Mycophagy among Japanese macaques in Yakushima: fungal species diversity and behavioral patterns

Mycophagy (fungus-feeding) by Japanese macaques (Macaca fuscata yakui) in Yakushima has been observed by many researchers, but no detailed information is available on this behavior, including which fungal species are consumed. To provide a general description of mycophagy and to understand how and whether macaques avoid poisonous fungi, we conducted behavioral observation of wild Japanese macaques in Yakushima and used molecular techniques to identify fungal species. The results indicate that the diet of the macaques contains a large variety of fungal species (67 possible species in 31 genera), although they compose a very small portion of the total diet (2.2% of annual feeding time). Fungi which were eaten by macaques immediately after they were picked up were less likely to be poisonous than those which were examined (sniffed, nibbled, carefully handled) by macaques. However, such examining behaviors did not appear to increase the macaques' abilities to detect poisonous fungi. Fungi that were only partially consumed included more poisonous species than those fully consumed with/without examining behavior, yet this was not significant. Taste, therefore, might also play an important role in discriminating poisonous from non-poisonous.