Hot baths are not just relaxing for humans. Apparently, Japanese macaques enjoy them just as much, especially during harsh winter months when the furry primates are subject to stress.
These adorable-looking monkeys are considered native to Japan and live far up north of the country, particularly in its sub-forest and sub-alpine regions.
Although they enjoy living in evergreen forests, macaques have proven to be resilient against very cold weathers. To be specific, they can survive in areas where temperatures drop as low as 5 degrees Fahrenheit.
In such environments, they're often seen huddled in hot springs where temperatures are much warmer. This behavior has made researchers believe that taking baths in these waters offer some helpful benefits to the species.
A team from Kyoto University has recently discovered that these hot baths indeed influence the monkey's body temperature. Results of their study were published April 3 in the journal Primates.
How Macaque Feces Helped In Determining Stress Levels
To determine exactly how Japanese macaques benefit from hot baths, the team studied the behavior of 12 females in Nagano's Jigokudani Monkey Park during two different seasons: birth season, from April until June, and winter season, from October until December.
In particular, they sought to determine the period in which the primates bathed the most frequently and how long such baths normally last.
Then they collected fecal samples from the animals to measure levels of a hormone called "glucocorticoid," a steroid hormone which macaques produce when they are stressed, like when they are trying to regulate their body temperature to a level that's not too hot or too cold.
Japanese Monkeys Also Take Soothing Hot Baths
Based on the results of their study, Japanese monkeys have been confirmed to use hot springs more often during winter. They also found out that females of the species with a higher ranking in their social hierarchy take longer hot baths and are therefore more relaxed.
Because of this, such female macaques have been noted to get in lesser conflicts with other members of their group. When the team looked at the amount of glucocorticoid in these females, they exhibited lower stress levels than in those that don't use the hot springs at all.
"This unique habit of hot spring bathing by snow monkeys illustrates how behavioural flexibility can help counter cold-climate stress," explains lead author Rafaela Takeshita in a news release, adding that this may have implications on the animal's ability to reproduce and survive.
The team's study only investigates the effect of hot baths on glucocorticoid and excludes all other stress hormones. Furthermore, they also reported that getting hundreds of visitors every day does not affect stress levels in Japanese macaques.