Millions of birds die annually in North America by colliding with windows. I investigated differential vulnerability to window collision among migratory songbird species using long-term citizen science datasets from two bird banding stations and the fatal light awareness program. I used negative binomial regressions to model species-specific catch ratios, a mixed-effects negative binomial regression to model trophic guild-specific catch ratios and mixed-effects logistic regressions to model the odds of catching different age classes. Species-specific vulnerability varied significantly. Blue-headed Vireos, Yellow-rumped Warblers and Ruby-crowned Kinglets were least vulnerable, while Ovenbirds, Common Yellowthroats, Fox Sparrows and Bay-breasted Warblers were most vulnerable. Foraging height influenced vulnerability with ground foragers being most vulnerable. The effect of age varied across species, with only some species showing significant effects. This study contributes to the growing foundation that is required for future studies to investigate why these factors influence vulnerability and how to minimize future collision mortality
