Help! ID questions of Bornean Rats, mice and small flying squirrels…

Hi everyone!
Are you ready to play… ID THAT RODENT…??
Ok – so we saw tons of mice, rats, and even flying squirrels which we’re not 100% sure what species they are, based on Phillip’s Field Guide to the Mammals of Borneo.

Let’s start:
1. First – Tawau’s lowlands, around the HQ, we saw this rat on a tree (Photo – Jason Woolgar):

If you look close, the rat is pretty spiny. It has a uniform-colored light-gray naked tail that’s roughly the same color as the upper parts of the body. It has white underparts, and a grayish coat, with thin patches of orange around the waist and neck areas. The head and upper parts of the back are darker, where the spiny hairs are more pronounced. What do you all think? Your estimates of its dimensions based on the thin branch it’s on, and the leafs surrounding it, is as good as mine. From size and description, I’m leaning somewhat toward Dark-tailed Tree rat, but the illustration is way off… Any help?

2. Next rat is also from Tawau’s lowlands, around HQ altitude:

This is again a very spiny rat with white underparts and chestnut-colored upperparts. You can’t see the upper portion of the tail, which may be darker than the underpart of the tail, and we don’t see the entire tail. The dimensions based on the branch and the leafs is like 9-10cm HB, and can’t tell about the tail. I’m leaning toward Tajuddin’s or Whitehead’s Maxomys. What do you think?

3. The next one is also from Tawau, but from the “highlands” around 800-900m altitude

Jason and Jens both have better pictures than me, so I’d be happy if either of them would post one in the comments. This is clearly a flying squirrel, as it was active at night. I thermal-scoped it peeking out of the nest and then it went back inside. We waited several minutes with the lights off, for it to completely come out but it never did as long as we were around. I never saw it out completely out of the nest with the light nor with the thermal scope – but Jason is pretty sure he saw most if not all of it out of the nest at one point and said it was very small. Based purely on the description and illustration in the book, and given the small size, we are all leaning toward Temminck’s flying squirrel.

4. The next species we have is from Deramakot. Click on them for a larger view (4th picture – curtesy of Jason Woolgar):

When I first looked at the illustration in the book, it matched perfectly with Rapit Rat (Niviventer rapit), but considering how rare it is, and the fact that it’s generally found at much higher altitudes, make me skeptical. The book does say “tail may be all dark, or dark above and pale below”. And it does say it’s “Dark reddish-brown fur on sides of the body, […] and hard spines in the fur”. I can’t rule it out purely based on altitude, as there are few recent records of it. But the only other rats I’m looking at are Red Spiny, Rajah and Whitehead’s Maxomys. But I’m ruling out Red Spiny for “inner sides of thighs the same colour as upperparts”, which is clearly not the case here, and I don’t see a “streak on the underparts”, nor does the “white on inner side of thigh normally extend unbroken to feet”, which suggests it’s not Rajah either.  Whitehead’s is the smallest one with underparts being buffy… nor sure – what do people think?

5. Another one from Deramakot – video and then a still from the video. But both Jo and Jason have better pictures than my still (If you guys can add them):

Large Sunda Tree Mouse
Note that this one had its back to us for a very long time… But it gave us enough of a chance to conclude, based on the tail, that it would be one of the 3 Tree mice (tail with a hairy tuft at the end, and not much longer than HB – check out supposed Ranee mouse later in the post for comparison). If you go frame-by-frame from 30:00 seconds into the video, you can clearly see white underparts which would indicate Large Sunda Tree mouse. But I’m not sure if it’s sufficient to ID down to species level.. any help?

6. Also at Deramakot (video):
As you can see, this mouse has again chestnut-brown upper parts and white underparts. But the tail is like twice the HB size. Mike called it a Ranee mouse, and who am I to disagree… The only thing is that the tail looks different from (darker than) the illustration in the book – but as with all these – the illustrations are often not 100% accurate

7. Also from Deramkaot, on the ecology trail (photos 2-4 courtesy of Jason):

To me this one looks like either a juvenile version of the same species as 6, or a “Lesser Ranee mouse (Haeromys pusillus)” based on size – as it was even smaller than the first mouse, with similar coloration and proportion. But the nose, ears, and the fact that it didn’t move at all as we were within 30cm of it, kind of makes me feel like it was a juvenile. Maybe I’m wrong. Thoughts?

OK – all the next ones are from Kinabalu HQ:
8. I saw this one on from the restaurant:

Based on the ear spot, it can really only be one of 2 species – Ear-spot squirrel, or Sculptor squirrel. I really don’t have enough knowledge on these two to tell them apart, and the belly isn’t shown in either picture. Note that Bornean black-banded squirrel also has an ear spot, and is common around Kinabalu’s HQ. We saw plenty of them, but to me this one looks different because the b-b squirrel was lighter and the tail looked different. However, I’m happy to be corrected.

9. Gray rat near HQ bins:

Based on coloration and location I’d go with Grey Tree rat, Mountain Maxomys or Polynesian rat… Anyone? (note the white tip of the tail. It appears in all pictures I have of this individual, so it’s not just a lighting thing)


10. Brown rat near the HQ bins:

I’m not even sure these are all the same species. I think the first 4 pictures are of the same individual, with a broken tail. Of course the next 2 pictures are of 1 individual, and the last picture may be a different species, or it could be the same.. could even be the same individual as pictures 10.1 – 10.4 …. any help?

11. Summit rat/Kinabalu rat? Also next to the bins

I’m pretty sure this species looks different than species 10. I also know Summit rats are usually found higher up the mountain, and that forecasts predict them having to go up even further because of global warming. It does look like the pictures I saw of summit rats, but again, I’m happy to be corrected 🙂

12. Bin squirrels – we’ll divide them:

12.1 – Low’s squirrel?

12.2 – Brooke’s squirrel?

12.3 – One of the above, another Mountain Ground squirrel, or something else?

And last-but-not-least:

13. Mystery flying squirrel of Mt. Kinabalu  (3 photos courtesy of Jo Dale, and 1 video by me):


We saw this flying squirrel on a night drive from the HQ restaurant to the bins, around 2/3 of the way up. This is incidentally the same tree where we saw a Horsefield’s flying squirrel the night before, and a spotted flying squirrel at the same time as this individual, higher up the tree. I posted a terrible video which is also slowed down to 1/4 the speed. If you view the terrible video enough times you will be able to notice the squirrel pretty clearly cut off the frame in the beginning, and then again somewhat clearly before I zoom in and lose focus. Going together with Jo’s photos, it looks to be a very different squirrel than Horsefield’s, which we have photographed at the bottom for comparison. In comparison, the squirrel in question has a white patagium margin/edge, and a high contrast of white underparts and dark upperparts. Temminck’s may again come to mind (same as Species 3) but Temminck’s says “no orange tinge on base of body”.  The two that come to mind for me are Whiskered and Jentink’s Flying squirrel. When going frame-by-frame in the video, and to some extent also shown in Jo’s pictures, it has a light(er) patch going far “into” its face, right under the eye. And also, right between the 9th and 10th seconds of the video, you may see that it looks like the gliding membrane (patagium) gets darker as you go further from the center of the animal’s back, before you get to the very edge, which is white as I mentioned. Again – any help would be welcomed. Below is the Horsfield’s flying squirrel from the night before, which looks quite different (I also have a video of that one, part of my long Facebook video of Borneo’s mammals):

Holy crap – this was long!!! Any and every bit of help will be welcome.

Cheers, and thanks in advance!!


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