JAPANESE MACAQUE BEHAVIOR: TROOPS, BATHS AND PASSED ON WASHING

JAPANESE MACAQUE BEHAVIOR

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Japanese macaques are terricolous (live mainly on the ground), arboreal (can live in trees), scansorial (good at climbing), diurnal (active mainly during the daytime), motile (move around as opposed to being stationary), sedentary (remain in the same area), social (associates with others of its species; forms social groups), and have dominance hierarchies (ranking systems or pecking orders among members of a long-term social group, where dominance status affects access to resources or mates). [Source: Brandon Hardman, Animal Diversity Web (ADW) /=]

Japanese macaques are mostly quadrupedal (use all four limbs) when on the ground. Females spend more time in trees than males, who are on the ground more. The home range of Japanese macaques is correlated with habitat type and averages 3.7 square kilometers. Day ranges vary with season and region. Southern Japanese macaques travel up to 3.2 kilometers a day during August, whereas during winter months they travel up to five kilometers. The day range of northern Japanese macaques, which face colder weather, is restricted to 0.85 kilometers for males and 0.93 kilometers for females. When food availability is high, they tend to travel more often. /=\

Japanese macaques form alliances, engage in petty squabbling and focus a great deal of attention on sex. Females display their superiority to inferiors by displaying their rear end in front of them. They are also quite clever. Monkeys in Mino near Osaka have learned to steal purses and wallets and take out the coins use them to buy drinks and snacks from vending machines.

Macaques spend a lot of time grooming, mostly sorting out tangles, removing and picking out fleas and insects. Grooming also is important in establishing and maintaining social bonds. According to Animal Diversity Web: Grooming helps to remove parasites and also to create and maintain social bonds within the troop. Most grooming is performed between kin, usually mothers and daughters. Japanese solicit individuals to groom them by approaching an individual and presenting the neck, face, flank, or even rump. Adult females solicit individuals more often than immature offspring. Two different vocalizations are associated with grooming: one when they attempt to groom and one while soliciting grooming. /=\

Play is also often observed among Japanese macaques. In the Arashiyama area near Kyoto macaques bang stones together for what appears to be no special reason other than the sheer pleasure of it. When the macaques had less free time, when they became less dependent on humans for food, they stopped playing with the stones. Infants play around but are always aware of where their mother is. Adolescent males wander off during the mating season but come back if no other troop is in the vicinity. Young Japanese macaques have been observed making snowballs and carrying them as play objects. Adult have been seen playing with snow balls made by young monkeys. Although these animals have been seen standing on top of snowballs and rolling them, no one has ever seen a Japanese macaque throw a snowball.

Japanese Macaque Communication

Japanese macaque communicate with vision, touch and sound and sense using vision, touch, sound and chemicals usually detected with smell. Brandon Hardman wrote in Animal Diversity Web: Japanese macaques are social primates and often vocalize within their troop and with related species. There are six groups of vocalizations used by Japanese macaques, including peaceful, defensive, aggressive, and warning vocalizations, which signal their mood. Other vocalizations include those that occur during female estrus and during infancy. More than 50 percent of vocalizations are peaceful or soothing in nature. [Source: Brandon Hardman, Animal Diversity Web (ADW) /=]

When a predator or human threat is spotted, Japanese macaques make a hollering vocalization to warm others in the group. Japanese macaques have also been observed hollering when Japanese giant flying squirrels glide above them. This may be out of fear, as they may look like other avian predators.

Japanese macaques also make body gestures and facial expressions. In captivity during certain threatening situations, they display different facial expressions, including ear-flattening, opening their mouth to display teeth, raising their eyebrows, and even erecting their ears. Subordinate individuals also grimace, lip-smack, display their hindquarters and practice gaze-avoidance. Display behaviors are also common in Japanese macaques, with several different postures such as kicking, shaking, and leaping. These expressions increase in frequency in males during mating season, but they do not increase in females.

Japanese Macaque Greetings Differ Depending on Their Region

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In February 2015, a Kyoto University research group announced in an article published in an academic online journal of the University of Chicago Press that the way wild Japanese macaque monkeys exchange greetings is different according to where they live. Japan News reported: “The group headed by Naofumi Nakagawa, an associate professor of the university, concluded this type of behaviour may relate to social customs rooted in respective monkey groups or the areas in which they live. This is also the case for human beings, who have various ways of greeting depending on countries or areas. [Source: Japan News, February 13, 2015]

“The researchers observed wild adult female Japanese macaques on Yakushima island, Kagoshima Prefecture, and compared the results to those found in macaques on Kinkasan Island, Miyagi Prefecture. When a female monkey encounters another in both groups, they sit facing each other and put their arms around each other’s bodies, Nakagawa explained.

“During the embrace, Kinkasan monkeys always face each other, widely rocking each other’s bodies back and forth. This differs from the monkeys on Yakushima that sometimes embrace from the back or side, and never engage in body-rocking movement. Furthermore, Yakushima monkeys knead each other’s fur by rhythmically opening and closing their palms as they embrace, which tends to take less time when compared to Kinkasan monkeys.

“Greeting behaviours of embracing were observed among monkeys in the Shimokita Peninsula, Aomori Prefecture, and the Hakusan mountainous area in Ishikawa Prefecture, while such behaviour was not seen among monkeys in the Arashiyama district in Kyoto Prefecture and the Takasakiyama district in Oita Prefecture. "Greeting behaviours of embracing are mainly seen on occasions in which antagonistic females almost fight," said Nakagawa. "It is a very cultural behaviour if it corresponds to reducing stress and evading trouble."

Japanese Macaque Troops and Group Behavior

Japanese macaques live and travel in troops with a female-bonded social structure that vary a great deal in size, sometimes with hundreds, even thousands, of members. Social behavior is often determined by the environment. In places where food is plentiful and there are no threats from humans there is no leader. Troops in the colder north tend to smaller, more egalitarian with a looser hierarchy of males and females

Females do not leave their natal group, whereas males leave the troop as they mature. Troops usually have an alpha male, but social bonds between females exceed those between males. Social structure is centered around matrilineal subgroups, typically comprised of an older female, her daughters and their offspring, and even granddaughters of the offspring and some adult males. Large groups are comprised of a number of matrilineal subgroups, as well as adult males that have joined the troop.

Troops are always on the move but generally stay within a well-defined territory. Females usually spend their entire lives in the troop of their birth while males leave and join other troops as they mature. From an biological perspective this helps insure genetic diversity. Males stay in the group of their mother when they are young but later leave and look for a new group to join. Sometimes when the troops get too large they split up, with dominant families forming one troop and weaker families forming the second troop. When these splits occur, males over the age of five leave the troop with their closest female relatives, which results in the increasing of each group's genetic diversity.

Japanese macaques exhibit some altruistic behaviors. Usually observed between mothers and daughters, these behaviors include protection, support, food-sharing, and alarm calling when a predator is observed. They may also practice co-feeding, in which a dominant individual gives access of food to subordinate individuals. Japanese macaques can also be quite cold to those who do not fall in line with the group. Some individuals have not been accepted as adults until they are 14, quite old for a monkey. "Even at three or four," anthropologist Lou Griffin told Discover magazine, "Japanese macaques still make serious social mistakes — like not remembering who exactly is the boss of their troop."

Japanese Macaque Group Hierarchy

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Hierarchal rankings are important to the social structure of Japanese macaques. High ranking individuals have access to food first, and thus low ranking females usually eat less nutritious food. Japanese macaques are nepotistic, meaning daughters inherit the rank of their mother. Each monkey's social status is largely determined by the status of its family in the troop. On rare occasions a particularly intelligent or aggressive individual will move up the social ladder and take its family with it. [Source: Brandon Hardman, Animal Diversity Web (ADW) /=]

Yu Kaigaishi, a research fellow at the Japan Society for the Promotion of Science, told The New York Times. Japanese macaques live in strictly hierarchical societies. Higher-ranking monkeys get greater access to food and mates. A male's rank is usually determined by how much time he has spent in a particular troop, while female macaques inherit the rank just below their mother's. Sometimes, macaques can violently seize higher ranks. [Source: Brandon Specktor, Live Science, January 22, 2022]

Each group is ruled by a dominant alpha male and alpha female. "They are the absolute," said Griffin. "The others meekly follow along." The responsibilities of the leaders include getting the troop up in the morning and leading it to food and breaking up fights. Describing the social organization of Japanese macaques, Griffin told Discover magazine, "Their pecking order is unmistakable. It is not simply a matter of size or strength, age or intelligence. They have a rigid class system almost as rigid as ours. Any of them can move up or down the social ladder, and sometimes we can only guess why."

Studies of monkeys in Oita found that the leader is not necessarily the biggest and strongest and even the most well respected. The leader of a group with 700 monkeys appeared to have attained his position through seniority. He was the oldest monkey and got the choice of the best food but he was often rejected by females, avoided fights and often had his food stolen by young monkeys.

Large Monkey Troops and Their Leaders

Zoro was the name given to leader of a 696-member troop of monkeys at Takasakiyama Natural Zoological Garden in Oita Prefecture. He became leader after wrestling a banana away from the previous leader in December 1998 and was still leader 11 years and 11 months later — a record in Japan — in March 2010 when he was 28 years old. In February 2011, a new leader became the head of the 816-member monkey troop at the monkey park in Mt. Takasaki in Oita. The new leader, Benz, who was believed to be 32 years old in 2011, became leader after the former leader disappeared about a month before. Benz had been leader to the park’s other monkey group when he was about nine years old, but it later expelled him over “romantic relations” with a female who was in his current group, according to the park.

In 2021, a nine-year-old female named Yakei upended macaque norms by seizing control of the 677-member troop at Takasakiyama Natural Zoological Garden through a violent primate coup. A New York Times article chronicled the monkey matriarch's rise to power: After assaulting her own mother and assuming the role of top female in the troop, Yakei embarked on a violent vendetta against her troop's four highest-ranking males, finally assuming the troop's coveted alpha position after beating up Nanchu — an elderly, 31-year-old male who had ruled the troop for five years. [Source: Brandon Specktor, Live Science, January 22, 2022]

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Brandon Specktor wrote in Live Science: Hostile takeovers by aggressive females are exceptionally rare in Japanese macaque society, with only a handful of recorded cases preceding Yakei's coup, These contests for position are almost exclusively between males, Kaigaishi said, which is why Yakei's rise to power was at once shocking and exciting to researchers who followed her case. After toppling the top male, Yakei even started to exhibit traditionally male behaviors, such as walking with her tail up and shaking tree branches with her body, experts at the reserve said.

However, after nearly a year in the top spot, Yakei's position may be in jeopardy during the chaos that is mating season — which typically runs from November to March. According to reserve researchers, an 18-year-old male named Luffy has been making unwanted courtship advances on Yakei since this year's breeding season began. Queen Yakei, meanwhile, seems to regard Luffy with fear. "I observed that Yakei showed a facial expression (known as 'fear grimace') typical of subordinate individuals against Luffy," Kaigaishi told the Times in an email. "Also, I observed Luffy pushing Yakei away to monopolize food." It's possible that Luffy is in the process of dethroning Yakei to rise as the troop's new alpha, the researchers said. Or, this could just be a simple matter of courtship, with Yakei showing Luffy that she isn't buying into his monkeyshines For now, Yakei holds onto her proverbial crown. Stay tuned to find out if her tale is about to get even more bananas.

Can a Female Macaque Become Leader of a 700-Member Troop?

In 2014, female Japanese macaque named Mirusa appeared to be making an effort to take the lead of the largest troop at Takasakiyama Natural Zoological Park, a position occupied only by males. Chihaya Inagaki wrote in the Asahi Shimbun: The 1,350 or so monkeys at the zoo belong to two groups that have a hierarchy determined mainly by power relations within the membership. Mirusa belongs to Group C, which has about 710 monkeys. She is 15, which equates to about her late 40s in human terms. [Source: Chihaya Inagaki, Asahi Shimbun, October 21, 2014]

“Each group is led by a boss, and until now only male monkeys have assumed that post. Mirusa began showing signs of increasing influence within Group C following mating season in 2013, which is mainly between November and March. Mirusa began sitting on a tree stump normally reserved for high-ranking male group members. She also began threatening male primates she felt were weaker than she was.

“Zoo workers who have observed the monkeys said Mirusa’s influence arises from the skillful way she gets on the good side of high-ranking male monkeys. She has been found frequently cleaning the fur and grooming the more powerful males, and she has also been observed taking provocative poses toward group bosses. When she is on the verge of losing a fight to a male monkey, Mirusa will scream and call a high-ranking male primate to her rescue.

“In May, zoo keepers tested Mirusa and the male who was ranked No. five in the group at the time. The test involves dropping peanuts on the ground to see which one picks them up first. The monkey that picks up the peanuts first is considered higher in rank. Zoo workers were surprised because on both occasions Mirusa picked up the nuts first. However, on another occasion, the male monkey picked up the food first, so it is still unclear if Mirusa has actually established a position high on the group’s totem pole.

“The female primate’s possible accession up the hierarchy comes after the disappearance of the highly esteemed boss of Group C known as Benz became a grave concern to zoo staffers in the fall of 2013. Benz had been boss of Group B before he moved to Group C and became its "head." After his death was confirmed, Group C’s new boss became Zorome, another male monkey, who had been No. two behind Benz

Sweet Potato Washing Behavior by Japanese Macaques

Japanese macaques can convey new ideas through social groups and pass on skills from one generation to the next. In 1953 Japanese researchers on the island of Kojima observed a female monkey they named Imo wash sand from a dirty sweet potato. Later, other members picked up on the idea and before long almost every member of her troop did it, as did their offspring. Some did it fresh in water. Some did in salt water, possibly because they liked the salty taste. Later Imo displayed an even more extraordinary behavior. When she found grains of wheat mixed with sand she tossed the mixture into water. The sand sank. The grain floated, and she was able to eat it. This habit also spread among the other members of the troop. Long after Imo died, macaques still carried sweet potatoes to the shore to wash them in the sea.

Kojma Island, near Koshima Island, is about 200 meters of the Ishinami Coast in eastern Kushima, Miyazaki Prefecture. Today about 120 macaques live there. On Kojima, the scientists often provided food for the monkeys by simply tossing a bag of sweet potatoes on the beach. Some monkeys placed one in their mouth and limped away holding another in their hand. Some developed an ability to fill their arms with sweet potatoes and run off on their hinds legs. Some scientists have speculated that early humans may have starting walking on two legs for similar reasons.

Japanese anthropologist Kinji Imanishi set up the research station at Koshima and pioneered behavioral research with primates years before Western primatologists like Jane Goodall and Diane Fossey. Ben Crair wrote in Smithsonian magazine: “ Imanishi and his students arrived on the same beach in 1948. They were looking for evidence of “pre-culture” in animals, some fundamental process that might also be the evolutionary root of humans’ diverse and sophisticated societies. Their goal was to research how “a simple behavioral mechanism has developed into a higher complex one,” wrote Syunzo Kawamura, a student of Imanshi’s. They started their research nearby on semi-wild horses and switched to monkeys after they noticed how well-organized their troop was. They met a local teacher named Satsue Mito, who was familiar with the monkeys of Koshima. In 1952, she helped them provision 20 monkeys with grain and sweet potatoes on forest trails and the beach. [Source: Ben Crair, Smithsonian magazine, January-February 2021]

“It was unusual for researchers to feed wild animals, but there were a lot of things unusual about the research Imanishi planned. He needed to make the monkeys tolerant of human observers, so they could identify every individual animal and make detailed observations on their behavior and social relationships over multiple generations. It would be another decade before Western scientists like Jane Goodall and Dian Fossey started to look at apes this way. Most Western scientists had been drilled to never anthropomorphize animals. They gave them alphanumeric identities instead of names and hadn’t undertaken long-term observations: They thought individual animals were interchangeable and lacked the minds for complex social relationships.

Imanishi and his team had been on Koshima for five years when one day they watched a 11/2-year-old monkey named Imo take a sweet potato and carry it to the edge of a stream. She dipped the potato in the water and wiped the sand from its skin. It may have tasted better that way, because she continued to clean her potatoes. The first monkeys to copy Imo were two who spent a lot of time near her: her mother and a playmate. Soon her relatives tried it too, and their playmates copied them in turn. Sweet-potato washing became the rage among younger monkeys. By 1958, 15 of the 19 juvenile monkeys were washing their potatoes.

“Masao Kawai, another of Imanishi’s students, described this phase as “pre-cultural propagation.” Imo had innovated a new behavior that spread to her peers. Age and sex both influenced its transmission: Younger monkeys and females were more likely to learn potato washing than adult monkeys and males. The next stage began when Imo and her peers matured and reproduced. Now the behavior spread to the next generation with every new baby, males as well as females, learning sweet-potato washing from its mother. Age and sex were no longer factors. “Pre-cultural pressure is working,” Kawai wrote. A new behavior had become fixed within the troop. By 1961, most of the monkeys had switched from washing their potatoes in the stream to the sea. This may have been because the sea’s water was more plentiful, though scientists thought they might like the flavor of the saltwater better: Some dipped the potato after every bite.

“Before Imanishi’s team arrived, the monkeys spent nearly all their time in the forest. Now they were also spending much of their time on the beach and had learned a new repertoire of behaviors. “Since the scientists first started feeding the macaques on Koshima island, a whole new life style has developed,” the Israeli researchers Eva Jablonka and Eytan Avital wrote. They called it an example of “cumulative cultural evolution.” Kawai was surprised by how quickly the monkeys adapted to the beach, given their initial aversion to the water. “We learn through the Koshima troop that once that strong traditional conservatism began to break down by some cause or others, it can easily be removed,” he wrote.

Hot-Spring-Enjoying Japanese Macaques

At the onsen at Jigokudani near Nagano, Japanese macaque famously seek respite from the winter cold by sitting in hot springs, a behavioral trait that has also been passed on. The habit began with a troop of monkeys that lived in the mountains in northern Honshu began using a hot spring used by humans. As they extended their range they discovered some volcanic hot springs. First only a few took a bath in the warm water. But after they tried it others did and the habit spread and became an activity that the monkeys now do every winter. Japanese macaques often huddle together for warmth, Their lack of strict social hierarchy allows high-ranking and low ranking individuals to share tight spaces without major incidents.

Monkeys started to bathe at the onsen at Jigokudani in 1963. “I was the first to see them go in,” retired professor Kazuo Wada from the Primate Research Institute at Kyoto University told Smithsonian magazine. He said, and he was studying the monkeys at Jigokudani. Ben Crair wrote in Smithsonian magazine: The park at that time provisioned a group of 23 monkeys with apples near an outdoor onsen for guests of a local ryokan, a traditional Japanese inn. The monkeys avoided the water until one day, an apple rolled into the bath. “A monkey went after it and realized it was warm,” Wada recalled. The monkey took another dip a few minutes later. Young monkeys watching from the edge became curious and soon tried the onsen for themselves. [Source: Ben Crair, Smithsonian magazine, January-February 2021]

“Both scientists and locals had been watching the Jigokudani monkeys for years, but no one had seen them enter the water until that moment. Within a few months, bathing was popular with the younger monkeys in the group. It was more than just a fad. Their babies learned to swim as well. Eventually, a third of all monkeys in the troop were bathing. In 1967, the park had to build a dedicated monkey onsen nearby for hygienic reasons, to make sure they weren’t bathing with humans.

“Monkey see, monkey do” is usually a derisive phrase for learning by imitation, but scientists at Jigokudani believed they were witnessing something profound. They were disciples of Kinji Imanishi, an ecologist and anthropologist who co-founded the Primate Research Institute in 1967. While Western scientists viewed life as a Darwinian struggle for survival, Imanishi believed harmony undergirded nature, and that culture was one expression of this harmony. He predicted you would find a simple form of culture in any animals that lived in a “perpetual social group” where individuals learned from one another and stayed together over many generations. Anthropologists had never paid attention to animals because most of them assumed “culture” was strictly a human endeavor. Starting in the 1950s, Imanishi’s students at Jigokudani and other sites across Japan discovered that was not the case.

According to the study conducted in 2014 by the team led by Rafaela Sayuri Takeshita from Primate Research Institute Kyoto University and released in April 2018 in the electronic edition of primatology journal Primates, stress levels of the monkeys were about 20 percent lower on average after bathing. Kyodo reported: The research team observed 12 female monkeys at the Jigokudani Yaen-Koen monkey park in Nagano Prefecture and collected their dung to measure hormone called glucocorticoid to estimate their stress levels. Takeshita said because Japanese monkeys grow more aggressive during the mating season in winter and their stress levels should rise accordingly, the study results point to the benefit of hot spring bathing. [Source: Kyodo, April 4, 2018]

In 2017, at Wild Monkey Osarunokuni Park in Kagawa Prefecture one group of huddling monkeys grew from about 10 in the miday sun to more than 100 by sunset, [Source: Yomiuri Shimbun. January 2017]

Japanese Macaque Dialects and Passed on Behaviors

A study of the calls of Japanese macaque living on Yakushima island in Kagoshima and calls of some of their relatives moved from the island to Inuyama, Aichi prefecture in 1956 indicates that monkeys have different dialects, The study by researchers at Kyoto University Primate Research Institute found that the calls of the two monkey populations were the same until around age nine months. After that the monkeys on Yakushima began making high-pitched calls that they monkey in Aichi didn’t make. Yakushima is much densely wooded that the area where the monkeys lived in Aichi and it is reasoned that the Yakushima monkeys make high pitched calls because these sounds carry better in dense foliage.

Because the monkeys come from the same genetic stock it is reasoned that have to have changed their vocal patterns to adapt to their environment. One of scientists involved in the project. Prof. Nobou Masataka, told the Asahi Shimbun: “We proved that the pitch of monkey cries is not determined by heredity, but is learned according to their environment. These results offer clues to discovering how differences in human languages developed.” Prof. Masataka, told the Yomiuri Shimbun: “Regional differences in monkey calls can be regarded as dialects. Monkey sounds indicate the linguistic roots of human being, as young monkeys pass on their calls from their parents or other monkeys in their groups.”

The sweet potato washing and hot spring baths described above are viewed as examples of behaviors passed on from one generation to the next by Japanese macaques, In 1982 a troop of Japanese macaques was brought to Texas where they developed a taste for cactus and mesquite and invented new "words" for these food as well as warning against rattlesnakes and scorpions. They also began to sweat, something they never did in Japan. Today there are around 600 Japanese macaques in Texas.

Ben Crair wrote in Smithsonian magazine: “At Arashiyama near Kyoto, some monkeys started to play with stones in the 1970s and the behavior spread in the same pattern as sweet-potato washing at Koshima and bathing at Jigokudani: first horizontally among peers and then from one generation to the next. The scientist who first observed the behavior, an American named Michael Huffman now at the Primate Research Institute, noticed different groups of monkeys developing their own ways of handling stones over time. In some groups, the monkeys rubbed the stones together; in others, they cuddled the stones or banged them on the ground. [Source: Ben Crair, Smithsonian magazine, January-February 2021]

Japanese Macaque Aggression

Squabbles are common but fights are rare. Conflicts among males are avoided by symbolical acknowledgment of dominant-submissive relationships. Subordinate males show their deference to superiors by turning backwards and moving their rump forward in an action known as "presenting." The dominate male responds by "mounting" the subordinate monkey and assuming the copulation position for a few seconds. After this formality is observed the two males can then forage peacefully together.

Most Japanese macaque fights are vocal not physical. Usually the winner is the monkey who screams down his opponent. Most knock-down-drag-out fights occur during the mating season. Japanese macaques are not adverse to using their sharp teeth on other monkeys. According to Griffin one of the worst punishments one monkey can inflict on another is "holding the other firmly in its teeth and then pinching it."

On a visit to the “monkey onsen” at Jigokudani Monkey Park, Ben Crair wrote in Smithsonian magazine: “The photos I’d seen before the trip gave an impression of relaxed little animals, but the scene was anything but Zen. Scientists describe Japanese macaque societies as “despotic” and “nepotistic.” Every monkey in a given group had a place in a linear dominance hierarchy, one for males and one for females, and they constantly displaced inferiors to reinforce their rank. The monkeys were vigilant as they picked grain from the snow, constantly looking over their shoulders to keep tabs on their neighbors: A higher-ranking monkey might drag them by the leg or sink its teeth into their neck. [Source: Ben Crair, Smithsonian magazine, January-February 2021]

Japanese Macaques Ride and Have Sex with Deer

Yakushima is an island south of Kyushu, the southernmost of Japan’s main islands. Ben Crair wrote in Smithsonian magazine: “About 10,000 Japanese macaques live on the island.” The deer there are “as small as dogs and nearly as unafraid of people. The monkeys were messy eaters, and deer followed them to pick up their scraps. A relationship developed, and monkeys sometimes groomed and rode the deer. At another research site near Osaka, monkeys sometimes even mounted deer in a rare example of interspecies sex. It’s possible that the deer were gentle partners for small-bodied adolescents who were routinely rejected by the opposite sex or risked physical harm from aggresive adults. “Future observations at this site will indicate whether this group-specific sexual oddity was a short-lived fad or the beginning of a culturally maintained phenomenon,” the researchers there wrote. [Source: Ben Crair, Smithsonian magazine, January-February 2021]

Maiya Focht wrote in Business Insider: Wildlife photographer Atsuyuki Ohshima captured a rare interaction between a macaque and a deer. The photographer says the macaque took a ride on the deer just for fun. The photo was recognized in the Natural History Museum's Wildlife Photographer of the Year competition. Ohshima took the rare photo Yakushima Island and titled "Forest Rodeo." [Source: Maiya Focht, Business Insider, September 13, 2023]

Ohshima snapped the photo just after the monkey catapulted itself onto a sika deer, using a tree as a springboard, he described on Instagram. Macaques have been observed riding sika deer before, scientists said. As Ohshima suggested, sometimes the monkeys just take the rides for fun. The deer clean up after the monkeys, eating the fruit the primates leave behind. In return, the monkeys groom the deers, hopping on their backs to pull off bugs.

But other times, a macaque's motivations may be less pure. Both male and female macaques have been caught trying to get it on with sika deer during mating season, like in the video below at around eight seconds in: Ohshima said that didn't seem to be occurring in this case in the official caption for the photo on the Natural History Museum's website.

Image Sources: Japan-Animals blog, Wolfgang Kaehler, JNTO, Japan Zone, British Museum

Text Sources: Animal Diversity Web animaldiversity.org ; National Geographic, Live Science, Yomiuri Shimbun, Japan National Tourist Organization (JNTO), Natural History magazine, David Attenborough books, New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Discover magazine, The New Yorker, Time, Reuters, Associated Press, AFP, Lonely Planet Guides, Wikipedia, The Guardian, Top Secret Animal Attack Files website and various books and other publications.

Last updated March 2025