Characterizing Diet of the Least Tern <i>Sternula antillarum</i> using DNA Metabarcoding

A complete picture of diet composition is an essential element to understanding the ecological role of organisms. Moreover, diet studies can serve as an important tool for monitoring species and changes to the food web. One method to provide resolution when studying the diet of avian species is DNA metabarcoding of fecal samples. As such, we used DNA analysis to determine the diet of the Least Tern Sternula antillarum and compare results with diet analysis based on composition of fish dropped within breeding colonies. Comparisons between adult and chick fecal samples were also made across three years and within three zones of sample collection. Results show differences in diet composition between the two methods as well as across zones and years. Significant differences between prey items of adults and chicks were also identified. Metabarcoding data indicate that Least Terns are consuming Lionfish Pterois spp. (most likely in larval stages), a prey item that had not been previously recorded for Least Terns, and that data obtained from dropped fish might not be representative of chick diet. Differences across years and zones are likely due to shifts in the abundance and availability of prey items.