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,
Unclean animal animals" explicitly named in the Qur'an. If someone converts to Islam, Allah "allows them as lawful what is good and prohibits them from what is bad; he releases them from their heavy burdens and from the yokes that were upon them". For other animals, great importance is given to the manner of its death: forbidden are blood and carrion ("dead meat"), and any animal that has been "killed by strangling, or by a violent blow, or by a headlong fall, or by being gored to death". Also forbidden is any animal that has been eaten by a wild animal, unless