Now, it should be noted that should you search for mouse deer, you get results for the whole Chevrotain family, but here we are actually talking about the Mouse deer of the family. Chevrotain is used as a replacement for all of the species in this family of species (10) so care should be taken when looking at what is being spoken about.
The genus Tragulus, which originates in 2 words. Firstly, Tragos which is a Greek word meaning male goat, and the latin word ulus which means tiny.
All these species are nocturnal and behave in a similar way. They feed on leaves, fruit grasses and other vegetation that they encounter. They live in the dense forest undergrowth. This can have so much cover, that individuals freezing could be incredibly effective. It would be quite possible for a leopard to walk past a mouse deer that is curled up in the undergrowth and have no idea that anything was there.
They do not grow horns or antlers, though the males grow a pair of teeth which are particularly long – which are used in fighting.
It is unfortunate, but in general each of these separate species are considered data deficient. This ranges from some which are only occasionally seen, but have been recorded over a large area, to the Vietnam mouse-deer, which has only been recorded as having had 4 sightings. The other problem, is that it is only recent that the 6 different species were formally decided upon. Due to the fact that many are similar, and ranges often overlap it means that not only are historic data less reliable, but also even now, unless the sighting is made by an expert, only a good photo can allow us to clearly tell which species has been found