Stable Isotopes and Parasites Indicate Feeding Ecology in Florida, USA, Wading Birds

We assessed δ ¹³ C and δ ¹⁵ N profiles and endoparasite community composition in Great Egrets ( Ardea alba ), Great Blue Herons ( A. herodias ), and White Ibis ( Eudocimus albus ) from four wildlife rescue centers (two mainland, two on islands in the Florida Keys) in south Florida, USA to elucidate feeding ecology. We detected among-species differences for δ ¹⁵ N but not δ ¹³ C and noted decreased δ ¹³ C enrichment in Great Egrets and Great Blue Herons (but not White Ibis) from these centers. Parasite component community and infracommunity species richness were higher in Great Egrets and Great Blue Herons relative to White Ibis, and higher in birds of the same species from mainland centers. Multivariate analysis of parasite infracommunity structure detected co-occurring clusters of parasite taxa characteristic of Great Egrets and Great Blue Herons on the one part, and of White Ibis on the other; mainland Great Egrets and Great Blue Herons had similar parasite communities and clustered separately from conspecifics from the islands. We detected a significant (negative) correlation of infracommunity species richness with δ ¹³ C but not δ ¹⁵ N. Lastly, parasite infracommunity Bray-Curtis similarity correlated significantly with stable isotope Euclidean distances. We conclude that the two approaches converge towards similar outcomes, providing complementary and consilient information on host feeding ecology.