Ranging costs in wild spider monkeys
Authors: Asensio, N., Korstjens, A.H. and Aureli, F.
Conference: 2nd Congress of the European Federation for Primatology
Dates: 3-7 September 2007
Journal: Folia Primatologica
Volume: 79
Pages: 310
ISSN: 0015-5713
DOI: 10.1159/000137690
Abstract:Intragroup feeding competition is one of the most significant costs of group living. One important aspect of such a cost is a component of scramble competition, often reflected in a positive relationship between travel distance and group size. This is especially so for frugivorous animals living in habitats with seasonal variation in fruit availability. In species with high levels of fission-fusion dynamics, community members can adjust group size to local food availability by fissioning into small subgroups. This adjustment is viewed as a way to deal with scramble competition and thus reduce ranging costs. We studied the effect of subgroup size and seasonality on four components of ranging costs (travel distance, time spent travelling, speed and travel effort) focusing on the movements between food patches of the members of a community of spider monkeys in Santa Rosa National Park, Costa Rica. We did not find an effect of the two variables on any of the ranging cost components, suggesting that costs are kept to a similar level across seasons and subgroup size categories. Smaller subgroups could visit larger patches as well as smaller ones, but larger subgroups did not visit small patches. Compared to the food patch previously visited, spider monkeys visited larger patches just after fusions (and smaller patches just after fissions). However, there was a cost associated with such an adjustment as they covered a greater distance between patches after fusions. This rapid adjustment, even if it came at a short-term cost, is evidence of the effectiveness of fission-fusion dynamics, especially because the cost was not long/lasting, as larger subgroups did not, on average, experience greater ranging costs than smaller ones.
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Source: Manual
Preferred by: Amanda Korstjens
