Size & Build: This is a medium-sized, slender macaque with a characteristically long tail. The head and body length measures 40 to 47 cm (15.7 to 18.5 in) . The tail is notably longer than the body, typically 50 to 60 cm (19.7 to 23.6 in) in length, which aids in balance during arboreal locomotion .
Key Field Marks: The most defining feature is its extraordinarily long tail . The face is generally brownish-grey or pinkish-brown with prominent cheek whiskers . Males are distinguished by a distinctive mustache, while females have a beard . Both sexes often have white eyelids near the nose .
Sexual Dimorphism: Sexual dimorphism in size is pronounced. Males are significantly larger, weighing 4.8 to 8.3 kg (10.6 to 18.3 lbs), while females weigh 3.0 to 5.7 kg (6.6 to 12.6 lbs), approximately 69% of average male weight . Males also possess much larger canine teeth .
Similar Species: It can be confused with other macaque species within its range, such as the rhesus macaque (Macaca mulatta), with which it hybridizes in mainland Southeast Asia . The Long-tailed Macaque is generally more gracile and has a significantly longer tail relative to its body size compared to its stockier, shorter-tailed relatives.
Subspecies/Variants: Considerable geographical variation exists, with at least ten recognized subspecies that differ primarily in pelage color, tail length, and cheek whisker patterns . Key subspecies include the common long-tailed macaque (M. f. fascicularis), the Burmese long-tailed macaque (M. f. aureus), and the Con Song long-tailed macaque (M. f. condorensis) found in Vietnam . Most subspecies are isolated on small islands
Fur Coloration: The body fur is variable, ranging from grey-brown to reddish-brown on the back and limbs, with lighter, often pale grey or cream-colored underparts . The fur on the head sweeps back, sometimes forming a crest .
Soft Parts: The face has bare skin that is brownish-grey to pinkish-brown. The eyes are forward-facing with brown irises. Like other macaques, they possess cheek pouches used to store food while foraging . They have a flat nose with narrow, close-together nostrils (catarrhine condition) .
Juvenile/Immature Plumage: Infants are born with a distinctive black natal coat, which gradually lightens to the adult pelage as they mature, a transition typically complete by one year of age .
Molting: No specific information on molting cycles is detailed in the provided sources, but like most mammals, they undergo gradual hair replacement without dramatic seasonal plumage changes.
Geographic Range: Native range spans much of Southeast Asia. It is found from eastern Bangladesh and Myanmar through Thailand, Laos, Cambodia, Vietnam, Malaysia, Singapore, Indonesia, the Philippines, and Timor-Leste. Introduced populations exist in locations such as Mauritius, Palau, and Hong Kong.
Distribution in Vietnam: The Long-tailed Macaque is widely distributed throughout Vietnam. It is found in lowland and coastal forests from the north to the south, including key protected areas like Cat Tien National Park. The subspecies M. f. condorensis is endemic to Con Dao Archipelago. Despite its adaptability, populations are threatened by habitat loss and hunting.
Elevation Range: Primarily a lowland species, found from sea level up to approximately 2,000 meters, though it is most common below 1,200 meters.
Habitat Specifics: An extreme habitat generalist. It thrives in primary and secondary lowland rainforests, mangrove forests, riverine corridors, and coastal forests. It is equally successful in highly disturbed habitats, including agricultural areas (plantations, farmland) and urban peripheries, where it exploits human resources.
Habitat Sensitivity: While remarkably tolerant of habitat alteration, its long-term survival in natural ecosystems depends on forest connectivity and access to freshwater sources. Its proliferation in human landscapes is directly linked to habitat fragmentation and resource availability, making it a key indicator of anthropogenic pressure.
Foraging Strategy & Diet: An opportunistic omnivore with a strong preference for fruit. The diet consists of 60-90% fruit, supplemented with young leaves, flowers, seeds, insects, crustaceans (crabs), frogs, and small vertebrates. Notably, some populations (e.g., in Myanmar and Thailand) are renowned for using stone tools to crack open hard-shelled invertebrates like oysters and crabs.
Breeding Biology: Females exhibit a menstrual cycle with visible perineal swelling around ovulation. Breeding can occur year-round with seasonal peaks. After a gestation of 162-175 days, a single infant is born. Weaning occurs at 6-12 months. Females reach sexual maturity at 3.5-4 years, males at 6 years.
Vocalizations: Communicates with a rich repertoire of calls, including alarm barks, threat grunts, submissive screams, and affiliative coos. Facial expressions (e.g., "silent bared-teeth" display akin to a smile) and body postures are critical for social communication.
Social Structure: Lives in stable, multi-male, multi-female troops ranging from 10 to over 60 individuals. Troops are matrilineal; females remain in their natal group for life, forming strong kin alliances and a linear dominance hierarchy. Males emigrate at puberty and may transfer between groups multiple times.
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