According to local hunters, Borneo’s endemic tufted ground squirrel can kill a deer by dropping down on it from above and tearing out its jugular vein. Once the deer bleeds out, the squirrel proceeds to eat the stomach, heart, and liver, then leaves the rest to rot.
That rumor, along with research last year showing that the squirrel may have the largest tail compared to body size of any mammal on the planet, has sparked public interest in the species.
Now a research group has caught the first ever video of this elusive species from a camera-trapping project they hope will eventually reveal the squirrel’s diet.
According to local hunters, Borneo’s endemic tufted ground squirrel (Rheithrosciurus macrotis) is one BAMF. Hunters tell stories of how this 1-to-2 kilogram rodent can kill a muntjac deer by dropping down on it from above and tearing out its jugular vein. Once the deer bleeds out, the squirrel proceeds to eat the stomach, heart, and liver, then leaves the rest to rot.
To date, scientists have not been able to verify if there is any truth to these tales. But last year, a research paper headed by a 15-year-old scientist uncovered a different surprising fact about the purported blood-thirsty deer-stalker: the Bornean tufted ground squirrel may have the largest tail compared to body size of any mammal on the planet. Now, a year later, a research group has caught the first ever video of this elusive species.
“It is a really strange species about which we know almost nothing. Even the most basic elements of their biology are virtually unknown. We don’t know why they have such large tails, why they have tufted ears, or what type of social system they exhibit,” said Andrew Marshall, who co-runs the camera trap project at Cabang Panti Research Station in Gunung Palung National Park located in Kalimantan or Indonesian Borneo.
In June of this year, Marshall’s team — including Heiko Wittmer, a biologist with Victoria University of Wellington and Endro Setiawan with the Gunung Palung National Park Bureau — set up 35 cameras to survey wildlife in the forest. In just the few months that the camera traps have been active, they have managed to take two different videos of the Bornean tufted ground squirrel. In neither of them is the squirrel eating a deer, unfortunately.
“Alone [these videos] don’t tell us very much, but we hope that the 35 cameras we have placed across the diversity of forest types at the Cabang Panti Research Site will tell us much about their habitat use and basic ecology,” Marshall told Mongabay. However, he is hopeful that in time the cameras will help determine what the species actually eats.
“The videos are…starting to show us its unusual diet,” Erik Meijaard of the conservation group Borneo Futures told Mongabay. “We are working on this now, and I cannot yet reveal the details, but the Bornean tufted ground squirrel eats things that pretty much no other species on Borneo can consume,” said Meijaard, who was a co-author of the paper last year describing the squirrel’s remarkable tail.
While Meijaard isn’t a part of the camera-trapping project, he is working with Marshall on figuring out the small mammal’s diet.
“It is such an unusual species,” noted Meijaard. “It is most closely related to the South American squirrels but it has no known fossil relatives that indicate how the genus spread from South America and ended up in Borneo without leaving a trace anywhere else.”
Currently, the IUCN Red List categorizes the Bornean tufted ground squirrel as Vulnerable due to habitat destruction, forest fragmentation, and possibly hunting. In the past, indigenous people used to hunt the squirrel for its bizarrely fluffy tail to use as a decoration, but that practice seems to have died out.
“I suspect the Bornean tufted ground squirrel is not hunted or subject to any unusual threats, but we simply don’t know enough about the species to be sure,” noted Marshall. “If our camera traps indicate it is restricted to lowland forest, then it may be under substantial threat, as little undisturbed lowland forest remains in Borneo.”
Borneo’s once magnificent forests have undergone tremendous change in the last few decades. A paper last year, co-authored by Meijaard, found that the island has lost more than 30 percent of its forest over 40 years.
For his part, Meijaard worries that the sudden interest in the species could be a double-edged sword.
“One worry I have for the Bornean tufted ground squirrel is that the attention will drive commercial interests in the species (zoos, private collections, pet trade etc.),” he said. “We need to be careful that the attention is not going to negatively impact this or other species. The forests of Borneo are [being] emptied of their wildlife as we speak. Everything is up for collection, and nothing is done sustainably.”
The researchers hope that with time they can uncover the secrets of the squirrel: What does it use that supremely bushy tail for? Why are its nearest relatives in South America? And is there any truth to the gruesome stories of the squirrel’s muntjac hunting? After all, other seemingly far-fetched local tales have proven true, such as the one about several species of mouse deer that dive underwater for long periods to escape predators.
“[Bornean tufted ground squirrels] have captured the imagination of the public, both through their remarkable appearance and the fantastical legends told about their predatory behavior,” said Marshall. “Anything that raises the general public’s interest in and awareness of tropical biodiversity is important!”
- Gaveau D.L.A., Sloan S., Molidena E., Yaen H., Sheil D., et al. (2014). Four Decades of Forest Persistence, Clearance and Logging on Borneo. PLoS ONE 9(7): e101654.
- Meijaard, E.M., Dennis R.A., Meijaard E. (2014). Tall Tales of a Tropical Squirrel. TAPROBANICA: The Journal of Asian Biodiversity 6(1): 27-31.