Abstract # 8:

Scheduled for Thursday, August 17, 2006 11:00 AM-11:15 AM: Session 1 (Regency East #1) Oral Presentation

Comparative Socioecology of Sympatiric, Free-ranging Bearded Sakis and White-faced Sakis in Brownsberg Natuurpark, Suriname

T. Gregory and M. A. Norconk
Kent State University , Department of Anthropology, Kent, Ohio 44240, USA
     Bearded sakis (Chiropotes satanas) and white-faced sakis (Pithecia pithecia) share dental specializations that set them apart from other platyrrhines, but they are considerably different behaviorally. We conducted a comparative analysis of feeding ecology, ranging patterns, and social cohesion during a 10-week study from May-August 2005 at Brownsberg Natuurpark, Suriname. Using 10-minute scans to collect data on group size and composition, day range and rate of travel (using a digital pedometer), forest level used and feeding activities (n = 221 samples for bearded sakis, n = 286 for white-faced sakis), we found that bearded sakis used higher forest levels (Kruskal-Wallis H = 127.4, p < 0.001); larger feeding trees (H = 8.02, p < 0.01); faster travel rates (Independent Samples t = 10.4, p < 0.001). Bearded sakis formed larger, more dispersed multi-male groups (17.3 ± 5.6, n = 3) compared with white-faced saki single-male groups (4.5 ± 0.7, n = 2). Despite dental adaptations for seed predation, we found only 15% overlap between the two species in feeding species ingested. Using these findings and data from published sources, we suggest that white-faced sakis demonstrate socioecological traits similar to red howlers (Alouatta seniculus), while bearded sakis are similar to muriquis (Brachyteles arachnoides). Covert forms of male-male competition such as sperm competition may allow bearded sakis to live in multi-male, multi-female groups without being highly sexually dimorphic.