Mate Choice in Experimentally Parasitized Rock Doves: Lousy Males Lose

Synopsis. A recent model by Hamilton and Zuk (1982) suggests that exaggerated sec? ondary sexual traits facilitate mate choice for genetic resistance to parasites. The model predicts that individuals discriminate against parasitized mates by scrutinizing traits indic- ative of parasite load. In the case of birds and their feather-feeding lice, for example, individuals might avoid parasitized mates by detecting reduced plumage brightness, reduced courtship display, or increased grooming. I conducted a series of mate choice trials in which female Rock Doves (Columba livia) were allowed to choose between "clean" males without lice and "lousy" males with experimentally increased loads. Clean males displayed significantly more often than lousy males and females demonstrated a significant pref? erence for clean males. Lousy males were subject to plumage damage; however, none of the damage was externally visible, and the time spent grooming by clean and lousy males did not differ significantly. Female louse loads, which were also manipulated, were not significantly related to female mating preferences. These results are consistent with the Hamilton-Zuk model. They are also consistent with a model of sexual selection for the avoidance of parasite transmission, which is discussed. The general relevance of lice and other ectoparasites to models of parasite-mediated sexual selection is reviewed.