The signature whistles of related Atlantic spotted dolphins ( Stenella frontalis) in the Bahamas were evaluated for similarity. Judges compared the contour patterns of signature whistles pair-wise between 19 dolphins. Whistle parameters between the signature whistles of individuals were statistically compared. There were no significant differences between the signature whistles of male and female calves when the similarity of their whistles was compared to their mothers. However, there was a tendency with female calves more likely to produce signature whistles similar to their mothers' whistles. Three out of five female calves produced signature whistles that were "very similar" or "similar" to the signature whistles of their mothers. Two out of four male calves produced signature whistles that were "similar" to the signature whistles of their mothers. The signature whistles of mother and calf pairs were more likely to be "similar" to each other than the signature whistles of sibling pairs.