Rio Mayo Titi

Rio Mayo titis usually live in dry woodland areas with a lot of vines and plants. They are found in Peru in the northern part of the Department of San Martin, at altitudes of 750–950 meters and also in the foothills of the Andes. One P. oenanthe family was studied by scientist DeLuycker from October 2004 to September 2005. The studied family consisted of a mother and father, two offspring, and a baby born within the study period. The family was observed to live in bamboo stands and low forests with trees with a mean height of 6.8 meters. The family used only five sleeping sites during the year-long study time, two of them only rarely. Sleeping and resting was the most common activity, followed by traveling, and then eating and foraging. The P. oenanthe also socialized with others of their own kind. However, forest degradation and disturbed habitats had a negative effect on P. oenanthe sociability.

The diet of the Rio Mayo titi consists of mostly leaves, seeds, fruits, and arthropods. In one study, it was found that 54% of their diet was fruit, and 22% insects (consisting of at least 10 different types of insects), with the remainder consisting of leaves, tendrils, meristems, flowers and seeds. The 22% of the P. oenanthe diet that consists of insects is gathered in a variety of ways. There are three main types of foraging technique that the species uses to catch insects: lunging and grabbing exposed prey, biting and inspecting hidden prey, and stealth foraging or scanning for prey. Out of the three techniques, the most frequently used technique for hunting insects was found to be lunging and grabbing exposed prey. They have a high success rate of catching insects, reaching up to 83%. This species' ability to hunt insects so easily is especially important for survival in times of scarce food availability.