Sika, Shansi sika, Spotted deer, Japanese deer
The Sika deer (Cervus nippon) is a species of deer native to much of East Asia and introduced to other parts of the world. Its name comes from the Japanese word shika which means "deer". In Japan, the species is known as the nihonjika (Japan deer) and in Chinese, it is known as méihuālù (‘plum blossom deer').
The Sika deer is one of the few deer species that does not lose its spots upon reaching maturity. Spot patterns vary with region. The mainland subspecies have larger and more obvious spots, in contrast to the Taiwanese and Japanese subspecies, whose spots are nearly invisible. Many introduced populations are from Japan, so they also lack significant spots. The color of the pelage ranges from mahogany to black, and white individuals are also known. During winter, the coat becomes darker and shaggier and the spots less prominent, and a mane forms on the back of the males' necks. Sika stags (males) have stout, upright antlers with an extra buttress up from the brow tine and a very thick wall. A forward-facing intermediate tine breaks the line to the top, which is usually forked. Occasionally, sika antlers develop some palmation (flat areas). Females carry a pair of distinctive black bumps on the forehead. Stags also have distinctive manes during their mating period (rut). All Sika deer are compact and dainty-legged, with short, trim, wedge-shaped heads and a boisterous disposition. When alarmed, they often display a distinctive flared rump, much like the American elk.
Sika deer are native to Eastern Asia and Japan and have also been introduced to other regions of the world, including Europe, North America, Australia, New Zealand, and the Philippines. They prefer to live in forested areas that have a dense understory and migrate seasonally to mountainous areas, such as Japan.
Primarily nocturnal, sika deer sometimes forage during the day, either singly or in small groups. Adult males remain solitary most of the year though they sometimes group together, while females with their fawns form groups of 2 or 3 only during the birthing season. Males mark their territorial boundaries by digging holes using their forefeet and antlers. When territorial disputes between males occur, hooves and antlers are used as the main weapons. Sika deer are excellent swimmers and will readily enter the water in order to escape from predators or for other reasons. They are also highly vocal animals, with over 10 individual sounds, ranging from soft whistles to loud screams.
Sika deer are polygynous and a male can successfully gather a harem of up to 12 females within his territory during the mating season, which is in autumn (September and October). A single fawn is born in May or June following a gestation period of about 30 weeks. When a fawn is born, the mother hides her baby in thick undergrowth. The young stays very quiet and still while it waits for the mother to return. Surprisingly, fawns have almost no smell, and even hunting dogs cannot detect their scent. When fawns are a few weeks old they venture out to play with the other fawns. The newborn is nursed for up to 10 months with increasingly fatty milk. It becomes independent 10 to 12 months after birth and attains reproductive maturity at 16 to 18 months of age.
The main threats to Sika deer include water pollution, habitat loss, and hunting for their meat, as well as their antler velvet, which has a use in traditional medicines. Loss of genetic diversity due to fragmentation of their habitat is also a cause for concern, as well as competition with goats and other feral animals. Another threat is collisions with vehicles. Hybridization with native red deer in places like the United Kingdom is a conservation risk, threatening the genetic integrity of both species.
Japan has the largest Sika deer population in the world with 3,080,000 individuals as of 2015 estimation by the Japanese Ministry of the Environment. It is still increasing due to conservation efforts and the extinction of its main predator, the Grey wolf, over a century ago. There are also relatively small native populations in Russia (8,500-9,000 individuals) and China (less than 1,000 individuals).
Sika deer are important to control native vegetation by browsing, and they are large prey for local predators.