DOI: 10.5061/dryad.37pvmcvwr
title: Data from: The breeding distribution of a migratory bird fluctuates with nonbreeding season rainfall over the last century

description: Species responses to climate change include shifts in distribution,
 abundance, and range limits. Predicting such shifts for migratory birds is
 inherently complex given the diversity of ways climate change can impact
 species throughout their annual cycles. For example, recent findings
 demonstrate that the breeding origin of a nonbreeding population of
 American Redstarts (Setophaga ruticilla) in Jamaica is shifting southward
 in response to prolonged drought on the nonbreeding grounds differentially
 causing lower survival in longer migrating individuals. Here, we examine
 how widespread this mechanism has operated over the past century and
 across the range of this species. We sampled tail feathers from redstart
 museum specimens and live birds from three time periods dating back to the
 turn of the 20th century from 5 regions across their nonbreeding range
 (Andean, Greater Antillean, Isthmian, Pacific Slope, and Yucatan) and used
 stable hydrogen isotopes to estimate changes in breeding origins. We used
 an ANCOVA to estimate the strength of the shift in mean breeding origin
 for each population of nonbreeding redstarts since the turn of the 20th
 century, and the role of nonbreeding season rainfall in driving observed
 shifts. Populations of redstarts on their tropical nonbreeding grounds
 experiencing a drying trend in rainfall showed a corresponding southward
 shift in their mean breeding origin (and vice versa) in subsequent years.
 The link between nonbreeding rainfall and mean breeding origin was most
 pronounced in the modern time period, where nonbreeding rainfall has
 decreased across most of the redstart nonbreeding range. Our findings
 illustrate how complex mechanistic drivers operate over space and time to
 help shape breeding range dynamics for a migratory bird, and emphasize how
 climate impacts species distributions throughout the annual cycle.
description: # Data from: The breeding distribution of a migratory bird fluctuates with
 nonbreeding season rainfall over the last century Dataset DOI:
 [10.5061/dryad.37pvmcvwr](10.5061/dryad.37pvmcvwr) ## Description of the
 data and file structure See Methods section of associated manuscript
 entitled "The breeding distribution of a migratory bird fluctuates
 with nonbreeding season rainfall over the last century". Note that
 some data used were originally published in Studds et al. (2021) and
 Dossman et al. (2023), referenced below. ### Files and variables ####
 File: Ecoregions2017.dbf, Ecoregions2017.prj, Ecoregions2017.shp,
 Ecoregions2017.shx **Description:** used to load shapefile of world
 ecoregions. #### File: nonbreeding.cpg, nonbreeding.dbf, nonbreeding.prj,
 nonbreeding.shp, nonbreeding.shx **Description:** used to load shapefile
 of American Redstart nonbreeding regions relevant to analysis originally
 derived from migratory connectivity estimates. #### File:
 isotopeanalysis-GCB.R **Description:** R script to reproduce entire
 analysis from Stevens et al. 2025. #### File: isodata_final.csv
 **Description:** stable hydrogen isotopic ratio data derived from American
 Redstart (*Setophaga ruticilla*) tail feathers. Note that this a
 combination of new and existing data. Existing data come from Studds et
 al. (2021) and Dossman et al. (2023), referenced below. ##### Variables *
 RowID: row of dataset * Source: source of collected American Redstart *
 ID: individual identifying number of American Redstart * locality:
 geocoded locality where individual American Redstart was collected *
 country: country where individual American Redstart was collected *
 ECO_NAME: name of major ecoregion in which individual American Redstart
 was collected * BIOME_NAME: name of major biome in which individual
 American Redstart was collected * dD_bird: ratio of stable hydrogen
 isotopes present in the sampled tail feather of the individual American
 Redstart * year: calendar year when individual American Redstart was
 collected * sex: sex of individual sampled American Redstart * geography:
 associated nonbreeding population of American Redstarts #### File:
 isotopedata_spatial.csv **Description:**  ##### Variables * RowID: row of
 dataset * Source: source of collected American Redstart * dD_bird: ratio
 of stable hydrogen isotopes present in the sampled tail feather of the
 individual American Redstart * sex: sex of individual sampled American
 Redstart * year: calendar year when individual American Redstart was
 collected * country: country where individual American Redstart was
 collected * locality: geocoded locality where individual American Redstart
 was collected * Latitude: latitude of sample site * Longitude: longitude
 of sample site * ID: individual identifying number of American Redstart ##
 Supplementary files hosted on Zenodo #### File: amered_range_2021.gpkg
 **Description:** shapefile of American Redstart breeding range derived
 from eBird. These data require a CC BY license and can be downloaded from
 eBird Science (https://science.ebird.org/en). #### File:
 historic_rainfall.csv **Description:** historic nonbreeding rainfall
 (January to March) dating back to 1900 downloaded from Copernicus Climate
 Change Service. These data require a CC BY license and be downloaded from
 the Copernicus Climate Change Service Climate Data Store
 (https://cds.climate.copernicus.eu/datasets). ##### Variables * year:
 calendar year * winter_rain: cumulative mean rainfall from January 1 to
 March 31 * group: associated nonbreeding population of American Redstarts
 ## Code/software These data are all used in the accompanying R script. All
 associated analyses with these data were conducted in R v. 4.4.0. ##
 Access information Other publicly accessible locations of the data: * Some
 isotope data were originally published in other manuscripts: * Dossman, B.
 C., Studds, C. E., LaDeau, S. L., Sillett, T. S., & Marra, P. P.
 (2023). The role of tropical rainfall in driving range dynamics for a
 long-distance migratory bird. *Proceedings of the National Academy of
 Sciences*, *120*(52), e2301055120.
 [https://doi.org/10.1073/pnas.2301055120](https://doi.org/10.1073/pnas.2301055120) * Studds, C. E., Wunderle, J. M., & Marra, P. P. (2021). Strong differences in migratory connectivity patterns among species of Neotropical‐Nearctic migratory birds revealed by combining stable isotopes and abundance in a Bayesian assignment analysis. *Journal of Biogeography*, *48*(7), 1746–1757. [https://doi.org/10.1111/jbi.14111](https://doi.org/10.1111/jbi.14111)