Japanese macaques are originally the species that inhabit the coldest areas of monkeys (primates other than humans), but among them, Japanese macaques in Kamikochi are the group that live in the coldest areas in the world.A group at Shinshu University has long observed that Japanese macaques in Kamikochi often behave like collecting aquatic insects, which is called "river drying" in the midwinter.

　Since "river drying" is an unprecedented behavior in the world, this time, in order to elucidate the eating habits of Japanese macaques in Kamikochi during the midwinter, we comprehensively investigated DNA derived from food resources by metagenomic analysis of fecal samples. rice field.As a result, DNA of salmonaceae fish, aquatic insects (larvae of stoneflies and crane flies), shellfish, and clams were detected, and some animals thought to be derived from land were included, but many. It was revealed that aquatic animals living in freshwater areas are actually the food resources for Japanese monkeys in the upper highlands.

　This feature was stably confirmed from samples collected over multiple winter seasons, suggesting that Kamikochi Japanese macaques are likely to constantly use aquatic insects and fish as food resources.This is the first time that the actual condition of Japanese macaques, which depend on animals living in rivers as a nutrient source in the midwinter, has been scientifically proved.It is also the world's first surprising report of fish predation among monkeys.

　However, since it has not been possible to observe the catching scenes of salmonids on site, this is a future issue for this group.

Paper information:[Scientific Reports] Winter diet of Japanese macaques from Chubu Sangaku National Park, Japan incorporates freshwater biota