In our paper on stable isotopes from cave bears (Ursus spelaeus) in the Peçstera cu Oase (1), we erroneously misquoted the hypothesis of Fernández et al. (2). For this we apologize. However, this misinterpretation and their comments here have no impact our basic conclusion that the available stable isotope data indicate that U. spelaeus were basically omnivores with the ecological flexibility to be more or less omnivorous depending upon available resources, dietary requirements, and competition.
First, arguments regarding increased δ15N with dormancy (≈1‰) are insufficient to explain the δ15N values of most of the Oase cave bears (1). Second, modern hibernating bear bone turnover has been shown to be normal (albeit reduced) (3), and blood plasma (4) and muscle (5) δ15N values in modern hibernating bears are similar to summer values, especially when normal δ15N variance for cave bears (1) and modern bears (6) is considered and statistical multiple comparison corrections are employed. Third, a major effect of dormancy to elevate cave bear δ15N levels is inconsistent with the abundance of very low δ15N values for cave bear samples (1). The detailed effects of dormancy on modern ursid, or U. spelaeus, bone stable isotopes have yet to be fully resolved, but current data and dietary logic show that dormancy does not account for the high cave bear δ15N values seen at the Peçstera cu Oase. Flexible omnivory does.
Footnotes
The authors declare no conflict of interest.
References
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