Hematozoa of hatch-year common mergansers from Michigan

Fifty-five hatch-year common mergansers (Mergus merganser) were sampled for hematozoa from Douglas Lake (Michigan, USA) on 17 July 1995. Forty-one (75 %) were infected with hematozoa. Haemoproteus greineri and Leucocytozoon si mondi were common, infecting 28 (51%) and 26 (47%) common mergansers, respe ctively. Plasmodium circumflexum infected two (4%) birds. The common mergan ser is a new host record for H. greineri and P. circumflexum. Intensity dat a indicate possible negative interspecific interaction between H. greineri and L. simondi.