Diet of moulting Swainson's Thrushes (Catharus ustulatus) and Tennessee Warblers (Leiothlypis peregrina) at a stopover site during fall migration measured with fecal DNA metabarcoding

Plain language summary

Moult and migration are energetically demanding and require adequate nutrition. Here, we use DNA barcoding of fecal samples to compare the diet of moulting and actively migrating (post-moult) Swainson’s thrushes (Catharus ustulatus) and Tennessee warblers (Leiothlypis peregrina) during their fall migration stopover at a large urban greenspace in Montreal, Canada. Diet differed according to moult status, species, and seasonality. Swainson’s thrushes had a broad diet with frequent detections of both insects and berry-producing shrubs, while detections in Tennessee warblers’ diets were mainly arthropods. For both species, more actively migrating individuals consumed fleshy-fruiting plants than moulting individuals. A higher proportion of moulting birds consumed arthropods compared to active migrants, due to either arthropod availability or a dietary preference for proteinaceous foods to grow feathers. Both species and moult classes consumed more native plants than non-native plants later in the season. We show the importance of managing urban greenspaces with native plants and diverse food sources that can provide for the different dietary needs of migratory birds.

Subject

• Nature and environment,
• Science and technology

Pagination

12 pages

Peer review

Yes

Open access level

Gold