Abstract # 6:

Scheduled for Thursday, August 17, 2006 10:30 AM-10:45 AM: Session 1 (Regency East #1) Oral Presentation

Sex differences in the foraging ecology of squirrel monkeys in Eastern Amazonia, Brazil

A. I. Stone
University of California, Davis, One Shields Avenue, Davis, CA 95616, USA
     Sex differences in foraging behaviors of wild primates may be caused by sex differences in energetic requirements due to reproduction, body size or by differences in social behaviors. I investigated the feeding ecology of squirrel monkeys in Eastern Amazonia during a 12 month period (March 2002-March 2003). Sex differences in behavior were investigated in relation to seasonal changes in food availability and reproductive events. The wet season corresponded to birth and lactation and the dry season corresponded to mating and gestation. Data were collected on adult males and females in two groups of squirrel monkeys using focal animal samples and intensive sampling of foraging bouts. Insects were the most common dietary item for both sexes (76% of feeding time), followed by the mesocarp of the palm Attalea maripa (28% of plant-feeding time). Sex differences in activity budgets and foraging success were significant primarily during the dry season (t-tests conducted at p<0.05). Females foraged significantly more than adult males but did not eat more. Males were significantly more efficient at obtaining insects (0.72 captures/attempts vs. 0.35 for females). No differences existed in palm feeding rates. During fruit foraging, however, females stayed in closest proximity to other females and juveniles, whereas adult males foraged alone. These sex differences in foraging are best explained by reproductive costs incurred by females and by the social structure of Saimiri troops.