Snow monkeys (in Japanese, nihonzaru 日本猿), also known as Japanese macaques (Macaca fuscata), are the only species of primate living in the wild in Japan. This species is also endemic to the Japanese archipelago. These monkeys are mainly found in mountainous regions, at altitudes ranging from 500 to 2,500 meters. In winter, when temperatures become harsh, these monkeys have developed a surprising habit: soaking in natural hot springs to keep warm!
The Macaca fuscata is endemic to the Japanese archipelago.
The fur of these monkeys, which ranges from gray to brown, is dense and thick, allowing them to withstand the freezing temperatures and snowy conditions of the mountainous regions where they live.
Like many other monkeys, the Japanese macaque is omnivorous. Its diet includes fruits, roots, seeds, insects, and occasionally even small animals. These monkeys live in complex social groups, ranging from 20 to 100 individuals. These groups are mainly composed of females and their young, while adult males often live on the outskirts of the group or frequently change groups. The nihonzaru, like other primates, have developed complex interactions such as grooming, food sharing, and vocal communication. However, it is another behavior that makes these monkeys truly unique: Japanese macaques have become famous for their habit of frequenting natural hot springs, known as onsen (温泉) in Japanese.
Winter serenity: Japanese macaques enjoying a warm bath amidst the snow.
A macaque savoring the warmth of an onsen.
This unusual behavior is believed to have emerged in the 1960s-1970s, when a harsh winter reportedly pushed groups of nihonzaru to seek refuge in natural hot springs. It is even possible that this behavior developed by imitating humans, as bathing in hot springs is a long-standing tradition in the Japanese archipelago. Since then, it has become a habit: every winter, monkeys can be seen relaxing in the warm waters of the onsen. This phenomenon is particularly visible in the Jigokudani (地獄谷) region, located in the mountains of Nagano. The photos presented in this article come from there.
Female nihonzaru nursing her baby in an onsen.
Family grooming time.
A more solitary male also enjoys the comfort provided by the warm water.
As with many other primate species, social hierarchy plays a central role in the organization of Japanese macaque groups. These groups are led by a dominant female, often the oldest and most experienced, who exerts significant influence over the other members. Adult males also hold an important status, but they often have to prove their strength to lead a group. This hierarchy is also reflected in access to the onsen. Dominant macaques, whether male or female, are the first to access the hot springs and can enjoy them for as long as they wish. Subordinate individuals, however, must wait their turn and only have limited access to the onsen. This difference in privileges can create tension within the group. Competition for these thermal spots can be particularly intense during the coldest months, when the monkeys need warmth to survive.
Time to give up the spot.
Searching for parasites.
Drinking or admiring its reflection?
While some Japanese macaques protect themselves from the winter cold by immersing in natural hot springs far from cities, other groups of monkeys regularly visit public onsen located in spa towns. For hygiene and safety reasons, these onsen were eventually abandoned by city dwellers and have since been frequented only by monkeys. Tolerance towards monkeys in urban areas is not so surprising. In Japanese culture, the macaque is often associated with spiritual and mythological elements. It is considered a messenger of the gods and is revered in many Shinto traditions. Moreover, the image of a macaque relaxing in hot water echoes the concept of purification, an essential practice in Japanese culture, particularly in traditional thermal baths. Monkeys in onsen embody a form of communion with nature and the divine, which explains why they are warmly welcomed in certain urban hot spring resorts.
Old male.
Comfortable grooming.
The presence of macaques bathing in onsen during winter has since generated additional tourist interest for certain hot spring towns. The nihonzaru have, in a way, become mascots that people can observe in winter as they relax in the warm waters. However, this growing proximity between macaques and humans has also led to some challenges, particularly due to tourists developing the habit of feeding the bathing monkeys. This disrupted the monkeys’ feeding behavior to the point where they no longer searched for food on their own, becoming dependent on humans. Some even became ill due to an unsuitable diet. Many tourists also sought close contact with the monkeys, wanting, for example, to pet them, which caused additional stress for the animals. Strict regulations have since been put in place to ensure that macaques are no longer fed by visitors and that interactions between monkeys and humans remain respectful. This allows the monkeys to fully enjoy the comfort provided by the hot springs.
At peace in an onsen.
Thoughtful gaze and winter steam: a tranquil immersion for these macaques in the mountains of Nagano.
