Foraging Specializations of Individual Seed-Harvester Ants.

Summary. 1. When presented with a patch of 3 different grass species' seeds, a Pogonomyrmex rugosus colony harvested a mix of all species available. Individually marked workers, however, specialized on a single species. These individual specializations hold for at least several days but can also be shifted rapidly. Workers of a similar species, Veromessor pergandei, also appear to specialize to seed species, taking larger than average seeds of one species from a mixed seed patch when seeds of a larger species were available and being collected by colony-mates in that same patch. 2. Seed choice in both ants is not a function of worker size; this variable explains <4% of the variance in seed size harvested by either ant species. Foraging specializations may enhance individual and colony-wide foraging efficiency in a manner similar to that of "majoring" in bumblebees. [ABSTRACT FROM AUTHOR]