If you walk slowly and carefully in one of the trails in Kinabalu Park or Poring Hot Springs, you might be able to see the smallest squirrel in Borneo – the plain pygmy squirrel (exilisciurus exilis). Endemic to Borneo, the plain pygmy squirrel moves like Speedy Gonzales in cartoons, zig-zagging up and down a tree with such speed that it seems to be flying, more than climbing. Measuring a little more than 10cm if you include its tail, it is the smallest of three species of pygmy squirrels in Borneo. Another species is the black-eared squirrel (nannosciurus melanotis), which is distributed in Sarawak and Kalimantan.
Due to its small size and its brownish fur colour which lets it blends in among the tree trunks and branches, it can be difficult to spot the plain pygmy squirrel. More often, the squirrel is heard before it is seen.
Can also be seen at Danum Valley, Tabin Wildlife Reserve, Sukau, etc.
Also known as Least Pygmy Squirrel.