Factors influencing a common but neglected blood parasite prevalence in breeding populations of passerines.

Abstract

The occurrence of avian blood protists is affected by multiple factors that include the characteristics of the hosts, the vectors, the parasites, as well as the environmental factors. This study provides an insight into some of the factors that influence the prevalence of avian, neglected but common blood parasites in breeding populations of common passerines. The highest prevalences ofinfection were observed in 1 great tit () population at 63%, 1 blue tit () population at 49% and a sedge warbler () population at 33%. Prevalence was found to be significantly influenced by sampling site followed by host age, species and sex. Julian date had no significant effect onprevalence. Prevalence data from different sampling sites can reveal different patterns and should be combined critically. Higher prevalence in adults suggest that the infections are chronic, which helps the parasite to persist in host populations. The differences between sexes might be related to different exposure to the transmitting vectors (e. g., mites or mosquitoes) during breeding.