Abstract # 62:

Scheduled for Friday, June 20, 2008 09:30 AM-09:40 AM: Session 7 (Meeting Room 2DEF) Oral Presentation

Cheek pouch use in Macaca mulatta: tests of the feeding competition and multitasking hypotheses

D. L. Hannibal
University of Oregon, Eugene, OR, USA
     Previous studies have produced conflicting results regarding the selective pressures for the evolution of the cercopithecine cheek pouch. Three hypotheses, originally suggested by Murray (1975), include predator avoidance, feeding competition and multitasking (feeding while traveling or socializing). The goal of this study was to assess the feeding competition and multitasking hypotheses. Focal animal follows were conducted using 56 subjects from the Cayo Santiago Macaca mulatta population for a total of 243 hours. Tests of independence between feeding priority and cheek pouch use were significant [G(4)=158.33; p<0.001], with high feeding priority individuals (38.96%) feeding without cheek pouching more often than middle (20.15%) and low (28.05%) feeding priority individuals. Middle (54.64%) and low (58.03%) feeding priority individuals fed from their cheek pouches more often than high feeding priority individuals (35.39%). Tests of independence for activity categories and cheek pouch behavior were significant [G(15)=923.23; p<0.001], but support feeding (61.21%) as the primary activity for the majority of the time subjects were processing food from the cheek pouch, and do not support affiliative (2.10%) or traveling (16.36%) behaviors as the primary activities. Additionally, most time spent in affiliative (93.39%) and traveling (70.35%) behavior states was not coincident with cheek pouch use. These results refute the multitasking hypothesis and support the feeding competition hypothesis for the evolution of the cercopithecine cheek pouch.