BLOOD PARASITES OF BLUE GROUSE - VARIATION IN PREVALENCE AND PATTERNSOF INTERSPECIFIC ASSOCIATION

Blood parasites of blue grouse (Dendragapus obscurus) were sampled and the factors responsible for variation in prevalence of blood parasite s, and patterns of association among parasite species, were investigat ed. Five genera of haematozoa were surveyed including four protozoans (Haemoproteus, Leucocytozoon, Plasmodium, and Trypanosoma) and a nemat ode (Splendidofilaria). Prevalence of blood parasites varied significa ntly between years; sexes differed in number of parasite species in on e of two years. Both positive and negative 'overall' associations amon g all parasites were found when variance-ratio tests were used indicat ing that blood parasites often were not independent of one another. In general, Leucocytozoon and Trypanosoma often co-occurred; the stronge st associations between these two parasites appeared in samples of hos ts most heavily infected by other parasites. Negative associations bet ween parasite species always involved Haemoproteus. Associations betwe en pairs of species did not account wholly for overall patterns of ass ociation within the parasite assemblage. Studies of associations withi n blood parasite assemblages are important for understanding the ecolo gy of haemotropic infections and for elucidating the need for multi-pa rasite models of parasite-host interactions.