That’s no mystery carnivore (part II)… it’s a giant squirrel!

In the previous post we looked anew at the controversial Kayan Mentarang animal: that reddish long-tailed Bornean mammal, photographed in 2003 by a World Wildlife Fund team, and announced to the world in December 2005. Widely hailed by many as a probable civet, it was argued by Chapron et al. (2006) to most likely represent Hose’s civet Diplogale hosei, a poorly known, apparently rare civet named in 1892. But despite the apparent strengths of this identification (and the fact that it came from an authoritative source: one of the authors in particular [Géraldine Veron] is a noted expert on viverrids), it was really a non-starter for several obvious reasons.

The Kayan Mentarang animal is reddish-brown while Hose’s civet is dark brown or blackish. Chapron et al. (2006) got round this by arguing either that the animal’s colour had been ‘affected by the flash of the camera’, or that the individual was an unusual colour variant. Both suggestions fail to explain the absence of the pale facial, neck and flank markings present in Hose’s civet. Shuker (2006) noted that – contrary to Chapron et al.’s claims of morphological similarity – the long hindlimbs of the Kayan Mentarang animal made it look more suited for arboreal life than is the predominantly terrestrial Hose’s civet. Furthermore, the Kayan Mentarang animal has really tiny ears while Hose’s civet has far larger ones, and the Kayan Mentarang animal also has (proportionally) a much longer tail than Hose’s civet. So the idea that the Kayan Mentarang animal is actually a specimen of Hose’s civet is poorly founded and not likely.

Hose’s civet not so poorly known

Worth noting here is that – while undeniably rarely recorded and poorly known – Hose’s civet isn’t as rarely recorded and poorly known as some authors have recently been saying. Observations were published in 2002 (Francis 2002) and 2003 (Dinets 2003), and camera-trap photos were taken between December 2003 and March 2004 (Wells et al. 2005): the adjacent image shows one of the latter photos, taken in lowland rainforest in Sabah, Borneo. The fact that Hose’s civet has now been recorded in lowland forest as well as in montane regions at least suggests that it’s ‘more common and widespread than previously thought’ (Wells et al. 2005, p. 13).

The case for the squirrel

Anyway, if the Kayan Mentarang animal isn’t Hose’s civet, what is it? As mentioned above, a new identification has now been published, and hasn’t been as well reported as was the viverrid identification, which is surprising given that it is perhaps the most interesting and surprising idea so far proposed. It would seem that the animal is actually…. a flying squirrel. Despite the fact that it’s only just becoming well known, this theory has been around since March 2006, when Andrew Kitchener published an article on Erik Meijaard’s thoughts about the creature (Kitchener 2006). Both authors are noted mammalogists. Meijaard observed that the creature seems to have ‘the suggestion of a membrane between the front and hind limbs’. I agree, and had always wondered why the animal seemed to have such a deep ‘belly’.

In fact the case for the squirrel identity is strong: by tabulating all the morphological features present in the two photos, and then doing likewise for all 16 similar-sized mammals from Borneo (they included one Sulawesi viverrid too), Meijaard et al. (2006) showed that the Kayan Mentarang animal agrees well in recordable details with two flying squirrels found on Borneo: Thomas’ flying squirrel Aeromys thomasi and the Red giant flying squirrel Petaurista petaurista (taxiderm specimen shown at left, close-up head shot at top of article, and painting shown at bottom of article. Sorry, no picture of A. thomasi to hand). Of the 13 morphological characters available for comparison, A. thomasi matches the Kayan Mentarang animal in 12 of them (the 13th character – orientation of the tail when on the ground – remains uncertain in A. thomasi). In contrast to viverrids, mongooses, linsangs, mustelids, the Bornean bay cat, the Groove-toothed squirrel (aka Tufted ground squirrel) Rheithosciurus macrotis, and various primates, only A. thomasi agrees with the Kayan Mentarang animal in having a short face, small, rounded ears, a reddish non-patterned coat, a tail that exceeds head and body length, and a rounded tail tip. The two also agree in size (the Kayan Mentarang animal is estimated to be 350-450 mm in head and body length) and limb proportions.

When the two ‘mystery’ photos are looked at with all of this in mind we see, with hindsight I suppose, hitherto unappreciated squirreley-ness. The way the animal holds its long hindlimbs (referring here to the photo showing the animal from behind) and the suggestion of a patagium now make sense, and the unusual curving shape of the long tail matches the tail posture reported for giant flying squirrels (Meijaard et al. 2006, p. 321) and is unlike that of viverrids and other carnivorans. The white eye-shine present in the Kayan Mentarang animal reportedly matches that of flying squirrels, ‘whereas the civets and cats normally have less bright, yellowish or orange eye-shine’ (Meijaard et al. 2006, p. 321). Look at the image at the top of the article: I’m not too sure about this. To help convince people, Meijaard et al. (2006) have provided two paintings of the Kayan Mentarang animal, this time ‘reconstructed’ using A. thomasi to fill in the gaps.

If Meijaard et al. (2006) are correct, then two factors have helped obscure the animal’s true identity. Firstly, there is the frustrating fact that its face is obscured by some vegetation, or, as WWF’s Head of Borneo programme director Stuart Chapman put it, ‘As with all good yeti shots, there is a leaf that obscures its snout’ (Fair 2006). I don’t quite understand the yeti reference, as there aren’t any photos of purported yetis that have leaves in the way… but, then, there aren’t any good yeti photos at all :) (maybe he was thinking of the Myakka skunk ape photos?). If this really is a squirrel, we would surely all have realised sooner had we been able to see its pointed, distinctively rodent-type snout. Secondly, people just aren’t used to seeing flying squirrels walking around on the ground, which isn’t surprising given that forest-dwelling flying squirrels are arboreal animals of the canopy. It stands to reason that a ground-walking flying squirrel looked unfamiliar, even to Bornean locals with good knowledge of wildlife, and to experienced field biologists.

Of course none of this demonstrates that the Kayan Mentarang animal really is a ground-walking specimen of A. thomasi, and not an unknown species. But I’d say that the case is very good and more likely than the new species hypothesis.

Given that giant flying squirrels are awesome and deeply weird I’m no less impressed by the Kayan Mentarang animal than I was when I thought it likely to be an unusual new viverrid. Some species of Petaurista truly are giants (for squirrels), reaching 2.5 kg and more than 100 cm in total length. Though experts at manoeuvrable gliding, they might undergo periods of occasional flightlessness when, in Spring, they gorge on buds and new leaves.

As has been noted by both John Lynch and Loren Coleman, of incidental interest in this story is that the squirrel A. thomasi was described by Sir Charles Hose (1863-1929) in 1900*, while the civet D. hosei was described by Michael Rogers Oldfield Thomas (1858-1929) in 1892. I also like the fact that Meijaard et al. submitted their paper on April 1st… so far as I can tell this didn’t delay its eventual publication however (woe betide forgetful authors who submit papers announcing bizarre results on April 1st, as Charles Paxton will attest). Note also that I wasn’t planning to blog on the Kayan Mentarang animal so soon, but after John Lynch wrote about it at Stranger Fruit on New Year’s Day (go here) I figured that it was only a matter of time before it become old news. For proof that I’ve been planning to post about the Kayan Mentarang since 2006, look at the last paragraph here.. ha, as if proof were needed.

* Entirely by coincidence, I recently wrote about Hose in the Baikal seal post. I’ve also written about Meijaard’s research before: see The many babirusa species.

And that is that. I just finished writing an article on those green lizards from Bournemouth and have lately been deeply immersed in literature on European herpetofauna. More details soon. Oh, and for the latest news on Tetrapod Zoology please go here.

Refs - -

Chapron, G., Veron, G. & Jennings, A. 2006. New carnivore species in Borneo may not be new. Oryx 40, 138.

Dinets, V. 2003. Records of small carnivores from Mount Kinabalu, Sabah. Small Carnivore Conservation 28, 9.

Fair, J. 2006. Scientists foxed by new carnivore. BBC Wildlife 24 (1), 30.

Francis, C. M. 2002. An observation of Hose’s civet in Brunei. Small Carnivore Conservation 26, 16.

Kitchener, A. 2006. Mystery beast revealed. BBC Wildlife 24 (3), 29.

Meijaard, E., Kitchener, A. C. & Smeenk, C. 2006. ‘New Bornean carnivore’ is most likely a little known flying squirrel. Mammal Review 36, 318-324.

Shuker, K. P. N. 2006. Mystery beast in Borneo. Fortean Times 206, 4.

Wells, K., Biun, A. & Gabin, M. 2005. Viverrid and herpestid observations by camera and small mamal cage trapping in the lowland rainforests on Borneo including a record of Hose’s civet, Diplogale hosei. Small Carnivore Conservation 32, 12-14.