Ant‐following and the prevalence of blood parasites in birds of African rainforests

Abstract

Blood parasites are widespread in birds, several are pathogenic and may affect the fitness of their hosts, and their evolution. By reanalyzing recently published data I show that parts of the variation in prevalences of parasites in the blood of African rainforest birds and the occurrence of similar or same parasite haplotypes in rather unrelated birds are well understood when considering the ecological aspects of foraging of some of these birds. Specialized ant‐following birds, which regularly follow the massive swarm raids of army ants and feed on insects flushed by the ants, have higher prevalences of nematode microfilariae (~10×),Trypanosoma(~10×), andPlasmodiumparasites (~2×) and a much higher probability of infection with multiple parasites than other birds. Moreover, birds regularly attending army ant swarms share identicalTrypanosomahaplotypes and show genetically similar microfilariae haplotypes. I conclude that ant‐following increases the probability of birds to get infected with blood parasites and may facilitate the switch of a parasite species from one host species to another. The costs of higher parasite intensities involved when specializing on following ant swarms may have influenced the evolution of foraging behaviour in birds of African rainforests and may help to explain the relatively low number of specialized ant‐following bird species on the African continent.