White-Cheeked Spider Monkey, Ateles marginatus
WHITE-CHEEKED SPIDER MONKEY
Ateles marginatus
Geographic Distribution and Habitat
Sometimes also referred to as the white-whiskered spider monkey, the white-cheeked spider monkey is found only in the Brazilian Amazon in the states of Mato Grosso and Pará. The region has a tropical climate, with temperatures typically ranging from 75°F–82°F (24°C–28°C), but can reach up to 93°F (34°C). Things are usually on the cooler side during the dry season between May and September, and warmer during the rainy season from October to April.
White-cheeked spider monkeys range west of the Rio Tapajos to the Rio Xingu at the eastern side of their range, and south of the Rio Amazonas, typically frequenting primary lowland forests and swamps that have not undergone a lot of human disturbance. Unfortunately, their range is divided by several major highways, isolating some populations from each other and potential food sources, which is especially limiting in the dry season when resources aren’t as abundant.
Researchers have had a difficult time piecing together spider monkeys’ taxonomy. Originally, the white-cheeked spider monkey was classified as a subspecies of the white-bellied spider monkey, along with the brown spider monkey. Researchers then lumped all spider monkey species together as subspecies of the red-faced spider monkey.
Other researchers later decided this was a bit too simplistic and reclassified several distinct species of spider monkey, with the white-cheeked spider monkey considered a subspecies of the white-bellied spider monkey, along with the black-faced black spider monkey.
With genetic analysis, researchers have finally started to get a clearer idea of the spider monkey taxonomic tree. Now the white-cheeked spider monkey is recognized as a distinct species, but just how closely related they are to the black-faced black spider monkey and the white-bellied spider monkey is still debated.
Size, Weight, and Lifespan
Male white-cheeked spider monkeys have a head and body length of 1.64–2.30 feet (50–70 cm), an average tail length of 2.5 feet (75 cm), and an average weight of 22.93 pounds (10.40 kg). Females have a head and body length of 1.12–1.90 feet (34.4–58.0 cm), an average tail length of 2.01 feet (61.3 cm), and an average weight of 12.84 pounds (5.82 kg). This noticeable size difference between sexes is referred to by scientists as sexual dimorphism.
There haven’t been enough long-term studies on white-cheeked spider monkeys to know exactly how long their lifespans are, but they are likely similar to other spider monkeys that live to around 25 years of age.
Appearance
Like other spider monkeys, the white-cheeked spider monkey has long, lanky limbs that help them gracefully navigate the tree tops. Their extended fingers and reduced thumbs help them hold tight while performing their aerial acrobatics. Spider monkeys are also characterized by a strong prehensile tail that functions like a fifth limb to aid in gripping branches. For extra grip, the underside of their tails is hairless and marked by distinct grooves similar to our fingerprints in both function and individual uniqueness.
White-cheeked spider monkeys have entirely black bodies, contrasted only by their namesake white cheeks and their white crested brows that frame their face. Their pinkish skin sometimes peeks out around their eyes, nose, and mouth, highlighting their features against their black fur.
Diet
White-cheeked spider monkeys love fruit (scientifically known as frugivory) and eat as many mature fruits as they can while in season. Spider monkeys have teeth similar to other frugivores, with broad incisors and proportionately smaller molars that easily chew soft ripe fruit. During dry seasons when less mature fruit is available, they will also eat young leaves (which are more nutritionally valuable than mature leaves), flowers, seeds, buds, bark, and, sometimes, bugs like termites and caterpillars. They’ll even get their sweet-fix by stealing honey from bee hives when they can.
A popular fruit among spider monkeys is figs, which are known for providing a nursery for aptly named fig wasps inside the fruit. These buggy additions to the fruits give them a nice boost in protein for the spider monkeys and other animals that feed on them. In regions where figs are not particularly abundant, white-cheeked spider monkeys have been observed selectively eating fruits infested with different insects to meet their daily protein requirement.
Behavior and Lifestyle
White-cheeked spider monkeys are the least studied of all the spider monkey species, so a lot of their specific behaviors and lifestyles are unknown to us. We do know that, like other spider monkeys, white-cheeked spider monkeys are active during the day and spend most of their time in the upper levels of the forest canopy. Occasionally, they will also spend some time in the mid to lower levels of the canopy, but rarely descend to the forest understory.
To navigate life high up in the trees, white-cheeked spider monkeys have a large repertoire of locomotion strategies. They most often travel quadrupedally (on all fours) by climbing and leaping between trees. Occasionally, they will also move bipedally (on two feet) along branches. Leaps can cover distances between trees of about 6.6–16.4 feet (2–5 m). Their favorite way to get around is by suspensory movement, swinging from branch to branch by alternating their forearms, often with the help of their prehensile tails as a backup grip. When they want to speed up, spider monkeys will travel by brachiation, where they alternate support of their weight by each forelimb (also with the help of their tails), although they’re not quite as skilled at it as true brachiators like gibbons and siamangs. Their expert swinging is aided by the shape of their shoulders, which allows for better reach and rotation. When stationary, spider monkeys will hang out by supporting themselves with their arms and tail, or even with their tail on its own.
Predators of spider monkeys include jaguars, pumas, raptors, and large snakes. The spider monkeys’ residence in the higher levels of the forest canopy and skill in navigating it help them avoid predators.
White-cheeked spider monkeys live in large multi-male multi-female groups, typically with 20–30 individuals, with fission-fusion group dynamics. This means, rather than moving as one large group, members will split off into small sub-groups of about 2-4 individuals, or they may even travel alone within the group’s range. Researchers think this type of grouping system allows animals that use it to mitigate the costs and benefits of group living, like adequate access to food sources and protection from predators. Sub-groups are typically led by the senior-most member. Often, this will be a male, as males do not leave their natal group, while females will join a new group once they are mature.
Females will typically travel with their children, and are known to have a core area within the group’s home range where she spends most of their time. Males typically have a larger range within the group than females, and will often patrol the outer edges of the group’s range, looking out for any possible intruders. Males tend to have closer relationships with other males than they do with females, and are known to groom each other more frequently than females groom each other.
White-cheeked spider monkeys rarely associate with other primates, although they do overlap in range with black-faced black spider monkeys along the Teles Pires River.
The exact ways the white-cheeked spider monkey communicates have not been directly studied, but we can draw some ideas from studies on communication in other species of spider monkey.
With their large and often spread-out groups, vocalizations are an important way spider monkeys communicate with each other. They use long calls to advertise their location to distant members of their group. In closer conditions, spider monkeys will greet each other with calls such as tee-tee for friendly greetings, growls for less than friendly greetings. When subgroups come together, spider monkeys will use a whinny to identify themselves, and will bid each other farewell with a tschook when subgroups split. Whoops are used exclusively by males to advertise their location. Should a spider monkey notice a potential threat, they’ll warn other group members with a chitter or with barks.
Spider monkeys also use olfactory communication, via scent marking, which is useful for their fission-fusion lifestyle, as smells will stay in an area longer than the individual that left them. Think of scent marking like leaving a sticky note on the fridge for a family member to find later. Females often do this by leaving a urine trail, which, due to males’ habit of sniffing these spots, researchers think advertises the female’s reproductive status. Spider monkeys will also sometimes greet their friends with a hug, during which they will sniff special scent glands on each other to strengthen their social bond. This is particularly common amongst males.
Spider monkeys, in general, seem to maintain a level of privacy around their mating habits. This likely serves to keep the peace in the group, particularly among males, but also makes it difficult for researchers to understand spider monkeys’ reproductive behaviors, particularly for less studied species like the white-cheeked spider monkey.
We can guess from what we know about other spider monkey species that white-cheeked spider monkeys likely reach sexual maturity at about 4–5 years of age. At this point, females will leave their natal group for a new one. Researchers think that female spider monkeys use their extended clitoris (which can be longer than the males’ penis) to help with scent marking to advertise to males when they’re ready to copulate. This is supported by the unique groove along the outer surface, which may help facilitate the flow and spreading of urine. Females will mate with multiple males in the group.
Although they become sexually mature at about 5 years of age, female spider monkeys typically only have their first birth closer to 7 years of age. Reproduction goes rather slowly for spider monkeys, considering their “late bloomer” age of maturity and extended periods between births (about 2–4 years), which makes it difficult for them to recover from hunting and deforestation pressures. Gestation is typically around 7.5 months, usually resulting in a single infant.
Like many fruit-loving primates, white-cheeked spider monkeys act as seed dispersers and play an important role in maintaining the plant diversity of the forests they live in. Researchers have found that seeds that have been “processed” by spider monkeys, after having gone through their digestive systems, often have better germination rates than those that fall to the forest floor on their own. This makes sense because the monkeys have eaten the pulp that would otherwise attract fungi and insects, and the seeds come out conveniently packaged in fertilizer. Researchers also think that consuming fruits that are infested with insects, as the white-cheeked spider monkeys do, gives those plants a better chance at reproducing, since other frugivores might pass up the combo meal.
The white-cheeked spider monkey is classified as Endangered by the International Union for Conservation of Nature (IUCN, 2019), appearing on the IUCN Red List of Threatened Species. Their population is decreasing and is expected to decline by 50% between 2006 and 2050.
Spider monkeys all together are among the most endangered Latin American primates. White-cheeked spider monkeys are among those living in the “arc of deforestation”—a region particularly plagued by habitat destruction due to cattle ranches, soy bean production (which is largely used to produce feed for the cattle), and urbanization. White-cheeked spider monkeys prefer primary forests, and don’t seem to do as well in forests that have undergone disturbance. They are also a popular target of hunters, and have gone locally extinct in some parts of their range due to hunting pressures, particularly in the Arapiuns region in Pará, Brazil. The highways that divide the white-cheeked spider monkey’s range also give hunters greater access to the monkey’s habitat.
White-cheeked spider monkeys 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. They are also included on the national action plan for the middle and lower Xingú, and that national action plan for Amazon primates
The white-cheeked spider monkey’s range covers a number of protected areas; many of these areas are still subject to habitat destruction.
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Written by Lina Rademacher, January 2026