Standard sampling techniques underestimate prevalence of avian hematozoa in willow ptarmigan (Lagopus lagopus)

A total of 68 willow ptarmigan (Lagopus lagopus L.) was collected during September 1995 from two localities in Troms County, northern Norway. Thin blood smears were prepared and examined for blood parasites. Of the 68 willow ptarmigan examined, 94% harbored one or more species of hematozoa. There were four (6%), 44 (65%), 16 (24%), and four (6%) birds infected by zero, one, two, and three species of parasites, respectively. Prevalences at the coastal locality, Kattfjord (n = 43), were Leucocytozoon lovati 86%, Trypanosoma avium (26%), and microfilariae (30%). At the inland locality, Iselvdalen (n = 25), prevalences were L. lovati 96%, T. avium 12%, and microfilariae 0%. We also searched connective tissues for the filaroid nematode Splendidofilaria papillocerca; in Kattfjord this parasite only occurred in adult hosts where prevalence was 94%, but the parasite was not found in Iselvdalen. To estimate the efficiency of parasite detection by standard blood sampling techniques, we sampled peripheral blood from the brachial wing vein and blood from the pulmonary system from willow ptarmigan. Sampling peripheral blood from the brachial vein led to underestimates of the prevalence of microfilariae. There was no significant difference between L. lovati and T. avium prevalence in blood collected from the brachial vein or deep circulation. Age of host had a strong impact on prevalence, especially for S. papillocerca and microfilariae.