Integrating behavioral observations with stable isotopic data to clarify ant trophic ecology

A fundamental question in ecology is who eats whom, as this informs our understanding of energy flow and ecosystem functioning. Understanding variation in the trophic positions of native ants is critical for clarifying their ecological roles within green and brown food webs. As facultative scavengers, ants function as both predators and detritivores, linking these two food web pathways. This study investigates six native ant species on Santa Cruz Island using stable isotope analysis (δ¹⁵N) and ant-specific camera traps to explore how ant foraging behavior—predation versus scavenging—affects their trophic position. Contrary to traditional expectations, larger-bodied species (e.g., Camponotus) occupied lower trophic positions than smaller species. Stable isotopic findings do not provide information on behavior therefore, camera traps designed to exclude non-ant arthropods will provide insights into foraging behavior by distinguishing predation from scavenging. Camera data will be used to test the hypothesis that higher δ15N values indicate a greater reliance on scavenging behavior. Preliminary isotopic analyses reveal spatial and temporal variation in δ15N across years and plots; however, species-specific differences remain consistent after accounting for these variables. Results from camera traps deployed in the 2025 field season will further clarify behavioral mechanisms underlying observed trophic positions.