camera traps in the same area, and five months later they had another 1,881 photos of the chevrotain.

A camera trap captures two silver-backed chevrotains. Photo Credit: Southern Institute of Ecology/Global Wildlife Conservation/Leibniz Institute for Zoo and Wildlife Research/NCNP).

“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,” An Nguyen, an associate conservation scientist for the NGO Global Wildlife Conservation (GWC) and leader of the expedition team that rediscovered the silver-backed chevrotain, said in a statement.

Nguyen and colleagues at Vietnam’s Southern Institute of Ecology and Germany’s Leibniz Institute for Zoo and Wildlife Research published the results of their camera trap survey in the journal Nature Ecology & Evolution this month.

Though chevrotains are nicknamed “mouse-deer,” they are not mice or deer. The 10 known chevrotain species, mostly endemic to Asia (one species is known from Central and West Africa), are the world’s smallest ungulates, or hoofed mammals. They walk on the tips of their hooves and have two small fangs.

The silver-backed chevrotain is about the size of a rabbit and was first described to science in 1910 based on four specimens collected near Nha Trang. A joint Vietnamese-Russian expedition to central Vietnam undertaken in 1990 collected a fifth specimen, which had been killed by a hunter. That was the last any scientist saw of the species, which is why almost nothing is known about the silver-backed chevrotain’s general ecology or conservation status.

The rediscovery of the species is all the more remarkable because the forested area of Vietnam where it is found, which is part of the Greater Annamites Ecoregion, has been ravaged by deforestation and indiscriminate hunting via snares for the wildlife trade. “Given the considerable increase in hunting pressure that has occurred in Vietnam since the early 1990s, it was unclear whether the species still existed,” the researchers note in the study.

A camera trap captures the silver flanks of the rediscovered silver-backed chevrotain. Photo Credit: Southern Institute of Ecology/Global Wildlife Conservation/Leibniz Institute for Zoo and Wildlife Research/NCNP).

“The rediscovery of the silver-backed chevrotain provides big hope for the conservation of biodiversity, especially threatened species, in Vietnam,” study co-author Hoang Minh Duc, head of the Southern Institute of Ecology’s Department of Zoology, said in a statement. “This also encourages us, together with relevant and international partners, to devote time and effort to further investigation and conservation of Vietnam’s biodiversity heritage.”

It is crucial that confirmation of the silver-backed chevrotain’s continued survival be followed up with actions on the ground to protect the species, according to the researchers.

“For so long this species has seemingly only existed as part of our imagination,” Nguyen said. “Discovering that it is, indeed, still out there, is the first step in ensuring we don’t lose it again, and we’re moving quickly now to figure out how best to protect it.”

Nguyen and co-authors write in the study that “The most pressing needs are to assess the status of the newly recorded population, search for additional populations and assess the major threats that the species faces. Together, this information can provide the foundation for an evidence-based conservation plan for the silver-backed chevrotain.”

CITATION

• Nguyen, A., Hoang, D. M., Nguyen, T. A. M., Nguyen, D. T., Long, B., Meijaard, E., … & Tilker, A. (2019). Camera-trap evidence that the silver-backed chevrotain Tragulus versicolor remains in the wild in Vietnam. Nature ecology & evolution, 1-5. doi:10.1038/s41559-019-1027-7

Article Source: Mongabay