Introduction Morphological changes concurrent with climate change are increasingly identified in birds, and long-term studies have provided key data demonstrating these trends (Weeks et al. 2020, Jirinec et al. 2021, Shipley et al. 2022, Youngflesh et al. 2022, Bosco et al. 2023). Primary among these morphological responses are decreases in body mass, which have been found in birds across the world (Weeks et al. 2020, Jirinec et al. 2021, Youngflesh et al. 2022).