Habitat, world geographic range, and embryonic development of hosts explain the prevalence of avian hematozoa at small spatial and phylogenetic scales

The factors explaining interspecific differences in prevalences of blood pa rasites in birds are poorly known. We simultaneously assessed 20 social, ec ological, life history, and sampling-related variables that could influence hemoparasite prevalences among diurnal birds of prey in Spain. Our results show that multiple factors are responsible for the studied host-parasite a ssociation. We confirmed for the first time that prevalence is inversely co rrelated to the embryonic development period, and thus probably to immune p erformance, even among closely related birds, Macrohabitat features related to vector availability are also important, prevalences being higher in spe cies breeding in forested habitats. Finally, prevalence is positively corre lated with the host's world geographic range. We hypothesize that larger ge ographic ranges offered more opportunities for host-vector-hemoparasite ass ociations to become established. The results from our multivariate analyses differ from those obtained through univariate ones, showing that all poten tial factors should be assessed jointly when testing any ecological or evol utionary hypothesis dealing with parasites.