Unseen for decades, elusive 'mouse deer' spotted tiptoeing through Vietnamese forest

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For almost 30 years, scientists have considered the silver-backed chevrotain a lost species.

They haven't seen the small, hooved animal in the wild since 1990. They feared it had disappeared — until now.

Researchers with a conservation group have caught the tiny ungulate — nicknamed the Vietnamese mouse deer — on camera in Vietnam. Their findings have been published in Nature Ecology and Evolution.

Andrew Tilker worked on the project with Global Wildlife Conservation and spoke to As It Happens guest host Helen Mann about the elusive creature.

Here is part of their conversation.

What does this mouse deer look like?

It's a really interesting animal. The silver-backed chevrotain looks like a small deer that's been shrunk down to the size of a toy poodle or a really large rabbit.

They have two large canines that almost look like miniature fangs and the silver-backed chevrotain actually has two distinct colours. So it's red at the front and silver grey in the back.

I mean it looks like somebody just kind of dropped it halfway into a bucket of grey paint.

Wow. So it isn't really a mouse or a deer. So what makes them distinct from other species of chevrotain?

It's not a mouse. It's not a deer. It's related to deer. But it's kind of its own thing in the ungulate family.

The silver-backed chevrotain is different from others chevrotain species primarily because it has the two distinct colours with the silvery grey back. And some of the markings on its throat are also different than other species.

And do you assume that the markings, being as distinctive as they are, are for some sort of camouflage?

We actually don't know at this point. Honestly, that's unfortunately the answer for a lot of questions that people ask about the silver-backed chevrotain just because so little is known about the species. It's a bit of a ecological black hole, if you will.

So what was it like then to finally get evidence that these creatures actually exist in the wild still?

It was thrilling. I've been working in conservation work in Vietnam for many years, as have my colleagues, and it's just nice to get a positive story in the conservation field.

You captured hundreds of photos of these mouse deer. How did you find them? 

We had very little information to go on. There were only two known places where we had evidence of scientific records.

So we chose a region of Vietnam to search in based on where one of those records had been located. But that still left a pretty large area to search.

So what we did was we spent a lot of time talking to local people — local people who have incredible in-depth knowledge about the forest and its biodiversity.

So it was by interviewing local people, and then later actually going into the forest with local people, that we were eventually able to get these photographs.

Tell me what it was like the first time you saw one of the images of this creature.

I almost fell out of my seat, I mean, quite literally.

I just couldn't believe that this animal that my colleagues and I had thought about, had wondered about, for so many years ... was now ... we had evidence of it.

It was really a special moment for all of us.

I understand you documented about 280 events or sightings. Do you know how many individual animals you saw there?

We actually don't know how many animals there were. And the reason for that is simply because the chevrotain look very similar. They don't have stripes like a tiger or spots like a leopard. So it's very difficult to count individuals.

But, given the fact that we recorded so many silver-backed chevrotain in this area, we think that the species is probably fairly abundant in this location. But I also want to caution that just because the species may be common in this location doesn't mean it's common in other places.

We really need more information before we can make any assessment about how common or rare it is and how threatened it might be.

What are the threats then to the silver-backed chevrotain? Why are they perhaps so rare or have been perceived to be so rare?

In terms of the major threats to the species, habitat loss in Vietnam has almost certainly been a factor in biodiversity declines over the previous decades.

But in Southeast Asia, and in Vietnam in particular, snaring, the setting of wire snares to to hunt wildlife, is the biggest threat to ground-dwelling mammals and ground-dwelling birds.

What hope does this give you that there might be other species we've considered lost to science that are still out there?

It gives me a lot of hope actually. There are dozens, hundreds, of species that haven't been sighted by science in recent years. But from our work on the silver-backed chevrotain project I think that it's likely that a lot of them are still out there.

Written by Kate Swoger and John McGill. Interview produced by Kate Swoger​​​​​. Q&A has been edited for length and clarity.