Other records show it from Kutai and Peleben in East Kalimantan and Tanjung Maruwe in Central Kalimantan. This species can live in both primary and secondary forests, and it also lives in forests along the coasts or on the edge of plantations. Horsfield's tarsier is a nocturnal species. It sleeps alone during the day in a tangle of vines or creepers at a height of 3.5 to 5 meters. This species prefers to sleep, rest, or remain stationary on perches that are angled 5 degrees from the vertical tree trunks, 1 to 4 cm in diameter, and it sleeps solitarily. 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. Horsfield's tarsier can be found from ground level up to a height of 7m or more in the understory. This species is carnivorous. It mainly eats insects such as beetles, grasshoppers, cockroaches, butterflies, moths, praying mantis, ants, phasmids, and cicadas, but also will eat small vertebrates such as 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 poisonous snakes have been found to be consumed. For example, the poisonous snake "Maticora intestinalis" was found to be hunted for by this species. This species was also found to consume birds, including: spiderhunters, warblers, kingfishers, and pittas. It locates prey primarily by sound and catches the prey with its hands when foraging. The prey items get killed by bites to the back of the neck and the eyes are shut when attacking. It will consume the prey starting with the head and working its way down the body. This species gets water both by drinking from a pool or steam, and by licking drops from bamboo leaves or from trunks of trees when water is running down the bark. Horsfield's tarsier is a host of the Acanthocephalan intestinal parasite "Moniliformis tarsii". Horsfield's tarsier, like all tarsiers, is a vertical clinger and leaper known for its extraordinary leaping abilities.