Blood glucose and fat score did not differ between uninfected, single-infected, and co-infected birds, suggesting that short-term energy stores and immediate condition were not strongly affected by infection status. In contrast, hemoglobin and hematocrit were lowest in co-infected birds, indicating reduced physiological condition and a potential impact on oxygen transport. This reduced oxygen-carrying capacity may limit aerobic performance, making sustained activity more difficult. As a result, co-infections may make migration more challenging by decreasing endurance and energy efficiency, potentially lowering survival during long-distance flights.
Future work will examine corticosterone levels to assess long-term stress and quantify parasitemia to better understand infection intensity. Heterophil-to-lymphocyte (H:L) ratios, along with blood glucose, hemoglobin, and hematocrit, will be used to evaluate physiological stress and the broader health impacts of infection.