Ptilocercus lowii, also known as the Pen-tailed treeshrew, is the only species in the family Ptilocercidae while the other treeshrews such as the Common tree shrew (Tupaia glis) and Lesser treeshrew (T. minor) are grouped in the family Tupaiidae. This mammal is distributed in Peninsular Thailand, Malaysia, Sumatra, northern Borneo, including the small islands like Serasan in South Natuna (Phillips & Phillips, 2016). The dorsal part of its body is gray to light brown in colour and it has a white to yellowish belly (Gould, 1978). The body length ranges from 130-140 mm, with a tail about 160-190 mm long, and weight of around 40-60 g. The Pen-tailed treeshrew is easily identified by its long naked tail with a feather-like tip (Charles, 2008). It also has a black eye mask (Clarke, 1926). This treeshrew has a gestation period of around 45-55 days producing 1 to 4 offspring weighing about 10g individually (Parker, 1989).
This species inhabits primary and secondary forests, rubber plantations and houses near forest edges. The Pen-tailed treeshrew is the only nocturnal treeshrew species and can usually be found in areas with lots of vines and undergrowth which it requires to come down to the ground from the canopy to forage for insects (K.H. Han, pers. comm.). This species usually lives in a nest with a family of 2 to 5 individuals, unlike the other diurnal species. The nests are constructed inside trees, lined with dried leaves, twigs and fibres of soft woods (Lim, 1967). A study showed that both its oxygen consumption and body temperature dropped significantly during the day while sleeping, and this may be associated with energy conservation (Whittow & Gould, 1976).
The Pen-tailed treeshrew is the only known wild mammal that consumes alcohol every night. This mammal will spend an average of two hours every night sipping the naturally fermenting nectar from the flower of the Bertam palm (Eugeissona tristis Griff.) which is its primary food source. It frequently consumes alcoholic doses from the inflorescences that would normally intoxicate humans. Yet this flower-visiting mammal shows no signs of intoxication (Wiens et al., 2008). It is an omnivore as it has also been observed eating bananas, grapes, crickets, and grasshoppers (Gould, 1978).
Based on the IUCN Red List 2016, P. lowii is listed as Least Concern (LC). However, the population of this species is decreasing due to loss of forest canopy caused by land use changes, agriculture expansion and habitat fragmentation. Therefore, it is crucial to maintain the sustainability of the ecosystem including limiting deforestation for development, to ensure the continued existence of P. lowii for future generations.