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

loggerhead_d13C_isoscape.txt (md5: 75d5be745e2018c1fbf639224e598736)

loggerhead_d15N_isoscape.txt (md5: d76570667098245e4102e8380b588324)

loggerhead_d13C_error.txt (md5: 7f8bb3cc91d34eb8ad033942bd2f93cf)

loggerhead_d15N_error.txt (md5:995ce245c4e066001d6f8322e33038ef )

loggerhead_d13C_isoscape.txt – krigged surface of δ¹³C values from 41 calibration loggerhead sea turtles in coastal waters < 200m depth of the Gulf of Mexico and Greater Caribbean

loggerhead_d15N_isoscape.txt – krigged surface of δ¹⁵N values from 41 calibration loggerhead sea turtles in coastal waters < 200m depth of the Gulf of Mexico and Greater Caribbean

loggerhead_d13C_error.txt – standard deviation of the kriging prediction ofδ¹³C values

loggerhead_d15N_error.txt – standard deviation of the kriging prediction ofδ¹⁵N values

These four files are theδ¹³C andδ¹⁵N 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.