Food collection within an ant community in semi-arid Australia, with special reference to seed harvesters

The trophic structure of an ant community near Deniliquin, in south western New South Wales, was found to be complex. Individual species covered a range of trophic levels and, apart from a few specialized predators, most species showed a broad diet. A total of twenty-seven species were placed in six different categories, according to food usage patterns:- specialist predators (2 spp.), generalist predators (1 sp.), predator-scavengers (4 spp.), omnivore-nectar collectors (10 spp.), omnivore-seed collectors (5 spp.) and seed harvesters (5 spp.). Almost 50% of ant colonies were of the five seed-harvester species and their food usage was examined more closely. They showed marked seasonal changes in composition of diet, corresponding closely to periods of seed production by different food plants. There were also differences in seed selection between species, and these were related to the size, phenology and probably chemical properties of the seed. Foraging behaviour by the various species showed differing adaptations to efficient utilization of a variable food supply.