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The fur of the Japanese macaque ranges from grayish or yellowish brown to exclusively brown in color, with lighter-colored fur on the belly and around the face. The face is naked of fur and become red during adulthood. Males weigh about 25 pounds and are about 22.5 inches long, while females weigh about 20 pounds are are about 20.5 inches long. The tail is short, with an average length of 3 to 3.6 inches. Both sexes have cheek pouches in which to carry food while foraging.
Distribution and Habitat
As its name implies, the Japanese macaque is native to Japan. It is found on the main islands of Honshu, Shikoku, and Kyushu, as well as the smaller islands near the coasts of those same islands. It is the northernmost wild non-human primate species in the world.
The habitat of the Japanese macaque ranges from sub-tropical forest in the south to sub-arctic mountain forest in the north, but the common factor is always broadleaf forest. The Japanese macaque is rarely found in lowland areas, due to the high concentrations of human populations, but will on occasion raid fields for easy food.
Breeding takes place throughout the year. Males and females frequently have multiple partners within the same breeding season, but a female will typically refrain from mating with the same male more than once to lessen the chances of inbreeding. One young is born after a gestation period of five to six months, and will be nursed by its mother for up to two years. The entire troop participates in the care of young, with males being just as attentive as females. Sexual maturity is reached at about three years. Males can live up to 28 years in the wild, females up to 32.
Japanese macaques feed on over 213 species of plants, with fruits, nuts and seeds being favored over other plant parts. They also eat insects and other invertebrates, fungi, and even soil. Specific foods vary according to habitat and season.
Other Habits and Behaviors
Troop size ranges from 10 to 160 individuals, depending on the size of the dependent food supply, with the average being around 40. Home ranges average about 1.4 square miles in area, with smaller ranges common in areas with greater food potential. Females stay with their natal group, but males typically move from troop to troop over their lifetimes.
Social hierarchies exist in all troops, with dominance passing from mothers to daughters. Learning within a troop also tends to follow matrineal lines. In one classic case, a female was observed gleaning grain from sand by washing handfuls of sand in water and letting the grain float to the surface. She then taught the practice to her oldest daughter, who in turn passed it on to her younger siblings.
Japanese macaques are predominantly quadrupedal. Although they may leap from one tree to another, they are more likely to "walk" from place to place. And, even though they live in forests, Japanese macaques typically spend more time on the ground than in the trees. In winter, however, it is not uncommon to find entire troops huddled in one tree in an effort to conserve body heat. This is also the species often seen in television documentaries "lounging" in hot springs during the winter.
There are estimated to be about 100,000 Japanese macaques in the wild. Although protected by Japanese law, up to 1,000 or more individuals may be killed in any given year by farmers trying to protect their crops.
This page was last updated on January 26, 2017.