Abstract # 127:

Scheduled for Sunday, September 18, 2011 10:45 AM-11:00 AM: Session 17 (Meeting Room 408) Oral Presentation


S. Van Belle1, A. Estrada2 and P. A. Garber1
1University of Illinois, Urbana-Champaign, Department of Anthropology, Urbana, IL 61801, USA, 2Instituto de Biología, Universidad Nacional Autónoma de México

Coordinating traveling time and direction and maintaining social cohesion is a primary benefit of group living in mammals. During a 10-month study, we investigated the behavioral factors underlying collective group movements in three multimale-multifemale groups of black howler monkeys (Alouatta pigra) at Palenque National Park, Mexico. A total of 344 travel bouts, defined as movement in which all group members traveled together for a distance of ? 25 m, were collected. Both adult males (N = 9) and females (N = 7) were observed to lead group movement, yet females initiated group movements significantly more frequently than males (X2(1) = 7.9, p = 0.005). The leading position was overtaken by another group member in 70 travel bouts, with males and females losing leadership during 26% and 16%, respectively, of their leading travel bouts. For 274 travel bouts in which leadership did not change, the sex of the leader had no influence on the distance traveled (U(1) = 838, P > 0.05), or the probability that the group would feed or rest upon arrival (X2(1) = 0.7, p > 0.05). However, travel bouts led by males, compare to those led by females, were significantly more frequently followed by howling (X2(1) =7.5, p = 0.015). The results suggest that black howler females play a more prominent role than adult males in initiating and directing group travel.