Supplement 1. Raster format of loggerhead δ13C and δ15N isoscapes and associated standard deviation.

File List loggerhead_d13C_isoscape.txt (md5: 75d5be745e2018c1fbf639224e598736) loggerhead_d15N_isoscape.txt (md5: d76570667098245e4102e8380b588324) loggerhead_d13C_error.txt (md5: 7f8bb3cc91d34eb8ad033942bd2f93cf) loggerhead_d15N_error.txt (md5:995ce245c4e066001d6f8322e33038ef ) Description loggerhead_d13C_isoscape.txt – krigged surface of <i>δ</i>¹³C values from 41 calibration loggerhead sea turtles in coastal waters &lt; 200m depth of the Gulf of Mexico and Greater Caribbean loggerhead_d15N_isoscape.txt – krigged surface of <i>δ</i>¹⁵N values from 41 calibration loggerhead sea turtles in coastal waters &lt; 200m depth of the Gulf of Mexico and Greater Caribbean loggerhead_d13C_error.txt – standard deviation of the kriging prediction of<i>δ</i>¹³C values loggerhead_d15N_error.txt – standard deviation of the kriging prediction of<i>δ</i>¹⁵N values These four files are the<i>δ</i>¹³C and<i>δ</i>¹⁵N isoscapes and standard deviation rasters that are depicted in Fig. 1 of the main text. They are ASCII-formatted text files and contain a header to identify the structure of the file. They can be opened in ArcGIS by using the ASCII to Raster conversion tool or in R with the raster() function using the Raster package and then assigned a spatial reference within the program used. Resolution of each of the files is 0.0572 degrees.