伊豆大島
In the 1960s, several specimens escaped from an exhibition zoo in the Bōsō Peninsula in eastern Japan. By 2017, their numbers had reached at least 60,000. It is considered a harmful invasive species and has inflicted severe damage to ashitaba plantations. Also, Reeves's muntjac escaped a zoo on Izu Ōshima in 1970 when a fence fell due to a typhoon. A muntjac eradication effort on Izu Ōshima was undertaken in 2007–2014 but failed, and as of 2014, at least 11,000 individuals exist and have a yearly population growth rate of 15%. This failure has been blamed on inadequate survey methods that underestimated the population of the nocturnal species.