Isotopic evidence for dietary flexibility among European Late Pleistocene cave bears (Ursus spelaeus)

Abstract

The proposed dietary pattern of extinct Late Pleistocene cave bears (Ursus spelaeus Rosenmüller, 1794) has become controversial, as some authors have suggested that they were strictly vegetarian, whereas others maintain they were omnivores that at times ate large amounts of animal protein. We evaluated these alternatives by compiling stable isotope data of carbon (δ13C) and nitrogen (δ15N) from the bone collagen of adult European cave bears from the Late Pleistocene (Marine Isotopic Stage 3). The data include previously published analyses and additional data from the southeastern European (Carpathian) sites of Cioclovina, Muierii, Oase, and Urşilor. The cave bear isotopic values from bone collagen were compared with those from hair keratin occurring in grizzly bears (Ursus arctos horribilis Ord, 1815) collected from 1989 to 2009 in the western United States (Yellowstone National Park). The Yellowstone bears have access to a wide diversity of plants and animals, such that their diets can range from vegetarian to carnivorous. Thus, there was considerable δ13C and δ15N variation among the grizzly bear isotopic values, and the cave bear isotopic variation was encompassed within the overall grizzly bear isotopic distribution. More importantly, the δ15N distributions, reflecting principally trophic level, were not different between the cave bears and the grizzly bears; the cave bear values are, on average, slightly higher or lower than those of the grizzly bears, depending on the criteria for inclusion in the comparisons. It is therefore no longer appropriate to view Late Pleistocene cave bears as strictly or even predominantly vegetarian but as flexible omnivores within their diverse communities.

Non‐traditional isotope perspectives in vertebrate palaeobiology

“…If we consider those values to represent trophic levels, then U. arctos from Jaurens could be interpreted as omnivorous or herbivorous in agreement with modern observations (Robu et al . ). As for the Sclayn bone dataset, U. spelaeus also falls with other herbivores within the δ 15 N vs δ 44/42 Ca space.…”

“…Robu et al . ) although recent studies have underlined mostly plant‐based consumption for U. spelaeus (e.g. Krajcarz et al .…”

Genetic turnovers and northern survival during the last glacial maximum in European brown bears

“…This has previously been done on both modern and ancient bears, mainly to characterize dietary variation in geographically and temporally diverse bear populations (Bocherens et al, 2004;Döppes, Rosendahl, Pacher, & Bocherens, 2010;Hilderbrand et al, 1992;Münzel et al, 2011;Robu et al, 2013). Due to its varied diet, the brown bear is well suited as a model species to study changes in physiological ecology through time.…”

Evidence for herbivorous cave bears (Ursus spelaeus) in Goyet Cave, Belgium: implications for palaeodietary reconstruction of fossil bears using amino acid δ15N approaches

“…Bocherens et al ., , , , 2011, 2013, 2014a,b; Münzel et al ., ; Krajcarz et al ., ) could support the former hypothesis of strict herbivory (Bocherens, ). Possible exceptions are cave bears from two Romanian sites with δ 15 N values of collagen as high as associated carnivorous fauna (Richards et al ., ; Robu et al ., ) and cave bears from some European sites whose collagen δ 15 N values were higher than those of herbivores of similar age, although exact sampling locations were not mentioned (Hilderbrand et al ., ). By contrast, hibernation and suckling have been suggested to alter δ 13 C and δ 15 N values of cave bears (Fernández‐Mosquera et al ., ; Jenkins et al ., ).…”