Previous research involving the DNA analysis of fecal samples from macaques living in Chubu Sangaku National Park during winter revealed evidence not only of the bark and leaves of bamboo (that stand out above the snow), but also of freshwater fish, mollusks and aquatic arthropods. It is very rare for monkeys to eat fish, unless the fish are dead or dying, trapped in receding pools. A research team led by scientists from Shinshu University therefore decided to investigate how and where the macaques are catching fish to supplement their winter diet.