Fallen Branches as Part of Leaf‐Cutting Ant Trails: Their Role in Resource Discovery and Leaf Transport Rates inAtta cephalotes

Abstract

ABSTRACTFallen branches, logs, and exposed roots (fallen branches hereafter) commonly form part of the trunk trail system of leaf‐cutting ants that inhabit the tropical rain forest. We studied the role of fallen branches on resource discovering and on leaf transport rates inAtta cephalotes. Fallen branches were common components of theA. cephalotestrail system; they were present in all the nests, and in the majority of the trunk trails examined (13/16). A field experiment revealed that, at the beginning of their foraging activity, ants discovered food sources located at the end of fallen branches earlier than those located on the leaf litter. Additionally, laden ants walked faster along a fallen branch than along soil tracks of the trunk trails. This increment in speed was higher in slow‐walking ants (e.g., with larger loads) than in fast‐walking ants (e.g., with smaller loads). These results suggest that the presence of fallen branches may direct the searching effort of leaf‐cutters and increase the foraging speed of laden ants when these structures are part of the trunk trail system. The advantages of using fallen branches as part of a trail system, and their potential consequences in the spatial foraging pattern of leaf‐cutting ants, are discussed.