[4] In fact, over 20 years few studies have been done on C. bancanus and a taxonomic revision based upon intensive and systematic field surveys is overdue.

[5] When splitting the species into its own genus, Colin Groves and Myron Shekelle recognized the natunensis population as a distinct subspecies.

[7] The pelage coloration ranges from pale-olive or reddish brown to pale or dark grey-brown, possibly varying with age.

Horsfield's tarsier has an extremely long tail which can reach 181 to 224 mm (7.1 to 8.8 in) and is hairless except for tufts of hair at the end.

[13] Before sunset, Horsfield's tarsier will wake up and wait 10 to 20 minutes before moving around the understory and spending 1.5 to 2 hours of the night foraging for food.

It mainly eats arthropods such as beetles, orthopterans like grasshoppers, katydids, and crickets, butterflies, moths, cockroaches, praying mantis, ants, phasmids, cicadas, dragonflies, freshwater crabs, and spiders,[7][14] but also will eat small vertebrates such as flying frogs,[14] bats (Chiroptera) including members of the genus Taphozous, the lesser short-nosed fruit bat (Cynopterus brachyotis), and the spotted-winged fruit bat (Balionycteris maculata), and snakes, of which venomous snakes have been found to be consumed, such as the elapid Calliophis intestinalis.

[19] Social grooming in this species only occurs between mothers and infants,[22] removing dead skin and parasites by scratching with their toe claws and licking their fur, avoiding their faces.

[19] Horsfield's tarsiers mark their territory with scents from urine and glandular secretions on a substrate while scratching the surface with its hind-limb toe claws.

[18] The rapid loss of habitat due to forest conversion, oil palm plantations, fire, and logging is cause for concern.

[23] Additionally, the species is also collected for the illegal pet trade and wrongly considered a pest to agricultural crops.

In February 2007, the governments of Brunei, Malaysia, and Indonesia agreed to protect roughly 220,000 km2 (85,000 sq mi) of tropical forest in the "Heart of Borneo" region.

[24] In the "Heart of Borneo" project, non-governmental organizations (NGOs) have played a role in promoting the critical initiative and in assisting the neighboring nations in its conceptualization, design, and implementation.