Helminth community structure and pattern in a migratory host (Anas platyrhynchos)

Abstract

The helminth community at the southern periphery of the mallard (Anas platyrhynchos) breeding range on the Southern High Plains of Texas consisted of species commonly reported in this host at northern latitudes. Although prevalence, abundance, and dominance values varied and this helminth community was species-rich and diverse, species composition was relatively consistent over temporal and host variables. Mallards had higher mean abundances of helminths in summer than winter; 80% of all helminth individuals occurred in juveniles. Recurrent groups formed during summer and within juvenile mallards were larger and more complex than groups formed during winter or in adults. Of the 15 helminth species forming group memberships, only Cloacotaenia megalops, Microsomacanthus hopkinsi, Amidostomum acutum, and Tetrameres spp. commonly co-occurred during each of four seasons in juvenile mallards, whereas C. megalops and Capillaria contorta persisted temporally in adult mallards. These species occupy different host microhabitats, suggesting little or no interaction between temporally persistent species that commonly co-occur in mallards. The results of our study suggest that helminth communities reflect the density distribution of the host species across their annual geographic range, where the breeding range represents the epicenter of origin for this host–helminth system.