Volume 49, No. 1

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Stable isotope analysis of multiple tissues from chick carcasses of three pygoscelid penguins in Antarctica


1University of North Carolina Wilmington, Department of Biology and Marine Biology, 601 S. College Rd., Wilmington, NC 28403, USA
2Departamento de Biología de Predadores Tope, Coordinación de Ciencias de la Vida, Instituto Antártico Argentino, 25 de Mayo 1143, San Martín, Buenos Aires B1650CSP, Argentina
3Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Av. Rivadavia 1917, Buenos Aires C1033AAJ, Argentina
4Laboratorios Anexos, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, Calle 64 N8 3, La Plata, Buenos Aires B1904AMA, Argentina


CIRIANI, Y.A., JUÁRES, M.A., SANTOS, M.M. & EMSLIE, S.D. 2021. Stable isotope analysis of multiple tissues from chick carcasses of three pygoscelid penguins in Antarctica. Marine Ornithology 49: 9 - 17

Received 07 July 2020, accepted 08 August 2020

Date Published: 2021/04/15
Date Online: 2021/02/02
Key words: 25 de Mayo/King George Island, δ15N, δ13C, Pygoscelis penguins, dietary shifts, opportunistic sampling


Many types of animal tissues are increasingly being used for stable isotope analysis, with their application dependent on the time frame they reflect and their availability for collection. Here, we investigated the isotopic values (δ13C and δ15N) of four tissues (feather, skin, toenail, and bone) collected from fledgling-period chick carcasses of three species of pygoscelid penguins to compare the variability and accuracy of the data among tissues. Samples were collected at 25 de Mayo/King George Island during the 2017/18 austral summer. Chick carcasses are commonly found at active penguin colonies, and “opportunistic sampling” can easily be performed without disturbing nesting penguins. A total of 25-36 carcasses per species were sampled at active colonies of Adélie Pygoscelis adeliae, Gentoo P. papua, and Chinstrap P. antarcticus penguins. A linear mixed model showed that δ13C values varied significantly between tissues, presumably due to tissue-specific isotopic discrimination. In contrast, the only tissue with significantly different δ15N values was toenail. Stable isotope data revealed dietary differences among species, with Gentoo Penguins having higher average isotopic values in tissues compared to Adélie and Chinstrap penguins. In addition, Chinstrap Penguins showed a consistent, but not statistically significant, trend in having higher δ13C values compared to Adélie Penguins. Gentoo Penguins displayed the highest isotopic variability of any species for all tissues. Isotopic composition was most variable in skin in all three species making skin the least reliable tissue for isotope analysis, whereas isotopic values were least variable in toenails. Comparison of isotopic values between two bones (tibiotarsus and coracoid) showed no significant differences in isotopic values, indicating that when the same bone is not available for sampling from carcasses, sampling of any major skeletal element is likely to provide a meaningful comparison. These results allow for more informed opportunistic sampling to accurately estimate and compare penguin diet among species and between ancient and active colonies.


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