Golden-bellied capuchin, Sapajus xanthosternos
GOLDEN-BELLIED CAPUCHIN
Sapajus xanthosternos
Geographic Distribution and Habitat
The golden-bellied capuchin, also known as the yellow-breasted capuchin or the buffy- or buff-headed capuchin, can be found in Brazil, typically residing in the southeastern states of Bahia, Minas Gerais, and Sergipe. Some of their geographic boundaries include the Rio San Francisco, the Atlantic Ocean, and the Rio Jequitinhonha. They can survive in many different habitat types, including forests, savannas, and shrublands. Within that range, there is a vast range of climates and environments that these monkeys have been seen living in, from humid, coastal, tropical rainforests that can average around 71 inches (180cm) of rainfall a year, to dry, deciduous forests. Being arboreal creatures, they tend to stick to the lower to mid-canopy and understory range of the forest.
In the early 2000s, it was suggested that tufted and untufted capuchin monkeys were too physically different to be named under the same genus, which led to the separate classification of two genera Cebus (untufted capuchins) and Sapajus (tufted capuchins).
Size, Weight, and Lifespan
Male golden-bellied capuchins are slightly larger than females, with a head-body length of about 15.7 inches (40 cm) and a weight of around 8.8 pounds (4 kg). Females weigh approximately 5.5 pounds (2.5 kg) and have an average head-body length of 14.6 inches (37 cm). Both males and females have tails roughly as long as their bodies, give or take an inch or two.
While some capuchins have been known to live up to 50 years in captivity, golden-bellied capuchins typically live about 30 years in captivity and 15 to 25 years in the wild.
Appearance
Golden-bellies are known for their, you guessed it, golden-yellow bellies and chests! This lighter color is contrasted with the dark brown to black fur that covers their back and tail and encircles their faces. Their arms and legs also appear to be “dipped” in this darker fur color, almost giving them the illusion of wearing long gloves — so stylish! It is not uncommon for there to be golden-yellow patches or streaks throughout this darker fur. Their faces are lighter in color, with grayer fur and peachy-tan skin peeking through.
The capuchin’s body is built for easy climbing. Their long fingers, spaced far apart from a short thumb, make it possible to grasp wide branches while still managing to handle small items like berries and nuts. Additionally, their fully opposable big toe allows them to grip various branches with ease. Their prehensile tail aids in maintaining balance as they move through the treetops.
Diet
A classic omnivore, golden-bellied capuchins feed on a wide range of foods, including fruits, seeds, berries, flowers, insects, bird eggs, nuts, leaves, stems, nectar, and sometimes even small mammals. If they are living near the coast, it is not uncommon for them to eat marine matter like oysters, crabs, and other shellfish. A study from 2013 even found that some golden-bellied capuchins feed on small lizards.
More specifically, fruits make up around 40% of their diet, with invertebrates covering another 36%. They are known to eat a wide range of fruit, an average of 16.5 fruit species a month to be exact!
Behavior and Lifestyle
Golden-bellied capuchins are highly social, diurnal (active during the daytime) primates that spend most of their time in trees, although habitat loss sometimes forces them to the forest floor. They are agile climbers, using their long fingers and prehensile tails to gracefully travel through the mid-canopy and understory with speed and balance, most often searching for food. They are known to use tools like stones to crack open tough nuts; some believe this behavior is a response to worsening food scarcity.
These capuchins have a wide range of predators to look out for, which we will specify more in the ecological role section. Their primary defense against these predators involves designating a sentry, or a capuchin within the group that serves as a “lookout,” while the others are focused on foraging.
These monkeys are known for “urine washing.” This is a form of olfactory (scent related) communication, where they cover themselves with their own urine to mark their territory. This scent trail usually follows them and helps identify their presence as well.
The golden-bellied capuchin monkey was the first capuchin species to be observed and described by European scientists around 500 years ago
Golden-bellied capuchins typically live in social groups that range from 9 to 30 individuals, adhering to an established dominance hierarchy with roles for both an alpha male and an alpha female. The alpha male holds the highest rank, commanding access to the best foraging areas and first choice in mating opportunities. He also assumes the responsibility of protecting the group from threats, particularly when territories, which cover about 3 square miles, overlap with neighboring groups. Alpha males also are prioritized when it comes to grooming, a valuable interaction for social bonding within the group. An alpha female leads the other females, though she holds a lesser rank than the alpha male.
Golden-bellied capuchins are very vocal, with a wide range of sounds that they use to communicate with one another. Their calls range from short yipping noises to more complex two-toned clunking, often used as alarm signals to warn about predators or other monkey groups. When moving through the trees, they make chattering and squealing sounds to keep track of their group’s location, ensuring they stay close while foraging. If a member becomes separated, their calls become more intense and change in tone, depending on how far they get from the group.
Beyond vocalizations, they engage in scent-marking through urine-washing, rubbing their urine on their fur to strengthen their scent and mark their territory. Additionally, they may rub the sternal gland on their chests on tree branches to signal their presence to others in the area.
Physical interactions, such as grooming, also play a key role in their communication, helping to maintain social bonds and group cohesion.
Golden-bellied capuchins have a polygynandrous mating system, where both males and females mate with multiple partners throughout their mating season, which is year-round. Females typically reach sexual maturity between 4 and 5 years of age, though they often do not give birth until around 7 or 8; males mature a bit later at around age 6 to 8.
Once pregnant, the gestation period lasts around 5 to 6 months, with single infant births being the most common (twin births are rare). During the first month, newborns are entirely dependent on their mothers, clinging to them as they travel through the trees. Infants become more independent between the ages of 2 to 11 months. The entire troop, particularly younger members, assists in caring for the young, ensuring the mother has support. While females tend to remain with their birth group, males usually leave to find new groups at around 2 years old.
Golden-bellied capuchins play a valuable ecological role in their environment, particularly as seed dispersers. As they move through the forest eating fruits and seeds, they inadvertently help regenerate plant life by spreading seeds via their feces. Furthermore, their feces serve as a fertilizer for these seeds, stimulating germination.
They also serve as a food source to many of the natural predators in the area, including snakes — like boa constrictors — harpy eagles, jaguars, ocelots, and caimans.
The golden-bellied capuchin is classified as Critically Endangered by the International Union for Conservation of Nature (IUCN, 2020), appearing on the IUCN Red List of Threatened Species.
Unfortunately, this species has been facing critical threats that have caused its population to drop 80% in just the past 50 years, with another 80% decline being predicted for the future. Their primary threat is habitat loss from deforestation, logging, and land development. On top of these factors challenging their survival directly, forest fragmentation has restricted their ability to interbreed (breed with other golden-bellied capuchins outside of their gene pool), and increased inbreeding, in turn reducing their genetic diversity.
Another major threat is hunting and illegal trapping for the pet trade. This species is also at risk of diseases, like yellow fever.
Golden-bellied capuchin 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 international trade in specimens of wild animals and plants does not threaten their survival.
These monkeys have been seriously threatened by habitat loss. Luckily, the remaining regions in which they can be found are mainly all protected. Their most notable safe haven is the Una Biological Reserve, which houses over 180 golden-bellies. Other protected zones include the Refúgio de Via Silvestre de Una, Serra do Conduru State Park, RPPN Fazenda Pé de SerraSete Passagens State Park, and Serra da Lontras National Park. There are also private protection areas, including RPPN Reserva Capitão, RPPN Pedra do Sabiá, and RPPN Reserva Ecológica Rio Capitão.
Numerous activists around Brazil are adamant about preserving their country’s natural environment, risking their own lives to help fight for this conservation; Brazil is consistently ranked as one of the most dangerous countries for conservation workers, with over 50 activists being assassinated in 2017 alone. This is why international conservation groups are so vital, especially in areas like Brazil, as they can continue to push for the protection of these natural environments without risking their lives. Fortunately, the United Nations partnered with the NGA Global Witness in creating a program to help keep these activists safe in September 2018.
There have been numerous conservation measures and field study programs to help protect the wide range of monkeys within the country of Brazil. Currently, all conservation actions are done by researchers and institutions involved with the “National Action Plan for the Northeastern Primates” and the “National Action Plan for the Mammals of the Atlantic Forest”.
- https://www.iucnredlist.org/species/4074/192592138#assessment-information
- https://animalia.bio/golden-bellied-capuchin#google_vignette
- https://www.researchgate.net/publication/287576066_Predation_of_lizards_by_a_critically-endangered_primate_Sapajus_xanthosternos_in_a_tropical_biodiversity_hotspot_in_Brazil
- https://wildark.org/species/golden-bellied-capuchin/
- https://www.bioexplorer.net/animals/mammals/monkeys/golden-bellied-capuchin/
- https://www.dudleyzoo.org.uk/animal/capuchin-yellow-breasted/#:~:text=The%20yellow-breasted%20or%20golden,%2C%20screams%2C%20whistles%20and%20chattering.
Written by Hannah Broadland, September 2024