Mammals

A mystery rat makes an appearance

long-tailed-rat

This dry season we had been exploring new set areas in Kaeng Krachan National Park with smaller video cameras (bushnell type camera traps) to see what resident species occurred and what species with larger territories might be passing through.

To our surprise we had noticed that two of our sets had quite a high incidence of a long tailed forest rat. The videos are great for seeing what animals enter the set areas and how they react but their image quality made it impossible to define any features of the animals other than a) rat and b) long tail.

We were intrigued by the creatures and considered re-rigging the sets with stills cameras to get a closer look at these small mammals.

This was a gamble because when the set is rigged for small mammals it means that we forsake any pictures of transitory larger mammals that may be passing through the area as they would simply overfill the frame. We procrastinated at length, as it was the possibility of pictures of the larger iconic mammal species that had brought us to these new locations.

We decided it was an opportunity we should not miss, as we had never witnessed so many hits in one of our sets from these mystery rodents and we knew this might be temporary opportunity. Movement of mammals in the forest is driven by food, water and reproduction and as we were now in the height of the dry season we believed it was possible the sheer volume of camera trap hits could be linked to food foraging, a pattern that could change as soon as the forest started to dampen again.

So we hastily rigged two sets specifically to get a closer view at our mystery rodents.

Four weeks later we had a great collection of images and with the very kind help of Muridea specialist Uraiporn Pimsai from the Princess Maha Chakri Sirindhorn Natural History Museum we had an ID.

Our mystery nocturnal rodent is the Long-tailed Giant Rat, Leopoldamys sabanus, also known as the Noisy Rat.

A common species by all accounts, but the camera traps had allowed us to succeed in getting great natural behavior close up shots of the species as it darted around our sets hunting for our fruit stashes.

The Long-tailed Giant Rat can be found in lowland, hill and lower montane forest throughout Thailand and in many parts of Southeast Asia, typically up to elevations of around 1200 metres.

The magnificent tail is scaly with short bristles and is markedly paler on its underside, can be over 40 cm long.

The Long-tailed Giant Rat is mainly a ground dweller, however is very well adapted for climbing and is semi-arboreal. It nests in tree holes and burrows, and feeds on fruits, vegetation and insects.

{gallery}Long Tailed Giant Rat{/gallery}

The experience has really made us reconsider our philosophy re-camera trapping and we may dedicate at least two sets to small mammals from now on. Who would have though a rat could be so cute?

Order : RODENTIA 
Family : Muridae 
Species : Leopoldamys sabanus

 

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onflipflops's Avatar
onflipflops replied the topic: #2754 3 years 6 months ago
Great images!
Due to the difficulties of identifying I often overlook these smaller mammals; actually I like to know everything and every species, but when finding an ID is so hard without a proper image (or even with a clear image) and the help of an expert (I don't personally know rodent experts :( ), I often decide not to be bothered at all. A glance online or in the books and they all look the same, and online you never know what to trust when it comes to ID's.
Getting a good shot is virtually impossible if shot in person through the lens, but apparently possible with traps ;) Good work!
And great that you found the right person that actually knows what he/ she is talking about.
Hopefully you can get some more species that help me and others to recognize the differences whenever we encounter these little critters.
So please, keep posting. I understand that capturing the charismatic large mammals is exciting and fun to do, but the smaller critters make up the bigger numbers and this possible could lead to discovering new ranges for species. In the end we probably know more about leopards and tigers in this country than we do about the small rodents.

The animal in the last picture seems to have a shorter tail, larger eyes, the ears a bit differently positioned, but then again, it might just be the angle in which the creature has positioned itself compared to the camera. So never mind, haha It is probably even the same individual. And that shows how hard it is.

What focal length lens did you use for these shots? Are they cropped or is this the actual photo?
Thanks for sharing!
Paul T's Avatar
Paul T replied the topic: #2755 3 years 6 months ago
Many thanks Ton,

"Q" A glance online or in the books and they all look the same, and online you never know what to trust when it comes to ID's."

Too true, and I have made a few mistakes myself with online resources. Especially problematic with arthropods as well.
Muridae are considered to be particularly problematic and hard to ID, which was an surprise for me seeing as they are so abundent.
When you see all of the images (about 100) side by side there are quire a few anomalies and variations.

Q: What focal length lens did you use for these shots? Are they cropped or is this the actual photo?

Both sets are 35 mm on an APC. There is very little cropping outside of centering the rat in the photo.
olliewearn's Avatar
olliewearn replied the topic: #3467 2 years 6 months ago
Hi, indeed the last image is definitely not Leopoldamys sabanus - colouration wrong and tail too short. It looks to me like Maxomys whiteheadi, which would be a significant record, because it's currently only known south of the Isthmus of Kra:
www.iucnredlist.org/details/12907/0
www.thainationalparks.com/specie/whiteheads-spiny-rat
www.researchgate.net/publication/2646979...on_keys_INTRODUCTION

Perhaps a bit big for M. whiteheadi though (difficult to judge scale). Not sure what else it could be...

Cheers
Ollie

"Each species is a masterpiece, a creation assembled with extreme care and genius." > Edward O. Wilson

"An understanding of the Natural World and whats in it is a source of not only a great curiosity but great fulfillment." > Sir David Attenborough

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