Sex Differences and Spatial Proximity on Feeding Behaviors in a Free- ranging Population of Mantled Howler Monkeys (Alouatta palliate) in northeastern Costa Rica

In general, primates are long lived and invest more time in the post-natal care of their young than do other mammals (Richard, 1985). This longer period of parental investment increases the females' cost in providing for infants but may playa major role in ensuring offspring survival. Studies on the cost of reproduction indicate that lactating females have higher nutritional requirements than both non-lactating females and adult males (Richard, 1985). Therefore, lactating females face certain feeding challenges in order to meet these metabolic needs. For instance, females may attempt to accommodate their increased nutritional requirements of reproduction by placing themselves in close proximity to the adult males during feeding in order to obtain access to productive feeding sites (Richard, 1985). Females may also space themselves near viguant adult males in an attempt to avoid infanticide by invading males. Given these two alternative spacing strategies, three important questions can be addressed: (1) Are there sex differences in feeding behavior, diet, traveling and resting in mantled howler (Alouatta palliata) monkeys? (2) Do certain sex classes maintain proximity to other sex classes more frequently than expected by chance and if so, does this change during different activities? (3) If males have priority access to productive feeding sites, do females avoid feeding near adult males due to male aggressiveness or do they maintain proximity to males in order to obtain access to better feeding opportunities and protection for their young? These questions were examined during a field study of a free-ranging population of mantled howlers (Alouatta palliata). The study compared the distances that lactating females and non-lactating females/subadult males maintained from adult males during feeding, foraging, traveling and resting.