Using Stable Isotopes to Determine Seabird Trophic Relationships

TLDR

Stable‑carbon isotope analysis may be a good indicator of inshore vs. offshore feeding preference. The authors analysed δ15N and δ13C stable isotopes in 22 marine bird species from the northeast Pacific Ocean. Stable nitrogen isotopes predict seabird trophic positions and, compared with conventional dietary studies, indicate that lower‑trophic organisms are more important to several seabirds than previously recognized.

Abstract

1. The stable isotopes of nitrogen (δ 15 N) and carbon (δ 13 C) were analysed in 22 species of marine birds from coastal waters of the northeast Pacific Ocean. Analyses confirm that stable nitrogen isotopes can predict seabird trophic positions. 2. Based on δ 15 N analyses, seabird trophic-level inferences generally agree with those of conventional dietary studies, but suggest that lower trophic-level organisms are more important to several seabirds than was recognized previously. 3. Stable-carbon isotope analysis may be a good indicator of inshore vs. offshore feeding preference