Host-pathogen network and eco-evolutionary drivers of avian influenza transmission in wild birds

Multi-host pathogens vary in how they utilise different hosts, yet the traits determining which species occupy central positions in transmission networks remain poorly understood. We tested whether the wild bird-avian influenza virus (AIV) network exhibits a scale-free structure, implying that hub hosts disproportionately contribute to transmission and whether ecological and evolutionary traits jointly predict hub status. Using global infection records, we constructed a bipartite network linking 247 bird species to 105 AIV subtypes. Degree distributions followed a power-law pattern, confirming substantial heterogeneity in host importance. We identified 23 hub species, exclusively from Anseriformes and Charadriiformes. Interpretable machine learning revealed that hub species share strong flightability, prolonged water-surface foraging, greater longevity and higher diversification rates, indicating that both ecological exposure and evolutionary history influence hub status. These findings provide insight into host-pathogen network dynamics and highlight priority species for targeted AIV surveillance and control.