Look at the birds: avian malaria and other haemosporidians as global health sentinels

Abstract Vector-borne diseases (VBDs) have long been recognized as sensitive indicators of environmental conditions, and historical records reveal that associations between climate, landscape, wildlife, and disease have shaped human understanding of epidemics for centuries. In the context of accelerating global environmental change, this perspective has gained renewed relevance as climate warming, land-use transformation, and urbanization increasingly alter interactions among hosts, vectors, and pathogens. Birds and their haemosporidian parasites ( Plasmodium , Haemoproteus , and Leucocytozoon ) have emerged as powerful sentinel systems for detecting these changes because they are widely distributed, ecologically diverse, and supported by extensive long-term datasets. Here, I synthesize evidence demonstrating how avian malaria systems reveal climate- and landscape-driven shifts in parasite prevalence, transmission intensity, and geographic range across broad spatial and temporal scales. Long-term and large-scale studies show consistent associations between rising temperatures and increased haemosporidian transmission, including altitudinal and latitudinal range expansions into previously unsuitable environments. Complementary research highlights how habitat fragmentation, deforestation, agricultural intensification, and urbanization modify vector communities, host condition, immune function, and parasite assemblages in context-dependent ways. While these findings underscore the sensitivity of avian host–parasite systems to environmental change, they also reveal important limitations to extrapolation, including non-linear transmission dynamics, parasite- and host-specific responses, and the frequent lack of long-term vector data. I argue that birds and their haemosporidian parasites provide robust early-warning indicators of environmental change when interpreted within an integrative framework that accounts for ecological heterogeneity and socio-environmental context, strengthening their value for anticipating emerging VBD risks under ongoing global change.