PARASITE INFESTATION AND PARENTAL CARE IN THE BARN SWALLOW HIRUNDO-RUSTICA - A TEST OF THE RESOURCE-PROVISIONING MODEL OF PARASITE-MEDIATEDSEXUAL SELECTION

Barn swallows, Hirundo rustica, are commonly infested by the haematoph agous tropical fowl mite Ornithonyssus bursa (Macronyssidae, Gamasida) , which severely reduces various measures of reproductive success amon g the barn swallow hosts. Food provisioning rate by parent barn swallo ws, measured in terms of absolute feeding-rare by males and females an d relative feeding rate by males (percentage of food provided by the m ale parent), was not significantly related to natural levels of infest ation of nests. Experimental manipulation of mire loads in nests durin g the egg-laying period of the first clutch, which also affected mite loads of parent barn swallows, significantly affected food-provisionin g rates of single-brooded, but not of double-brooded barn swallows. Th ese results suggest that effects of mites on the parenting ability of barn swallow hosts depend on host resistance towards parasites. This i s consistent with the resource-provisioning hypothesis of parasite-med iated sexual selection, suggesting that females prefer parasite-free m ales because they are efficient parents, bur also with the hypothesis that females prefer males with traits signalling genetic resistance to parasites.