屋久島のニホンザル生息状況の過去20年間の変化

Abstract

We studied changes in the abundance of wild Japanese macaques (Macaca fuscata) in lowland Yakushima from 1991-1994 to 2013-2014. We quantified abundance based on the detection frequency during point observation. Data included 271 points censused between July and August from 1991 to 1994 and 58 points censused between July and September in 2013 and 2014. Abundance of Japanese macaques significantly decreased in northern and eastern areas, but not in the western and southern areas. Comparing the estimated population between 1991 and 1994 and the number of hunted macaques for pest control between 2007 and 2013, hunting pressure seems to be high in northern and eastern areas, low in southern areas, and absent in western areas. Conifer plantation is more widespread in eastern and northern areas, which may also explain the declining trend of the macaque population in these areas. The number of macaques hunted for pest control exceeded 1,000 each year following 2009 in Yakushima. Our results suggest that macaques are overhunted in Yakushima, so we recommend putting more emphasis on measures against crop-raiding other than pest control, in particular in eastern and northern areas.