MATE CHOICE AND REPRODUCTIVE SUCCESS IN THE AMERICAN KESTREL - A ROLEFOR BLOOD PARASITES

Blood parasites of breeding American kestrels, Falco sparverius (40 ma les and 27 females), were investigated to determine their connections to male showiness, mating success and host fitness. The only haematozo an found in the blood films was Haemoproteus tinnunculi (overall preva lence of 74% for females and 53% for males). In adult (+1-year-old) ma les, the subterminal tail band (character apparently used in female ma te choice) was wider in infected malts than in non-infected males. Thi s was consistent with the Hamilton-Zuk hypothesis of parasite-mediated sexual selection. Our results also suggest that reproductive effort m ay increase susceptibility to parasitism. In yearling males. the propo rtion of individuals infected with H. tinnunculi mas higher among chos e tending a large than a small brood at the time of fledging Hunting e ffort (proportion of time spent in flight-hunting and wind-hovering) m as also higher for malts tending large broods than for those tending s mall broods, and it was higher for yearling than adult males on a give n brood size. Reproductive effort may result in greater exposure and/o r decreased ability to control chronic latent infections. Parasitic in fections, in turn, may have detrimental effects tin host fitness.