Differences in δ ~(13)C and δ ~(15)N values between feathers and blood of seabird chicks: implications for non-invasive isotopic investigations

摘要

Blood and feathers are the most targeted tissues for isotopic investigations in avian ecology, primarily because they can be easily and non-destructively sampled on live individuals. Comparing blood and feather isotopic ratios can provide valuable information on dietary shifts, trophic specialization and migration patterns, but it requires a good knowledge of the isotopic differences between the two tissues. Here, δ ~(13)C and δ ~(15)N values of whole blood (in blood cells of a few species) and simultaneously grown body feathers were measured in seabird chicks to quantify the tissue-related isotopic differences. Seabirds include 27 populations of 22 wild species that were sampled in 2000-2008, and a review of the literature added 8 groups (including adult birds) to the analysis. The use of a large data set that overall encompasses wide δ ~(13)C and δ ~(15)N ranges allowed us to depict for the first time accurate relationships between blood and feather isotopic ratios across avian taxa. Blood was impoverished in ~(13)C and generally in ~(15)N compared with feathers. Both mean δ ~(13)C and δ ~(15)N values of feathers and blood were highly positively and linearly related [feather δ~(13)C = 0.972 (±0.020) blood δ~(13)C + 0.962 (±0.414), and feather δ~(15)N = 1.014 (±0.056) blood + 0.447 (±0.665), respectively; both P < 0.0001]. The regressions should be applied to mathematically correct feather or whole blood δ~(13)C and δ~(15)N values when comparing isotopic ratios within and between ecological studies on birds.