Sika have rapidly disappeared from much of their natural range due to habitat loss. Sika are woodland deer characteristic of broad- leaved and mixed forests where snowfall does not exceed 10-20 cm and snow-free sites are also available. Large forest tracts with dense understory and occasional clearings are ideal. Six subspecies are nearly extinct - in Taiwan, Japan's Ryukyu Islands, China, Siberia, Manchuria and Korea. In some places, the deer have been uncontrollably hunted or their forests have been destroyed. In others, predators such as wolves and wild dogs have taken their toll. In China, the deer's antlers are used to make medicine. The Ryukyu subspecies is listed as endangered.
Formerly, sika were native throughout eastern Asia, from southern Siberia and the adjacent Japanese island of Hokkaido south, along both the mainland and islands, to southeastern China and Formosa. including Manchuria, Korea, China, Vietnam, Japan and Taiwan. They have been introduced by humans to Australia, New Zealand, several European countries and several U.S. states, including Wisconsin, Maryland, Texas, Virginia and Oklahoma. Free-ranging populations can be found in 12 Texan counties. In 1988, the total Texas population was estimated to be 11,879. In general they have adjusted well to the cultivated man-made landscapes. Since many sika deer live in a semi-tame state in parks and on farms, they are easily introduced into other countries, especially since the northern subspecies does well in the climate of Europe. In addition to European forests and parks, they now also inhabit the island of Madagascar. In Germany, there are several populations living in the wild.