Host escape behavior and blood parasite infections in birds

Active and risk-taking behavior may bring animals into contact with predators but can also result in frequent encounters with parasites and vectors via the exploration of risky or diverse habitats. Therefore, we predicted that antipredator behavior, here measured as escape behavior when captured by a human, would correlate with risk of parasite infection at the interspecific level with bolder species having more parasites than risk-averse species. Here we tested whether species with more active escape behavior also tended to have high prevalence of blood parasites, specifically hemosporidian parasites. Focusing on effect sizes we found that escape behavior was intermediately and positively related to prevalence of infection with Haemoproteus and Leucocytozoon, whereas that was not the case for the more virulent Plasmodium. Species that were habitat generalists and hence encountered a greater diversity of habitats had higher prevalence of blood parasites than specialists. In addition, some components of escape behavior were correlated at an intermediate magnitude with habitat exploration, as reflected by the relative frequency of feeding innovations, and coloniality. We failed to find considerable patterns of correlations between most of the behavioral variables and flight initiation distance, another commonly used antipredator behavior. Therefore, behavioral responses to an approaching predator and to being caught by a human likely represent 2 independent axes of antipredator behavior that do not evolve in concert. These findings are consistent with the hypothesis that escape behavior is related to risk of infection with blood parasites partially mediated by the effect of habitat generalism.