Stable Isotope Analysis in Foraging Ecology of Marine Birds

Stable isotope analysis has emerged as a central tool for elucidating the foraging ecology of marine birds by linking tissue‐specific isotopic signatures to spatial and trophic dimensions of diet. Ratios of carbon (13C/12C) indicate the primary foraging habitat, distinguishing inshore, offshore or pelagic sources, while nitrogen ratios (15N/14N) resolve trophic position within marine food webs. By sampling blood, feathers, keratinous tissues or eggshells, researchers capture temporal integration scales ranging from days to months, enabling the reconstruction of seasonal diets, migratory connectivity and individual specialisations. When combined with movement data from geolocators or GPS loggers, isotope analysis refines our understanding of sex-specific foraging strategies, colony-level dietary shifts and responses to environmental variability. As seabirds often occupy apex or mesopredator roles, they serve as sentinels of ocean health; isotope-based approaches inform conservation measures, fisheries management and assessments of ecosystem change under climate pressure.

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Stable Isotope Analysis in Foraging Ecology of Marine Birds publication trend

The graph below shows the total number of articles in stable isotope analysis in foraging ecology of marine birds across all publications each year (not limited to Nature Index journals).

Technical terms

δ13C: Permil deviation in 13C/12C ratio of a sample relative to a standard, indicating primary carbon sources and foraging habitat.

δ15N: Permil deviation in 15N/14N ratio, reflecting an organism’s trophic level within the food web.

Isotopic niche: Multidimensional space defined by stable isotope ratios that represents the range of dietary and habitat use strategies.

Keratin: Durable protein in feathers, claws or beaks that records dietary isotopic values over the growth period of the tissue.

References

1. Sex-specific spatial use of the winter foraging areas by Magellanic penguins and assessment of potential conflicts with fisheries during winter dispersal. PLOS ONE (2021).
2. Diferencias estacionales en la dieta de individuos juveniles del Pingüino Patagónico (Spheniscus magellanicus) reveladas en base al análisis de isótopos estables en uñas. El Hornero (2015).
3. The influence of tourist visitation on the heterophyl to lymphocyte ratios and trophic values of Magellanic penguins (Spheniscus magellanicus) at Martillo Island, Argentina. Conservation Physiology (2023).