The Complex-Toothed Flying Squirrel: Spotted in Sichuan, China

Surely having the most unhelpful common name for the casual observer of any mammal, the Complex-toothed Flying Squirrel suffers two other great disadvantages—it is, well its faeces are, used in Chinese medicine and it is also hunted for human consumption. Although no figures on population are available because studies have not been made, loss of habitat and pressure from hunting have led it to be classified as ‘Near Threatened’ by IUCN.

Over three evenings out with the spotlights at Labahe in Sichuan, we had 32 sightings of the huge Red and White Giant Flying Squirrels (Petaurista alborufus) on the rock faces and high trees along the valley walls. The next most common squirrel was the Complex-toothed (Trogopterus xanthipes). We also saw a Grey-headed Flying Squirrel (Petaurista caniceps). We were at an altitude of about 1,800 metres.

Two Complex-toothed Flying Squirrels were highly co-operative. The first was in the road while the second was on a rock face next to the road. This is the video:

But why complex-toothed? The name refers to the ‘complicated and wrinkled dental ridge’ of the crowns of the upper and lower cheek teeth. Now as all of you who have read Roy Lewis’s Evolution Man know, ‘…there is nothing that an evolving animal worries about more than how his teeth are getting along’. So why does this squirrel have ‘complex’ teeth when others do not. It is not stretching too much into the realms of a just-so story to suggest there must be something special about its diet. Indeed, that does seem to be the case since the diet is stated to be primarily oak leaves—hardly the most digestible material to live on. An efficient chew to grind the leaves must get the digestive process off to a good start. By contrast, the diet of the larger—huge in fact—Red and White Flying Squirrel is said to be ‘acorns, other nuts, fruit and leafy vegetation, as well as insects, larvae and, perhaps, bird’s [sic] eggs’.

Whether this diet and what must, even with fermentation in the hind-gut, involve a large intake—and output—of material, is connected with the use of the faeces in Chinese medicine and the keeping of these squirrels in captivity for that purpose might also be worthy of speculation. I read there are reports of studies to look at biologically-active substances in faecal extracts but of course there is huge gap between demonstrating an effect on isolated cells and there being any effect in vivo. But I am still left wondering: who on earth would have thought of turning to the faeces of a particular squirrel to cure anything?

But no, since you ask, we did not see one of the flying squirrels in flight. That would be just greedy.

A still grabbed from video of the Red and White Giant Flying Squirrel (Petaurista alborufus).
These flying squirrels are over a metre in length. This one is on a rock face above the river.

Smith AT, Xie Y. (Editors). 2008. A Guide to the Mammals of China. Princeton University Press.

Wilson DE, Lacher TE, Mittermeier RA. 2016. Handbook of Mammals of the World. Volume 6. Lagomorphs and Rodents I. Barcelona: Lynx Edicions.