which are accumulated at a faster rate by carnivores as opposed to herbivores. Among Mediterranean cave bears such as those found in Toll Cave in northeastern Spain, the particularly low ?¹⁵N values may be a result of their high intake of nitrogen-fixing plants.

However, some evidence points toward the occasional inclusion of animal protein in cave bear diets. For example, toothmarks on cave bear remains in areas where cave bears are the only recorded potential carnivores