The Japanese sika deer lives in herds composed of females accompanied by their youngest offspring and sometimes the young from the previous year. Males are generally solitary but may occasionally form groups. In autumn, the rutting season begins. Males establish and mark their territory by urinating. They fight violently, with the defeated remaining on the periphery while the dominant males take the females into their territory to mate.

Sika deer forage for food from dusk to dawn. Among the hundred or so plants they consume, bamboo can account for up to 80% of their diet.

The Japanese sika deer is a small deer with a reddish-brown coat spotted with white in summer. In winter, the spots disappear and the coat becomes darker. Only the rump and tail remain white. The antlers are sparsely branched and can measure up to 60 cm..

Considered the protector of cities and messenger of the gods, the Japanese sika deer has been sacred to the Japanese for centuries. Imported to Europe, the United States and New Zealand in the 19th century for its meat and antlers, a few populations escaped on each of these continents. It is now found in the wild, particularly in France, where it can hybridise with red deer, causing dramatic genetic pollution.

The Japanese sika deer represents hope for other endangered sika deer species (pseudaxis, Formosan, etc.). By receiving embryos from these closely related subspecies, Japanese sika deer become surrogate mothers. This assisted reproduction work is being carried out by the team at the Haute-Touche Zoological Reserve, which hopes to obtain enough births of rare individuals to develop reintroduction plans in the coming years.