Mapping the seasonal wild bird–livestock interface to support global early warning of avian influenza under planetary change

Climate change, land-use intensification, and biodiversity loss are rapidly reshaping animal distributions and human–animal interfaces, altering the geography and seasonality of zoonotic disease hazards. For avian influenza, migratory wild birds act as long-distance carriers while domesticated hosts amplify transmission and generate major socioeconomic impacts through poultry losses, trade disruption, and livelihood shocks. Yet the global, seasonally varying wildlife–livestock interface that underpins spillover and amplification risk remains poorly quantified. Here we develop a data- and model-based indicator that captures the potential for contact between wild avian hosts and key domesticated host groups across seasons. We combine seasonal distribution estimates for thousands of confirmed or putative avian influenza host species with spatially explicit domestic host layers to derive a gridded, season-resolved "interface intensity" index. We then assess whether spatial and seasonal fluctuations in interface intensity align with reported outbreak occurrence. The indicator reveals pronounced seasonal reorganization of high-interface zones, with peak interface intensity concentrated in low latitudes during boreal winter and expanding toward temperate regions in boreal summer. Persistent high-interface areas emerge in parts of Southeast Asia and several regions in Africa, consistent with long-recognized surveillance priorities. Interface intensity is strongly associated with outbreak reports, particularly for poultry in boreal winter, highlighting its value for anticipating periods and places of elevated transmission pressure. Our approach provides a scalable One Health tool that can be integrated with climate and land-use projections to evaluate future shifts in zoonotic risk and to inform targeted surveillance and preventative interventions.