variety of forest foliage. Unfortunately, more research needs to be conducted on this hypothesis to test its validity as currently no studies have been conducted on the toxicity levels in the fruit eaten by the masked titis. It is also important to note that termite mound soil was preferred by the titis in addition to the ant soil. Both the ant mound soil as well as the termite mound soil perform the same function for the monkeys, however some researchers have observed that the monkeys usually tend to prefer termite mound soil to ant mound soil when given both options. The reason for such a preference is not yet known. Survival Regardless of the presence of humans in Brazilian forests, titi monkeys customarily venture to dwell in "disturbed" forests (forests that have been cut down or invaded by humans) as long as the food availability is higher than in undisturbed forests. The use of disturbed and undisturbed forest by masked titi monkeys Callicebus personatus melanochir is proportional to food availability. The Atlantic Forest of eastern Brazil has been cut down to 5% of its original state with only 2% of that being undisturbed forest. Their existence is completely dependent on their ability to successfully reside in disturbed forests. However, titis do not seem to be aware of the difference between a disturbed and undisturbed forest. As previously mentioned, they feed opportunistically and therefore will reside in whatever forest has the most food available. As long as food is available to them (even if humans provide this food), it is feasible that the monkeys survive the deforestation of much of the Southern American rain forests. Reproduction Atlantic titis are usually monogamous (they stay with one mate throughout their entire lifespan). They have one offspring per year. It is difficult to distinguish between the sexes externally, however Atlantic titi family dynamics indicate that the father carries the infant at all times during the nursing. Level of daily activity Two major types of activity have been observed in masked titis. The first is characterized by two feeding periods separated by a relatively long resting period. The two feeding periods are in different locations in which a significant portion of the day was spent traveling to the second location to feed. The second activity pattern contained three feeding periods also separated by resting periods. However, travel was much more evenly dispersed throughout the day