Lesser chevrotains were once classified as Tragulus javanicus, and much of the literature prior to 2004 with this name actually refers to T. kanchil. However, in 2004 the Javan chevrotain was split off from other lesser chevrotains as a distinct species; since T. javanicus was first described from Java, this new species retained the original name. Location is the best way to determine what species was being studied in older studies.

Head and body length: 37-56 cm

Shoulder height: 25-30 cm

Tail length: 6-9 cm

Adult weight: 1.3-2.4 kg

The smallest ungulate, with a slender build, arched back, and pencil-thin legs. Females tend to be slightly larger than males. The general color is reddish-brown; populations across the species' range vary in the degree of redness and relative brightness. On several smaller islands, there is a trend towards melanism (blackness), particularly on the head, neck, and back. However, these color variations are less striking than in the greater Malayan chevrotain (Tragulus napu). The underparts are white. A dark streak is present on the nape of the neck, although this is less evident in the northern parts of the species' distribution. The underside of the jaw is white; this area connects directly with three white stripes on the throat such that there is a continuous smooth edge from the chin to the lateral stripes. Facial markings are generally lacking. There are no horns or antlers, but males develop enlarged upper canine teeth that protrude from the mouth.

Similar species

• Very similar to the Javan chevrotain (Tragulus javanicus) in size, coloration, and markings. Range is the most definitive identifier; some Javan chevrotain populations also have distinctive gray necks.
• The differentiation between the lesser chevrotain and northern chevrotain (Tragulus williamsoni) has not been well-studied. Northern chevrotains are significantly larger in size and they do not appear to overlap in range.
• The sympatric greater Malayan chevrotain (Tragulus napu) can be challenging to differentiate in the field. Size is generally unreliable (particularly if dealing with immature animals). Greater chevrotains have more distinctive facial markings and the long white throat stripes do not flow smoothly into the white underside of the jaw.

Gestation period: 132-145 days reported.

Litter size: One.

Weaning: Unknown, but a nursing 21-day-old fawn transitioned easily to solid food upon the death of its mother.

Sexual maturity: As early as 125 days (females) and 166 days (males).

Lesser chevrotains breed throughout the year and are one of the fastest-reproducing ungulates, with a short gestation (4.5 months) and the ability for females to become pregnant again within two hours of giving birth. The estrous cycle in roughly 14 days in length. Infants weigh 120-190 g at birth and are able to stand within 30 minutes of being born. However, they generally "lie up" in dense brush and are visited by their mothers for nursing, typically twice per day. The milk is very high in fat (26.8%) and the young grow quickly; adult size is reached by 5 months of age.

The retiring nature and small size of the lesser chevrotain make it a challenging species to study in the wild. In response to danger, the first reaction is to "freeze" in position; like the greater chevrotain, the lesser chevrotain may repeatedly and rapidly stamp its hind legs when alarmed. Data from radio-collared individuals and camera-trap images indicate that the species is most active in the morning (05:00-07:00, up to 10:00) and late afternoon (15:00-18:00). The average distance travelled is 550 m per day; this diurnal activity is broken up by short periods of rest in sheltered areas, such as fallen tree trunks and brush. In contrast, long overnight rests (up to eight hours in length) typically occur in open forest with little undergrowth. Both males and females occupy home ranges around 5 hectares in size, each with a core area of heavy use. Females generally have distinct core ranges from neighbouring females, and male core ranges do not overlap those of other males; there is some evidence of territorial behavior among males. A wide overlap exists between the home ranges of the sexes.

Family group: Solitary. Pairs account for fewer than 5% of wild observations.

Diet: Fallen fruits (1-5 g in size), leaves, fungi.

Main Predators: Many large and medium-sized carnivores in its range.

The lesser Malayan chevrotain is native to forests throughout southeast Asia, including Sumatra, Borneo, and numerous smaller Indonesian islands. The species' preferred habitat appears to be immature forest with edge environments, clearings, and gaps in the forest canopy, and it is typically found at elevations from sea level to at least 600 m. On Java, the species is replaced by the Javan chevrotain (T. javanicus).The approximate range is depicted in the map below.

IUCN Red List: Least concern (2015).

CITES Listing: Not listed (2019).

Threats: Hunting (snares, shooting), habitat degradation.

The lesser chevrotain is widespread and appears to be at least locally common across its range. Unlike the greater chevrotain (Tragulus napu), this species readily uses disturbed habitats. Its small size makes it less susceptible to snares set for larger species, although it may be heavy hunting using spot-lighting at night. No species-specific estimates of population size have been made.