Snow Monkeys Love Hot Baths Too!

Apr 16, 2018 By Hannah N, Writer Intern
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We all experience stress when we deal with pressure from family members, friends, work, societal expectations, and more. To deal with stress, many people listen to music, watch television, go for a walk outside, or take deep breaths.

But for female Japanese macaques, they love to bathe in hot tubs to relax.

It was not until 1963 that humans discovered the macaques’ unique activity. A couple of tourists noticed a young macaque bathing in a hot spring owned by a hotel in Japan’s Jigokudani Monkey Park. Soon, more monkeys had joined the young macaque in bathing.

The problem was that humans could not bathe in the same water due to the monkeys’ unhygienic lifestyles. Therefore, park management decided to build a hot spring made solely for the monkeys and now, around ⅓ of the female monkeys living in Jigokudani bathe there.

Japanese Macaques

Japanese macaques have red faces and brown coats. They usually are around 2 to 4 feet tall and weigh about 22 to 66 pounds, with males being larger than the females. What is fascinating about their coats is that the length of their fur will change depending on the season. During the wintertime, macaques can be spotted with long brown fur, however, during the summer, their coat is not as long.

These monkeys typically live in troops of around 20 to 30, with alpha-male and female monkeys who play the role as leaders of the troop. One’s social status for males in the group is established based on one’s age, whereas for females, it is based upon the status of their mothers.

Japanese macaques can be found in a wide variety of habitats some filled with forestry or next to the ocean. In the central region, the monkeys live in Nagano, an extremely cold, mountainous and snowy area located in northern Japan. Their habitat is filled with naturally formed hot springs that are over 140 degrees Fahrenheit, and often during the wintertime, these macaques can be spotted soaking in these naturally-formed pools!

Depending on seasonal changes, the monkeys will travel to new areas to live such as the island of Yaku-Shima where there are subtropical temperatures. In fact, the majority of macaques live there. Based on their environment and the season, macaques are omnivores and eat a wide array of foods ranging from tree bark in the wintertime and fruits in the fall.

Monkeys and Hot Tubs

At first, scientists believed that monkeys bathed in hot tubs to stay warm during the cold and harsh climate. However, scientists from Kyoto University thought that the monkeys bathed to lower their stress levels. To determine whether this hypothesis was true, they obtained and tested monkey feces for levels of glucocorticoids, a hormone which increases stress.

Researchers tracked 12 macaques during their birth season (April to June) and winter season (October to December) to analyze which monkeys bathed the longest and their traits. The results showed that macaques typically stopped bathing once temperatures warmed up, and that those who bathed in hot tubs exhibited 20% lower glucocorticoid levels. This discovery was crucial as monkeys released more stress hormones in colder temperatures, like humans, and they too, bathe to relax.

It was also interesting to note that the majority of bathing monkeys were, in fact, dominant females who were involved in more aggressive conflicts and were using up more energy. This showed scientists a correlation between high amounts of stress and bathing.

For now, scientists intend to look at the monkeys’ saliva to measure other hormones related to stress. They predict that with less stress comes an increase in reproduction, a scenario that could solve for animal extinction. So the next time you feel stressed, try taking a bath to unwind.

Sources: NYTimes, Livescience, Newsweek, ScienceDaily, National geographic, blueplantbiomes.org