Image Credit: Lincoln Park Zoo

Chicago’s Lincoln Park Zoo welcomed a new baby snow monkey earlier this week, the first since the zoo’s troop of new macaques arrived from Japan. In honor of the adorable baby monkey, a yet-unnamed boy, here are 11 intriguing facts about snow monkeys, also known as Japanese Macaques. 

1. They are excellent swimmers.

Japanese macaques have been reported to swim up to half a kilometer.

2. They can handle a little chill ...

Native to northern Japan, snow monkeys live farther north than any other non-human primate. The macaque’s thick fur allows the monkeys to deal with temperatures as low as -4 degrees Fahrenheit, and they can live at elevations of up to 9600 feet above sea level. 

3. ... But they love a good hot tub.

Image Credit: Yosemite, Wikimedia Commons // CC BY-SA 3.0

Jigokudani Monkey Park near Nagano, Japan is known for its large population of snow monkeys, which descend from the steep surrounding cliffs during the day to sit in the warm hot springs.

4. They can live to be more than 30 years old.

Last September, Nikko, a snow monkey at the Minnesota Zoo, celebrated her 31st birthday. In the wild, snow monkeys tend to live much shorter lives, though. One estimate puts the average lifespan for a female snow monkey at 6.3 years.

5. They’ll eat anything.

The omnivorous monkeys aren’t picky about their meals, and will eat everything from fruit to insects, ferns, roots, invertebrates, bird eggs, and, when times are tough, fish and even soil.

6. They have a distinct class system, and it’s definitely not democratic.

As a snow monkey, you’re born into your social class, which dictates your access to food. However, class rankings can change over time. In the case of the Lincoln Park Zoo, for instance, the new baby’s mother, Ono, is only a middle-ranking female, but she’s the first to give birth since the monkeys moved from Japan, which may change the group’s dynamic, zoo president Kevin Bell writes

7. Younger siblings dominate older ones.

Image Credit: Noneotuho via Wikimedia Commons // CC BY-SA 3.0

Snow monkeys inherit their dominance from their mother. Daughters outrank any monkey who is subordinate to her mother, as well as any of her older sisters [PDF]. Rank among sisters decreases as age increases. (Male snow monkeys leave their family after they mature.)

8. They play with rocks.

To make it easier to observe them, scientists studying macaques on the Japanese island of Koshima began feeding wild monkeys sweet potatoes and wheat starting in the late 1940s. As the monkeys began to get used to human rations, they began exhibiting novel behaviors in their newfound free time, like bashing rocks together. ”People smoke or fiddle with prayer or worry beads in their leisure time," researcher Michael Huffman told National Geographic of the phenomenon. "Stone handling is a similar situation."

9. They’ve been known to wash their food before eating.

In the ‘80s, Japanese primatologist Toshisada Nishida [PDF] observed a female Japanese macaque washing her sweet potato in water before eating it, including in seawater, which may have added the taste of salt to her meal as well as cleansing it of sand. 

10. They have their own culture.

Over the years, the potato-washing monkey, named Imo, taught this cleansing behavior to the rest of her family. Even years after her death, the group still washes their food—suggesting that Japanese macaques are capable of developing unique cultures.

11. They’re considered agricultural pests.

A 2011 report [PDF] estimated that the omnivorous Macaca fuscata causes more than $15.4 million in damage to crops and infrastructure each year. About 10,000 of the monkeys are killed each year in the name of crop protection.