Data for Youngflesh and Tonelli Submitted

These are data to reproduce analyses in Youngflesh and Tonelli Submitted. Life history strategies vary widely across the world, yet the mechanisms that structure this variation have been the subject of extensive historical debate. In birds, species typically have larger clutch sizes at higher latitudes. However, the causes of this gradient, and whether it reflects patterns of reproductive investment more broadly, remain unresolved. Moreover, while processes thought to shape clutch size vary substantially across species’ ranges, intraspecific variation has been largely overlooked. Using nest monitoring data from more than 110,000 nests from 65 North American bird species and a hierarchical Bayesian approach that accounts for breeding phenology, we show that reproductive investment varies markedly within species across latitude. Our results provide support for several long-debated hypothesis explaining geographic variation in life histories. Despite strong phylogenetic constraint, substantial variation in clutch size existed within species, illustrating how environmental gradients shape life history strategies across multiple levels of biological organization. The following file structure is contained in data.zip. * `L2/` * `nwdf5-archive.rds` `L2/nwdf5-archive.rds` Fully processed data to conduct analyses in `2a-model-dpo-egg.R`, `2b-model-zib-bs.R`, and `3-model-dpo-egg-cov.R` - created from `1d-process-cov.R` with code available here. Raw data used in object creation are publicly available at the below sources. sn - Species English common nameSCI_NAME - Species scientific nameLatitude - latitudeLongitude - longitudewint - 0/1 whether a location falls west of 100° W longitudeegg_count - clutch sizefledge_count - number of chicks fledgedest_lay - estimated lay dateavg_temp - average temperature of 31-day window centered on lay datelog_rat_ET - seasonality of productivity (log ratio of Actual Evapotranspiration in summer and winter months)los - length of season (green-up to green-down)daylength - number of daylight hours at average lay date for that species at that locationcross_year_mean_ET - total productivity (mean Actual Evapotranspiration in summer months across all years) Nest data were processed from NestWatch (Cornell Lab of Ornithology) and Project Nestwatch (Birds Canada): Bailey, R. L., L. Larson, and D. N. Bonter. 2024. NestWatch: An open‐access, long‐term data set on avian reproductive success. Ecology 105:e4230. Data portal: https://nestwatch.org/nw/public/export Birds Canada and Environment and Climate Change Canada. 2026. Project Nestwatch. Data accessed from NatureCounts, Birds Canada. 10.71842/j14s-0w53. Data portal: https://www.birdscanada.org/bird-science/project-nestwatch Environmental data were processed from the following sources: Senay, G. B., M. Friedrichs, C. Morton, G. E. L. Parrish, M. Schauer, K. Khand, S. Kagone, O. Boiko, and J. Huntington. 2022. Mapping actual evapotranspiration using Landsat for the conterminous United States: Google Earth Engine implementation and assessment of the SSEBop model. Remote Sensing of Environment 275:113011. Data portal: https://earlywarning.usgs.gov/fews/product/460/ European Union’s Copernicus Land Monitoring Service information. 2024. Land Surface Phenology 2023-present. Data portal: https://land.copernicus.eu/en/news/global-land-surface-phenology-2024-product-available Copernicus Climate Change Service, Climate Data Store. 2024. ERA5-land post-processed daily-statistics from 1950 to present. Data portal: https://cds.climate.copernicus.eu/datasets/reanalysis-era5-land?tab=overview