Figure 1

Hypothetical model depicting when isotopic values among sites are similar (A) and two scenarios of corresponding within-site patterns that can occur due to trophic coupling (B,C) or compartmentalization (D,E). In (B) dolphins sampled within and outside bays and sounds have similar, intermediate isotope values, indicating individuals use both estuarine and nearshore, marine habitats. (C) Individual dolphins have broad niches and the within-individual component (WIC) comprises most of the total niche width (TNW), indicating trophic coupling of habitats. In (D) dolphins sampled within and outside bays and sounds have different isotopic values, indicating individual dolphins use either estuarine or nearshore, marine habitats. (E) Individuals have narrow niches and the between-individual component (BIC) comprises most of the TNW, indicating dolphins maintain trophic compartments between habitats. Maps were generated using the ggmap package (version 3.0.0) in R¹⁰⁶.