Figure 4

Individual variation in δ¹³C (A) and δ¹⁵N (C) values of stranded dolphins from Alabama. Ellipses (B) represent the 95% confidence intervals of δ¹³C and δ¹⁵N values in each individual calculated using three tissue types (liver, skin, muscle). Each color corresponds to an individual, with ellipse size corresponding to isotopic niche size. The black, dotted ellipse reflects the niche size for all tissues from all individuals. The normal distributions of our δ¹³C and δ¹⁵N values are presented as the dashed lines in (A) and (B), respectively. For (A), the panel has been presented as the mirror image of the original because the negative values associated with δ¹³C flip the signs of the differences (i.e., − to + and + to −) when subtracted from the mean, which explains why the x-axis goes from positive to negative. The colored bars in (A) and (B) indicate the range of differences between the mean δ¹³C (− 18.4‰) or δ¹⁵N (14.9‰) value and each tissue for every individual. Individuals were organized by year along the y-axis to help space the colored bars and prevent them for overlapping and are not related to the values on the y-axis.