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Data from: Unexpected migration patterns in a high-latitude breeding songbird: Evidence from multi-sensor geolocators and isotopes

Szarmach, Stephanie12; Beam, Johanna1; Moore, Mads3; Van Doren, Benjamin4; Brelsford, Alan5; Toews, David1

Published Jan 08, 2026 on Dryad. https://doi.org/10.5061/dryad.cfxpnvxhp

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Jan 08, 2026 version files 76.51 MB

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Abstract

Seasonal migration allows animals to use habitat where conditions are unfavorable for part of the year but may constrain breeding ranges due to the costs of longer migrations as ranges expand poleward. In species with large ranges, high-latitude breeding populations may employ different migration strategies allowing them to persist far from other core nonbreeding areas. The myrtle warbler (Setophaga coronata coronata) has two disjunct nonbreeding ranges in North and Central America—one along the Gulf Coast and the other on the Pacific. Previous work indirectly linked birds breeding in Alaska with the Pacific nonbreeding area, suggesting that high latitude populations evolved a shorter migration route. We directly tested this hypothesis using geolocators measuring both light and atmospheric pressure to track Alaskan myrtle warbler migration in fine detail and inferred nonbreeding areas using hydrogen isotopes for a larger sample of birds breeding in Alaska, British Columbia, and Alberta. We found, contrary to expectations, that all geolocator-tracked birds—and 95% of birds with stable isotope data—migrated to the southeastern United States, a much longer migration than expected for a species commonly considered a “short-distance” migrant. We additionally demonstrate the advantages of pressure geolocation for characterizing migratory behavior at a fine scale.