“…Range shifts are another phenomenon documented in high-latitude/high-elevation breeders (Couet et al, 2022;Freeman et al, 2018;Prytula et al, 2023). While mountain bluebirds themselves have yet to see significant changes to their breeding range, their congenerics (the western bluebird, Sialia mexicana, and the eastern bluebird, Sialia sialis) have (Duckworth & Badyaev, 2007;Sonnleitner et al, 2022). In some cases, renewed secondary contact may even result in hybridization (e.g., Duckworth & Semenov, 2017) which also impacts genetic diversity (Grant & Grant, 2019).…”