Parasite Pressure and its Effects on Blood Parameters in a Stable and Dense Population of the Endangered Lesser Grey Shrike

The risk that pathogens and parasites pose to endangered species is increasingly evident. Nonetheless, this is frequently overlooked when considering causes of decline of species and conservation practices. Here, we study the ecto and haemoparasites of adult and nestling Lesser grey shrikes Lanius minor from a dense and stable breeding population in central Europe and their effect on host blood parameters. We found three species of haemoparasites (Haemoproteus sp., microfilariae tentatively assigned to the family Splendidofilariae and Trypanosoma sp.) and two ectoparasite taxa (Menacanthus camelinus and feather mites – Acarina-). Our data suggest that the studied population, located in an area with traditional and extensive farming, is not under a strong parasite pressure. Despite this, indirect measures of immunocompetence (haematocrit and sedimentation rate) showed an association between haemoparasites and health status: while haematocrit did not differ between parasitised and non-parasitised individuals, adult shrikes with haematozoa had significantly lower sedimentation rates than did non-parasitised birds.