Determinants of the host-parasite relationship in a system formed by a cavity-nesting bird and its ectoparasites in an arid ecosystem

Abstract

Here we study the effect of off-host and host-related factors on the relationship between a cavity-nesting bird species, the European roller (Coracias garrulus) and its ectoparasites, mainly the haematophagous fly Carnus hemapterus. The main factors considered in this study involve habitat characteristics at the mesoscale (the host nest and the immediate surroundings) like nest-site type (a major source of habitat heterogeneity in our study area) as well as host and parasite density, breeding phenology of the host (i.e. seasonal effects) and host total brood mass (as a surrogate of cues for the parasites). We study the effect of these factors on the colonization success and distribution (prevalence and abundance) of the most common ectoparasite (Carnus hemapterus). However, since a given host species usually harbours several parasite species, the approach “one host-one parasite” overlooks the effect of the interactions among parasites that mainly occur at the infracommunity level. Therefore, we also explore the effect of the above-mentioned factors on the ectoparasite infracommunity of the European roller.