Foraging behaviour and colony structure in ants

Abstract

Among social insects, foraging behaviour serves as a principal link in the translation between individual-level performance and colony-level success. Because nest size has been implicated as an important variable in that translation, foraging behaviour was studied in an ant species that spontaneously changes its nest size over the summer. Effects of queen presence/absence and nest size on speed, linearity and directionality of movement were measured for (1) a series of undisturbed nests and (2) nests that were altered in a pseudo-mutant experiment to simulate nest fractionation in the field. Ants looking for food behaved differently for each of these three measures than did ants carrying food to the nest. Furthermore, nest size had strong effects on the behaviour of ants, but queen presence/absence was not a consistently important factor. Our results show that an ant forager’s behaviour reflects the social milieu within her nest, even when she is outside that milieu.