Presence of Feces in the Abandoned Nokado Mine, Tochigi Prefecture of Central Japan, Provides Further Evidence of Cave Use by Japanese Macaques

Abstract

In October 2015, large quantities of the feces from Japanese macaques (Macaca fuscata) were found within the gallery of the abandoned Nokado Mine in Nikko City, Tochigi Prefecture, central Japan. More than 100 feces specimens were concentrated in two narrow areas of 1-2 m² less than 8 m inward from the mine entrance. The feces were quite similar in outline and plural-connectivity by woody fibers to typical macaque winter feces. Analysis showed that the feces were almost entirely composed of plant-derived fibers. The locations and morphological characteristics of the feces support that the macaques used the gallery during winter, particularly from December 2014 to March 2015, and most likely huddled together for warmth. The amount of snowfall during the winter of 2014 was greater than average, likely forcing the macaques to use the abandoned gallery as a shelter from the heavy snow/wind. Although the Nokado Mine constitutes the second case of cave use by macaques in Japan, it is noteworthy that the macaques used an artificial cave excavated through mining. This is in contrast to the first report of cave use where macaques used a natural limestone cave in the karst regions. By accumulating cases of cave use by macaques, our understanding of adaptive traits in cold areas will be advanced.