Geographic Distribution and Habitat
The Tibetan macaque—also called the Chinese stump-tailed macaque, Pére David’s macaque, or Milne-Edwards’ macaque—is a large, Old World monkey found in eastern Tibet and certain regions of China, particularly the Sichuan province. They have also reportedly been found in India. They prefer subtropical, deciduous, and evergreen broadleaf forests at altitudes between 2,625 and 6,561 ft (800-2,000 m).
Size, Weight, and Lifespan
Tibetan macaques are sexually dimorphic, that is, there is a great disparity in size between males and females. Male Tibetan macaques measure 24-27 in (61-71 cm), with tails anywhere from 3 to 5.5 in (8-14 cm). Weight-wise, males typically fall between 30 and 38.5 lb (14-17.5 kg), but there have been cases of some tipping the scales at over 66 lb (30 kg). Females, on the other hand, are much smaller: they range in length from 20 to 24 in (51-63 cm); their tails range from 1.5 to 3 in (4-8 cm); and they weigh from 20 to 28.5 lb (9-13 kg). They commonly live to be older than 20, sometimes even reaching 30.
What Does It Mean?
When a male member of one species uses an infant of the same species to regulate his interactions with other males.
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Tibetan macaques are the largest of the macaques and have a solid muscular build with a dense coat that ranges in color from gray to brown. Their coats tend to lighten—even grow white—as they grow older. When children are under two years old, their fur is much darker, mostly black with white accents around the face and stomach. They sport an ample beard and hair on its cheeks that sprouts out from the face much like sideburns or a mustache. Their faces are otherwise hairless, and coloration varies between the sexes: females have brighter faces, that are a reddish pink, while males have paler, more flesh-colored face. Their eyes are large and dark brown, with expressive eyelids. One of the most notable features of this macaque species is its short tail, which earned it the moniker of the “Chinese stump-tailed macaque.”
Tibetan macaques are omnivores. For the most part they are vegetarians, eating fruit, leaves, and occasionally bamboo or grass. They will also, from time to time, eat insects, birds, or snakes.
Behavior and Lifestyle
Tibetan macaques are diurnal, meaning they’re active during the daytime. They primarily dwell on the ground, though they are very agile and capable when up in the trees, and they prefer to sleep in caves. Females stay with their natal groups, but males leave after about eight years.
These macaques are rather aggressive, and conflict is common both between Tibetan macaques themselves and with members of other species. Being so large and bellicose, the Tibetan macaque tends to be at the top of the hierarchy among primate species in its habitat. They are known to fight when threatened, in defense of themselves or their groups.
Tibetan macaques have large cheek pouches to store food while foraging.
Daily Life and Group Dynamics
Groups of Tibetan macaques can be as small as ten individuals or as large as 100. These groups consist of multiple males and females, but there is still an established pecking order among the group. Groups are led by an alpha male, who gets first priority when it comes to resources. Alpha males are typically on the younger side—eight or nine years old—as they are stronger than older males and therefore more dominant. As younger males seek to rise through the ranks, or enter a group after leaving their natal groups, they challenge existing alpha males, trying to usurp the position. In larger groups, males are more likely to break off and form their own smaller groups, where there will be less competition for the alpha position.
A 2016 study accounted for eleven different types of Tibetan macaque vocalizations: coo, squawk, squeal, noisy scream, growl, bark, compound squeak, leap coo, weeping, modulated tonal scream, and pant. This means, compared to other macaques, Tibetan macaques have a much more diverse range of communication. Beyond vocalizations, these intelligent monkeys use an arsenal of facial expressions, postures, and gestures to communicate.
Reproduction and Family
Female Tibetan macaques reach sexual maturity and start mating after about five years. As with the males, the females in a group are hierarchical, and higher ranked individuals mate with the most frequency. After a gestation period of 165 days, females give birth to one offspring at a time, most often in January or February. The offspring spend four years entirely reliant on their mothers.
Male Tibetan macaques engage in an act called “bridging,” in which they handle and groom infants in a parental ritual. Two males lift an infant, then each male touches or sucks the infant’s genitalia. The two male monkeys then groom each other—sometimes embracing, mounting each other, and touching or sucking each other’s genitals. In bridging, the infant serves as a means for the male monkeys to engage with each other in a non-confrontational way, and to develop strong relationships. A male carrying an infant is less likely to be harmed by another male. A 2014 study found that male infants are more likely to be bridged than females. The study found that whichever infant was selected most frequently for bridging by the alpha male was then preferred by lower-ranking males as well. One hypothesis is that bridging is a form of “agonistic buffering,” or using the baby as a form of protection. Low ranking males engage in bridging with the alpha’s preferred offspring, so the alpha will not harm them.
Though the Tibetan macaque is an omnivore, it is predominantly a herbivore; therefore it likely aids in seed dispersal, as many primates do. Though some species of macaque are notorious for invading farmland and eating crops, the Tibetan macaque does not do this.
Conservation Status and Threats
The Tibetan macaque is listed as Near Threatened by the International Union for Conservation of Nature (IUCN, 2015). Although the species is widespread, like so many species, their primary threat is habitat loss. There has been significant habitat loss and decline in the last 25-30 years (approximately three generations), nearly qualifying the species for Vulnerable status.
Humans also pose a threat because of growing regional reliance on pesticides, which make these monkeys sick. Poaching and human transmitted diseases also play a role. On a smaller scale, animosity between adult males often leads to altercations, injuries, or death.
There has been serious deforestation across its range, but recent measures seem to have stabilized the situation, and the future decline of the species will probably not be as serious as its past decline. Locally, non-targeted hunting is a minor threat, as is trapping.
Under Chinese law, the Tibetan macaque is a protected species. It is also listed in Appendix II of the Convention on International Trade in Endangered Species (CITES) list, which, as explained by CITES, “includes species not necessarily threatened with extinction, but in which trade must be controlled in order to avoid utilization incompatible with their survival.” As always, a key component to conservation is education; it is imperative that people learn about these monkeys to understand how to best protect them.
Written by James Freitas, October 2018. Conservation status updated July 2020.