The Lesser mouse-deer is the smallest known hoofed mammal that is widely distributed across Southeast Asia. They are generally reddish-brown in color with white underparts. Mouse-deer don't possess horns, but males have enlarged sharp upper canine teeth that protrude from the mouth. Females of this species are usually slightly larger than males.
Lesser mouse-deer are found in Indochina, Burma (Kra Isthmus), Brunei, Cambodia, China (Southern Yunnan), Indonesia (Kalimantan, Sumatra, and many other small islands), Laos, Malaysia (Peninsular Malaysia, Sarawak, and many other small islands), Singapore, Thailand, and Vietnam. They live in tropical moist forests, swamp forests, mangrove forests, and moist savanna and shrubland. They can also be found in cultivated areas.
Lesser mouse-deer are shy and generally solitary animals; however, they may sometimes be seen spending time in pairs. Both the males and females occupy home territories which overlap considerably; however, individuals of the same sex do not share their territories. Lesser mouse-deer are often thought to be nocturnal but in fact, they are typically active in the morning and in the afternoon. During the day, they roam in crown-gap areas with dense undergrowth, and at night, they typically move to higher and drier ridge areas. When sensing danger Lesser mouse-deer "freeze" and remain motionless and when alarmed they may repeatedly and rapidly stamp their hind legs.
The breeding season of Lesser mouse-deer occurs throughout the year. The gestation period lasts around 140-177 days and females may produce 2-3 fawns per year. The newly born fawn is able to stand within 30 minutes after birth, however, it remains hidden in the dense brush until it's weaned. Young Lesser mouse-deer grow very quickly and females become reproductively mature at age of 125 days while males are ready to breed when they are 166 days old.
Lesser mouse-deer are threatened by habitat loss due to urban development and farming, hunting, and predation by feral dogs.
The IUCN Red List and other sources don’t provide the number of the Lesser mouse-deer total population size. Currently, this species is classified as Least Concern (LC) on the IUCN Red List.