Japanese macaque | |
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Conservation status | |
Scientific classification | |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Primates |
Family: | Cercopithecidae |
Genus: | Macaca |
Species: | M. fuscata |
Binomial name | |
Macaca fuscata Blyth, 1875 |
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Subspecies | |
Macaca fuscata fuscata |
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Japanese Macaque range (green — extant, black — extinct) |
The Japanese macaque ( /məˈkɑːk/;[2] Macaca fuscata), historically known as saru ("monkey"), but now known as Nihonzaru (Nihon "Japan" + saru) to distinguish it from other primates, is a terrestrial Old World monkey species native to Japan.
It is also sometimes known as the snow monkey from the fact that it lives in areas where snow covers the ground for months each year—no primate, with the exception of humans, is more northern-living, nor lives in a colder climate.[3][4]
Individuals have brown-grey fur, a red face, and a short tail. There are two subspecies[5]
An introduced free-ranging population has been living near Laredo, Texas[6] since 1972.[7][8][9]
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The Japanese macaque is sexually dimorphic. Males weigh on average 11.3 kg (24.91 lb) while females average 8.4 kg (18.52 lb).[10] Macaques from colder areas tend to weigh more than ones from warmer areas.[11] Male average height is 570.1 mm (22.44 in) and female average height is 522.8 mm (20.58 in).[10] Japanese macaques have short stumps for tails that average 92.51 mm (3.64 in) in males and 79.08 mm (3.11 in) in females.[11] The macaque has a pinkish face and posterior.[12] The rest of its body is covered in hair that can be brown, greyish, or yellowish.[10] The coat of the macaque is well adapted to the cold and its thickness increases as temperature decreases. The macaque can cope with temperatures as low as -20° C (-4° F).[13]
Macaques mostly move on all fours. They are semi-terrestrial with females spending more time in the trees and males spending more time on the ground. Macaques are known to leap. They are also great swimmers and have been reported to swim over half a kilometer.[10] The longevity for the macaque averages 6.3 years, (at least for females).[14] However, they have been known to live much longer; males have lived up to 28 years and females up to 32 years.[15]
The Japanese macaque is the northernmost-living non-human primate. It is found on three of the four main Japanese islands: Honshu, Shikoku, and Kyushu.[10] The northernmost populations live on the Shimokita Peninsula, the northernmost point of Honshu.[16] Several of Japan’s smaller islands are also inhabited by macaques.[10] The southernmost population lives on Yakushima Island and are a subspecies of the mainland macaques.[16] The total population of Japanese macaques has been estimated to be 114,431 monkeys.[10]
The Japanese macaque lives in a variety of habitats. It inhabits sub-tropical forests in the southern part of its range and sub-arctic forests in mountainous areas in the northern part of its range. It can be found in both warm and cool forests, though usually between those extremes.[16] This includes the deciduous forests of central and northern Japan and the broadleaf evergreen forests in the southwest of the islands. Warm temperate evergreen and broadleaf forests and the cool temperate deciduous broadleaf forests are the most important habitats for macaques.[10]
In 1972, a troop of about 150 Japanese macaques were relocated from Kyoto to a primate observatory in southwest Texas. The observatory is an enclosed ranch-style environment and the macaques have been allowed to roam with minimal human interference. At first many perished in the unfamiliar habitat, which consists of arid brushland. The macaques eventually adapted to the environment, and learned to forage for mesquite beans, cactus fruits, and other foods. The macaques flourished and by 1995 the troop consisted of 500 to 600 individuals. In 1996, hunters maimed or killed four escaped macaques, and as a result legal restrictions were publicly clarified and funds were raised to establish a new 186 acres (75 ha) sanctuary near Dilley, Texas.[17][18]
The Japanese macaque is omnivorous and will eat a variety of foods. Over 213 species of plant are included on the macaque’s diet.[19] It also eats insects and soil.[19] On Yakushima island, fruit, mature leaves and fallen seeds are primarily eaten.[20] Here the macaque also eats fungi, ferns, invertebrates, soil and other parts of plants.[20] In addition, on Yakushima, their diet varies seasonally with fruits being eaten in the summer and herbs being eaten in the winter.[21] Further north, macaque most eat foods like fruit and nuts to store fat for the winter, which is when food is scarce.[22] On the northern island of Kinkazan, macaques mostly eat fallen seeds, herbs, young leaves and fruits.[23] When preferred food items are not available, macaques will dig up underground plant parts such as roots or eat soil and fish.[19]
The Japanese macaque is diurnal. In colder areas, from autumn to early winter, the daily activities of macaques are made of three bouts of feed separated by other activities. In the winter, macaques have 2-4 feeding bouts each day with fewer daily activities. In the spring and summer, macaques have 2-3 bouts of feeding each day.[24] In warmer areas like Yakushima, daily activities are more varied. The typical day for a macaque is 20.9% inactive, 22.8% traveling, 23.5% feeding, 27.9% social grooming, 1.2% self-grooming, and 3.7% other activities.[25] Macaque usually sleep in trees but will also sleep on the ground and often sleep on flat rocks and fallen trees or behind them.[10] During the winter, macaques huddle together for warmth in sleeping grounds.[26] Macaques at Jigokudani Monkey Park are notable for visiting the hot springs in the winter to warm up.
Japanese macaques live in matrilineal groups[10] with females remaining in their natal groups for life and males emigrating before sexual maturity. [27] Macaque groups tend to contain both multiple males and multiple females.[10] In addition, a macaque troop contains multiple matrilines. These matrilines may exist in a dominance hierarchy with all members of a specific group ranking over members of a lower ranking group.[28] Temporary all-male groups also exist, composed of those that have recently left their natal groups and are about to transfer to another group.[10] However, many males spend a lot of time away from any group[29] and may leave and join several groups.[10]
Males within a group have a dominance hierarchy with one male having alpha status. The dominance status of male macaques usually changes with the death or departure of a former alpha male.[30] Other ways in which status changes is when an alpha male loses his rank or when a troop splits, leaving a new alpha position.[30] The longer a male is in a troop, the higher his status is likely to be.[31] Females also exist in a stable dominance hierarchy, and female offspring ranks are similar to those of their mothers. Younger females tend to rank higher than their older siblings.[28][32] Higher-ranking matrilines have greater social cohesion.[33] Strong relationships with dominant females can allow dominant males to retain their rank when they otherwise wouldn’t.[34]
Females maintain both social relationships and hygiene through grooming. Grooming occurs regardless of climate and seasonal difference.[35] Females who are matrilineally related groom each other more often than unrelated individuals.[36] Grooming between unrelated females does occur and serves to maintain group cohesion and social relationships between different kinships in a troop.[37] Nevertheless a female will only groom a small consort of other females even if the group increases in number.[37] Females will also groom males. This is usually for hygienic purposes but can serve to attract dominant males to the group.[38] Mothers pass their grooming techniques to their offspring most likely though social rather than genetic means.[39]
A key feature of Japanese macaque reproductive behavior is consortship. A male and female will form a pair bond and mate, feed, rest and travel together and this typically lasts 1.6 days on average during the mating season.[40] Female enter into consortships with an average of four males a season.[41] Higher-ranking males have longer consortships than their subordinates.[40] In addition, higher-ranking males will try to disrupt consortships of lower-ranking males.[42] Females will attempt to mate with males of all ranks. However, they are more likely to mate with dominant males as they are more successful in mate guarding.[43] It is the female that ultimately decides whether mating will occur. In addition, dominance does not insure mating opportunities with receptive females.[10] Many of the females’ copulations are with non-troop males who will leave soon after the mating season.[44] Females will also engage in same-sex mounting. Such behavior is likely linked to hormones and is more common than male mounting behavior.[45]
During the mating season, the face and genitalia of males turn deep red and the tail will stand erect to expose the bright genitals.[46] In addition, females' faces and anogenital regions turn scarlet. [46] Macaques will copulate both arboreally and terrestrially.[24] Macaques signal when they are really to mate by looking backward over a shoulder, remaining very still, or walking backwards towards the potential partner.[47] A female will emit a "smooth-late-high coo", or "squawk", "squeak", or produce an atonal "cackle" during copulation. Males have no copulatory vocalizations.
A macaque mother moves to the periphery of her troop to give birth in a private spot,[48] unless the group is moving by which the female will not separate from her troop.[49] Macaques usually give birth on the ground in the wild.[10] Infants are born with dark-brown hair.[50] They will consume their first solid food at 5-6 weeks and can forage independently from their mothers by 7 weeks. [50] A mother carries her infant ventrally for its first four weeks. After this time, the mother will carry her infant dorsally as well. Infants continue to be carried up to and past a year.[50] A mother and her infant have a somewhat avoidant relationship with other troop members and the mother only slowly resumes her social activities.[51] However, alloparenting has been observed, usually by females who have not had an infant of their own.[50] Male care of infants occurs in some groups but not in others: usually older males protecting, grooming, and carrying an infant as a female would.[52]
Infants have completed their locomotive development within 3–4 months.[53] When an infant is seven months old its mother discourages suckling; full weaning happens at least by its 18th month. In some populations, male infants tend to play in larger groups more often than females.[54] However, female infants have more social contact and groom more often than males.[54] Males prefer to associate with similar males by two years of age.[55] Females infants preferentially associate with other females of all age and sex classes as well as with infants and adult males.
During feeding or moving, Japanese macaques often emit "coos". These most likely maintain group cohesion, with females reinforcing their social ties.[56] When uttered, macaques respond in kind.[57] It is also uttered before grooming along with the "girney" call. Variants of the "girney" call have specific purposes and effect different outcomes.[58] This call also serves as appeasement between individuals during aggressive encounters.[59] Macaques have alarm calls for alerting to danger, and other calls to signal estrous. These sound similar. Threat calls are heard during aggressive encounters and are often uttered by supporters of those involved in antagonistic interactions. The individual being supported will support the caller in the future, fending off future attacks.[60]
The Japanese macaque is a very intelligent species. Researchers studying this species at Koshima island in Japan left sweet potatoes out on the beach for them to feed on, then witnessed one female, named Imo (Japanese for yam or potato), washing the food off with river water rather than brushing it off as the others were doing, and later even dipping her clean food into salty sea water.[61][62][63] After a while, others started to copy her behavior. This trait was then passed on from generation to generation, until eventually all except the oldest members of the troop were washing their food and even seasoning it in the sea.[61][62] She was similarly the first observed balling up wheat with air pockets, throwing it into the water, and waiting for it to float back up before picking it up and eating it free from dirt.[62][63] An entirely altered misaccount of this incident is the basis for the fictitious "hundredth monkey" effect .[64]
The macaque has other unusual behaviours, including bathing together in hot springs and rolling snowballs for fun.[62] Also in recent studies it has been found that the Japanese Macaque can develop different accents, like humans.[65] It was found that macaques in areas separated by only a few hundred miles can have very different pitches in their calls, their form of communication. The Japanese Macaque has been involved in many studies concerning neuroscience and also is used in drug testing.
Traditional manmade threats to macaques have been slash-and-burn agriculture, use of forest woods for construction and fuel, and hunting. These threats have declined due to social and economic changes in Japan since World War II.[66] But other threats have emerged. The replacement of natural forest with lumber plantation is the most serious threat.[66] As human settlement has grown, macaques have lost their fear of humans and have increased their presence in both rural and urban areas, with one macaque recorded living in central Tokyo for several months.[27]
The Japanese macaque has featured prominently in the religion, folklore, and art of Japan, as well as in proverbs and idiomatic expressions in the Japanese language. In Shinto belief, mythical beasts known as raijū sometimes appeared as monkeys and kept Raijin, the god of lightning, company. The "Three wise monkeys", who warn people to "see no evil, hear no evil, and speak no evil", are carved in relief over the door of the famous Tōshō-gū shrine in Nikkō. The Japanese macaque is a feature of several fairy tales, such as the tale of Momotaro and the fable about the The Crab and the Monkey.[67][68] As a monkey is a part of the Chinese zodiac, which has been used for centuries in Japan, the creature was sometimes portrayed in paintings of the Edo Period as a tangible metaphor for a particular year. The 19th-century artist and samurai Watanabe Kazan created a painting of a macaque.[69] During the Edo Period, numerous clasps for kimono or tobacco pouches (collectively called netsuke) were carved in the shape of macaques.[70]
Spoken references to macaques abound in the history of Japan. Before his rise to power, the famed samurai Toyotomi Hideyoshi was compared to a monkey in appearance and nicknamed Kozaru ("Little Monkey") by his lord and master, Oda Nobunaga.[71] This was a humorous jibe at first, but was later used pejoratively by Hideyoshi's rivals. In modern Japanese culture, because monkeys are considered to indulge their libido openly and frequently (much the same way as rabbits are thought to in some Western cultures), a man who is preoccupied with sex might be compared to or metaphorically referred to as a monkey, as might a romantically involved couple who are exceptionally amorous.