Differences in the stable isotope signatures of seabird egg membrane and albumen – implications for non‐invasive studies

• Published in: Rapid Communications in Mass Spectrometry
• Main Authors: Quillfeldt, Petra, McGill, Rona A. R., Masello, Juan F., Poisbleau, Maud, van Noordwijk, Hendrika, Demongin, Laurent, Furness, Robert W.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2009
• Subjects: Imperial Shag; Phalacrocorax atriceps; Rockhopper penguin
• Online Access: http://dx.doi.org/10.1002/rcm.4286; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Frcm.4286; http://onlinelibrary.wiley.com/wol1/doi/10.1002/rcm.4286/fullpdf

Abstract In many bird species, egg membranes can be obtained non‐invasively after the chicks have hatched, and stable isotope analysis of egg membranes can be used to study the diet and foraging distribution of these birds during egg formation. It has been suggested that the enrichment factors of albumen and egg membranes differ for 13 C, but are similar for 15 N. In this study, we compared carbon and nitrogen stable isotopes of the membranes and albumen of individual eggs of three wild seabird species, the Southern Rockhopper penguin Eudyptes chrysocome , the Imperial shag Phalacrocorax atriceps albiventer , and the Thin‐billed prion Pachyptila belcheri . We also included chicken eggs for comparison. Egg membranes were generally enriched in 13 C, compared with albumen. The difference varied between species, with 2.1‰ in Rockhopper penguins, 1.6‰ in Imperial shags, but only 0.5‰ in Thin‐billed prions and 0.4‰ in chicken eggs. Egg membranes were slightly enriched in 15 N in Imperial shags (0.9‰) and chickens (0.5‰), compared with albumen, while there was no difference for Thin‐billed prions and Rockhopper penguins. The isotopic values of carbon and nitrogen were correlated between albumen and egg membranes of individual eggs, suggesting that egg membranes can be used reliably to investigate trophic differences between individuals, seasons or colonies. Species‐specific mathematical corrections could be used to compare results across studies that use different egg components. Copyright © 2009 John Wiley & Sons, Ltd.