Japanese monkeys

The Japanese macaque (/məˈkɑːk/; Macaca fuscata), also known as the snow monkey, is a terrestrial Old World monkey species that is native to Japan. They get their name 'snow monkey' because they live in areas where snow covers the ground for months each year – no other nonhuman primate is more northern-living, nor lives in a colder climate. Individuals have brown-grey fur, red faces, and short tails. Two subspecies are known. In Japan, the species is known as Nihonzaru (ニホンザル, a combination of Nihon 日本 'Japan' + saru 猿 'monkey') to distinguish it from other primates, but the Japanese macaque is very familiar in Japan, so when Japanese people simply say saru, they usually have in mind the Japanese macaque. The Japanese macaque is sexually dimorphic. Males weigh on average 11.3 kg (25 lb), while females average 8.4 kg (19 lb). Macaques from colder areas tend to weigh more than ones from warmer areas. Male average height is 57.01 cm (22.44 in) and female average height is 52.28 cm (20.58 in). Their brain size is about 95 g (3.4 oz). Japanese macaques have short stumps for tails that average 92.51 mm (3.642 in) in males and 79.08 mm (3.113 in) in females. The macaque has a pinkish face and posterior. The rest of its body is covered in brown or greyish hair. The coat of the macaque is well-adapted to the cold and its thickness increases as temperatures decrease. The macaque can cope with temperatures as low as -20 °C (-4 °F). Macaques mostly move on all fours. They are semiterrestrial, 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. They have also been known to live much longer; males have lived up to 28 years and females up to 32 years. Japanese macaques live in matrilineal societies, and females stay in their natal groups for life, while males move out before they are sexually mature. Macaque groups tend to contain a number of adults of both sexes. In addition, a Japanese macaque troop contains several matrilines. These matrilines may exist in a dominance hierarchy with all members of a specific group ranking over members of a lower-ranking group. Temporary all-male groups also exist, composed of those that have recently left their natal groups and are about to transfer to another group. However, many males spend ample time away from any group and may leave and join several groups. Males within a group have a dominance hierarchy, with one male having alpha status. The dominance status of male macaques usually changes when a former alpha male leaves or dies. Other ways in which status changes is when an alpha male loses his rank or when a troop splits, leaving a new alpha position open. The longer a male is in a troop, the higher his status is likely to be. Females also exist in a stable dominance hierarchy, and a female's rank depends on her mother. Younger females tend to rank higher than their older siblings. Higher-ranking matrilines have greater social cohesion. Strong relationships with dominant females can allow dominant males to retain their rank when they otherwise would not. Females maintain both social relationships and hygiene through grooming. Grooming occurs regardless of climate or season. Females which are matrilineally related groom each other more often than unrelated individuals. Females will also groom unrelated females to maintain group cohesion and social relationships between different kinships in a troop. Nevertheless, a female will only groom a limited number of other females, even if the group expands. Females will also groom males, usually for hygienic purposes, but it can serve to attract dominant males to the group. Mothers pass their grooming techniques to their offspring most probably through social rather than genetic means. A male and female macaque form a pair bond and mate, feed, rest, and travel together, and this typically lasts 16 days on average during the mating season. Females enter into consortships with an average of four males a season. Higher-ranking males have longer consortships than their subordinates. In addition, higher-ranking males try to disrupt consortships of lower-ranking males. Females attempt to mate with males of any rank. However, dominant males mate more as they are more successful in mate guarding. The female decides whether mating takes place. In addition, dominance does not mean a male will successfully mate with a female. Males may also temporarily join another troop during the mating season and mate with the females. Females also engage in same-sex mounting. Such behavior is likely because of hormones and females are mounted more often by other females than males. It has been proposed that female Japanese macaques for unknown reasons are generally bisexual, rather than preferentially homo- or heterosexual.