Excellent choice — here is a deep, no-pictures scientific overview of the Stump-tailed Macaque (Macaca arctoides), a distinctive and fascinating Old World monkey species native to Southeast Asia.

🐒 Stump-tailed Macaque (Macaca arctoides)

🔹 Taxonomy

Order: Primates
Family: Cercopithecidae (Old World Monkeys)
Genus: Macaca
Species: M. arctoides
Common names: Stump-tailed macaque, Bear macaque
Authority: (I. Geoffroy, 1831)

🌍 Distribution & Range

Native to Southeast and South Asia, occupying a broad but fragmented range:

Eastern India (Assam, Arunachal Pradesh)
Bangladesh
Myanmar (Burma)
Thailand
Laos
Vietnam
Cambodia
Southern China (Yunnan and Guangxi provinces)
Peninsular Malaysia

Elevational range: up to ~2000 m above sea level, primarily in humid tropical and subtropical forests.

🏞️ Habitat

Prefers evergreen and semi-evergreen forests, including:

Primary forests with dense canopy cover
Secondary forests and bamboo thickets
Montane and hill forests
Riverine forest edges
Occasionally plantation mosaics near forested regions

They are highly terrestrial — spending most of their time on the ground — but capable climbers when foraging or evading predators.

🧬 Physical Description

A medium-to-large macaque, strongly built and easily recognized by its facial features and tail.

Feature	Description
Head & Face	Bare, dark red to purplish face that becomes brighter with age; expressive brow ridges
Body length	45–65 cm (males larger)
Tail	Very short — ~3–7 cm (“stump-tailed”)
Weight	Males: 9–15 kg; Females: 6–9 kg
Fur	Thick, shaggy, dark brown coat; lighter underparts
Distinctive trait	Bare red face and rump give a “bear-like” appearance

Older individuals may become almost bald-faced, giving rise to the nickname “bear macaque.”

🧠 Behavior & Social Structure

Highly social and intelligent species, typical of the Macaca genus.

Group structure

Multi-male, multi-female groups (average 15–40 individuals)
Matriarchal hierarchy, with dominant females influencing group movement
Males may transfer between groups upon reaching maturity

Social behavior

Frequent grooming strengthens social bonds
Play behavior common in juveniles
Adults display cooperation during foraging and collective vigilance

Although more terrestrial than other macaques, they still sleep in trees at night for safety.

🍼 Reproduction

Breeding season: varies regionally, but often October–March
Gestation: ~170–180 days
Offspring: typically one infant
Interbirth interval: 1.5–2 years
Infants are carried ventrally, then dorsally as they grow
Both sexes reach sexual maturity around 4–5 years

Females exhibit sexual swellings, and group males often form protective alliances around receptive females.

🍃 Diet

Omnivorous and opportunistic — diet shifts with season and habitat.

Primary foods:

Fruits and seeds
Leaves, shoots, bamboo
Roots and tubers
Insects, snails, and small vertebrates
Occasionally bird eggs or crop plants (in human-modified areas)

Known to forage both on the forest floor and in lower canopies.

🧩 Ecology & Role

Acts as a seed disperser, contributing to forest regeneration
Ground foraging promotes nutrient turnover and soil mixing
Competes with other macaques (e.g. M. nemestrina) where ranges overlap
Serves as prey for leopards, clouded leopards, and large birds of prey

⚖️ Conservation Status

IUCN Red List: Vulnerable (VU)
Population trend: Declining

Major threats:

Deforestation and habitat fragmentation
Hunting and poaching (for meat and traditional medicine)
Human–wildlife conflict near agricultural areas
Pet trade and illegal capture

Populations most secure in protected forests of Thailand and Vietnam.

🏞️ Conservation Measures

Legal protection in most range countries
Occurs in several national parks and reserves, e.g.:
- Nam Nao and Khao Yai National Parks (Thailand)
- Cat Tien National Park (Vietnam)
- Nam Et–Phou Louey (Laos)
Captive breeding programs active in some zoological institutions
Conservation priorities:
- Maintain continuous forest corridors
- Promote anti-poaching enforcement
- Increase community awareness and reduce hunting pressure

🧬 Evolutionary Notes

Member of the “sinica group” of macaques
Closely related to Assam macaque (M. assamensis) and Tibetan macaque (M. thibetana)
Molecular data suggest adaptation to cooler, montane environments during the Pleistocene

✅ Summary Table

Feature	Detail
Size	Medium-large macaque (males up to 15 kg)
Distinctive trait	Short “stump” tail; red bare face
Habitat	Moist evergreen & montane forests
Behavior	Terrestrial, social, diurnal
Diet	Fruits, leaves, invertebrates
Reproduction	Single young; gestation ~6 months
Conservation	Vulnerable; population decreasing