Forager Polymorphism and Foraging Ecology in the Leaf-Cutting Ant,Atta colombica
I compare forager size and foraging selectivity of the leaf-cutting antAtta colombicaand that of its close relativeAtta cephalotes. In both species, larger foragers cut fragments of greater mass and area, and at vegetation sources of greater specific density (mass/area). However, the size-range ofA. colombicaforagers (1.5–56.8 mg) was wider than the range typical forA. cephalotes(1.4–32.1 mg). InA. colombica, the maxima workers (24–60 mg) commonly participate in foraging, making up 13% of all foragers in this study and in a previous study. In contrast,A. cephalotesmaxima workers (24–100 mg) rarely forage (less than 1% of all foragers in two previous studies), but instead serve primarily as soldiers defending the nest. Thus,A. colombicamaxima workers are smaller and do not appear to be so specialized as soldiers as areA. cephalotesmaxima workers. The broader size-range of workers participating in foraging appears to allowA. colombicato exploit a wider range of resources thanA. cephalotes, including tougher, denser vegetation and fallen fruits.