Tiny Multisensor Tags Reveal Unexpected, Long-Distance Routes of Alaskan Warblers
Researchers fitted tiny multisensor backpacks to yellow-rumped warblers in Anchorage and discovered they travel east across Canada before heading south to the Gulf Coast, a far longer route than expected.
A Ph.D. study deployed miniature multisensor backpacks on yellow-rumped warblers breeding near Anchorage, Alaska, to map their full annual movements. After a year, recaptured individuals yielded detailed pressure-based geolocation data, showing an unexpected east-to-south migration across Canada to the Gulf Coast rather than a direct Pacific route. The round-trip spanned roughly 6,800 miles, longer than the species' typical classification as a short-distance migrant.
Researchers suggest the circuitous path stems from ancient glacial shifts that shaped genetic migration routes, a hypothesis supported by similar findings in blackpoll warblers and Swainson’s thrushes. The new barometric method improves location precision, aiding conservation by pinpointing critical stopover and wintering habitats and assessing collision risks with structures. Ongoing work at the Smithsonian Migratory Bird Center will integrate these data with satellite imagery to link migration timing to vegetation changes.
Why it matters
Better tracking of tiny birds clarifies migration routes, informing habitat protection and collision-risk mitigation.
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