Helminth community structure (prevalence and abundance) and patterns (associations and distributions) of gizzard worms were examined in blue-winged teal (Anas discors) migrating through south Texas to their wintering grounds (n = 50) and as they migrated back to their breeding grounds (n = 50). Three species of nematodes (Amidostomum acutum, Epomidiostomum uncinatum, and Streptocara crassicauda) and 1 species of cestode (Gastrotaenia cygni) were recovered, representing 1,164 helminth individuals. Amidostomum acutum was the most prevalent (92%) and abundant (817 individuals; 70% of total worms), while G. cygni was the least prevalent (16%) and abundant (23 individuals; 2%). Ninety-eight blue-winged teal were infected with 1 to 4 species. Amidostomum acutum and E. uncinatum were the most frequently (45%) observed association of 2 or more species, followed by A. acutum, E. uncinatum, and S. crassicauda (19%), and A. acutum and S. crassicauda (14%). Significant positive correlations were mainly between A. acutum and E. uncinatum, whereas negative correlations were found between each of these 2 species and S. crassicauda. Prevalence and abundance of A. acutum and S. crassicauda were not influenced by season, host age, or host sex. However, E. uncinatum varied by season and host age. The percent similarity index indicated a relatively consistent component community pattern of high similarity irrespective of season, host age, and sex. The same helminth species were found in both fall and spring, indicating that other helminth species were not being acquired on the wintering grounds.

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