Niche segregation among three sympatric species of swallows in southern Ontario

Kaelyn H. Bumelis, The University of Western Ontario

Abstract

Barn Swallows (Hirundo rustica), Cliff Swallows (Petrochelidon pyrrhonota) and Tree Swallows (Tachycineta bicolor) breed sympatrically in southern Ontario but it is unclear how these species differ ecologically, and their coexistence implies niche segregation. I investigated potential interspecific differences in nestling diet and post-fledging movements. Using DNA barcoding of nestling feces and stable isotope analysis (δ¹³C, δ¹⁵N, δ²H) of nestling feathers, I found evidence of differences in dietary sources of provisioned young. Barn Swallows showed evidence of provisioning more terrestrial-based prey, Cliff Swallows provisioned an intermediate diet, and Tree Swallows the most aquatic-based diet. To determine post-fledging movements, fledglings were tracked using automated telemetry.Cliff Swallow fledglings differed from the other two species in their post-fledging residency time at the natal site. This information may help to identify potential factors contributing to differential declines operating on the breeding grounds.