Foraging by Atta sexdens (Formicidae: Attini): seasonal patterns, caste and efficiency

Abstract. 1. Atta sexdens changes diel periods of foraging, the size of its foraging territory, the numbers and lengths of foraging trails, and its rate of foraging with respect to seasonality in subtropical Paraguay. Leaf loads are significantly larger in warmer months than loads carried in cooler months.
2. Foragers segregate into three labour groups in the field: a small subset climb trees, cut large quantities of vegetation, and drop them to the ground; the second subset of foragers searches out these leaf caches, cut diem into smaller pieces, and carry and deposit the leaf fragments on the foraging trail; the third subset of workers retrieves leaf fragments on the trail and carry them to the nest.
3. Pitfall trapping shows a large degree of patchiness in activity, with media workers dominating the foraging population, more so closer to vegetation which is being harvested.
4. The recovery efficiency of the multi-staged foraging behaviour is estimated to be only 49%, with the recovery of leaf caches near 50%. The impact of A. sexdens may, thus, be twice as great as previous estimates on their herbivory.