Trophic Relations of Brown and Black Bears in Several Western North American Ecosystems

Jacoby, Michael E.; Hilderbrand, Grant V.; Servheen, Christopher; Schwartz, Charles C.; Arthur, Stephen M.; Hanley, Thomas A.; Robbins, Charles T.; Michener, Robert H.

doi:10.2307/3802806

Cited by 155 publications

(171 citation statements)

References 26 publications

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“…In this variation U. spelaeus closely parallels the range of isotopic values seen for modern European and North American brown bears (5,7,(28)(29)(30)) and the few data available for Late Pleistocene brown bears (10,42).…”

Section: Discussionmentioning

confidence: 67%

“…All aspects of their omnivorous diets have limitations in availability, potential feeding rates, and nutritional value in any given environment; adequate weight gain for survival, reproduction, and hibernation therefore depends on a mix of as many food resources as are available (19,21). Meat consumption, in particular, varies widely among and within brown bear populations, due, among nonmaritime bears, to the availability of ungulate fauna (29,30,44,45). Large adult males also appear to be more carnivorous than females or subadult bears (28,29).…”

Section: Discussionmentioning

confidence: 99%

“…Meat consumption, in particular, varies widely among and within brown bear populations, due, among nonmaritime bears, to the availability of ungulate fauna (29,30,44,45). Large adult males also appear to be more carnivorous than females or subadult bears (28,29). North American black bears (U. americanus) appear to have similar plant/meat dietary proportions as brown bears (29), except that the larger brown bears are frequently more carnivorous when the prime meat is maritime (e.g., salmon) (46).…”

Section: Discussionmentioning

confidence: 99%

“…They ruled out the possibility that hibernation had an effect on ␦ 15 (7,(28)(29)(30), it is essential to establish the taxonomic affinities of the bear bones from the Peştera cu Oase.…”

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confidence: 99%

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Isotopic evidence for omnivory among European cave bears: Late Pleistocene Ursus spelaeus from the Peştera cu Oase, Romania

Richards

Pacher

Stiller

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

101

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Previous bone collagen carbon and nitrogen isotopic studies of Late Pleistocene European cave bears (Ursus spelaeus) have shown that these bears frequently had low nitrogen isotope values, similar to those of herbivores and indicating either unusual physiology related to hibernation or a herbivorous diet. Isotopic analysis of animal bone from the Peştera cu Oase (Cave with Bones), Romania, shows that most of its cave bears had higher nitrogen isotope values than the associated herbivores and were, therefore, omnivorous. The Oase bears are securely identified as cave bears by both their morphology and DNA sequences. Although many cave bear populations may have behaved like herbivores, the Oase isotopic data demonstrate that cave bears were capable of altering their diets to become omnivores or even carnivores. These data therefore broaden the dietary profile of U. spelaeus and raise questions about the nature of the carnivore guild in Pleistocene Europe.carbon isotopes ͉ nitrogen isotopes ͉ diets ͉ ancient DNA L ate Pleistocene cave bear (Ursus spelaeus) diet and physiology is not well known, although based on skull, mandible, and tooth morphology, they have been inferred to have been largely herbivorous (1-4). Moreover, isotopic studies of central and western European cave bears have shown that, in most cases where their values are compared with herbivores and carnivores from the same site, they have ␦ 15 N values that plot with, or lower than, herbivores (Table 1). These dietary inferences are in the context of bears that had a period of dormancy, similar to modern black bears (Ursus americanus) and brown bears (Ursus arctos), given the abundance of hibernation nests in European caves. This pattern has been interpreted in several ways.Based Table 1), is that some cave bears were largely herbivorous, as are some modern bears, but that other cave bears were more carnivorous and hence exhibit ␦ 15 N values similar to those of many modern omnivorous U. arctos and U. americanus. In this interpretation, the variation in trophic level indicated by ␦ 15 N values would reflect ecological plasticity among U. spelaeus, in which they were more or less carnivorous depending on available food resources, body-size requirements, interspecific competition, seasonality, and temperature.Regardless of the cause, 86.1% of the available individual European adult cave bear ␦ 15 N values (n ϭ 101) are Ͻ6.0‰, and hence within the basically vegetarian range [the number rises to 95.6%, n ϭ 91 without Hilderbrand et al.'s (14) 10 specimens] (Table 1). In the context of this distribution of ␦ 15 N values, routine isotopic assessment of a cave bear metapodial associated with an early modern human cranium in the Late Pleistocene Peştera cu Oase, Caraş-Severin, southwestern [supporting information (SI) Text and SI Figs. 4 and 5], provided an anomalously high ␦ 15 N value of 7.8‰ (SI Table 2, Oase O34-232). To further evaluate this result and address the cause of the generally low cave bear ␦ 15 N values, we measured the isotope values of c...

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Section: Discussionmentioning

confidence: 67%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

“…They ruled out the possibility that hibernation had an effect on ␦ 15 (7,(28)(29)(30), it is essential to establish the taxonomic affinities of the bear bones from the Peştera cu Oase.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Isotopic evidence for omnivory among European cave bears: Late Pleistocene Ursus spelaeus from the Peştera cu Oase, Romania

Richards

Pacher

Stiller

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

101

View full text Add to dashboard Cite

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“…To examine the diet of Arctic grizzly bears, I am comparing the carbon (δ 13 C) and nitrogen (δ 15 N) stable isotope ratios of hair and claw samples collected from research bears with those of bear foods found in the region. Stable isotope analysis can be used to increase our understanding of the proportional contribution of different dietary groups and their nutritional value and to determine the trophic position of this Arctic population in the food web (Jacoby et al, 1999). Since the isotopic signature found in the sampled tissue represents not only what the animal has ingested but also what the animal has assimilated, we can estimate the proportional contribution and nutritional importance of terrestrial plant and animal proteins as well as marine food types (Hobson et al, 2000).…”

Section: Diet Composition and Trophic Positionmentioning

confidence: 99%