Abstract # 6255 Event # 227:

Scheduled for Saturday, June 20, 2015 10:15 AM-10:30 AM: (Cascade H) Oral Presentation


EATING WELL ON THE ROAD: SPATIAL STRUCTURE AND FORAGING IN FREE-RANGING CHACMA BABOONS (PAPIO HAMADRYAS URSINUS).

M. J. Dostie1,2, D. Lusseau3, T. Bonnell1,2, S. Kienzle1,2, L. Barrett1,2 and P. Henzi1,2
1University of Lethbridge, Psychology Department, 4401 University Drive, Lethbridge, Alberta T1K3M4, USA, 2University of South Africa, Pretoria, South Africa, 3University of Aberdeen, UK
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     In 1974, Stuart Altmann proposed, as specific variant of a general optimality expectation, that baboons foraging on low-density resources should forage in rank formation (i.e., move as a ‘broad front’). We use spatially explicit data to test this idea. The GPS coordinates of all 13 adult members of a baboon troop at De Hoop Nature Reserve were collected across 74 all-day follows, using handheld data loggers. After correcting for temporal offset and estimating error, we extracted all inter-individual distances at 30-minute intervals (N=5204), applying the ‘socioecological’ model of group spacing to determine the closest distance at which moving adults will tolerate one another. This ‘point of repulsion’ (~3.9m) was then used to describe the distance separating optimally foraging animals. We used a subset of the data, for which we had detailed foraging information, to test the prediction that, as the proportion of optimally foraging animals increased, the bearing representing the group at its widest point would be increasingly perpendicular to the direction of travel, i.e., the animals would move in rank formation. As our data support this prediction (r=0.33; p=0.05, two-tailed test), we extend the analysis to the larger data set to provide a general description of movement dynamics, which we discuss in relation to individual decision-making.