The Diets of Modern and Historic Bottlenose Dolphin Populations Reflected Through Stable Isotopes

A bstract The δ 13 C and δ 15 N compositions of teeth used in combination with existing data provide dietary information for different populations of western North Atlantic bottlenose dolphins ( Tursiops truncatus ). The dental isotopic signatures of bottlenose dolphins collected during the 1980s significantly differ for coastal and offshore ecotypes and are consistent with reports that coastal forms feed primarily on fish whereas offshore individuals consume more squid. In a second study, the isotopic compositions of teeth from bottlenose dolphins that span a 100‐yr period and data from published stomach content analyses as well as field observations made during the past 100 yr provide evidence that coastal bottlenose dolphins from the 1880s, 1920s, and 1980s had similar diets.