Seasonal migration alters energetic trade-off optimization and shapes life history.

Trade-offs between current and future reproduction manifest as a set of co-varying life history and metabolic traits, collectively referred to as "pace of life" (POL). Seasonal migration modulates realized environmental dynamics and putatively affects realized POL, however, the mechanisms by which migratory behavior shapes POL remain unclear. We explored how migratory behavior interacts with environmental and metabolic dynamics to shape POL. Using an individual based model of movement and metabolism we compared fitness-optimized trade-offs among migration strategies. We found annual experienced seasonality and migration distance primarily drove POL differentiation through developmental and migration phenology trade-offs. Similarly, our analysis of empirically-estimated metabolic data from 265 bird species suggested seasonal niche conservatism and migration distance interact to drive POL. We show multiple viable life history strategies are conducive to a migratory lifestyle. Overall, our findings suggest metabolism mediates complex interactions between behavior, environment, and life history. Authorship statementAKP and SWY contributed equally to this work. AKP and SWY conceived the project, designed the model, performed analyses, and drafted the manuscript with support from MBW. Simulation and optimization model code written by AKP with input from SWY and MBW. Empirical data analysis and code lead by SWY with input from AKP and MBW. All authors contributed critical input to the manuscript. Data accessibility statementAll R code for models and analyses are available at https://doi.org/10.5281/zenodo.10145976 and https://github.com/allipierce/Pierce_et_al_2023_MigrationPOL. The empirically derived data used in this work are all publicly available. DEB data are available from the Add-My-Pet portal at https://www.bio.vu.nl/thb/deb/deblab/add_my_pet/. Geographic range data are available from BirdLife International at http://datazone.birdlife.org/species/requestdis. Niche dissimilarity data came from https://doi.org/10.1111/geb.13722 and phylogeny data are available from VertLife at http://vertlife.org/data/.