American shorebird-prey network patterns: Geographic variation in non-breeding habitats

Understanding trophic ecology is essential for elucidating species' life histories and the ecological interactions that sustain them. For migratory shorebirds, which are opportunistic feeders, survival across vast migratory routes depends on the availability of critical stopover sites, where local environmental conditions shape food resources. In this study, we applied a network-based approach to examine shorebird-prey interactions across the Americas, constructing an interaction matrix from a systematic literature review spanning publications from 1929 to the present. Our analysis, encompassing the diets of 36 migratory shorebird species across distinct biogeographic realms, revealed that shorebird-prey networks exhibit low nestedness, low connectance, and moderate modularity. These structural patterns suggest a balance between vulnerability to prey decline and potential resilience through reduced competition and disease transmission. Network structure varied more in tropical regions than in temperate zones. Contrary to our hypothesis, prey richness did not correlate with increased morphological specialization among shorebirds. This suggests that factors beyond morphology, such as behavioral plasticity or interspecific competition, may play a greater role in shaping foraging strategies. This research provides the first comprehensive analysis of structural patterns in antagonistic shorebird-prey networks across the Americas. While the observed modularity suggests some resilience during migration, climate change and anthropogenic pressures pose significant threats. Continued research into shorebird diets is imperative for informing conservation and management strategies at key stopover sites.