Effects of nutritional restriction on nitrogen and carbon stable isotopes in growing seabirds

Cory T. Williams, C. Loren Buck, Justine Sears, Alexander S. Kitaysky

Research output: Contribution to journalArticlepeer-review

103 Scopus citations


When using stable isotopes as dietary tracers it is essential to consider effects of nutritional state on isotopic fractionation. While starvation is known to induce enrichment of 15N in body tissues, effects of moderate food restriction on isotope signatures have rarely been tested. We conducted two experiments to investigate effects of a 50-55% reduction in food intake on δ15N and δ13C values in blood cells and whole blood of tufted puffin chicks, a species that exhibits a variety of adaptive responses to nutritional deficits. We found that blood from puffin chicks fed ad libitum became enriched in 15N and 13C compared to food-restricted chicks. Our results show that 15N enrichment is not always associated with food deprivation and argue effects of growth on diet-tissue fractionation of nitrogen stable isotopes (Δ15N) need to be considered in stable isotope studies. The decrease in δ13C of whole blood and blood cells in restricted birds is likely due to incorporation of carbon from 13C-depleted lipids into proteins. Effects of nutritional restriction on δ 15N and δ13C values were relatively small in both experiments (δ15N: 0.77 and 0.41‰, δ 13C: 0.20 and 0.25‰) compared to effects of ecological processes, indicating physiological effects do not preclude the use of carbon and nitrogen stable isotopes in studies of seabird ecology. Nevertheless, our results demonstrate that physiological processes affect nitrogen and carbon stable isotopes in growing birds and we caution isotope ecologists to consider these effects to avoid drawing spurious conclusions.

Original languageEnglish (US)
Pages (from-to)11-18
Number of pages8
Issue number1
StatePublished - Aug 2007
Externally publishedYes


  • Diet-tissue fractionation
  • Isotopic enrichment
  • Nitrogen balance
  • Physiological condition

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics


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