With the first imports of sika deer into Europe, cases of interbreeding were recorded, with the earliest reference dating back to 1884. During the 1930s and 1940s, deliberate hybridization was carried out on deer farms within the territory of the former Soviet Union, primarily to increase velvet antler production. Controlled hybridization experiments were also conducted by Rory Harrington in Ireland during the 1970s and 1980s, and similar practices continue in China today. In the Far East, particularly in the Ussuri River region, hybridization has occurred spontaneously and naturally since time immemorial, and local hunters are well aware of this phenomenon. Nevertheless, throughout Europe-since the very beginning and, to a large extent, even today-the hybridization between the sika deer and the red deer has been regarded by the hunting community as a rather insignificant curiosity rather than as a ticking time bomb.