The first lives in the border area between India, Bhutan and Tibet, the second thousands of kilometers further east, in the Chinese province of Yunnan. This was found in a study recently published in the Zoological Journal of the Linnean Society.
“The discovery is very exciting,” says John Koprowski, a squirrel expert at the University of Wyoming who was not part of the research team. “The fact that two relatively large animal species have remained hidden from us for so long shows how little we know about nature.”
The unknown croissant
The rock sliding squirrel’s habitat is remote and otherwise uninhabited at almost 5,000 meters above sea level – one of the reasons why only a few western scientists have been able to observe it in the wild so far. The fact that the animal is nocturnal and its gray-brown fur camouflages it perfectly against the rocky backdrop makes sightings even more difficult.
The rock sliding squirrel was “rediscovered” in 1994 by the zoologist Peter Zahler in Pakistan. In the years that followed, scientists were able to find out more about the mysterious animal: it feeds exclusively on pine needles and juniper leaves, and its large teeth are serrated so that it can grind the waxy leaves and extract some of the meager nutrients.
The front and rear legs of the rock gliding squirrels are connected to a flight membrane, which they stretch in order to glide through the air between the rocks. They use their fluffy tail, which is often longer than the rest of their body, as a rudder. But it also acts as an umbrella in the event of sudden showers. Thanks to their body size and dense, soft fur, the rodents can store heat well – an advantage in the frosty mountains.
One species becomes two
The more Helgen and his colleague Stephen Jackson learned, the more certain they were that more large rock squirrels had to live in the Himalayas than previously thought.
The two visited eight museums around the world and examined 24 exhibits of the rock sliding squirrel – the newest one was 50 years old. When comparing the skulls of the squirrels, they noticed great differences, and also that one specimen, now named as E. tibetensis, had a black tail tip that was absent from other skins. The DNA analysis finally proved that it was not one but two different species.
“For a hundred years, these species have waited in a museum archive for their secret to be revealed,” said Melissa Roberts Hawkins, Mammalian Curator and Squirrel Expert at the Smithsonian Institute.