Long-term increases in wing length occur independently of changes in climate and climate-driven shifts in body size

Recent widespread reductions in body size across species have been linked to increasing temperatures; simultaneous increases in wing length relative to body size have been broadly observed, but remain unexplained. Size and shape may change independently of one another, or these morphological shifts may be linked, with body size mediating or directly driving the degree to which shape changes. Using hierarchical Bayesian models and a morphological time series of 27,366 specimens from five North American migratory passerine bird species, we tested the roles that climate and body size have played in shifting wing length allometry over four decades. We found that colder temperatures and reduced precipitation during the first year of life were associated with increases in wing length relative to body size, but did not explain long-term increases in wing length. We found no conclusive evidence that the slope of the relationship between body size and wing length changed among adult birds in res..., Morphological data were collected from museum specimens located at the Field Museum.
Environmental data were sourced from NOAA PSL. The datasets accessed included CPC global unified temperature data (daily), CPC global unified gauge-based precipitation data (daily), NASA GISS surface temperature data (monthly), and GPCP precipitation data (monthly). Data were cropped and aggregated according to species and season for each year. Data were also transformed within species to have a mean of 0 and a standard deviation of 1.
Additional details are provided in the methods section of the manuscript., , # Long-term increases in wing length occur independently of changes in climate and climate-driven shifts in body size

[https://doi.org/10.5061/dryad.bvq83bkk9](https://doi.org/10.5061/dryad.bvq83bkk9)

## Description of the data and file structure

This dataset contains the data and code required to perform the main and supplementary analyses in **Long-term increases in wing length occur independently of changes in climate and climate-driven shifts in body size** (Dias et al. 2024. *Proc. Royal Soc. B.* [https://doi.org/10.1098/rspb.2024.2556](https://doi.org/10.1098/rspb.2024.2556)). The paper tests whether body size and climate drive allometric shifts in wing length across five North American migratory passerine bird species.

### Files and variables

#### File: Data.zip

**Description:** Contains two folders: Datasets and Files

A. **Datasets** (4 .csv files)

A1. **morphdata.csv** - contains all the morphological data used in the study [note: some of these specimens were filtered o...