Japanese Macaque Guide: The Snow Monkey That Bathes in Hot Springs

The Japanese macaque is the world’s northernmost non-human primate, surviving winters where snow lies for months and temperatures drop below minus 15°C. It is best known as the “snow monkey” that soaks in volcanic hot springs in Nagano — and as the species that gave primatology its first documented animal culture.

Japanese macaque at a glance

Scientific name	Macaca fuscata
Family	Cercopithecidae (Old World monkey)
Weight	8-11 kg males; 8 kg females
Lifespan	22-27 years wild; 30+ captive
Diet	Fruit, seeds, leaves, bark, fungi, insects
Troop size	20-100 individuals
Range	Honshu, Kyushu, Shikoku and Yakushima, Japan
Status	Least concern

Key takeaways

• Lives further north than any other primate except humans, up to about 41°N.
• Grows a dense double-layered winter coat and loses roughly a fifth of body weight over winter.
• Hot-spring bathing at Jigokudani is a learned cultural behaviour that began in the 1960s.
• The sweet-potato-washing tradition on Koshima Island is the classic case study of cultural transmission in animals.
• Troops have strict matrilineal hierarchies where a daughter inherits rank just below her mother.

Surviving the cold

Japanese macaques handle winter through insulation, behaviour and diet. Their coat thickens dramatically; they huddle in sleeping clusters; they shift to bark, buds, winter twigs and fungi when fruit disappears; and they reduce daily travel to conserve energy. Some coastal populations dive for seaweed and shellfish. Compare with other cold-climate primates in Monkeys That Live in Snowy Climates and Mountain Monkeys.

The hot springs

At Jigokudani Monkey Park in Nagano, macaques enter geothermal pools to raise body temperature and reduce winter stress hormones. It began when one juvenile female followed people into an inn’s outdoor bath in the early 1960s; the habit spread through the troop and is now passed to each new generation. Only some troops do it — proof that this is culture rather than instinct.

Culture and learning

On Koshima Island in 1953, a young female named Imo began washing sand off sweet potatoes in a stream, then later in the sea, apparently for the salt. The behaviour spread first among playmates and younger relatives, then upward through the troop. It became the founding example of socially transmitted behaviour in non-human animals and reshaped how researchers think about monkey intelligence and monkey memory and learning.

Diet

Highly seasonal and one of the broadest of any monkey — over 200 plant species recorded. Summer brings fruit, seeds, flowers and insects; autumn is nut and acorn season with heavy cheek-pouch stuffing; winter reduces them to bark, buds, evergreen leaves and fungi. See Seasonal Diet Changes and Monkey Diet by Species.

Social structure

Troops are female-bonded and matrilineal. A female’s rank is inherited and remarkably stable across generations; males emigrate at maturity and must work their way up in a new troop. Grooming networks track kinship closely. See Monkey Social Hierarchy.

Where and when to see them

Jigokudani Monkey Park near Yudanaka is the classic destination, best between late December and early March when snow-covered macaques use the pools most. Yakushima, Arashiyama in Kyoto and Shodoshima also have habituated troops. Never feed them, never make eye contact, and keep bags closed. Planning help in Best Time to See Monkeys, Monkey Watching Tips and Wildlife Photography Tips.

Frequently asked questions

Why do snow monkeys bathe in hot springs?

It raises body temperature and lowers winter stress. The behaviour is learned, not instinctive, and only some troops do it.

How cold can Japanese macaques survive?

They live through winters below minus 15°C with snow cover lasting several months.

Are Japanese macaques endangered?

No — they are least concern, though local populations face conflict with farmers.

What do snow monkeys eat in winter?

Bark, buds, twigs, evergreen leaves, fungi and cached nuts, plus seaweed and shellfish in coastal troops.

Can you touch the monkeys at Jigokudani?

No. Touching, feeding and direct eye contact are prohibited and can provoke bites.

Related: Asian Monkeys, Golden Snub-Nosed Monkey, Ultimate Guide to Monkeys.