The Slender Squirrel Sundasciurus tenuis is a common squirrel in the lowland forests of Sarawak and Brunei but absent from Sabah except for one record from Sipitang on the southern Sabah boundary with Sarawak. The “slender” in the name refers to the slender tail in comparison with the bushy tails of other squirrels.

Liz Bennet’s 1987 mammal survey of Ulu Temburong found that the Slender Squirrel  was the most common squirrel in Ulu Temburong with a density calculated at 11 individuals per km2. However it appears to be uncommon around the Ulu Ulu Resort. The photo of the individual above by Hans Hazebroek was taken at Kubah in Sarawak.