[5] Black-capped squirrel monkeys are primarily tree-dwelling and are found in both native and plantation forests as well as some farmed areas near running water.

[4] Their diet is omnivorous and mostly consists of flowers, fruit, leaves, nuts, seeds, insects, arachnids, eggs and small vertebrates.

[12][13] It has been hypothesised that this diversification occurred due to environmental changes in the Pleistocene period which allowed for thicker vegetation to appear in the Amazonian rainforest.

[18] The dispute over the taxonomic and genetic classification of the black-capped squirrel monkey has become increasingly relevant with regards to their use in biomedical research, due to the fact that hybridisation may have an effect on the reproductive capabilities of the monkey,[19] and has the potential to cause a differentiation in its susceptibility to certain pathogens and infections.

[20] Alternative or previously proposed taxonomic names include:[2] Saimiri displaying the characteristic 'Roman arch' facial pattern of the black-capped squirrel monkey have been documented throughout most of Bolivia, northern Peru, and between the Jurua and Purus Rivers in Brazil.

[21][10] They are predominantly arboreal, and while they utilise all levels of the forests they have been observed to keep mostly to the lower canopies for the purposes of travel and foraging[10] It has been proposed that matrilineal troops of Saimiri boliviensis are formed due to an abundance of fruit and insects present in their habitat, which is not present in the habitats of other species of the Saimiri genus.

[21]  When they reach sexual maturity, male Black-capped squirrel monkeys will disperse from their natal troop into smaller all-male groups, and will eventually join a larger mixed-sex troop, often together with other males from the all-male group.

[10]  During the mating season, males of the species will gain a large amount of subcutaneous upper body fat, leading to what is known as a 'fatted' appearance.

[10] The scent and behavioural cues of a female monkey assist a male in his judgement of whether or not she will be receptive to his approach and attempt at mating with her.

[10] Squirrel monkeys have been found to be some of the most vocal primates, with a large range of different types of calls documented throughout their lifespan.

[4] Commonly used sounds include 'chucks',[23] a variety of purrs and squawks elicited during the birthing and mating seasons, chirps and peeps used for alarm or attention, as well as aggressive screaming and 'barking'.

[23] After maturation, the most commonly used call for adult females is a variety of 'chucks', used to maintain contact in dense vegetation where visual identification is not possible.

[8] It has been determined that the black-capped squirrel monkey adapts easily to changes or potential threats to its environment, and is not subject to high levels of hunting by humans.