HMW 8 – Species accounts: Pen-tailed Treeshrew (Ptilocercus lowii)

Genus PTILOCERCUS

Gray, 1848

Pen-tailed Treeshrew Ptilocercus lowii

French: Ptilocerque de Low / German: Federschwanz-Spitzhörnchen / Spanish: Musaraña arborícola de cola plumosa

Other common names: Feather-tailed Treeshrew, Low’s Treeshrew

Taxonomy. Ptilocercus lowii Gray, 1848, Kuching, Sarawak, Borneo, Malaysia.

Two subspecies are recognized.

Subspecies and Distribution.

P. l. lowii Gray, 1848 – Borneo and offshore Labuan I.

P. l. continentis Thomas, 1910 – Malay Peninsula (from extreme S Thailand to the S tip).

Descriptive notes. Head–body 130–150 mm, tail 160–200 mm, ear c.17 mm, hindfoot c.26 mm; weight 50–60 g. The Pen-tailed Treeshrew is the most distinct treeshrew, with large round black eyes, gray dorsal fur, and ivory/white ventral surfaces. Tail is scaled, long, and mouse-like, with distinct feathering beginning about halfway down its length, black feathering at the proximate end, and white fur at the distal end. Ears are large and mouse-like. Eyes have black mask around them; eye shine is silver-colored, making it easily distinguishable when illuminated with a flashlight. Muzzle is thin and pointed, with pink skin around nose and whiskers. Subspecies continentis from Kuala Lumpur has wider black stripe on face. The Pen-tailed Treeshrew is adapted for an arboreal lifestyle, with curved claws, broad and strong limbs, and tail used for balance. Face is short, with premolars in lateral contact with enlarged temporal muscles; it is assumed to have the strongest bite force of all treeshrews.

Habitat. Most commonly lowland primary tropical rainforests, but sometimes secondary forests and gardens, up to elevations of c.1200 m. The Pen-tailed Treeshrew appears to be dependent on large dipterocarp trees for nest sites.

Food and Feeding. The Pen-tailed Treeshrew is known to forage on insects and fruit. It eats fermented nectar from bertam palm (Eugeissona, Arecaceae), but individuals do not seem to be affected by the alcohol. It forages at night for insects on tree trunks, ranging from near the forest floor to high in the canopy. It very rarely spends time foraging on foliage, almost exclusively on trunks of trees. It has been caught in traps with bananas, but feces indicate that fruit is only a sporadic part of the diet.

Breeding. Specific behaviors of the Pen-tailed Treeshrew are unknown; however, nests are large (c.60 cm in length) and constructed of fibers and leaves inside hollow trees. Nests are thought to occur in large trees with natural cavities and multiple entrances. Seasonality of breeding is unknown. Unlike species of Tupaiidae, Pen-tailed Treeshrews are not believed to practice absentee parental care because nests are shared by mothers and offspring. Litters likely consist of two offspring, but data are limited.

Activity patterns. The Pen-tailed Treeshrew is typically considered strictly arboreal, but it occasionally visits the forest floor where it has been trapped. It is the only nocturnal treeshrew; it emerges shortly after sunset and returns to its nest around dawn.

Movements, Home range and Social organization. Pen-tailed Treeshrews are known to use communal tree nests with up to five individuals, probably related family groups. They appear to forage alone, but all individuals that share a nest seem to disperse and return to the nest simultaneously. Shared nest sites might assist with metabolic demands. Individuals make bird-like chirps when leaving a shared nest. Home ranges of adults are not well characterized but likely encompass c.6 ha. Although the home range might seem small, vertical habitat is vast in lowland dipterocarp forests, giving individuals large amounts of vertical foraging space. Movements occur on trunks of trees, with little use of foliage. Pen-tailed Treeshrews do not make large leaps between trees but walk along branches in contact with nearby trees.

Status and Conservation. CITES Appendix II. Classified as Least Concern on The IUCN Red List. In most forests, Pen-tailed Treeshrews are thought to be rare, with relict distributions. Based on observations from L. H. Emmons in 2000, they are thought to be common only in Danum Valley, Sabah, Malaysia. Additional studies are necessary to better understand the natural history and conservation needs of the Pen-tailed Treeshrew.

Bibliography. Butler (1972), Corbet & Hill (1992), Dunn et al. (1968), Emmons (2000), Gray (1848), Gregory (1910), Helgen (2005), Huxley (1872), Li Qiang & Ni Xijun (2016), Lim (1967), Lyon (1913), Mason et al. (2016), McKenna (1966, 1975), Muul & Lim (1971), O’Leary et al. (2013), Roberts et al. (2011), Sargis (2002a, 2002b), Szalay (1977), Van Valen (1965), Wagner (1855), Whittow & Gould (1976), Wiens et al. (2008), Zeller (1986).