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.
Helminth communities of mottled ducks (Anas fulvigula) from Florida and Texas were species rich and diverse. The helminth component community in the mottled duck population from Texas contained more species than were found in the Florida host population. However, infracommunities of birds from Florida and Texas contained 9.5 ± 0.7 (mean ± SE) and 9.3 + 0.7 species, respectively. Similarity indices indicated less commonality of helminth species between the 2 host populations; 23 of the 42 species found across the 2 populations co-occurred. Eight helminth species from each host population were recurrent group or associate members; however, only 3 species (Amidostomum acutum, Capillaria contorta, and Tetrameres spp.) maintained group membership across both host populations. Maritrema paracadiae and Psilochasmus oxyurus were absent in birds from Florida but were recurrent group members in the host population from Texas. Only 2 recurrent group members (A. acutum and Epomidiostomum uncinatum) in birds from Florida were members of the same feeding guild and shared the same microhabitat. Three distinct feeding guilds, each containing 2 species, were found in birds from Texas. Results suggest that habitat diversity of the host plays an important part in determining species richness; however, important helminth species in both mottled duck populations are those commonly found in other Anatini from North America.
New host, geographic records, or both are established for 14 species of hypoderatid deutonymphs from 14 species of birds in North America. Ten of these records are regarded as examples of a potential host colonization event where these hypopi have become established in hosts other than those with which they are normally associated. Herein, potential host colonization events by hypoderatid deutonymphs are regarded as more of an ecologically determined than physiologically specific phenomenon, often specifically related to sharing of nesting sites in the same rookeries by different host taxa. Neottialges ibisicola Young & Pence is placed as a junior synonym of Neottialges plegadicola Fain. The taxonomic status of Hypodectes propus from columbid versus ardeid hosts needs further study.
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