CELEBES CRESTED MACAQUE
Celebes crested macaques (Macaca nigra) are one of the eight species of macaque endemic to the island of Sulawesi (Celebes) in Indonesia. They are now restricted to northeast Sulawesi and the adjacent islands of Pulau Manadotua and Pulau Talise. They were once found on Pulai Lembeh but are no longer are. An introduced population of at least 100,000 individuals resides on Pulau Bacan, in the Maluku Islands hundreds of kilometers from Sulawesi, rumored to have been introduced in the mid-1800s as a gift to the local sultan. [Source: Rae Ellen Bichell, Animal Diversity Web (ADW) /=]
Celebes crested macaques are popular zoo animals in part because they have interesting, human-like facial expressions. They are also known as black crested macaques, crested black macaques, Sulawesi black macaques, Sulawesi macaques, and incorrectly as Celebes black apes. Locals call them yaki. Among the species of macaques of Sulawesi, Celebes crested macaques are difficult to distinguish from Gorontalo macaques (Macaca nigrescens). Both have black skin and fur, but the upper half of the body of Celebes crested macaques is darker and more dull. Hybrids of Celebes crested macaques and Gorontalo macaques have been recorded. /=\
Celebes crested macaques are island endemic (live only on an island or set of islands). Their average lifespan in the wild is 18 years. They have lived up to 34 years on captivity and occupy in many protected areas including Gunung Lokon, Gunung Amban, Tangkoko Batuangus, Dua Saudara, and Batu Putih.
Celebes crested macaques live in tropical areas at elevations of 700 to 1100 meters (2297 to 3609 feet), most likely determined by fruit abundance. These areas have relatively constant temperatures, although there are fluctuations in rainfall between dry and wet seasons. These macaques prefer humid, tropical lowland and upland rainforests, but they are also known to frequent agricultural areas that have encroached on their habitat.
National Geographic Article: “For These Monkeys, It’s a Fight for Survival” by Jennifer S. Holland, National Geographic, March 2017 nationalgeographic.com
Celebes Crested Macaque Characteristics
Celebes crested macaques range in weight from five to 18 kilograms (11 to 39.6 pounds) and range in length from 44.5 to 57 centimeters (17.5 to 22.4 inches). Sexual Dimorphism (differences between males and females) is present: Males are larger than females. Males are typically 52 to 57 centimeters in length while females are 44.5 to 57 centimeters. Males have an average weight of 9.9 kilograms; Females on average weigh 5.5 kilograms. Adult females are also paler in color than adult males. [Source: Rae Ellen Bichell, Animal Diversity Web (ADW) /=]
Celebes crested macaques are relatively large primates with black faces and bodies. Their skulls are more baboon-like than those of other macaques, and their crown hairs form a crest, pointing backward and up. Celebes crested macaques also have a short “nubbin-like” tail and bright- pink, kidney-shaped ischial callosities (thickened pads of tissue at the top of the hip bones and around the rump that helps some primates sit on thin branches while feeding or sleeping). They have been misidentified as apes because of their short tails, which are only about two centimeters millimeters long.
The face of Celebes crested macaques is thinly covered with hairs. Their body hair is coarse, woolly and dense. Juveniles are paler than adults, appearing more brown than black and have black hairs where the crest will develop. As adult males age, their hair grays and becomes grizzled, most noticeably in the upper body; this occasionally occurs on the arms of younger males as well. /=\
Celebes Crested Macaque Feeding, Predators and Ecological Roles
Celebes crested macaques are primarily frugivores (eat mainly fruits) but are also classified as herbivores (primarily eat plants or plants parts) and omnivores (eats a variety of things, including plants and animals). Animal foods include mammals amphibians, reptiles, eggs, insects terrestrial non-insect arthropods terrestrial worms. Crested macaques have been observed plucking ants from a tree for a snack. These monkeys are opportunists, feeding mostly on forest fruits but willingly to eat nutritious insects when the they present themselves. Among the plant foods they eat are leaves, wood, bark, or stems seeds, grains, and nuts fruit flowers. [Source: Rae Ellen Bichell, Animal Diversity Web (ADW) /=]
Celebes crested macaques forage throughout the day, occasionally storing food reserves in their cheek pouches. Figs comprise the majority of the diet of Celebes crested macaques. However, they eat a lot of other things. By one count they consume more than 145 species of plants, mostly fruit, as well as some invertebrates. When fruit is scarce, they eat insects, shoots, young leaves, and the stems of flowering plants. These macaques have been observed preying on fruit bats, forest geckos, frogs, and the eggs of the red junglefowl and black-naped monarch flycatchers. They also raid crops, and particularly fond of maize, yams, cassava, papayas, bananas and cacao.
Celebes crested macaques have no major predators, except reticulated pythons, or primate competitors.. They are, however, hunted by humans for their meat. Many macaques on the island of Sulawesi are known to associate with birds, including hair-crested drongos and yellow-billed malkoha. These birds prey on the insects that leave the canopy when macaques pass through. As frugivores, Celebes crested macaques help the ecosystem by dispersing seeds, especially for rainforst tree species such as Dracomelon and Ficus.
Celebes Crested Macaque Behavior
Celebes crested macaques are terricolous (living on the ground), diurnal (active mainly during the daytime), motile (move around as opposed to being stationary), nomadic (move from place to place, generally within a well-defined range), social (associates with others of its species; forms social groups), colonial (living together in groups or in close proximity to each other), and have dominance hierarchies (ranking systems or pecking orders among members of a long-term social group, where dominance status affects access to resources or mates). The size of their range territory is 0.47 to 3.48 square kilometers, with an average of 216 hectares. Macaques that feed on fruit stay closer to their central home range, as there is need to travel while foraging. [Source: Rae Ellen Bichell, Animal Diversity Web(ADW) /=]
Rae Ellen Bichell wrote in Animal Diversity Web: Groups are unusually large, ranging from 50 to 97 individuals. The average population density of Celebes crested macaques is three individuals per square kilometers, although in Tangkoko Batuangus, population density reaches as many as 60 individuals per square kilometers. In some cases, population density is correlated with density of fig trees. /=\
Celebes crested macaques spend 59 percent of their waking hours foraging, feeding, and moving. They are primarily travel an average of 2.4 kilometers per day, though time spent on the ground and distance traveled per day changes in primary forest, where fruit is abundant and does not require as much travel. Celebes crested macaques generally socialize in the morning, rest in the afternoon, and sleep in trees.
Celebes Crested Macaque Social Behavior
Celebes crested macaques live in groups of 50 to 97 individuals, which is unusually large for the genus. Groups generally include more females than males. Females remain within the group into which they were born, while males disperse to unrelated groups when they reach sexual maturity.. Females have an egalitarian social structure, whereas males form a linear and transitive dominance hierarchy. Groups are generally tolerant, characterized by appeasement displays, minimal aggression (biting each other), and “symmetry in conflict”. /=\
Jennifer S. Holland wrote in National Geographic: scientists are studying three main yaki groups in Tangkoko. They call the most gregarious Rambo II; its members, having been studied previously and loved by tourists, were quite tame when Engelhardt arrived a decade ago. Rambo I was also studied previously, but many years ago. Engelhardt’s team has rehabituated them. The third group, Pantai Batu Hitam (or Beach of the Black Rocks, for the volcanic beaches the animals visit), is the most wary of humans. [Source: Jennifer S. Holland, National Geographic, March 2017]
Each group has about 80 members, with a strict hierarchy. An alpha male is the preferred mate of females, but his dominance is fragile. Takeovers are often swift and bloodless, and once an alpha loses his spot, he can’t get it back. Some ousted males leave the group and try to take over another. Females mostly get along, resolving spats with grooming and other peacemaking behaviors.
Where macaque territories overlap, raucous clashes can erupt. Stragglers hearing the screeches and screams of battle will rush to join in, shrieking in solidarity with those on the front line. “They can get pretty mean,” Engelhardt said, referring to the skirmishes. But death in action is rare. Fights usually are quick and more theatrical than injurious, said Maura Tyrrell, a Ph.D. student from New York’s University of Buffalo. That’s especially true with females, “who lip-smack and nervously touch one another until males arrive. Then boom!—it’s time to chase and fight.” Males will herd females away from amorous competitors, but sometimes they’re rough on their mates, even scarring them with bites. “It can be brutal to watch,” Tyrrell said.
Interactions Between Celebes Crested Macaque Males
Jennifer S. Holland wrote in in National Geographic: Tyrrell follows macaques from sunrise to sunset five days a week, studying male interactions. She’s trying to learn when and how males build coalitions, which, she said, “may shed light on the same behavior in early human societies.” A day’s notes are routinely R-rated. “Usually tense relationships are moderated by ritualized greetings and a genital grab,” she said. “Touching another’s penis may be a way for males to test their relationships and negotiate future alliances.” It’s not about rank, she said, as grasping can be mutual. Whoever starts it, “it’s a pretty vulnerable position to let another male handle your genitals.” [Source: Jennifer S. Holland, National Geographic, March 2017]
There are other ways to make a point. During my first day in the woods, Raoul, the big alpha male of Rambo II, opened wide to show me his dagger-sharp canines, then sauntered by and swatted my calf with a stick—letting me know my place in the social order. (Low.)
With each other, the macaques rely heavily on sexual signals. “They’re extreme when it comes to sexual selection,” Engelhardt told me as we saw females with hyperswollen, rosy-red rear ends parade in front of potential mates. A similarly vivid scrotum on a male signifies his testosterone level and accordingly his dominance. “The redder it is, the higher his rank,” she said.
The males constantly test their standing, looking to move up in the hierarchy. Higher rank means more chances to spread one’s DNA via fertile females (those with the biggest, reddest bottoms). “Still,” Engelhardt said, “being a beta [number two] might be ideal. You don’t have to be the strongest, and you still get plenty of action.”
The researchers are teasing out fine details of the yaki’s private life. “One exciting discovery is that males with certain personality traits—being self-confident and part of a big, diverse social network—are more likely to reach a high rank and thus sire more offspring,” Engelhardt said. “So it’s not your social status that affects your personality, but your personality affects your social status.” The principle is true for humans too, with personality influencing social “rank” and sexual opportunities. But exactly which traits bring benefits “might be very specific,” she said. “What works for male macaques might not work for men.”
Celebes Crested Macaque Senses and Communication
Celebes crested macaques communicate with vision, touch and sound and sense using vision, touch, sound and chemicals usually detected with smell. They communicate with a wide variety of facial expressions. A smile, for example, can be an expression of friendliness or submission depending on the situation.
According to Animal Diversity Web: Celebes crested macaques utilize a variety of visual and physical behaviors to communicate. To indicate aggression, males stare with an open mouth, grin with the mouth closed, yawn, lunge, and chase. Submission and satisfaction are signaled with a grimace and lip smacking. As with other macaques, males are known to silently bare their teeth, postulated as a display of “peaceful intentions”. Dominant males also bare their canines in a “yawn” to indicate supremacy. [Source: Rae Ellen Bichell, Animal Diversity Web(ADW) /=]
Celebes crested macaques also use vocalizations. They are known for a loud, bird-like call that may be a method of intervening in conflicts, signaling to keep away from other groups, or as a “signal of dominance to prevent contests between males for mates”. Frequency and complexity of calls correlates with male rank, with high-ranking males emitting complex calls more frequently than subordinates. /=\
Celebes Crested Macaque Mating and Reproduction
Celebes crested macaques are polygynandrous (promiscuous), with both males and females having multiple partners. Females have an estrous cycle, which is similar to the menstrual cycle of human females. Celebes crested macaques engage in year-round breeding, although periods of high ovarian activity by adult females occur from August to June, and birthing peaks between January and May. The average number of offspring is one. [Source: Rae Ellen Bichell, Animal Diversity Web (ADW) /=]
Rae Ellen Bichell wrote in Animal Diversity Web: Females exhibit sexual swelling in the anogenital area to indicate ovarian activity and sexual receptivity, sending visual and olfactory cues, which males sense by sniffing female genitalia. However, the degree to which males use visual, olfactory, and behavioral signs to determine female fertility remains unclear. /=\
Adult females approach high-ranking males for sex more often than they do low-ranking males, although all males copulate about the same amount. A female presents herself to a male by facing her swollen genitals, slightly raised, toward the male, and smacking her lips. The male holds the female’s legs and waist during copulation. The pair engages in reciprocal grooming following intercourse. There are two types of ejaculatory patterns among species of macaques. Male Celebes crested macaques mount the female multiple times but only ejaculate during the last mount (multiple-mount ejaculation).
Little is known about the reproductive biology of Celebes crested macaques in the wild. Fertility of males and females overlaps. Females have a menstrual cycle of approximately 32 days, which is unusually long for macaques and occurs because of an extended follicular phase. Cycle length and maximal genital swelling period are extended when males are absent. Sexual swelling of the female anogenital area also occurs when females are not ovulating, which promotes non-procreative copulation. Homosexual behavior such as displaying, mounting, and genetal contact has also been observed among males of this species. /=\
Celebes Crested Macaque Offspring and Parenting
Celebes crested macaques typically give birth once every 18 months. The gestation period ranges from five to six months, with an average of 5.5 months. Offspring spend much less time with their mother at four months of age and are completely weaned by one year of age. Females reach sexual or reproductive maturity at four to six years and males do so at four to six years. One mother macaque was observed carrying her newborn for days after it died of unknown causes. Such behavior is rarely documented in the wild. [Source: Rae Ellen Bichell, Animal Diversity Web (ADW) /=]
According to Animal Diversity Web: In most populations, the adult sex ratio is three females to five males. Macaques are sexual bimaturists, with females reaching physical maturity faster than males, though the hormonal processes responsible for maturation are identical in both sexes. Males produce sperm around three or four years of age, though they do not reach a body mass necessary for mating (physical maturity) for another three to six years. Based on comparable patterns of behavior and social structure of other macaques, care is primarily maternal, though aunting behavior occurs, in which an infant is carried by juvenile females supervised by the mother. Celebes crested macaque infants often cling to their mother's belly for protection. Some parental care is provided by males. Because a lot non-ovulation copulation occurs and different males copulate with a female when she is ovulating, who the father is often not clear.
Jennifer S. Holland wrote in in National Geographic: Mother macaques bear one baby every 20 months or so and do most of the parenting. Wee ones nurse for less than a year but stick close for several more. Young males eventually leave to vie for position in another group. Yet the macaques seem fearless in their forest home. They climb high and swing far, snapping branches as they tumble through the canopy after missed connections. Cartoonish, wide-eyed infants cling to their mothers or play together low to the ground. Cooing calls link individuals as they forage on the move, chewing on figs and other fruits, plus bugs and leaves. Facial expressions convey moods: Ritualized yawning—which starts with an oval mouth that breaks into a gaping one as the animal flings its head back—suggests tension. Scalp retraction with ears flat invites play or grooming. Chuckles, rattles, grunts, and barks—macaque talk—each have context-dependent meaning. [Source: Jennifer S. Holland, National Geographic, March 2017]
Celebes Crested Macaque and Humans
Celebes crested macaques are featured in local folklore and are sometimes kept as pets. Considered a delicacy, they are hunted for bush meat that is served on holidays and special occasions. Because Celebes crested macaques are the only non-human primate model for Type II diabetes mellitus, they are valuable in scientific research. The species is also an ecotourism attraction. [Source: Rae Ellen Bichell, Animal Diversity Web (ADW) /=]
According to Animal Diversity Web: As humans reduce habitat, cut down fig trees, which are a key component to the diet of macaques, and as farms expand into forests, macaques have adapted to include crops in their diet, exploiting human resources. Although local folklore describes humans and macaques as intertwined, crop raiding has earned them reputations as “pests” and “weed species”. Humans cut down trees that are important to the diet and habitat of macaques, such as fig trees . Human-macaque sharing of resources is occasionally possible, as with Arenga pinnata palm trees, from which macaques gather fruit and humans take palm fronds. However, deforestation for timber and firewood and clearing for agriculture permanently removes resources utilized by macaques. Despite their critical conservation condition, the total area of protected land inhabited by Celebes crested macaques (16,848 hectares) is less than any other macaques on the island of Sulawesi.
Jennifer S. Holland wrote in National Geographic: In recent years the critically endangered macaques have suffered as they’ve been hunted for their meat, taken as pets, and squeezed into ever smaller areas by illegal tree clearing for coconut plantations and villagers’ garden plots. Meanwhile conservationists are fighting government plans to open wildlands to roads and industries. Surveys from 2009 to 2010 put yaki numbers at about 2,000 in the reserve, called simply Tangkoko, and primatologist Antje Engelhardt, of England’s Liverpool John Moores University, says their numbers have dropped since then. It’s not known how many live elsewhere in North Sulawesi.[Source: Jennifer S. Holland, National Geographic, March 2017]
Some farmers trap macaques on purpose to keep the monkeys from raiding crops. Monkeys also get caught in traps set for pigs, birds, or rats, which can mean quick cash for a trapper. “My staff has counted [up to] a hundred traps just within a small area inside the reserve boundaries,” Engelhardt said. “Unfortunately,” she added, “macaques that escape traps may lose a limb to loss of circulation.”
The local pet trade thrives on captured or orphaned baby macaques—often malnourished and kept in tight quarters. But the bigger threat is that people in Sulawesi have been eating macaque meat for centuries. Today it goes for about two dollars a pound (an adult macaque weighs 18 to 23 pounds), and demand spikes at holidays. The town of Tompasobaru, a six-hour drive from Tangkoko, is known for the fragrant cloves that carpet the front yards of homes,and its open market, where dried fish, chicken feet, bats (their wings in a pile like leather scraps) and cut-up pigs and monkeys, their faces intact.
Nofi Raranta, 37, the town’s main clove dealer, is also the top hunter, employing about a hundred men who comb the surrounding forests for quarry. Raranta greeted me from the porch of his newly built house a short walk from the market, then led me into a storage room where, from a large freezer, he pulled out the top third of a crested black macaque and propped it on a stool for my inspection. He told me that his family sells about 15 macaques a week, a quarter of them yaki.
What if, I asked, you took every crested black macaque from the wild? Raranta allowed that hunters now have to go farther to find the monkeys. “I’m a businessman,” he said. “We also have cloves. And there are always more rats, pigs, bats. If one animal is gone, we just look for others.” But Indonesian law protects the endangered macaques. Does he worry about getting caught with them? “Just a little. The police,” Raranta said with a half smile, “they come sit and eat with us!”
Celebes Crested Macaque Conservation
On the International Union for Conservation of Nature (IUCN) Red List Celebes crested macaques are listed as Critically Endangered. In CITES (Convention on International Trade in Endangered Species of Wild) they are in Appendix II, which lists species not necessarily threatened with extinction now but that may become so unless trade is closely controlled. CITES prohibits live trade of this species, though illegal trafficking may still occur. [Source: Rae Ellen Bichell, Animal Diversity Web (ADW) /=]
In 2008, the International Union for Conservation of Nature (IUCN) listed Celebes crested macaques as Critically Endangered. Population size decreased by 80 percent between 1965 and 2005, years, primarily due to hunting and loss of habitat. There are estimated to be 4,000 to 6,000 individuals in the wild. On Bacan Island in the Moluccas in Indonesia there is an introduced population of 100,000 individuals, which is not included in the population estimate, but could become the last surviving population of Celebes crested macaques in the near future. /=\
Main threats to the conservation of Celebes crested macaques include human population growth and land conversion. Following recent spikes in human habitation, which in 2002 was 132 individuals per square kilometers, is large-scale deforestation by logging, the transmigration program, and cash crop farming, most of which is partially funded by the government.
Image Sources: Wikimedia Commons
Text Sources: Animal Diversity Web animaldiversity.org ; National Geographic, Live Science, Natural History magazine, David Attenborough books, New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Discover magazine, The New Yorker, Time, Reuters, Associated Press, AFP, Lonely Planet Guides, Wikipedia, The Guardian, Top Secret Animal Attack Files website and various books and other publications.
Last updated December 2024