Data from: Shared origins of 6 songbird species occurring as vagrants in California

This dataset contains stable hydrogen isotope measurements, geographic origin probability surfaces, and simulated origin distributions for 155 vagrant wood-warbler (Parulidae) specimens collected in California during fall migration. Six species were analyzed: Blackpoll Warbler, Magnolia Warbler, Chestnut-sided Warbler, Blackburnian Warbler, Palm Warbler, and Tennessee Warbler. Using feather δ²H values, we generated individual-level geographic origin probability surfaces masked to species breeding ranges using eBird Status and Trends. We conducted simulations weighted by breeding abundance to test whether vagrant origins could be explained by abundance patterns. Results demonstrate that vagrant individuals of all six species most likely originated from the western portions of their breeding ranges, not areas of greatest abundance, with five species showing geographic overlap in probable origins. The dataset includes raw isotope measurements, processed probability surfaces (n=155 GeoTIFF rasters), species-level simulated origin distributions using both eBird Status and Trends and Boreal Avian Modelling Project abundance data, breeding range shapefiles, and all code for reproducibility. These data support the hypothesis that common mechanisms underlie wood-warbler vagrancy to California and provide a framework for studying vagrancy in other migratory systems. This dataset supports the following publication: Heiser ER, Farnsworth A, Tietz J, Iliff MJ, Van Doren BM. 2025. Shared origins of 6 songbird species occurring as vagrants in California. Ornithology ukaf057. doi: https://doi.org/10.1093/ornithology/ukaf057