Panamanian White-Throated Capuchin, Cebus imitator
PANAMANIAN WHITE-THROATED CAPUCHIN
Geographic Distribution and Habitat
As their name suggests, Panamanian white-throated capuchins, also called Panamanian white-faced capuchins, are native to Central America—from Honduras to Panama. They thrive in the neotropical rainforests of this region, and most of the research on wild populations was conducted in Costa Rica. Neotropical rainforests have varied dry and wet seasons, resulting in habitats that have a large change in temperature and rainfall. The plant life that depends on these climatic fluctuations has different fruiting seasons and therefore the capuchin’s food sources are sometimes unpredictable.
Capuchin taxonomy is probably one of the most controversial topics in South American primatology. When capuchins were described in 1949, they were all classified under the genus Cebus with multiple subspecies. Since then, capuchins have separated into two genera—Cebus capuchins, which are slender and do not have tufts on their head, and Sapajus capuchins, which are robust and tufted. The Panamanian white-throated capuchin was classified as Cebus capucinus imitator, a subspecies of the Colombian white-throated capuchin (Cebus capucinus). It was only in 2012 that genetic studies revealed that the Panamanian white-throated capuchin separated as a species about 2 million years ago and so they are now given their own species designation of Cebus imitator.
As their name suggests, the Panamanian and Colombian capuchins differ in their geographical distribution in South America. The Panamanian white-throated capuchin is found in Central America and the Colombian white-throated capuchin is found in the Northwestern Andes, a major mountain system in South America. The two capuchin species also vary slightly in appearance. Female Panamanian white-throated capuchins have frontal tufts that are absent in the Colombian white-throated capuchin females.
There have been extensive publications on Cebus capucinus, but the research was mostly conducted in Costa Rica and Panama. Therefore, the subject of those studies were actually Panamanian white-throated capuchins and not the Colombian white-throated capuchin. Panamanian white-throated capuchins are one of the best studied wild capuchin in the world.
Size, Weight, and Lifespan
Panamanian white-throated capuchins are medium-sized monkeys, with males weighing 7.3 lbs (3.3 kg) and females being slightly smaller at 5.1 lbs (2.3 kg). As adults, they can grow to a body length (head to tail) of about 32 inches (81 cm) with an additional tail length of 18 inches (45 cm).
These monkeys are relatively long-living species, with one captive male Panamanian white-throated capuchin living to be an impressive 54 years old. In the wild, we expect lifespans for these capuchins to be closer to 37 years (noted in females).
The Panamanian white-throated capuchin is probably one of the most famous primates in the world. You may have seen them in action as “Jack the monkey” from the Pirates of the Caribbean movies and Ross’s companion Marcel from Friends.
Their contrasting black and white fur, intelligent eyes, and pink human-like face give these monkeys their Hollywood good looks. They also have prehensile tails, which they use to balance while they sit upright and use their hands to manipulate their food. Their intense stares and head tilts when they communicate are so relatable to how we humans communicate with each other that most of us immediately feel a connection with these monkeys.
Panamanian white-throated capuchins are classified as omnivores. Capuchins are mostly frugivores, but Panamanian white-throated capuchins also consume a lot of insects (especially butterflies, ants, and beetles) to supplement their diet, especially females who are lactating and feeding their young. One study on Barro Colorado Island in Panama reported a capuchin diet comprising 26% carbohydrates (mostly from fruits) and 14% proteins (mostly from insects). Panamanian white-throated capuchins are opportunistic hunters that have been seen eating squirrels and lizards! So they have a varied diet that depends on what is abundant. In their neotropical home, fruits are not always in season and so to meet their energy needs, they have evolved to become generalist feeders.
Capuchins have varying levels of tri-chromatic vision. You may have heard of colorblindness in humans—it is where some people cannot differentiate between the colors green and red. Primates (including us humans) are the only mammals that have evolved to see red-green colors and the gene responsible for this color perception is on the X chromosome, which is partially responsible for determining the sex of the animal. And so variation in a primate’s ability to perceive variation in the red-green spectrum can be predicted based on whether they are males (all males are colorblind) and females (half or fewer number of females have some level of colorblindness). Fruits tend to be green when unripe (low in nutrients) and red when they ripen (high in sugar and nutrients). The ability to distinguish between the two colors means Panamanian white-throated capuchins that have color vision can spot and choose higher nutrition foods. This becomes important for juvenile capuchins that have not learned to determine ripeness from smell or texture.
Most primates can get water from the food they eat or from water collected in trees. They do not need fresh ponds to drink from. An exception to this norm are the Panamanian white-throated capuchins in Santa Rosa, Costa Rica, who will travel to drink from fresh waterholes every day in the dry season and sometimes even make these water holes a central foraging place from where they make short excursions to find food.
Behavior and Lifestyle
In Costa Rica, Panamanian white-throated capuchins are sometimes called “monos muy bravos” or “bold monkeys” because these monkeys are clever foragers that can find and extract food no matter what the challenge. Field biologists have reported that some Panamanian white-throated capuchins steal food from live traps or from predators. This intelligence most likely stems from the fact that capuchins live in forests where food sources are unpredictable and they are also generalist feeders that have to be on the lookout for different food types. Anatomically, capuchins have the largest body-to-brain size ratio of nonhuman primates. Their brain has many folds and creases, which indicate that their brain is capable of handling complex actions.
Panamanian white-throated capuchins are diurnal (active during daylight hours), are mostly arboreal (tree-dwelling, though they descend to the ground many times a day), and spend much of their day foraging for food. In the capuchin environment, trees fruit at different times—and so for the capuchins, food is available in patches of space (different areas of the forest) and patches of time (different times of the year). So, in order to gain energy (by eating), they have to expend a lot of energy by traveling to find food. For this reason, capuchins have adapted some cool strategies that show their resourcefulness. They have foraging routes, where they move from tree to tree, stopping to consume a few fruits before moving along. If they find a large fruiting tree, they will choose that as a temporary home-base to consume the fruits—and then they will make short excursions away to find other types of food. This strategy increases the chances of the capuchins finding a tree that can feed the entire troop for a long time, rather than spending all their time eating at a low-fruiting tree that will leave them hungry afterwards. Researchers have also noted that Panamanian white-throated capuchins forage alone or in dispersed groups, which can help reduce intra-group competition. These capuchins are also opportunistic feeders, so if they find a tasty insect, such as a nest of ants, they will stop and spend time extracting the protein-rich snack. This flexibility in feeding habits (referred to as foraging plasticity) means that capuchins can consume more energy per search area or time and they reduce competition with other primates species that are more dependent on fruits.
Using tools was long considered a human trait, until explorers reported different monkey species were also seen using sticks as “scoops” or “hammers,” though these were usually larger and more terrestrial species. The Panamanian white-throated capuchin is one of the few slender capuchins (belonging to species Cebus) that were seen using sticks to pound open nuts and crustaceans. Some researchers have also reported these capuchins using sticks to fend off and kill snakes. Their tool-use reaffirms the capuchins’ ability to adapt and learn in a complex environment.
Fur-rubbing is a behavior where primates will rub their fur use strong-smelling plants or insects. Panamanian white-throated capuchins are known to roll around in plants to get the plants oils and secretions on their body, though the choice of plants seems to vary by troop. It is likely the capuchins have learned that these smells reduce insect bites and have inadvertently used the antibacterial and insect-repelling properties of the plant.
The fact that Panamanian white-throated capuchins have become Hollywood celebrities are a mark of their intelligence and ability to learn and adapt to new environments. Unfortunately, this means that these wild animals are often captured as pets. There are also cases of capuchins being trained to help assist disabled humans accomplish tasks such picking up things or turning switches. These practices raise ethical questions of whether a wild and social animal, such as a capuchin, should be used as a service animal. Scholars argue that interacting with their mothers and siblings is a vital part of a young capuchin’s health, which can never be replaced by human relationships, no matter how well-intended.
Panamanian white-throated capuchins are the most studied wild capuchins in the world.
They are capable of using tools, especially to pound open nuts and hard-shelled animals.
They are highly intelligent learners with the largest brain-to-body size ratio of non-human primates.
Panamanian white-throated capuchins are called “monos muy bravos” or “bold monkeys” because they have been seen taking on bees nests and live traps belonging to researchers just to get food.
These capuchins are often captured as pets and their intelligence makes them highly trainable. However, monkeys should never be pets.
Despite ethical arguments against captive wildlife, these capuchins even appear in movies or are used as service animals in some cases.
Survival for most capuchin species depends on their access to food sources and their family dynamics; young are fed by aunts and protected by the alpha male, and finding food is a group effort.
As mentioned above, food sources for the Panamanian white-throated capuchin are variable, as they depend mostly on fruits (which occur seasonally) and insects (which move around and require more energy to find). So foraging is a vital part of their daily life. About 70% of their time looking for food is used to find insects.
Capuchins are often up at dawn, moving through the forest in search of fruits for most of the early morning, after which they may stay at a watering hole, forage for insects, and rest for the hottest part of the day. When it cools down in the late afternoon, the capuchin uses the remaining daylight hours to find a sleeping site while opportunistically feeding. Sleeping often occurs in small groups huddling for warmth. Panamanian white-throated capuchins tend to choose tall trees and stable branch forks high up as sleeping sites, to reduce the risk of predation. The capuchins can have a favorite sleeping site but they rarely use the same site for two nights in a row.
Panamanian white-throated capuchins live in troops of about 16 individuals (but the troop can be as large as 40) that include the alpha male (in his prime at about 10 to 15 years old), closely related females (sisters and cousins), juveniles (siblings and half-siblings), and immigrant males. They form long-lasting social bonds with their family members, which are reinforced through grooming and close contact with each other. Mothers especially form strong bonds with their daughters, and full siblings develop stronger relationships than other family members do.
In a Panamanian white-throated capuchin troop, the alpha male has the reproductive advantage and mates with most of the females in the troop. This mating system is called polygamy. Subordinate males (often sub-adult males) can spend their entire lives without producing offspring and they provide support in securing the troop from other potential alphas. Sometimes, subordinate males may mate with females in the troop, but this is usually a daughter of the alpha and is most likely because alphas have an aversion to mating with close kin. We know that mating between close relations can lead to genetic mutations and low survival rates. Allowing subordinate males to mate with females who might otherwise go unmated by the alpha can be a beneficial strategy for the troop.
Alphas are considered keystone individuals who have significant impact on the survival of the troop. Not only do alphas father many young capuchins, but they are also the most vigilant protectors from threats to the troop and their early warning can reduce capuchin mortality. Perhaps most importantly, the death of an alpha, especially through replacement by a new alpha, will result in infanticide (where all the young offspring of the previous alpha are killed by the new-comer). The new alpha will want to start passing on his own genetic material to a new generation of offspring. It is not in the alpha’s best interest to maintain a troop that will raise young capuchins that have the genes of his rival. Therefore, infanticide is seen in many mammal species, where reproductive success is dependent on having exclusive mating access to females in a group. It is the leading cause of infant death in Panamanian white-throated capuchins.
Female capuchins usually stay close to their natal troop (they are philopatric) and display a dominance hierarchy that depends on the mother’s status in the troop. Daughters assume a status lower than their mother, and older sisters can assume their mother’s status when the mother dies. Thus, female capuchins bond stronger with the maternal side of their troop (mothers, sisters, aunts, and cousins) rather than their paternal side. This form of hierarchy is categorized as “relaxed despotic dominance.” These rankings are stable throughout the female’s life, but if there is a significant life-changing event—such as the change in the alpha or death of a high-ranking capuchin—then dominance rankings can get disrupted.
As social animals, Panamanian white-throated capuchins have a repertoire of gestures, facial expressions, and sounds to help communicate to other troop members. Sound signals are most effective in their forest habitat because it does not require a direct visual of their troop-mate, and the message can be sent to all members at the same time.
Adult female capuchins in Costa Rica make a “trill” call as they move ahead to tell others it is time to move to the next foraging spot. Similar trilling noises are made by juveniles when they see family members, which triggers reciprocal “affectionate” noises from the adults. Physical conflicts within the troop are relatively low compared to other primates, and most of hierarchy issues are resolved vocally through squabbles and threats. However, there are cases of injury and sometimes deaths, especially when the alpha is challenged.
Social bonds and close relations are maintained through tactile communications like allogrooming (social grooming) and mutual finger sucking or tail sucking, which is where one monkey will take the other’s finger or tail in its mouth and engage in a self-soothing behavior of sucking. This is similar to how human babies may suck in their own thumbs or pacifiers. Playing behavior between juveniles and adults is another tactile form of communication; it’s an important time for the young to exercise their muscles and learn the social norms of the troop.
One amazing phenomenon in these capuchins is that when a male attains alpha status, he undergoes a physical and behavioral change. He becomes bigger and more aggressive. Initially, researchers assumed that males have to be naturally bigger and more dominant to become alphas—but because Panamanian white-throated capuchins are so well studied, researchers could combine data across time scales and genetic analyses to determine that physical and hormonal changes emerged only as the males became more dominant. Alpha males produce significantly higher male hormones (or androgens) than subordinate males. Therefore you can always tell which capuchin is the alpha. There is an obvious difference in appearance (a phenomenon called dimorphism) between alpha males and other adult males in a troop.
Female Panamanian white-throated capuchins are reproductively active at about 6 years of age and have a gestation period of 5.5 months. Like many primates, parental care is vital for physical and social development. The mother will feed the young milk for 14–23 months. The number of offspring a female has in her lifetime (a measure of reproductive success) depends on social conditions (such as number of siblings she has to help take care of the young), biological conditions (such as genetic health), and ecological conditions (such as the amount of food available).
Male Panamanian white-throated capuchins take longer, about 10 years, to mature fully into adults and attain their maximum body size. Biologically speaking, regarding hormones and physical attributes, males can reproduce from the age of 6 or 7. However, researchers have observed that capuchins wait until fully grown before mating and this is most likely a social adaptation that allows subadult males to move between social groups without conflict. Adult males are a threat to the status of the alpha male. Therefore, subadult males will not challenge alphas for mating rights and can move safely in and out of troops without fights that can cause them bodily harm.
Male Panamanian white-throated capuchins disperse from their natal troop before reaching sexual maturity (at about 6 years old) and then they may move from troop to troop for the rest of their lives. Typically, males may stay in a troop for 4 months to about 5.5 years. On average, they may change troops every 4 years or so. As capuchins are social, male relatives develop strong bonds with each other and often choose to disperse between troops together.
Panamanian white-throated capuchins form an important ecological link in their habitat as pollinators and fruit dispersers. Fruiting season varies with tree species and capuchins track and follow ripe fruit patches to feed. This behavior results in capuchins spreading seeds of the fruits they eat, which contributes to forest regeneration. Panamanian white-throated capuchins also feed on flowers, but in the case of one tree species, Luehea speciosa, they have been observed to just lick the flowers (probably for the nectar) in a “traplining” behavior, where they rapidly move from tree to tree. By doing this, capuchins help pollinate the tree species.
Because Panamanian white-throated capuchins are skilled at extracting ants from nests and beetles from inside bark, they are predators to many insects that would otherwise escape from less dexterous primates. Similarly, capuchins are also a source of food for predators such as jaguars and raptors. As a link in the food web, capuchins are a part of the ecosystem balance through their role in insect population control and nutrition for apex predators.
The International Union for Conservation of Nature lists the Panamanian white-throated capuchin as Vulnerable (IUCN, 2020), appearing on the IUCN’s Red List of Threatened Species.
Like most vulnerable and threatened species, habitat loss is the major contributor to population declines, including conversion of forests to agricultural and livestock farms. In Central America, deforestation for logging is a battle between environmental health and economic progress and in most cases, economy and human welfare are prioritized over conservation.
The Panamanian white-throated capuchin is capable of living in forest edges and human-altered natural landscapes (such as timber forests). However, farmers often consider them pests and hunt them. They are sometimes hunted as bushmeat and sold in local markets to supplement local diets. Because these capuchins are so intelligent and cute, unfortunately, they are also held captive as pets. Hunting, trapping, and the illegal pet trade contribute to declines in populations and disruption of the capuchin’s families that rely on their social bonds to survive.
Panamanian white-throated capuchins (Cebus imitator) 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.
The Appendix II classification means that CITES regards the Panamanian white-throated capuchin as a species that is not necessarily threatened with extinction but may become extinct if their trade is not strictly regulated. Panamanian white-throated capuchins are adaptable to habitat degradation and varied food sources. These survival qualities have probably given capuchins the advantage over other primate whose populations have been decimated due to habitat destruction.
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Written by Acima Cherian, June 2022