Endogenous biomarkers reveal diet partitioning among three sympatric species of swallows

Abstract Since the early 1990s, aerial insectivorous birds have shown serious population declines in North America, but it is not clear if factors common to all species within this guild account for these declines. Among sympatric swallows, trends differ, and may be due differences ecology operating throughout annual cycle. Although feed on insects, prey taxa can differ tremendously their “aeroecology” use by swallows. We examined potential dietary among three of Barn Swallow (Hirundo rustica), Cliff (Petrochelidon pyrrhonota), Tree (Tachycineta bicolor), breeding sympatrically southern Ontario, Canada. Potential interspecific nestling diet were using two endogenous biomarkers, DNA barcoding feces stable isotope analysis (δ 2H, δ 13C, 15N) feathers. found evidence sources provisioned young where Swallows more terrestrial-based prey, an intermediate diet, most aquatic-emergent insect diet. suggest information help identify contributing differential insectivores grounds, including quality.