Seasonal Food Abundance and Foraging Activity in Some Desert Ants

Abstract

Three species of desert seed-eating ants differ in response to an altitudinal environmental gradient; peak abundances of colonies occur at unique points on the gradient, thereby indicating some ecological differences. Time of daily foraging activity differs between species, and these differences are regulated by species-specific responses to soil surface temperatures. No species uses the entire range of temperatures available for above-ground activity. Such restricted foraging schedules are most likely adaptations to seasonal production of food rather than to daily events. Seed production by annual plants is estimated to occur at different times of the year along the gradient. Each of the three ant species has a foraging schedule that minimizes activity at times other than the estimated season of seed production at the particular part of the gradient where the ant species is most abundant.