Natural selection after severe winter favors larger and duller bluebirds

Extreme cold events, which have become more frequent, can revert the direction of long-term responses to climate change. In 2021, record snowstorms swept the United States, causing wildlife die-offs that may have been associated with rapid natural selection. Our objective was to determine if the snowstorms caused natural selection in Eastern Bluebirds (Sialia sialis). To test which mechanism most influenced their survival, we measured the morphology and coloration of fatalities and survivors at three sites. Survival was associated with a longer tarsus, and a wider, longer, and deeper beak in support of the starvation and thermal endurance hypotheses. Additionally, bluebirds with more-ornamented plumage were less likely to have survived, maybe because of an early energy investment in mate and site acquisition. As bluebirds encounter increasingly warm summer conditions, the longer extremities favored during the snowstorms may continue to be favored through their thermoregulatory benefits...., , , # Data from: Natural selection after severe winter favors larger and duller bluebirds

Rolland V.*, Grindstaff J., Balenger S., and Siefferman L.

*Corresponding author: [[e-mail]](mailto:[e-mail]) 

[https://doi.org/10.5061/dryad.2ngf1vhwh](https://doi.org/10.5061/dryad.2ngf1vhwh)

## Descripiton of the data files

This document describes columns in Excel files used for the study of natural selection in Eastern Bluebirds that survived the 2021 snowstorms in the south-central US. Only fatalities encountered in nest boxes were included in the first file, but both fatalities and survivors caught during the nesting season that followed the storms are included in the second file. Scripts are for analyses in Program R. Scripts for analyses were run in Program R version 4.4.1 on Windows 11 x64.

**Responsibilities**

·         Data collection: Rolland (AR), Grindstaff (OK), Balenger (MS) collected feathers from and measured dead and live bluebirds

·         Feather data...,