Javan Chevrotain

Appearance

Mouse-deer possess a triangular-shaped head, arched back, and round body with elevated rear quarters. The thin, short legs which support the mouse-deer are about the diameter of an average pencil. Although Java mouse-deer do not possess antlers or horns like regular deer, male Java mouse-deer have elongated, tusk-like upper canines which protrude downward from the upper jaw along the sides of their mouth. Males use these “tusks” to defend themselves and their mates against rivals. Females can be distinguished from males because they lack these prominent canines, and they are slightly smaller than the males. Java mouse-deer can furthermore be distinguished by their lack of upper incisors. The coat coloration of the Java mouse-deer is reddish-brown with a white underside. Pale white spots or vertical markings are also present on the animal's neck.

With an average length of 45 cm and an average height of 30 cm, the Java mouse-deer is the smallest extant ungulate or hoofed mammal, as well as the smallest extant even-toed ungulate. The weight of the Java mouse-deer ranges from 1 to 2 kilograms, with males being heavier than females. It has an average tail length of about 5 cm. Mouse-deer are thought to be the most primitive ruminants based on their behaviour and the fossil record, thus they are the living link between ruminants and non-ruminants....hieroglyph snipped...

The Java mouse-deer is endothermic and homoeothermic, and has an average basal metabolic rate of about 4.883 watts. It also has the smallest red blood cells of any mammal, and about 12.8% of the cells have pits on them. The pits range in diameter from 68 to 390 nanometres. Red blood cells with pits are unique and have not been reported before either physiologically or pathologically.

Habitat

The Java mouse-deer prefers habitats of higher elevations and the tropical forest regions of Java, although it does appear at lower elevations between 400–700 metres above sea level. During the day, Java mouse-deer can be seen roaming in crown-gap areas with dense undergrowth of creeping bamboo, through which they make tunnels through the thick vegetation which lead to resting places and feeding areas. At night, the Java mouse-deer moves to higher and drier ridge areas. It has been argued that Java mouse-deer are an “edge” species, favoring areas of dense vegetation along riverbanks. Additionally, Java mouse-deer have been found to be more prevalent in logged areas than in the more mature forests, and their densities tended to decrease proportionately as the logged forests matured.

Reproduction

Java mouse-deer are capable of breeding at any time during the year, and this has been observed during captivity. However, some sources have observed that the breeding season for the Java mouse-deer in nature occurs from November to December. Additionally, female mouse-deer have the potential to be pregnant throughout most of their adult life, and they are capable of conceiving 85–155 minutes after giving birth. The Java mouse-deer's gestation period usually lasts 4.5 months, or 144 days. Typical litters consist of a single fawn, which resembles a miniature adult, although the tusk-like incisors prevalent in males are not visible in the young mouse-deer. The average mass of a newborn fawn is 370 grams, and these precocial young are capable of standing within 30 minutes after birth. Fawns are capable of eating solid food within two weeks, yet it takes around 12 weeks to completely wean the fawns. On average, it takes the young, both male and female, 167 days to reach sexual maturity. Mouse-deer have been observed to live up to 14 years in captivity, but their lifespan in nature is still an open question.

Food

Java mouse-deer are primarily herbivores, although in captivity they have been observed to eat insects as well as foliage. Their diet consists primarily of that which they find on the ground in the dense vegetation they inhabit, and they prefer the plants of the faster-growing gap species over the closed forest understory species, likely due to the increased richness of secondary protective compounds which the gap species provide. They are often classified as folivores, eating primarily leaves, shrubs, shoots, buds, and fungi, in addition to fruits which have fallen from trees. The fruits which Java mouse-deer commonly consume range from 1–5 grams, while the seeds range from 0.01–0.5 g.

Predators

One of the main predators which the Java mouse-deer face is humans. Through the destruction of their habitat, as well as from hunting and trapping the mouse-deer for food, their pelts, and for pets, humans have considerably reduced the Java mouse-deer population. Mouse-deer are particularly vulnerable to being hunted by humans at night because of their tendency to freeze when illuminated by having a spotlight shone on them. Because of the small size of the Java mouse-deer, dogs are also a common predator for them, as well as crocodiles, big cats, birds of prey, and snakes.