John F. Piatt Jay Pitocchelli Keith A. Hobson 1994 <p><span><strong>1.</strong> The stable isotopes of nitrogen (δ¹⁵<span>N</span>) and carbon (δ¹³C) 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.</span></p><p><span><strong>2.</strong> Based on δ¹⁵N 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.</span></p><p><span><strong>3.</strong> Stable-carbon isotope analysis may be a good indicator of inshore vs. offshore feeding preference.</span></p><p><span><strong>4.</strong> In general, stable-isotope analysis to determine trophic level offers many advantages over conventional dietary approaches since trophic inferences are based on time-integrated estimates of assimilated and not just ingested foods, and isotopic abundance represents a continuous variable that is amenable to statistical analysis.</span></p> application/pdf 10.2307/5256 en The British Ecological Society Using stable isotopes to determine seabird trophic relationships article