The relationship of endoparasite diversity and feeding ecology in the seabird complex of South Florida

Endoparasite community structure has been poorly studied in migratory birds, particularly among the seabirds of south Florida. We examined parasite communities in seven south Florida seabird species: brown pelican Pelecanus occidentalis (n=33), northern gannet Morus bassanus (n=31), double-crested cormorant Phalacrocorax auritus (n=33), osprey Pandion haliaetus (n=27), royal tern Thalasseus maximus (n=30), herring gull Larus argentatus (n=12), and laughing gull Leucophaeus atricilla (n=40). We identified 33 parasitic helminth species: 6 nematodes, 2 cestodes, 3 acanthocephalans, and 22 digeneans. Subsequent pairwise tests and similarity profile analysis identified four distinct clusters with similar parasite community structures: (1) pelican and gannet; (2) cormorant; (3) osprey; and (4) tern and both gull species. The mean infracommunity observed species richness differed among the several seabird host species with the highest observed values in pelicans (5.7±0.4) and gannets (5.1±0.4), while the lowest values were seen in herring (0.8±0.7) and laughing (0.4±0.4) gulls. RELATE analyses indicated that the factors of host phylogeny (Rho=0.564, p=0.017), host feeding range (Rho=0.553, p=0.005), and host feeding technique (Rho=0.553, p=0.039) were significant and had similar magnitudes of effect on the structure of observed parasite communities within the several seabird species of this study. Host prey preference was not significant from the RELATE analyses (Rho=0.124, p=0.278), suggesting that preferred prey items of the several seabird hosts had a negligible impact in the structuring of parasite communities. From our results, host phylogeny and host feeding ecology are important driving factors of parasite community composition and structure of these south Florida seabirds, while host prey preference had little influence on parasite communities