Influence of social status on the helminth community of late-winter mallards

Abstract

The influence of body condition, molting status, sex, and pairing status on the helminth community at the component community level (all parasites in all individuals of a given host species in a defined geographic region) of an infrapopulation of mallards (Anas platyrhynchos) wintering on the Southern High Plains of Texas was examined. From a data matrix of 45 mallards (15 pairs and 15 unpaired males), pairing status was the most important variable that accounted for significant differences in helminth abundances. In six of 15 common helminth species (Sobolevicanthus gracilis, Microsomacanthus hopkinsi, Amidostomum acutum, Capillaria anatis, Capillaria contorta, and Epomidiostomum uncinatum), abundances were significantly higher in unpaired males than in paired birds. Abundance of only one of 15 helminth species (E. uncinatum) differed significantly between paired males and females. The significantly higher helminth abundances of unpaired males may be due to their potentially more gregarious and mobile behavior, which increases their exposure to certain helminth species. This study emphasizes the importance of incorporating social status in experimental designs involving waterfowl.