Japanese macaque
Macaca fuscata

TAXONOMY

Suborder: Haplorrhini
Infraorder: Simiiformes
Superfamily: Cercopithecoidea
Family: Cercopithecidae
Subfamily: Cercopithecinae
Genus: Macaca
Species: M. fuscata
Subspecies: M. f. fuscata, M. f. yakui

Other names: Japanese macaque, Japanese monkey, Snow monkey; macaque japonais, macaque à face rouge (French); japansk makak (Swedish); macaca japonesa (Spanish); Nihon zaru (Japanese) (for vernacular names see Fooden & Aimi 2005:77); M. fuscata yakui: Yaku monkey; Yakushimazaru, Yakuzaru (Japanese).

Two subspecies of Japanese macaque have been described, Macaca fuscata fuscata and Macaca fuscata yakui. M. f. fuscata is the mainland subspecies of the Japanese macaque. M. f. yakui is restricted to the island of Yakushima at the southern limit of Macaca fuscata distribution and is distinguishable from M. fuscata due to differences in pelage and body size (Fooden & Aimi 2005).

MORPHOLOGY

Photo: Alisha Eisert

The fur of the Japanese macaque can vary among shades of brown from grey or yellow brown to exclusively brown (Fooden & Aimi 2005). Japanese macaques have a pinkish face and posterior with a short stump of a tail (Rowe 1996). There is a degree of sexual dimorphism between male and female Japanese macaques with the males weighing somewhat more than the females and on average having a longer body length than the females. The average body weight of the Japanese monkey is 11.3 kg (24.91 lb) (M) and 8.4 kg (18.52 lb) (F) (Fooden & Aimi 2005). In addition, there appears to be a correlation between climate and body weight, as Japanese monkeys from northern colder areas weigh more than those from warmer areas of Japan (Hamada et al. 1996). Average body length for males is 570.1 mm (22.44 in) and for females is 522.8 mm (20.58 in) (Fooden & Aimi 2005). The tail is short, averaging 92.51 mm (3.64 in) in males and 79.08 mm (3.11 in) in females (Hamada et al. 1996). Longevity for males has been confirmed as long as 28 years and into the 32nd year of life for females (Fedigan 1991; Nakamichi et al. 1995; Fedigan & Pavelka 2001). Actual average lifespan, however, is significantly shorter; with wild females living for an average of just 6.3 years (Takahata et al. 1998).

Japanese macaques are predominantly quadrupedal and can be considered semi-terrestrial. Females spend more time in trees than males and males spend more time on the ground than females. Leaping is seen in the Japanese macaque, but suspension from supports is not common (Chatani 2003). Japanese macaques are excellent swimmers and are reportedly able to swim distances of over half a kilometer (Mito 1980 cited in Fooden & Aimi 2005). This macaque's fur is a unique adaptation to cold, as fur thickness increases as habitat temperature decreases and allows the monkey to cope with winter temperatures as low as -20° C (-4° F) (Hori et al. 1977).

RANGE

The Japanese macaque is native to the islands of Japan. Of the four main Japanese islands, Hokkaido, Honshu, Shikoku, and Kyushu, Japanese macaques are found on all but Hokkaido, the northernmost (Fooden & Aimi 2005). Even though its range is restricted to the three southern main islands of Japan, the species nevertheless represents the northernmost wild populations of non-human primates in the world. The absolute northernmost Japanese macaque populations are found at the northern tip of the island of Honshu on the Shimokita peninsula (Izawa & Nishida 1963; Uehara 1975). These northern populations exhibit significant cold adaptation as northern Honshu can be snowbound for up to a third of the year (Izawa & Nishida 1963). Japanese macaques also inhabit several smaller islands near the coasts of Honshu, Shikoku, and Kyushu (Fooden & Aimi 2005).

The southernmost population of Japanese macaques is that on Yakushima Island off of the south coast of Japan and has been assigned its own subspecies, M.f.yakui (Uehara 1975; Hanya 2004). In February 1972, a complete group of Japanese macaques numbering 150 individuals was transplanted from Arashiyama, near Kyoto on Honshu to Laredo, Texas where it was established in an arid brushland habitat and grew, having reached 470 individuals by 1989 (Fedigan 1991). The total population of Japanese macaques has been estimated to be 114,431 individuals and likely numbers around 100,000 individuals in its natural habitat (Hashiba 1989; Fooden & Aimi 2005). The Japanese macaque is rarely found in lowland areas owing to the high levels of human habitation in those areas (Amagasa & Ito 1978 cited in Fooden & Aimi 2005). The Japanese macaque has been studied in the wild longer than most primate species, having been observed in numerous habitats and locations throughout Japan for over 50 years (Yamagiwa & Hill 1998). Since the 1950's, study of Japanese macaques has been undertaken at Arashiyama, near Kyoto (Huffman 1991a). This long-term study site has not only served to provide information as to the long-term changes within a Japanese macaque population, but also to serve as the source of the introduced Arashiyama West troop in Texas which has provided not only a study site for the Japanese macaque in north America, but a place to study adaptations of the species to a new habitat (Fedigan 1991). Within their range, the distribution of the Japanese macaque is expanding, at least partially as a result of the species losing their fear of humans, coupled with demographic and economic shifts in the Japanese human population (Watanabe & Muroyama 2005). This expansion may be misleading as to the status of the species however, because within the range, the total population is significantly limited by the distribution of the natural broadleaf forest that is available. In addition, the expansion of the range distribution was found to be correlated with the reduction of forests (Hashiba 1989).

HABITAT

Due to variations in the latitude and altitude of the Japanese islands, the habitat of the Japanese macaque varies greatly between the extremes of its distribution. Near the southern end of the population distribution, habitats include sub-tropical forest and at the northernmost reaches, sub-arctic forest is found in mountainous regions. Between these two extremes, both warm and cool temperate forests are found (Uehara 1975). These types of forest include both the deciduous forests of central and northern Japan and the broadleaf evergreen forests of the southwest of the islands. As is expected in a variable range, there is a large spectrum of vegetation within the distribution of the Japanese macaque (Suzuki 1965). The highest elevation at which the Japanese macaque has been reported is 3180 m (10,433 ft) (Izumiyama pers. comm. cited in Fooden & Aimi 2005). Of the habitats of the Japanese macaque, the two most important are the warm temperate evergreen broadleaf forest and the cool temperate deciduous broadleaf forest (Fooden & Aimi 2005). In the northern deciduous forests, leaves are absent from the trees for up to 5 months of the year (Suzuki 1965). Near the northern end of the range in the cool temperate deciduous broadleaf forest on the island of Kinkazan, annual rainfall averages 1500mm (59.06 in) with an average temperature of 11° C (51.8° F). At the extreme southern end of the macaque range on the island of Yakushima in warm temperate evergreen broadleaf forest, annual rainfall averages 3000mm (118.11 in) with an average temperature of 20° C (68° F). During the winter in high altitude or latitude areas of the Japanese macaque range, snow is often quite deep, having been recorded on the Shimokita peninsula and in the Shiga Heights in central Honshu to be between 2-3 meters deep during the winter (Izawa & Nishida 1963; Hori et al. 1977).

ECOLOGY

Photo: Frans de Waal

The omnivorous Japanese macaque is not a picky eater and will eat a great variety of foods including over 213 species of plant (Koganezawa 1975). Other main foods eaten include insects and soil (Koganezawa 1975). As expected, variable types of foods are available in different habitats and in some cases food availability is profoundly seasonal. In the south of the range in temperate evergreen broadleaf forest of Yakushima island, fruit predominates in the diet. At this location, the macaques will eat fungi, ferns, invertebrates, soil and other parts of plants, but the main foods were fruits, mature leaves, and fallen seeds (Maruhashi 1980; Agetsuma & Nakagawa 1998). Seasonality of the diet is seen on Yakushima, with a greater number of fruits being eaten in the summer and more herbs being eaten in the winter (Hanya 2004). In the deciduous broadleaf forests habitat of the north where food is scarce in the winter, the species must eat surplus high quality foods such as fruits and nuts prior to winter to store enough fat to survive through the lean winter (Hanya et al. 2006). This storage of fat is important because during snowbound winter months the only available foods are dead and poor in nutrition, including leaves and bark (Tsuji et al. 2006). In the deciduous broadleaf forest habitat on the northern island of Kinkazan, food items are mainly fallen seeds, herbs, young leaves and fruits (Agetsuma & Nakagawa 1998). The Japanese macaque has been observed digging up underground plant parts such as roots, eating soil, and consuming raw fish if other preferred food items are not to be found (Koganezawa 1975; Watanabe 1989; Iguchi & Izawa 1990).

The average group size of the Japanese macaque is 41 individuals but they can range from 10 to as large as 161 (Fooden & Aimi 2005). If provisioned, groups are typically larger than wild groups and in an extreme example a provisioned group grew to over a thousand individuals (Sugiyama & Ohsawa 1988; Fooden & Aimi 2005). The home range averages around 3.7 km² (1.43 mi²) and correlates with habitat type (Fooden & Aimi 2005). Home range decreases with access to cultivated land, as this provides concentrated food sources which the macaque troops can utilize (Izumiyama et al. 2003). There is also pronounced seasonality of daily path length, even in the southern reaches of the Japanese macaque range on Yakushima. At this location, the daily path decreased from an average of 2.0 km (1.24 mi) per day during August and September to 1.2 km (.75 mi) per day later in winter (Maruhashi 1979 cited in Maruhashi 1981). In habitats further north during the winter, movement is even further restricted, averaging only .577 km (.36mi) for females and .529km (.33 mi) for males (Koganesawa 1986). As less food is available in the winter and more in the summer and fall, daily travel seems to be directly influenced by food availability; with less food there less travel (Yotsumoto 1976).

Photo: Alisha Eisert

The Japanese macaque is diurnal. Daily activities vary with the seasons as well as with habitat. In colder areas during the summer and fall when food is abundant, discrete daily patterns of activity emerge with little variation. In the winter and spring when less food is available, levels of activity fall and vary significantly from day to day (Yotsumoto 1976). In the autumn to early winter, the daily activities are characterized by three bouts of feeding separated by other activities. In the winter, two to four periods of feeding are observed with conspicuously less daily activity. Finally, in the spring and summer, there are two or three bouts of feeding per day (Yotsumoto 1976). The macaques typically sleep in trees but they also sleep on the ground, often on flat rocks and fallen trees or behind rocks or fallen trees (Wada & Tokida 1985 cited in Fooden & Aimi 2005; Takahashi 1997). In the winter, Japanese macaques will huddle together on the ground for warmth in sleeping groups which grow larger with lower temperatures (Takahashi 1997). In warmer areas of the Japanese macaque range on the island of Yakushima, daily activities were highly variable but time is spent on average, 20.9% inactive, 22.8% traveling, 23.5% feeding, 27.9% social grooming, 1.2% self-grooming, and 3.7% other activities (Maruhashi 1981). In Shiga Heights in central Japan, the macaques enter and remain in hot springs in the winter, probably to regulate their body temperature behaviorally (Hori et al. 1977).

Japanese macaques are preyed upon by several species including feral dogs and Mountain Hawk Eagles (Spizaetus nipalensis) (Miyamoto 1976 cited in Fooden & Aimi 2005; Iida 1999). In addition, raccoon dogs (Nyctereutes procyonoides) may be a predator of the Japanese macaques, especially infants (Iwamoto 1974). Japanese macaques are also killed in Japan when their crop-raiding and interactions with humans become a problem. The annual kill surpassed 10,000 individuals annually in 1998 (Watanabe & Muroyama 2005). This is significant because this annual kill represents around a tenth of the entire estimated population.

Content last modified: April 26, 2007

Written by Kurt Gron. Reviewed by Sarah Turner.

Cite this page as:
Gron KJ. 2007 April 26. Primate Factsheets: Japanese macaque (Macaca fuscata) Taxonomy, Morphology, & Ecology . <http://pin.primate.wisc.edu/factsheets/entry/Japanese_macaque>. Accessed 2014 April 23.