Top photo-credit: Frans de Waal
Bottom photo-credit: Frans de Waal
Species: M. Fuscata
Subspecies: M. f. fuscata is the mainland subspecies and M. f. yakui is from the island of Yakushima.
Common Name: Japanese Macaque; Snow Monkey
Physical Description: They have brown to gray colored fur and short tails. They do not have hair on their face. As they go from infant to adult their face turns red. There is some sexual dimorphism. Males weigh more than females. The average weight for male: 11.3 kilograms and the average weight for female: 8.4 kilograms. Infant brain sizes range from 63.0g-76.0g and adult brain sizes range from 89.1g-132.2g. Males are 570.1 mm long and females are 522.8 mm long. There is a correlation between a Japanese Macaque’s weight and the region in which it lives in. Japanese Macaques who live in the northern regions weigh more than those in the south. Dentition: 2:1:2:3. They are quadrupedal. Females spend more time in the trees than males. They leap around but do not hang or swing and are really good swimmers.
Geographic location and range: The Japanese Macaque can be found on three of the four Japanese Islands: Honshu, Shikoku, and Kyushu. The environments that the Japanese Macaques live in range from one extreme to another, depending on whether they live in the north or south. Populations living at the northern tip live in a sub-arctic tropical environment. They generally go through very cold, snowy winters; which gives them the name “Snow Monkeys.” To stay warm, these Snow Monkeys often linger around in the nearby hot springs. Populations living at the southernmost end of Yakushima experience warm temperatures and a sub-tropical forest habitat. Japanese Macaque troops cover a territory size of 7.5-11.5 miles squared or smaller.
Diet: Japanese Macaques are omnivores. Their diets are determined by season and but mostly feed on nuts, berries, bark, fungi, roots, and seeds. On average 23.5% of their daily activity is spent on feeding while 20.9% is inactive, 22.8% is spent traveling, 27.9% is spent social grooming, 1.2% is spent self grooming, and 3.7% is spent on other activities.
Social Organization: Japanese Macaque groups average a size of 20-100 individuals; about 18% males, 32% female, 35% juveniles, and 15% infants. Groups are matrilineal meaning that females stay in the group they were born into and males venture to a new one before becoming sexually mature. Japanese Macaques have a pair mating system in which a male and female will stick together for about 1.6 days during the mating season. Females engage in over four pair matings during mating season. Males generally gain alpha male when there is a death or departure of the former alpha male. Seniority determines hierarchy. Female offspring take on similar rank to their mothers. Troops overlap 20% of the time but tend to avoid each other when they are close; but aggressive behavior will occur in order to protect food and to guard mates.
Birth Seasonality: Birth periods are between March and September
Gestation Length: 5 to 6 months
Number of Infants/Litter: 1 infant
Interbirth Interval: Every 2-3 years
Age of Sexual Maturity: 3 years
How long are estrus swellings present: Approximately 27 days during the mating season but irregular during the non-mating season.
Age of weaning: 2 years
Age of walking: 3-4 months
Offspring stay with mothers until what age: Males stay until they reach age of sexual maturity. Females remain for life.
Evidence of infanticide: Very rare, but in some troops, males commit infanticide to increase their chances of more offspring.
What kind of infant/father relationship: Males help carry, groom, and protect
Does the species communicate with noises: Yes, they make screaming calls and infants coo when they want contact from mothers.
Scents: Chemical signals which indicate estrous
Visual Cues: Yes, facial expressions and body postures. Example: Fear Grimace-lips are retracted so teeth are shown; Threat Expression- stare with mouth open but teeth covered.
What kinds: Physical contact, play, grooming, mating
Evidence of Culture: Japanese Macaques do have a culture. There are two specific examples of this:
1. Imo was the first Japanese Macaque to wash sweet potatoes in water in 1953. This behavior spread through the group with younger and some older ones adopting this behavior. In 1957 she put grains of wheat into water so they floated to the top and could be eaten; generations later, these behaviors are still being followed by the Japanese Macaques of Koshima Island.
2. Chonpe was found flossing her teeth with her own hair. She came up with three different techniques of doing it (“stretching with mouth,” “stretching with hand,” and “plucking”). This behavior has not spread through her troop as quickly as Imo’s behavior did because Chonpe does not have children, she has a mother and a sibling; therefore diffusion of knowledge is limited by her only sibling. Behaviors can be passed through relatives, but the mother-infant relationship has a big influence on the culture.
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Leca, Jean B., Noelle Gunst, and Michael A. Huffman. “The first case of dental flossing by a Japanese macaque (Macaca fuscata): implications for the determinants of behavioral innovation and the constraints on social transmission.” Primates 511 Apr. (2009): 13-22. Print.
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Gron KJ. 2007 April 26. Primate Factsheets. Japanese macaque (Macaca fuscata) Behavior. <http://pin.primate.wisc.edu/factsheets/entry/japanese_macaque/behv>.Acessed 2011 February 5.