Order : CETARTIODACTYLA
Family : Cervidae
Species : Muntiacus atherodes

Head-Body Length : Males up to 85 cm ?
Tail Length : Males up to 18 cm ? 
Weight : Males up to 20 kg ?

The Bornean Yellow Muntjac was first formally described in 1982 by Groves & Grubb, however local people familiar with forest animals were long aware of the existence of the species and were able to distinguish it from the Red Muntjac.

This is one of twelve species of muntjac or 'barking deer' that are currently recognised (11 of which occur in Southeast Asia). These small ungulates are called 'barking deer' due to the alarm call they make when a predator or other threat is nearby - the call sounds like the piercing bark of a small dog.
 
The Bornean Yellow Muntjac is endemic to the island of Borneo, where it appears to be widespread in coastal areas and in low hills. It is mainly diurnal and tends to remain in the shade of the forest. Its diet comprises fallen fruits and seeds, grasses and young leaves.

This species often lives sympatrically with the slightly larger Red Muntjac (i.e. it inhabits the same geographical area).

Separating a Bornean Yellow Muntjac from a Red Muntjac in the field is no easy matter, unless one is looking at an adult male with antlers: in the former these are straight and lack any branches (tines), but in the latter there is a small tine at the base of each antler, and the antlers curve sharply at the tip.

The Bornean Yellow Muntjac also lacks the 'frontal tuft' which occurs in the Red Muntjac i.e. the dark 'eyebrows'.

In the field, separating the two species on the basis of general fur colour is difficult. For the Bornean Yellow Muntjac this is described as 'light orange-yellow' and 'general colour ... bright ochraceous orange' (Groves & Grubb, 1982), however the patch of fur on top of the head is consistently pale in the Red Muntjac, and dark in the Bornean Yellow Muntjac (Oliver Wearn, pers. comm.).

Figs 1 and 2 : A male Bornean Yellow Muntjac at the Brantian-Tatulit Virgin Jungle Reserve, Sabah (elevation = 418 metres): note the absence of a branch (tine) at the base of the straight antlers which confirms this identification, also the absence of a 'frontal tuft' above the eye. Photos thanks to Oliver Wearn.


References :

Groves, C. P., & Grubb, P. (1982). The species of muntjac (genus Muntiacus) in Borneo: unrecognised sympatry in tropical deer. Zoologische Mededelingen, 56(17), 203-216.

Payne, J., Francis, C.M., 1998. A Field Guide to the Mammals of Borneo. The Sabah Society.

Phillipps Q. & Phillipps K. (2016). Phillipps’ Field Guide to the Mammals of Borneo and Their Ecology: Sabah, Sarawak, Brunei, and Kalimantan. Second Edition. John Beaufoy Publishing. 400 pp.