Foraging ecology of the thermophilic Australian desert ant, Melophorus bagoti

Abstract

The paper describes the foraging ecology of the Australian desert ant, Melophorus bagoti, a thermophilic, diurnal scavenger with ground-nesting colonies. Overlapping foraging ranges, low foraging success rates, and intercolony aggression suggest intense competition for food between colonies. Daily foraging starts when soil surface temperatures approach 50°C. Workers search individually and collect predominantly dead insects. Occasionally, they consume plant secretions. Foraging activity peaks on mid-summer days. On cloudy days the onset of foraging is delayed, and the foraging activity is low. Ants do not forage on rainy days. Typically, workers start their above-ground activities with a few short exploration runs. On average, they perform one foraging run on the first day of their outdoor lives. With age they gradually increase foraging site fidelity and daily foraging effort. Individual foraging efficiency is low at the beginning but grows with experience. However, due to a high mortality rate and, hence, high forager turnover, average rates of foraging success for a colony remain rather low. The outdoor activity gradually decreases towards the end of summer and appears to stop completely during the winter months.