Social structure The Panamanian white-faced capuchin is a
diurnal and
arboreal animal. It moves primarily by walking on all four limbs. It lives in troops, or groups, of up to 40 monkeys (mean 16, range 4–40) and has a male/female adult sex ratio of 0.71 on average (range 0.54–0.88). Males migrate to new social groups multiple times during the course of their lifetimes, migrating for the first time between 20 months and 11 years of age. The median age of migration in the Santa Rosa population is 4.5 years. Alpha males have been known to keep their positions as long as 17 years in this species Coalitionary aggression is common both among males and females, and capuchins seem to have an excellent understanding of the alliance structure in their group. For example, when capuchins are fighting, they sensibly recruit aid from someone who is both higher ranking than they are and also better friends with themselves than with their opponent. Female capuchins have linear dominance hierarchies. In contrast to many Old World monkeys such as
macaques, in which females socially inherit the rank just below their mothers and just above their next oldest sisters, capuchins do not have a highly predictable ranking within their matrilines. The alpha male is always easy to discern, but there are sometimes ambiguous rankings among subordinate males. Male-male relationships are tense, and affiliation between males is typically expressed by resting in contact, playing, or
non-conceptive sex rather than by grooming. Males cooperate in coalitions against potential predators, and also in defense of the group against other males. Because aggression from other male capuchins is the leading cause of death (aside from poaching by humans, where there is contact between humans and capuchins), male allies are critical for self-defense during migration, and to assist in taking over other groups. Immigrating males often kill young infants when they take over a group. Females band together to defend their infants from infanticidal males, but they rarely succeed in saving their infants. Females do often mate with the killers of their infants, and with time, they typically become as supportive of the new alpha male as they had been of the previous one. Although they engage in activity that has been described as "territorial", more recent research indicates that white-faced capuchin troops tend to behave aggressively to other white-faced capuchin troops regardless of where they meet, and the aggression is not necessarily intended to exclude the other troops from a specific home range. Home ranges overlap extensively, so groups are not territorial in the strictest sense of the word. Perhaps because of the intensity of male-male competition and the threat of infanticide, interactions between groups are typically hostile: the males display aggressively toward one another and sometimes engage in physical aggression (even killing an opponent), while females grab their infants and run. Interactions between the Panamanian white-faced capuchin and
mantled howler are infrequent, and sometimes result in the capuchins threatening the larger howlers. On the island of
Jicarón, Panamanian white-faced capuchins coexist with
Coiba Island howler monkeys (
Alouatta coibensis coibensis). In early 2022, motion-triggered cameras detected male capuchins carrying infant howlers on their backs while walking or smashing seeds with rocks. Further research indicated that during 2022 and 2023, at least five male capuchins abducted at least 11 infant howler monkeys and carried them on their backs. The capuchins were unable to properly care for or feed the infants, and at least four — and probably most or all — of the baby howlers died. By the time they announced their findings in May 2025, researchers had concluded that the cameras had captured a rare behavior that had arisen as a "fashion fad" among a single population of male capuchins, and described the capuchins' behavior as "the first known documentation of a social tradition in which animals repeatedly abduct and carry infants of another species — without any clear benefit to themselves." Several non-primate animal species tend to follow troops of white-faced monkeys or are otherwise attracted by their presence.
white-lipped peccaries and
agoutis are attracted by feeding white-faced capuchins, looking for fruit that the capuchins drop. It will also eat fruits from
Euphorbiaceae such as Mexican jumping bean
Sebastiania pavoniana. It generally only eats ripe fruit, testing for ripeness by smelling, tasting and prodding the fruit. It also uses the bromeliads as a water source, drinking the water that gets trapped inside. Insect prey eaten includes
beetle larvae, butterfly and moth
caterpillars,
ants,
wasps, and ant and wasp larvae. The population in
Guanacaste,
Costa Rica in particular is noted for hunting
squirrels,
magpies,
white-crowned parrots The amount of
vertebrate prey eaten varies by troop. The diet can vary between the rainy and dry season. For example, in
Guanacaste,
Costa Rica the Panamanian white-faced capuchin can eat a wide variety of fruits as well as caterpillars in the early rainy season (June to November). The use of stone tools is a marked difference between the
gracile capuchins of the genus
Cebus and the
robust capuchins of the genus
Sapajus. Although widespread in robust capuchins, only one case of habitual stone tool use has been reported by gracile capuchins. One population of Panamanian white-faced capuchins found in
Coiba National Park in Panama has been observed using
hammerstones and anvils to process fruits from
Terminalia catappa, Bactris major, and
Cocos nucifera (coconuts) and invertebrates such as
nerite snails,
hermit crabs, and
Halloween crabs. The Panamanian white-faced capuchin is known to rub parts of certain plants into their hair. Plants used in this manner include
citrus fruits, vines of the genera
Piper and
Clematis, monkey comb (genus
Sloanea),
dumb cane and
custard apple. In captivity, it has been known to use tools to get to food or to defend itself, and in one case a white-faced capuchin used a squirrel monkey as a projectile, hurling it at a human observer. Other species of
capuchin monkeys are also trained in this manner. Panamanian white-faced capuchins can also be trained for roles on
television and
movies, such as Marcel on the television series
Friends. They were also traditionally used as
organ grinder monkeys. It sometimes engages in a practice known as "
urine washing", in which the monkey rubs urine on its feet. The exact purpose of this practice is unknown, but it may be a form of
olfactory signal. == Reproduction ==