ECOLOGY OF PARASITISM OF NESTLING AMERICAN KESTRELS BY CARNUS-HEMAPTERUS (DIPTERA, CARNIDAE)

Little is known about the basic biology of Carnus hemapterus (Diptera: Carnidae), a haematophagous parasite of nestling birds. We therefore explored the patterns of C. hemapterus infestations by repeatedly exam ining American kestrel (Falco sparverius) nestlings from 50 nests in n orth-central Saskatchewan. Most infestations occurred before chicks we re 12 days old and were more frequent early in the breeding season. Ne stlings from larger broods had higher prevalences of C. hemapterus, bu t we did not detect differences in intensity of infestations between b roods of different sizes. Within broods up to 5 days old, the heaviest nestlings were preferentially infested by C. hemapterus. Although evi dence suggests that ectoparasite infestations are harmful to hosts, we did not detect any mortality attributable to C. hemapterus. Similarly , we did not observe negative effects of C. hemapterus infestations on nestling mass, length of the tenth primary flight feather, haematocri t, or total plasma protein concentration at 24 days old.