Bonnet Macaque, Macaca radiata
BONNET MACAQUE
Macaca radiata
Geographic Distribution and Habitat
Bonnet Macaque monkeys, also known as “zatis,” are native to the southern region of India, particularly found across the peninsular states of Telangana, Andhra Pradesh, Goa, Gujarat, Karnataka, Kerala, Maharashtra, and Tamil Nadu. These areas, surrounded by the Indian Ocean on three sides, span from the southern tip of India up through the southern banks of the Tapti River in the north and the Krishna River in the northeast.
These adaptable monkeys can make their homes within a wide range of habitat and climate types, with each of their two subspecies showcasing distinct preferences. The more common dark-bellied bonnet macaque (M. r. radiata) can be found in a range of environments, from evergreen high forests and deciduous forests to dry prairies and even urban locations brimming with human life. The less abundant pale-bellied bonnet macaques (M. r. diluta) tend to reside in southeastern coastal India, the Western Ghats mountain range, and Pondicherry in the northeast.
There are currently twenty-four recognized macaque species living on Earth, all classified under the genus Macaca within the Cercopithecinae family. Twenty-three of those species reside in Asia. Just one, the Barbary macaque (Macaca sylvanus), is endemic to North Africa.
As touched upon earlier, the two recognized subspecies of the Bonnet Macaque are the macaca radiata radiata (M. r. radiata) and the macaca radiata diluta (M. r. diluta).
Size, Weight, and Lifespan
Slightly smaller than most other macaque species, bonnet macaques are around the size of a household cat. With females being about 14 inches (35 cm) long and 8.5 pounds (3.9 kg), compared to males’ average length of 24 inches (60 cm) and weight of 14 pounds (6.7 kg). Size is one of the few instances of sexual dimorphism in these monkeys.
In the wild, while navigating the pressures of disease, predators, and adverse human interactions, like car-related accidents, bonnet macaques usually live around 20-25 years. When protected from these elements in captivity, they can live up to 35 years.
Appearance
As their name suggests, bonnet macaques are distinguished by a small cap of tufted fur that falls behind a slightly receding hairline. Their hairdo is complete with an adorably messy middle part—almost like if Dwight Shrute from The Office woke up with bedhead! Their coat color is typically grey-brown, with either a dark-colored belly (M. r. radiata) or a pale-colored belly (M. r. diluta).
They are expressive monkeys, especially with their eyebrow movements and wide, round eyes. Their faces are wrinkled and relatively hairless—with the females having pink skin compared to the fleshy-tan shade of their male counterparts. A rather notable feature of the species is their large, sometimes pointed ears, as well as their long, sharp canines that are visible when they yawn or try to communicate aggression or fear.
Their thin limbs are proportional to their bodies in length. Their arms are outfitted with agile, dexterous hands that help them skillfully traverse their natural landscape. Their tails—though not prehensile—help as well by supporting their weight and balance while they climb.
Diet
Although the omnivorous bonnet macaques have a distinct preference for fruits and plant material, they also will strategically dwell in urban areas (as mentioned before), to capitalize on the easy-to-obtain, varied food sources that can be found there. This includes rummaging through trash piles, gardens, and even households. It is not uncommon for tourists to be found feeding these monkeys, all the more motivation for them to stick around human-dense areas.
Bonnet macaques that live in more remote forests and prairies are known to forage for fruits, nuts, seeds, leaves, insects, soil, small invertebrates, eggs, and reptiles. More specifically, the plants they typically feast upon include Neem, Tamarind, Indian Ash tree, Rattan, Duhat, Spanish Cherry, Spinous Flueggea, Fig, Algarrobo, Corn, Jackfruit, and Stickpea.
Behavior and Lifestyle
Bonnet macaques—being both arboreal and terrestrial—are very versatile in their behavioral characteristics, as exhibited in their diverse array of habitable environments. They are diurnal, meaning they are active during daylight hours and spend the majority of their days on the ground despite their impressive climbing skills. As quadrupeds, they use all four limbs when they climb (mainly to forage or protect themselves from predators), keeping multiple limbs in contact with tree branches and trunks.
As mentioned, some elements of the bonnet macaque’s diet (primarily the dark-bellied bonnet macaques) are sourced from human interactions. In some regions, the monkeys have become quite accustomed to hand-fed practices in spaces such as temples and villages. Locals sometimes even sell fruit or rice to tourists, encouraging them to feed it to the monkeys.
These intelligent monkeys have a special trick to help counter digestive issues: they have been observed eating soils from termite nests, known as termitaria, which are rich in kaolin and smectite! These ingredients are also used in certain African stomach ailment remedies and Western anti-diarrheal practices.
Bonnet macaques have tricolor vision, like humans!
As very social animals, bonnet macaques tend to be found in mixed-gender groups of around 30 individuals. These groups feature a linear, age-ranked hierarchical order. A critical factor of their daily bonding and routine is social grooming, called allogrooming, which boosts interpersonal relationships and can positively contribute to conflict resolution. This behavior is uniform throughout the entire group, meaning that even those at the top of the hierarchy participate reciprocally in the activity. Other social activities include cuddling amongst same-sex bonnet macaques at night. Some dominant males will keep warm by clutching juvenile males into their chests, while mothers have been observed to prefer to stick together, avoiding huddling with babies, juveniles, or single adult females.
These social groups are composed of related females (who remain in their birth groups) and unrelated males (who leave their natal groups to join other groups). This helps to promote genetic diversity. However, pale-bellied female bonnet macaques will sometimes change groups. Aside from these bonnet macaque social groups, these monkeys coexist with other primates including Nilgiri langurs (trachypithecus johnii) and northern plains gray langurs (semnopithecus entellus).
Since we’ve established that bonnet macaques are rather social creatures, it should come as no surprise to learn that they have adopted a wide array of communication methods through gestures, facial expressions, and sounds. These behaviors are critical in the function of their social hierarchy, with low-ranked macaques using specific submissive gestures and expressions when interacting with high-ranked counterparts. For example, some low-ranked members of the group will present their hand to be play-bitten by higher-ranked members.
The ritual of social grooming also plays a role in non-verbal group communication, helping to minimize tension and build social bonds.
These monkeys sometimes even communicate with humans, being observed employing coo-calls, hand-extension gestures, orientation, and monitoring behavior when attempting to coerce food from people.
In addition, they exhibit an array of facial expressions, each with a specific meaning. For example, grinning, lip-smacking, and tongue-clicking can be used to express affection or relieve stress while sneering or grimacing communicates a state of fear or submission.
Of course, sounds play an important role in their communication as well. Most notably, they emit alarm calls to warn other group members of potential predators in their midst. Bonnet macaques also recognize the alarm calls of coexisting primate species, like the aforementioned Nilgiri langurs and northern plains gray langurs.
As female bonnet macaques primarily reach sexual maturity within their original social group, males instead must leave to find new troops to join. Upon doing so, they must participate in grueling competition to earn status and earn reproductive opportunities. Male-on-male competition reaches its height during the mating season, in September and October. During that time, top-ranked males may allow younger males to mate with young, low-ranking females. With that being said, male-male mounting is not uncommon, as well as dominant males mounting juveniles. Furthermore, sometimes alliances are formed amongst lower-ranked males as a ploy to challenge their higher-ranked counterparts during this time.
The bonnet macaque gestation period (pregnancy) lasts around 5-6 months, so babies are typically born between February and April. On average females give birth to one offspring every year, then proceed to nurse and care for the infant closely for its first 6 months to a year. Once fully weaned, the role of caretaking for that specific newborn becomes communal—with the whole social group, both males and females, prioritizing the infant’s protection. Bonnet macaque juveniles are considered independent and able to protect themselves at around one-year-old.
Bonnet macaques that live within forests involuntarily help with tree reproduction by spreading their seeds throughout the landscape when eating and digesting fruit.
The bonnet macaque is classified as Vulnerable by the International Union for Conservation of Nature (IUCN, 2015), appearing on the IUCN Red List of Threatened Species. This classification is warranted based on significant population declines that exceeded 30% over three generations (36-39 years).
While certain natural predators threaten the bonnet macaque populations—including pythons, tigers, leopards, and eagles—the falling number of bonnet macaques is also an unfortunate result of human activities like hunting, persecution, group structures being adversely impacted through translocations, road expansion, the cutting of native trees, human feeding, and displacement. Furthermore, bonnet macaques are known to be hunted and sold as pets or for research.
The IUCN predicts these declining numbers to continue unless major conservation efforts and strategies are put in place.
Bonnet macaques are listed in Appendix II of the Convention on International Trade in Endangered Species (CITES), an international agreement between governments whose goal is to ensure that international trade in specimens of wild animals and plants does not threaten their survival. This means that although extinction isn’t an imminent threat, it is necessary to continue to monitor this species closely.
Research has been done to highlight the severity of the diminishing bonnet macaque population. In one study, roadsides with abundant ficus trees were listed as a preferred habitat. Unfortunately, between 2003 and 2015 the roadsides have been drastically altered and replaced with urban infrastructure and barren lands, resulting in more than a 65% population decrease in the past 25 years.
The study identified a handful of places—including small hillocks with natural vegetation and some temples and tourist spots—that are likely to maintain stability and recommended they be used as “bonnet macaque conservation reserves.”
- https://www.iucnredlist.org/species/12558/17951596#geographic-range
- https://animalia.bio/bonnet-macaque?letter=i
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- https://genomics.senescence.info/species/entry.php?species=Macaca_radiata
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- https://pubmed.ncbi.nlm.nih.gov/3803725/
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5897542/
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- https://ncbi.nlm.nih.gov/pmc/articles/PMC5568106/
- https://cites.org/eng/app/appendices.php
Written by Hannah Broadland, February 2024