Stable isotopes reveal the importance of seabirds and marine foods in the diet of St Kilda field mice

Stable isotope analysis reveals that seabirds and marine foods constitute a significant portion of the diet of St Kilda field mice, particularly during seabird breeding seasons. Mice sampled from Carn Mor, where the majority of the island's seabirds nest, exhibited distinct isotopic signatures compared to other locations, indicating a higher reliance on seabird-derived foods. This finding suggests that mice may be scavenging or predating seabirds or consuming their discarded food items, potentially impacting seabird populations. The study used δ13C and δ15N ratios from mouse blood and dietary items to examine foraging behavior across three years (2010–2012), employing isotope niche and mixing models to assess seasonal and spatial variations.

Bicknell, A. W. J., Walker, B. W., Black, T., Newton, J., Pemberton, J. M., Luxmoore, R., Inger, R., & Votier, S. C. (2020). Stable isotopes reveal the importance of seabirds and marine foods in the diet of St Kilda field mice. Scientific Reports, 10(1). https://doi.org/10.1038/s41598-020-62672-x