Of the 1224 analyses, 307 were on C. wuellerstorfi and 917 on U. peregrina. A total of 135 samples were measured for both species. Based on the median difference between these 135 paired analyses, we convert C. wuellerstorfi to values consistent with U. peregrina by subtracting 0.74 from the 13C values (making them lighter) and adding 0.64 to the 18O values (making them heavier). All data reported are relative to U. peregrina.