Coimbra-Filho’s titi monkeys are arboreal; that is, they spend the majority of their lives in trees, favoring the lower to middle forest strata (or layer), also referred to as the forest understory. In this warm, damp, and sheltered environment that consists of small trees and shrubs that grow between the forest canopy and forest floor, the titis advance through their habitat slowly and purposefully, using all four limbs (quadrupedally). Occasionally, they leap from tree to tree. Their long tail, though incapable of gripping, helps them to balance. While eating, the titis sit upright on branches and tree trunks. Individuals from a family group often eat together from the same food source, leading researchers to speculate that sharing a meal is a social activity, not solely about sustenance. Titi monkeys have been observed chewing leaves and then rubbing the pulp (or pith) on their chest. The reason for this behavior is unknown.

Titis only descend to the ground if they must—to cross gaps in forest patches or to seek alternative food resources, a necessary adaptation to scarce arboreal fruit availability, wildlife biologists believe. When on the ground, the titis move quickly, clambering forward. Younger titis might take this ground opportunity to play with one another.

During the warmer months, when fruits are plentiful, the titis rise before dawn (unless it’s raining) to begin their day of foraging. During the colder months, when fruits are scarce, they sleep in, rising up to 4 hours after sunrise. (Who wants to get out of their warm bed when it’s cold outside?) They forage until midday, when they take a generous nap before resuming their activities.

In fact, naps are important to this titi species, and these monkeys spend a considerable amount of time each day resting quietly in dense vegetation. But they can’t afford to be too lax, because predators lurk. Raptors are their foremost predators and include the Guianan crested eagle (Morphnus guianensis), ornate hawk-eagle (Spizaetus ornatus), and turkey vulture (Cathartes aura). The tiny monkeys are also preyed upon by larger primates, such as the yellow-breasted capuchin monkey (Sapajus xanthosternos).

In a field study, wildlife biologists observed the titi monkeys’ behavior in response to a threat by a yellow-breasted capuchin. The titis emitted a quiet vocalization, alerting group members of the threat, then descended to the dense undergrowth to avoid detection and predation. In another field study, in response to a threat by a turkey vulture, while they were feeding from a fruit tree, the titis jumped to the forest floor to escape.

Both these antipredator behaviors have been documented for other Latin American primates and, with regard to titi monkeys, add to our understanding of how these primates adapt to threats within their fragmented habitats.

Titis also practice crypsis—the art of camouflage—to avoid predator detection. Hiding in the dense foliage and tangled vines, they blend in with their environment.  

Coimbra-Filho’s titi monkeys usually end their traveling and foraging activities before sunset (likely a predator avoidance strategy). Overnight, they sleep together in the tangles of a tall, vine-encrusted tree and often return to the same tree each night. Besides providing the titis with an important food source, liana vines attach themselves to tree trunks and branches, thereby linking trees together to provide shelter and canopy-to-canopy access to the titis.