Unpaved roads alter foraging patterns of the leafcutter ant Atta colombica

Abstract

Leaf cutting ants are dominant herbivores and influential ecosystem engineers in the Neotropics. It has been suggested that habitat disturbances alter the architecture of foraging trail systems for colonies in their vicinity; however, the evidence remains scarce. In this study we investigated the effect of unpaved roads dissecting tropical lowland forest habitat on the structure of leafcutter foraging trail systems and foraging effort. We mapped trail systems for 16 mature Atta colombica colonies located at different distances from unpaved roads. Our results suggest exploitation of unpaved roads by leafcutters provides favorable foraging conditions, causing significant differences in foraging trail structure.

Keywords:

• disturbance
• human impact
• optimal foraging
• foraging trails
• tropical moist forest

Acknowledgments

We thank the Princeton Environmental Institute and the Ecology and Evolutionary Biology Department at Princeton University for research funding for M.E.W. and the Secretaría Nacional de Ciencia y Technología e Innovaciónde la República de Panamá (SENACYT) for a grant to H.H. [grant no. COL 08-067]. The Smithsonian Tropical Research Institute (STRI) provided logistic support, and thanks are due especially to J.S. Wright for his help. We thank S. Grossberg, P. Cowgill, B. Rubin and A. Olsen for programming tutorials, and helping us transform the data into the format necessary for spatial analyses. Lastly, we thank J. Mitchell and C. Moreau, advisor to M.E.W., for their comments on the manuscript.