Japanese Snow Macaque
Did you know that some monkeys love snow? Macaques, for example, can be found in more climates and habitats than any other primate except humans.
Japanese Macaques (Macaca fuscata) occupy the northernmost regions that range through the forested mountains and highlands of Japan. They thrive in winter temperatures that fall as low as 5ºF with snow more than three feet deep.
More commonly called Snow Monkeys, we are familiar with images of them bathing in hot thermal pools to keep warm in Japan’s icy winters. Interestingly, bathing in hot springs is a learned behavior. In the 1950’s, anthropologists believed that humans were the only animals that pass on learned behaviors from individual to individual and across generations, a process called "cultural transmission". Because it is fairly easy to observe Japanese Macaques living in troops in their natural environment, researchers determined that studying their behavior would provide accurate insight into whether they too engage in cultural transmission. Similar studies had been done with captive primates, but captive animals do not engage in natural behaviors.
In 1963, a young female snow monkey named Mukubili waded into a hot spring in the Nagano Mountains to retrieve some soybeans that had been thrown in by researchers who were provisioning the monkeys with food in an effort to keep them out of local orchards. She liked the warmth and soon other young monkeys joined her. At first the behavior caught on only with the young macaques and their mothers. Over some years, the rest of the troop took the plunge to find shelter in the 109º hot springs to escape the winter cold.
When they began to invade nearby hot tubs and human spas, it was decided to build the Nagano macaques their own hot springs.
The Japanese macaque is a medium sized, stocky monkey, about 2 to 4 feet long and weighing from 22 to 66 pounds, with a relatively short tail. Males are twice as large as females. Their coats range from gray to brown or mottled in color. In the winter they grow a heavy insulating coat to maintain their body temperatures. During the summer they have a lighter coat.
The Japanese macaque has a very human-like naked face and expressive eyes. In adulthood, the face and bottom become red. Like humans, all macaques have opposable thumbs that they use to manipulate objects. They use all four limbs to get around, but also walk just on their hind legs when holding something in both hands. They are very capable climbers and sleep in trees, either individually or snuggling together to keep warm. They do not make nests and they change sleep sites daily.
Diet and Lifestyle
Japanese macaques are adaptable frugivores, eating mostly fruit, as well as seeds, young leaves, flowers, tree bark, fungi, bird eggs, insects, and invertebrates such as snail, crabs and crayfish. The variety in their diet is mostly due to seasonal changes and the resulting abundance of food, as well as their large habitat range. They prefer to forage on the ground. Because they are primarily fruit eaters, it is likely that they help to disperse seeds.
Most can live to be 25-30 years of age in captivity and 8 to 10 years in the wild. They live in troops usually made up of 20 to 30 individuals, but sometimes including over 100. A major constraint on troop size is food availability.
Females remain in the same troop, usually for life. Rank for females is inherited matrilineally, with daughters receiving the rank of their mothers. Younger offspring are ranked higher than older siblings, so there is no advantage to being the first-born of a high-ranking mother.
There are strong social bonds between the members of a troop, especially among females. Females select their mate according to the rank of the male and how long he has been in the troop. She avoids choosing males whom she has mated with in the past 4-5 years. Therefore, the longer a male is in a troop, the fewer mating opportunities he has. For this reason, males often change troops. This mating strategy not only increases genetic diversity, but can also lessen the chances of inbreeding by offspring.
Males disperse from the troop around the time they reach sexual maturity and transfer among troops throughout their lives. Males emigrate to a new troop every 2-4 years, usually during mating season.
As with other primates, infant dependency is long. Males help with parental care. They carry young, huddle with them, groom and protect them.
Behavior and Play
Japanese macaques are gentle creatures that display frequent social interactions. They are seldom aggressive. Grooming helps maintain the intricate social bonds between them. Grooming partners reflect not only kinship lines, but also the group’s dominance hierarchy.
Young macaques spend a lot of time playing. They make snowballs and roll them along the ground to make them larger. This activity has no survival purpose. Entire troops of Japanese macaques engage in the activity simply because it is fun.
Culture and Communication
Provisioning of Japanese macaques with food has led to special developments and fascinating observations of their culture. One famous example of this is potato washing in a troop in Koshima, Japan. When researchers provisioned a troop by putting sweet potatoes along the beach to bring them out into the open, one old female named Imo began to wash the sand off of her sweet potato in water instead of brushing it off with her hand. Over time, this behavior spread to other members of the troop and was passed along from generation to generation. Potato washing became even more modified as they began washing their sweet potatoes in salt water rather than fresh to enhance the flavor.
Communication in all macaques is varied and complex. They usually use some combination of visual signals, vocalizations, and physical contact. Their bare faces, mobile lips, dramatic eyes, and body posture are used to successfully convey information about their moods and environment.
The IUCN lists Japanese macaques as "Least Concern".* However, like all other primates, are threatened by habitat destruction and human overpopulation. They live mainly in reserves, and in many cases, depend upon supplemental feeding by humans to survive the winter conditions.
*Conservation status update May 2016
As more development takes place in Japan, encounters between Japanese macaques and humans are becoming more frequent. They raid crops and are considered to be agricultural pests. As a result, they are shot; about 5,000 are killed per year, despite protection from the Japanese government. Snow monkeys have been officially protected in Japan since 1947. However, the rights of farmers have taken precedence over laws protecting the macaques that eat their crops
Today Japanese macaques are listed as threatened by the US Endangered Species Act. The subspecies found in Yakushima, Japan, is listed as endangered.
Like other primates, snow monkeys are capable of contracting many of the same diseases as humans. As a result, they are deemed useful for medical studies and research purposes.
The 100th Monkey
The story of Imo’s potato washing is retold in the book The 100th Monkey by Ken Keyes, Jr. as a parable to relate how cultural transmission can affect the collective unconscious to bring about social change. A moral of this story might be that threats of extinction can be reversed as a direct result of increased awareness and, most importantly, action toward change.
~ from our Spring 2006 Staying Connected newsletter
Lessons in Enjoying Snow
Historically, Japanese macaques were known as raiju (mythical beasts) and were the keepers of Raijin, the god of lightening and company in Shinto belief.
Of the 60 species and sub-species of macaques, the Japanese macaque (Macaca fuscata) is the most northern occupying non-human primate surviving in temperatures that drop to as low as 14 degrees during the winter months. Macaca fuscata is found in subalpine, deciduous and evergreen forests in the mountains of Japan. Today there are an estimated 150,000 snow monkeys living in Japan. Diets of these Old World Monkeys include: berries, invertebrates, eggs, bark, leaves, roots and buds.
Japanese macaques live in matrilineal troops ranging from 20 to 100 individuals which are ruled by an alpha female and alpha male. Females typically outnumber males in the troop 3 to 1 and are ranked by hierarchy that is inherited and passed from mother to infant. There is strong sexual dimorphism in this species with males weighing up to 31 pounds and females approximately 14 pounds. To keep warm these monkeys are blanketed with both thick soft course hairs on the outside and dense short tufts of hair serving as an undercoat.
This species is widely known for their intelligence. One noted cultural behavior is that of food washing. This behavior was first noted in a troop at Koshima island. Imo, a female monkey, was observed to wash her food in river water to first clean it and then salt water (perhaps for flavor?). This unique new behavior was then adopted by other members of the troop. This case study clearly proves that other species, both primate and non, are capable of learning and passing on behaviors, and therefore have unique and complex cultures.
Probably the most famous of Japanese macaque behavior is their luxurious bathing. In the winter months, monkeys gather together to soak in hot springs.
Research has also found specific accents in vocalizations that are used by different troops. And last but not least my favorite behavior, the making of snow balls. Snow balls are often made and played with amongst younger individuals in M. fuscata troops.
Macaques have larger brains than other monkey species. It is therefore no wonder that Sir David Attenborough wrote the “macaque is one of the most successful and versatile of all primates. If you wanted to pick a monkey that is bright, adaptable, versatile, resilient, enterprising, tough and capable of surviving in extreme conditions and taking on all corners, the macaque would win hands down.”
Although they are listed as Least Concern on the IUCN red list, Japanese macaques face serious threats from habitat loss, poaching and use in biomedical research.
Deforestation has led to loss of important habitat for these monkeys which, in turn, has led to human wildlife conflict. Japanese macaques have been known to raid homes and farms which have led to poaching, despite this being outlawed in Japan since 1947.
These monkeys are also used in biomedical research. Most commonly they are used for neurological studies and pharmaceutical testing. In addition, Creative Animodel has also described M. fuscata as being highly used in tests of bio-behavioral studies of attachment and parental behavior.
If you’ve read this page and familiarized yourself with the Japanese macaque, it is now your responsibility to share the news. Try forwarding this blog and/ or talking to at least 5 friends/ family about what you learned.
What does that mean?
Deciduous Forest: Forests that change seasonally. The word deciduous means to fall off at maturity. The opposite of deciduous is evergreen.
Matrilineal Society: Is based on a line of descent through the female. Offspring are traced back to the mother as opposed to a patrilineal society, from which descent is traced to the male.
Old Word Monkeys: Primates that fall into the superfamily Cercopithecoidea. These monkeys are native to Africa and Asia as opposed to New World Monkeys which occupy South America.
Sexual Dimorphism: Is the difference in physical form between males and females of the same species. This includes color, size and presence or absence of body parts. Examples of sexual dimorphism are: tusks in elephants, colors of feathers in birds of paradise, and body size and weight in primates.
Written by Kaitlyn-Elizabeth Foley for the January 2011 installment of her Letters from the Field blog series.
View video of wild Japanese snow macaques courtesy of ARKive.org