Dietary niche dynamics of breeding seabirds in coastal Newfoundland under shifting prey availability: A stable isotope-based approach

• Main Author: Jenkins, Edward
• Other Authors: Davoren, Gail (Biological Sciences), Roth, James (Biological Sciences) Ronconi, Robert (Canadian Wildlife Service), Yurkowski, David (Department of Fisheries and Oceans)
• Format: Master Thesis
• Language: English
• Published: 2018
• Subjects: Stable isotopes; Seabirds; Newfoundland; Alca torda; Atlantic puffin; Common Murre; fratercula; Fratercula arctica; Oceanodroma leucorhoa; Razorbill; Uria aalge; uria
• Online Access: http://hdl.handle.net/1993/33675

On the Newfoundland coast, an annual pulse of the capelin (Mallotus villosus), provides an excellent opportunity to investigate the influence of varying prey availability on seabird diet. We investigated seabird species- and assemblage-level dietary responses to shifting capelin availability of three breeding auk species (Atlantic puffin Fratercula arctica, razorbill Alca torda, common murre Uria aalge), and Leach’s storm-petrel (Oceanodroma leucorhoa) using stable isotope ratios (δ15N, δ13C). At the species level, trophic position increased, and dietary niche breadth narrowed for auks. We also conducted a controlled feeding experiment on captive adult puffins and murres to calculate diet-tissue discrimination factors (DTDFs), specifically two blood components (i.e., plasma, cellular component). After applying these DTDFs to wild birds, Bayesian mixing model results supported our other study. Using published DTDFs from other studies resulted in different prey proportions, reiterating the importance of species- and tissue-specific diet-tissue discrimination factors when reconstructing dietary proportions of wild seabirds. February 2019