Sika deer are contiguous with populations of the native red deer. Since the two species sometimes hybridize, a serious conservation concern exists. In research which rated the negative impact of introduced mammals in Europe, the sika deer was found to be among the most damaging to the environment and economy, along with the brown rat and muskrat. In the 1900s, King Edward VII presented a pair of sika deer to John, the second Baron Montagu of Beaulieu. This pair escaped into Sowley Wood and were the basis of the sika to be found in the New Forest today. They were so prolific,
Formosan sika deer the 17th century immigration from the Chinese mainland increased dramatically in response to political instability in China and economic opportunities on Taiwan, which from 1624 until 1662 was controlled by the Dutch East India Company (VOC). The VOC, operating from the port of Taoyuan (modern-day Anping, Tainan) in southwestern Taiwan, established a trading post whose main business was the export of sika skins to Europe. During the six decades of Dutch activity two to four million sika skins were exported to Europe. Exporting was reduced when the Dutch were forced out of Taiwan in 1662, but continued throughout the Qing