The blood parasite Haemoproteus reduces survival in a wild bird: a medication experiment

Abstract

While avian chronic haemoparasite infections induce reproductive costs, infection has not previously been shown to affect survival. Here, we experimentally reduced, through medication, the intensity of infection by Haemoproteus parasites in wild-breeding female blue tits Cyanistes caeruleus. However, this treatment did not reduce the intensity of infection in males or the intensity of infection by Leucocytozoon. Medicated females, but not males, showed increased local survival until the next breeding season compared with control birds. To our knowledge, this is the first empirical evidence showing long-term direct survival costs of chronic Haemoproteus infections in wild birds.

Figure 1.

Change in the intensity of infection by Haemoproteus parasites (log-transformed) in (a) female and (b) male blue tits with respect to the medication treatment (females: F_1,77 = 4.25, p = 0.04; males: F_1,73 = 0.34, p = 0.56). Bars denote 95% confidence intervals. Solid line connecting filled diamonds, control; dashed line connecting squares, medicated.