Tree-shrews (also known as treeshrews and banxrings) are small mammals native to the tropical forests of South and Southeast Asia. They make up the entire order Scandentia, split into two families:

• The Tupaiidae (19 species, “ordinary” treeshrews)
• The Ptilocercidae (one species, the pen-tailed treeshrew).

Though called ‘treeshrews’, and despite having previously been classified in Insectivora, they are not true shrews, and not all species live in trees. They are omnivores; among other things, treeshrews eat fruit.

Treeshrews have a higher brain to body mass ratio than any other mammal, including humans, but high ratios are not uncommon for animals weighing less than 1 kg. Among orders of mammals, treeshrews are closely related to primates, and have been used as an alternative to primates in experimental studies of myopia, psychosocial stress, and hepatitis.

With a pregnancy period of just 45-50 days, and generally 3 in a litter, the species can multiply fast, even from a low base.

Treeshrews live in small family groups, which defend their territory from intruders. Most are diurnal, although the pen-tailed treeshrew is nocturnal. They mark their territories using various scent glands or urine, depending on the particular species.

Treeshrews are omnivorous, feeding on insects, small vertebrates, fruit, and seeds. Among other things, treeshrews eat Rafflesia fruit.

One is of particular interest, the pen-tailed treeshrew from Malaysia as it can eat large quantities of naturally fermented nectar from flower buds of the bertam palm (with alcohol content of as much as 3.8% and never show any sign of effect.

Once considered a member of the Insectivora clade, they were moved to the primate clade, but then given their own clade, however being the closest clade to the primates.

The fossil record suggests a former far larger range than the current one, being found in China and India as well.

The large treeshrew is native to Sumatra and adjacent small islands, as well as in the lowlands and hills of Borneo. They are the most predominantly terrestrial of all treeshrew species, usually on the forest floor, the primary location for their foraging, although they spend part of their time in trees. T. tana has been described as mainly terrestrial based on field observations and their morphological traits. Large treeshrews are most abundant in primary tropical rainforest, but are also found in swamp forest and secondary growth forest. T. tana has many potential predators such as the marbled cat, leopard, and clouded leopard.

Large treeshrews contribute to the maintenance of their lowland rainforest ecosystem by dispersing seeds. Their range covers much of Borneo and Sumatra. They are currently considered least concern. However, while more terrestial than most treeshrews, they still rely on rainforest, which suggest that continued loss of their habitat may well threaten their future survival.