Bird community effects on avian malaria infections: Dilution or amplification?

The human modification of the landscape and subsequent changes in biotic variables, such as community structure and composition, can alter host-parasite dynamics. In addition, a beneficial effect of wildlife diversity on zoonotic disease risk and transmission has been proposed. Here, we studied the effects of the bird community on the prevalence and richness of lineages of avian haemosporidian in the highly diverse area of Antioquia, Colombia. We sampled birds in three human-altered areas (dams) and molecularly determined the prevalence and identity of haemosporidia blood parasites infecting birds. We analyzed the relationships of the bird community on the prevalence and richness of lineages of avian haemosporidian through generalized linear models. According to our results, there were non-significant effects of dominance and richness of the bird community on the prevalence of avian parasites. However, we found evidence of an amplification effect given the associations between host dominance and the number of infections (logarithmic relationship) and expected Haemoproteus and Plasmodium richness (exponential relationships). Our results suggest a fundamental role of host community dominance on the dynamics of parasite infections. Parasite amplification patterns shown in this study could be explained by the abundance of competent hosts for haemosporidian infection. Our results largely contribute to the knowledge of blood parasite diversity infecting wild birds in a poorly studied area of South America.