Abstract # 39:

Scheduled for Thursday, June 21, 2012 07:00 PM-09:00 PM: Session 9 (Gardenia) Poster Presentation


M. P. Tujague1,2,3 and C. Scarry2,4
1Universidad Nacional de La Plata, Facultad de Ciencias Naturales y Museo, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), La Plata, Buenos Aires, Argentina, 2Centro de Investigaciones del Bosque Atlántico (CeIBA), Puerto Iguazú, Argentina, 3Instituto de Biología Subtropical (IBS), Puerto Iguazú, Argentina, 4Interdepartmental Doctoral Program in Anthropological Sciences, Stony Brook University, Stony Brook, NY 11794-4364, USA
     Coordination of group movements is believed to emerge from decisions of key individuals, which are accepted and mimicked by other group members. Yet identifying these 'leaders' is frequently problematic. Here we examine the role of the dominant male on the coordination of group movements among tufted capuchin monkeys (Cebus apella nigritus) in Iguazú National Park, Argentina. In November 2009, intense intragroup aggression resulted in the death of the dominant male with no clear successor in the subsequent one-month period. During this period of instability, we recorded the location of the group’s center at 15-minute intervals (n=1011 locations) and spatial position of focal individuals. In order to examine the effect of the dominant male on group movements, we compared data from the period immediately following the death of the dominant male to matched-samples collected during the same season in 2007 (n=641 locations) and 2008 (n=700 locations). During the period of male hierarchy instability, the group exhibited erratic movements and frequently formed subgroups. The data sets showed a significant difference in the distribution of changes in travel direction (Watson’s test of homogeneity: p<0.001). Immediately following the death of the dominant male, directed forward movement (<60 degree change in travel direction) decreased and backtracking (>90 degrees) increased. These results suggest that, despite maintaining a central spatial position, the alpha male is a key factor in coordinating group movements.