Japanese Macaque

The Japanese macaque is a medium-sized Monkey found in a variety of different habitats throughout Japan. The Japanese macaque is also known as the “snow monkey” as they are often found living in colder regions of the country where heavy snowfall is common during the winter. They are the world’s most northern living monkey species and have adapted incredibly to their surroundings and changing seasons. There are two different subspecies of Japanese macaque, one which is found across northern and mainland Japan, and the other is restricted to one of the country’s southern islands. The two differ very slightly in size and appearance.

Scientific Name and Species

The Japanese macaque, (Macaca fuscata), is an Old World monkey species that is native to Japan. There are two subspecies:

• The Yakushima macaque (Macaca fuscata yakui), can be found on Yakushima Island and is also known as the Yaku macaque. These macaques are smaller and stockier than their northern counterparts and have black hands and feet. Adult males have a “momoware”, which parts their hair in the middle.
• Snow monkey (Macaca fuscata), lives in the colder regions of Japan and is renowned for bathing in hot springs. They have thick brown or grayish fur and pink hairless faces and posteriors.

Evolution

The macaque lineage originated around 9 million years ago in Africa, with modern macaques diverging around 5 – 6 million years ago. Those five species are the eastern rhesus macaque (Macaca mulatta), the long-tailed macaque (M. fascicularis), the Japanese macaque (M. fuscata), the pig-tailed macaque (M. nemestria), and the bonnet macaque (M. radiata). The Japanese macaque differentiated from the eastern rhesus macaque during the Pleistocene and the two are closely related. Japanese macaques colonized Japan after the separation of the two species, between 0.31 and 0.88 million years ago. Some scientists do not believe there is enough genetic evidence to consider the two types of Japanese macaques as two separate subspecies.

Anatomy and Appearance

The Japanese macaque has a stocky body with a naked, red face that looks astonishingly human. Their thick, furry coat is usually grey or brown in color, sometimes with a slightly mottled pattern, and grows thicker during the winter months to allow the Japanese macaque to stay warm in freezing conditions. Like other monkey species, the Japanese macaque has opposable thumbs, allowing it to grasp and hold objects and is able to walk on just its hind legs when it has something in its hands. The Japanese macaque also has large pouches in its cheeks, to allow the animal to store food whilst foraging. They have a relatively short tail for their body size (in the same way as other primarily ground-dwelling Monkeys), and males tend to be somewhat larger than their female counterparts.

Distribution and Habitat

The Japanese Macaque is found in four separate regions in Japan throughout a variety of habitats from subtropical jungles to hot mountain springs, in forested hills, across highlands, and high up in the mountains. In the northern and central parts of Japan, Japanese macaques have to withstand seasonal changes with temperatures ranging from -15 degrees Centigrade in the winter to more than 23 in the summer, where the vegetation primarily consists of deciduous trees and conifers. In their most southern range, on the island of Yaku-Shima, the Japanese macaques live amongst tropical broad-leaf forests that are subjected to less seasonal change. In central Japan, the Japanese macaques are found in the mountains, where they warm themselves in the hot springs that are heated by nearby volcanoes.

Behavior and Lifestyle

Japanese macaques live together in troops that are led by the alpha male and usually consist of between 20 and 30 individuals. The alpha male not only helps to sire young, but also decides where the troop should go, and protects it from both predators and other Japanese macaque troops. Social rank is very important in Japanese macaque society and consists of both males and females, with the male’s rank often determined by his age. Offspring are thought to inherit the rank of their mother. Japanese macaques are incredibly sociable animals, particularly the females who tend to remain in the same troop for their whole lives and spend their time together, grooming and raising the troop’s young.

Reproduction and Life Cycles

Female Japanese macaques tend to reach sexual maturity about a year earlier than males, between the ages of four and five. She usually chooses her mate by his rank, and after a gestation period that lasts for up to 6 months, the female gives birth to a single infant. Baby Japanese macaques are incredibly dependent on their mother and remain clinging to her for their first couple of years, meaning that mother and baby often have a very close bond. Once weaned, males often leave the troop and spend their lives traveling between others, while females generally remain in the same troop that they were born into. Japanese macaques tend to live for a relatively long time, often reaching age 30 or more.

Diet and Prey

The Japanese macaque is an omnivorous animal meaning that it forages for both plants and smaller animals in order to survive. Unlike a number of other monkey species, Japanese macaques are primarily ground-dwelling so the majority of their foraging is done on the ground. They mainly eat fruits, berries, seeds, young leaves, and flowers which they pick from the surrounding vegetation before storing them in their cheek pouches, so that they can continue to gather more. They also supplement their diet with Crabs, Insects, and birds’ eggs particularly during the colder winter months when there are slim pickings on the branches. Japanese macaque babies feed on their mother’s milk until they are able to begin eating more solid foods.

Predators and Threats

Due to their fairly large size and diverse habitat ranges, the Japanese macaque has no real predators in their natural environment, perhaps with the exception of the occasional hungry Wolf or feral Dog. Humans are the primary threat to the Japanese macaque as they are often killed by farmers when they approach livestock and crops. However, the only reason that these conflicts occur is that the Japanese macaque is being pushed into smaller and smaller pockets of its native ranges, due to deforestation and growing human settlements. During the colder winter months, Japanese macaque individuals in the north are also known to sleep in the deciduous trees to protect them from being buried in large amounts of snow during the night.

Interesting Facts and Features

The females are actually very picky when choosing a mate, as they will not mate with a male Japanese macaque that they have mated within the past few years, to prevent interbreeding within the troop. Japanese macaques, particularly in the north, have different home ranges for the changing seasons which leads to their wide variety in diet and different habitats. They are incredibly intelligent and adaptable animals and are known to pass new behaviors through the generations. In the mid-1900s a female was seen entering a hot spring to gather dropped soybeans and today, whole troops can be seen resting in the steaming waters to keep themselves warm.

Relationship with Humans

Like many of the 22 monkey species found across Japan, the Japanese macaque is often loved and protected by the native people. However, growing human settlements and land clearance for logging and agriculture has meant that Japanese macaques have lost vast areas of their natural habitats, and often have to approach farmland in order to find better food supplies. It is estimated that, despite being a protected species in Japan today, around 5,000 Japanese macaque individuals are killed every year by farmers who claim to be protecting their livestock and their crops. In the Nagano Mountains in central Japan though, the Japanese macaques that bathe in the hot springs have become one of the country’s most desirable tourist attractions.

Conservation Status and Life Today

Today, the Japanese macaque has been listed as a Threatened species by the IUCN, with the southern subspecies of the Japanese macaque listed as Endangered. It is estimated that there could be as few as 50,000 individuals remaining in Japan today, but numbers are still declining particularly seeing that they are often killed, as they are seen as pests by local people.