one ant’s trash is another ant’s treasure: army ant middens provide resources for diverse ant assemblages

The army ant Eciton burchellii boasts more animal associates than any other animal species yet described, but the relationship between army ants and other ant species has only been studied in the context of predation. The waste deposits (middens) of army ant colonies are nitrogen-rich, a potentially high-value nutrient source for leaflitter arthropods. We explored this bottom-up role of army ant middens in the context of tropical ant communities. Our three main questions were 1) Which ant species forage on army-ants middens? 2) How does the bi-phasic life cycle of army ant colonies (affecting midden size, persistence, and abundance) affect which and how many ant species a midden boasts? 3) How do the ants that forage on army ant middens differ across elevations? Across 39 bivouacs we found 36 species of ants foraging on army ant middens. These included highly predatory ants, nitrogen-limited arboreal ants, and fungus-farming ants. Per-midden richness was significantly lower for the usua...