Foraging and Spatial Ecology of a Polydomous Carpenter Ant, Camponotus leydigi (Hymenoptera: Formicidae), in Tropical Cerrado Savanna: A Natural History Account.

Abstract

Carpenter ants (genus Camponotus) are considered to be predominantly omnivorous, mixing several feeding habits that include predation, scavenging of animal matter, and plant-derived resources. Nitrogen acquisition is crucial for the nutritional ecology of ant colonies because growing larvae require sustainable protein provisioning. Here, we investigate the foraging ecology and the spatial nesting structure of the carpenter ant, Camponotus leydigi Forel, in Brazilian cerrado savanna. By marking workers from different nests with distinct colors, we revealed that C. leydigi occupies physically separated but socially connected nests (up to 30 m apart), a phenomenon known as polydomy. Observational data on aboveground internest movements in C. leydigi corroborate cooperative exchanges between nest units and confirm several types of social connections, including internest transfer of liquid and solid food, transport of colony members (brood, workers), movement of solitary workers, and internest recruitment. Polydomous C. leydigi allocate foragers throughout 1,700 m2, feeding mostly on termites and plant-derived exudates. Influx of exudates is threefold higher compared with solid food. Uric acid pellets excreted by lizards comprise 20% of the solid diet in C. leydigi, a rare quantitative assessment of this peculiar type of nitrogen complementation in ants. Based on video recordings, we hypothesize that nest decentralization in C. leydigi may reduce foraging constraints caused by overt interference by the aggressive ant, Ectatomma brunneum Smith, F. (Hymenoptera: Formicidae), which regularly blocks nest entrances. Our field study enhances the importance of natural history data to clarify selective pressures underlying the evolution of particular behavioral patterns (nutritional and nesting habits) in ants.