Researchers have discovered that snow monkeys living in a mountainous region in central Japan eat fish to survive the harsh winter.

A team of scientists headed by Shinshu University professor Tojo Koji studied Japanese macaques in Nagano Prefecture's Kamikochi valley. They released their finding in a British science journal.

The researchers collected the monkeys' feces in winter and carried out tests that confirmed DNA from fish, including chars.

They concluded that the monkeys regularly catch fish in the rivers for food during winter.

The journal featured photos taken in January 2019 that show one monkey carrying a fish in its mouth and another monkey eating a fish.

Professor Tojo says that this is the first time scientists have proven, complete with photographic evidence, that monkeys eat fish.

Japanese macaques in Kamikochi live in a harsh environment where temperatures frequently fall below minus 20 degrees Celsius in midwinter.

Tojo says the need to survive has led to the monkeys' unique behavior.