What kind of animal is a rhesus macaque? We will explain its characteristics, ecology, and habitat. It is a monkey of about the same size as a Japanese macaque and is found in the central part of Asia, mainly in northern India, and in China and Myanmar. The population is stable, but it is listed in the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).
What is Rhesus Monkey? Basic Stats
Rhesus macaques are a type of monkey classified in the genus Macaca, family Cercopithecidae, order Primates, class Mammalia. Their English name is Rhesus macaque, and their scientific name is Macaca mulatta. They are 40-60cm long and weigh 5-10kg. The list of information is as follows:
| Japanese（和名） | アカゲザル |
| English（英名） | Rhesus macaque |
| scientific name(学名) | Macaca mulatta |
| classification（分類） | Mammalia、 Primate、Cercopithecidae、Macaca 哺乳綱、霊長目、オナガザル科、マカク属 |
| IUCN Status(保全状況) | LEAST CONCERN |
| Length（体長） | 40-60cm |
| Weight（体重） | 5-10kg |
animal classification
- 界：動物界 Animalia
- 門：脊索動物門 Chordata
- 綱：哺乳綱 Mammalia
- 目：霊長目 Primates
- 亜目：直鼻猿亜目 Haplorhini
- 下目：狭鼻下目 Catarrhini
- 上科：オナガザル上科 Cercopithecoidea
- 科：オナガザル科 Cercopithecidae
- 亜科：オナガザル亜科 Cercopithecinae
- 属：マカク属 Macaca
- 種：アカゲザル Macaca mulatta
Habitat
Rhesus macaques are found in the wild, mainly in northern India, as well as in Afghanistan, China and Myanmar.
① Geographical Distribution
Natural Distribution (Place of Origin)
Rhesus macaques are one of the primates with the widest distribution in the world.
South Asia
India
Nepal
Bangladesh
Pakistan
Northern Southeast Asia
Myanmar
East Asia
China (wide area)
Southern edge of the Tibetan Plateau
👉 Characterized by an extremely wide range of latitudes and altitudes.
② Habitat Type (What kind of place do they live in?)
Adaptable to a wide variety of environments
Rhesus macaques are known for their extremely wide range of habitats.
Main Habitats
Forests
Tropical Rainforests
Deciduous Broadleaf Forests
Coniferous Forests
Grasslands and Shrubs
Rocky and Hilly Terrain
Rural Areas
Urban Areas (Temples, Parks, and City Centers)
👉 Neither “Forest Monkeys” nor “Mountain Monkeys,”
They are generalist primates that can live almost anywhere.
③ Adaptation to Altitude and Climate
Altitude
0m to over 4,000m above sea level
Also found in the Himalayan foothills
Climate
Tropical hot and humid
Temperate
Cold high altitudes
👉 Although not as cold-tolerant as Japanese macaques,
they are quite tolerant of the cold.
④ Coexistence with Humans (Special Habitat)
Adaptation to Human-Made Environments
Rhesus macaques are highly adaptable to human environments.
Temples and sacred sites (especially common in India)
Tourist attractions
Garbage dumps
Urban roofs and power lines
👉 By utilizing human food,
they have become successful urban wildlife.
⑤ Habitat Use Characteristics
Strongly terrestrial (combines tree and ground use)
Also uses waterside areas
Home ranges vary flexibly
Sedentary when resources are abundant, migratory when resources are scarce
What are its characteristics? What kind of creature is it?
Rhesus monkeys are small mammals and monkeys of about the same size as Japanese macaques. They have brown fur, a grayer upper body, and a red lower body. They live in a wide range of environments, including forests, swamp forests, and mountains at an altitude of nearly 3,000 meters, and are diurnal. Rhesus monkeys are mainly active on the ground, but also in trees.
Physical Characteristics
Physique
Body Length: 45-65cm
Weight:
Male: 6-12kg
Female: 4-8kg
Stout and muscular
Fur Color/Face
Fur: Yellowish-brown to Gray-brown
Face: Hairless and reddish
Eyes are forward-facing and expressive
👉 Overall impression of a “sturdy and realistic” appearance.
Tail
Medium length
Used for balance and emotional expression
Behavioral/Ecological Characteristics
① Highly intelligent
Excellent problem-solving skills
Learns through observation
Imitates human behavior
👉 Quickly learns how to find food and avoid danger.
② Omnivorous
Fruit, seeds, and leaves
Insects and small animals
Human food
👉 The main reason they are not picky about their habitat.
③ Strongly terrestrial
Uses both trees and the ground
Often wanders on the ground
Sociality/Personality
① Clear hierarchical society
Strict ranking system
Females remain in the group they were born in
Males move from group to group as they grow
👉 A clearly defined hierarchical society.
② Coexistence of aggression and cooperation
Cooperative within the group
Aggressive towards external enemies and rivals
Can be aggressive towards people
③ Facial expressions and communication
Wide range of facial expressions
Uses a variety of calls and gestures
Teethy expressions are a threat
Relationship with humans
Invades human habitats
May steal food
Some areas are religiously protected
👉
A creature with both “cute” and “scary” aspects.
What is their personality like?
Rhesus monkeys are very social animals and prefer to act in groups rather than alone. They live in groups of 10-50. Groups are matrilineal, and the offspring of high-ranking females are ranked higher than other females. They live in groups for their entire lives, but males may leave the group before reaching sexual maturity.
① Intelligence and learning ability
Learns by observation
Imitates successful examples
Distinguishes between dangerous and kind people
👉
Realistic, remembers who gets angry and who feeds.
② Social and values hierarchy
A clear hierarchy system
Does not defy superiors
Assails subordinates
👉
Highly skilled at reading the mood of the group.
③ Aggression: High, but not indiscriminate
May bite spontaneously
However, unprovoked attacks are rare
Threat → Wait and See → Act
👉
Appears to be rational but impatient
④ Cowardice and boldness coexist
Basically cautious
Bold in groups
Cautious alone
👉
Group psychology greatly influences personality.
⑤ Attitude toward humans
Closeness
Testing behavior
Targeting those who show weak reactions
👉
Evaluating humans as “part of the environment.”
⑥ Significant individual differences
Gentle individuals
Highly aggressive individuals
Curious individuals
👉
Personality changes depending on social rank, upbringing, and experience.
What is the ecology of rhesus monkeys?
Rhesus monkeys are omnivorous and live on fruits, bark, insects, bird eggs, etc. The breeding season is from February to March and from September to October, and they also give birth during these periods. Rhesus monkeys give birth once every two years. The average lifespan in the wild is about 15 years, and in captivity it can reach 26 to 30 years.
① Lifestyle/Behavior
Activity Period
Diurnal
Most active early morning to evening
Rests in trees or rocks at night
Range of Activity
Strongly terrestrial, but also good at climbing
Home range: several km² (varies greatly depending on the environment)
② Social Structure (Population Biology)
Basic Group Composition
Polymale/Polygyne
Population Size: 20-80 individuals (even over 100)
Mixed Age and Gender
Hierarchical Society
Strict Dominance System
Females inherit dominance matrilineally
Males move groups after maturity
👉 Very clear social rules.
③ Diet (What they eat)
Omnivorous
Plants:
Fruits
Leaves
Seeds
Animals:
Insects
Small vertebrates
Artificial Food:
Crops
Human Food Scraps
👉 Flexible and adaptable to the environment.
④ Breeding Biology
Breeding Season
Varies by region (most common in winter and spring)
Gestation and Birth
Gestation Period: Approximately 165 days
Little Birth: Usually 1 pup
Rearing
Mother-led
Other members of the group also participate (alloparenting)
⑤ Communication and Behavior
Communication Methods
Facial Expressions (teeth showing, eye contact)
Vocals
Body Contact (grooming)
Grooming
Maintaining Social Relationships
Stress Reduction
Alliance Formation
⑥ Movement and Foraging Strategies
Move over a Wide Area in Groups
Sedentary When Food is Abundant
Actively Utilizing the Human Environment
What are the natural enemies of rhesus macaques?
The natural enemies of rhesus macaques are tigers, leopards, clouded leopards, dholes, and crocodiles.
About baby rhesus monkeys
① Basic Information about the Pup
Number of Pups Born: Usually 1
Birth Weight: Approximately 450-550g
Gestation Period: Approximately 165 Days
Birth Season: Varies by Region (Usually Winter-Spring)
👉 Pups are born relatively light for primates, and have a long nursing period.
② Physical Characteristics
Body Color/Face
Immediately After Birth:
All Black Fur
Face: Pale Pink
Within a Few Weeks to a Few Months:
Fur Color Changes to Yellowish-Brown
Face: Reddish
👉 Stronger Contrast and More Conspicuous Than Adults
Body Shape
Slender Limbs and Large Head
Short Tail, Not Used Much at First
③ Behavioral Ecology (How They Behave)
Clinging Pups
Immediately After Birth:
Clings to Mother’s Belly or Chest
After a Few Weeks:
Starts Climbing on Her Back
👉 Primate-like Close Parenting
Exploration and Play
1-2 Months Old:
Exploring their surroundings
Playing with other young of the same age
Chasing
Wrestling
👉 Play helps them learn social skills.
④ Nursing and Changes in Diet
Nursing
Mainly breastfed (about 1 year)
Mothers are very protective
Weaning
Gradual weaning between 6-12 months
Shows interest in their mother’s food
⑤ Social Status and Learning
Inheritance of Maternal Rank
Female young
👉 Social rank is determined at birth
Mother’s rank = offspring’s rank
👉 Behavior toward other individuals is clearly different.
Are rhesus monkeys an endangered species?
Rhesus monkeys are widely used as experimental animals and are well bred. In Hinduism, rhesus monkeys are considered sacred animals, so there is no need to hunt them indiscriminately. Their population is stable, but they are listed in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).
IUCN (International Union for Conservation of Nature) Assessment
Classification: LC (Least Concern)
Meaning:
Current risk of extinction is low.
Population and distribution are stable or increasing.
👉 Globally, this is the safest conservation ranking.
Why is it not endangered?
① Extremely wide distribution range
Throughout Asia, from India to China
Found in lowlands to highlands, forests to cities
② Extremely adaptable to their environment
Omnivorous
Highly intelligent
Able to utilize human habitats
👉 Able to tolerate habitat destruction to some extent.
③ High fecundity
Birth usually involves one offspring, but
High reproductive success rate and stable populations
Can rhesus monkeys be kept as pets?
Rhesus monkeys are designated as specified alien species under the Invasive Alien Species Act in Japan, and are protected, so special permission is required to keep them, so it is not easy to keep them as pets. We recommend checking the information about events such as zoos.
① Are they actually kept in captivity?
Yes. They are kept all over the world.
Main breeding locations
Medical and biological research facilities
Universities and research centers
Zoos and specialized primate facilities
👉 Rhesus macaques
are one of the primates most extensively studied in the world.
② Why are they “possible” to keep in captivity?
There are biological factors that make them suitable for captivity.
They are omnivorous and have a wide range of diets.
They are highly adaptable to artificial environments.
Reproduction is relatively stable.
Group breeding is possible.
👉 However, this only applies to specialized facilities.
③ Why are private captivity nearly impossible?
① Legal and regulatory issues (especially in Japan)
Animal Welfare and Management Act
Many municipalities treat them as designated animals (dangerous animals).
Extremely strict standards for license, notification, and facility requirements.
High social risk in the event of escape.
👉 It is nearly impossible for individuals to legally keep them in Japan.
② Highly dangerous
Highly intelligent and unpredictable
Adults have a very powerful bite
Aggression is the result of territorial and hierarchical disputes
Even after becoming accustomed to humans, sudden attacks are common
👉 The “cute” period is short-lived.
③ Extremely difficult to care for
Keeping them alone can be psychologically abusive
Keeping them in groups requires a large facility
Lack of stimulation can lead to frequent behavioral problems
Long-lived animals, living for over 20 years
④ Risk of infectious diseases
Zoonotic diseases (e.g., B virus, etc.)
Possibility of serious infection from bites and scratches
👉 Extremely dangerous for humans.
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