Low Prevalence but High Intensity of Infestation by Amblyceran Lice in Red-Necked Grebes (Podiceps grisegena) in Eastern Poland

Patterns of louse infestation in waterbirds deserve attention due to potential impacts on host popu- lations. Red-necked Grebes (Podiceps grisegena) were visually examined for the presence of amblyceran chewing lice during the 2000-2015 breeding seasons in eastern Poland. Only one species of lice (Pseudomenopon dolium) was recorded. Amblyceran prevalence was low; four young birds (2.7%) were found infested out of 147 banded individuals (66 adults and 81 chicks). However, all infested Red-necked Grebes bore heavy parasite loads. Negative consequences of infestation for physiological condition were indicated by low hemoglobin and total protein values when compared with same-age non-infested birds. The low infestation rate can be related to the biology of the host (a diving species undergoing molt at sea, solitary breeder) and the apparent high pathogenicity of P. dolium, which left numerous holes in feathers and bleeding bites in all parasitized birds.