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Perez-Rama M.,Instituto Universitario Of Xeoloxia | Fernandez-Mosquera D.,Instituto Universitario Of Xeoloxia | Grandal-D'Anglade A.,Instituto Universitario Of Xeoloxia
Quaternaire, Supplement | Year: 2011

Stable isotope signatures (δ13C and δ15N) in bone collagen vary according to the metabolism, diet and environment of an animal, and are a valuable tool for paleoecological studies. In cave bears, the special metabolism during hibernation affects the proportion between light and heavy C and N isotopes in bone collagen. This effect is especially evident in neonates, whose tissue was formed during their mothers' hibernation, thus sharing the mother's δ13C y δ15N values during that period. By contrast, the values for adults represent the last years of life of the animal due to the slow turnover rate of the bone tissue. In this work we compare the δ13C and δ15N values in neonate and adult Ursus spelaeus from three caves of Galicia (Spain): Eirós, A Ceza and Liñares. The data obtained confirm that, even with differences in absolute values between the three populations, both in adults and neonates, hibernation produces in all populations an increase in δ15N values, and more negative values on δ13C. This is consistent with the current knowledge of the metabolism of bears during hibernation, during which the animals do not eat, drink, defecate or urinate, and have to rely on fat storages and urea reuse in order to survive the winter dormancy. Source


Garcia-Vazquez A.,Instituto Universitario Of Xeoloxia | Grandal-D'Anglade A.,Instituto Universitario Of Xeoloxia | Rodriguez M.V.,Instituto Universitario Of Xeoloxia | Romani J.R.V.,Instituto Universitario Of Xeoloxia
Quaternaire, Supplement | Year: 2011

In Galicia (NW of the Iberian Peninsula) the karstic cavities and the paleontological sites associated to them are scarce and concentrated on its Eastern border with León. Most cavities are located in O Courel Sierra (Lugo). The presence of two species of ursids (cave and brown bear) has been detected in these cavities during the Upper Quaternary. The present paper discusses the possibility of a simultaneous coincidence of both species in the zone. The population dynamics inferred from sediment, chronologic and geomorphologic data allow us to infer that during the Upper Quaternary brown bears inhabited the caves located at higher topographic heights than those occupied by cave bears. The last glacial cooling (end of MIS3 and MIS2) caused the retreat of both species from the zone. During MIS 2, cave bears were found only in zones far from the Sierra at lower altitudes, while brown bear fossil records are absent. In the Holocene, with the climatic improvement and after the extinction of the cave bear, brown bears inhabited again the Sierra occupying preferably the highest caves, coinciding with the increase of human pressure in the zone. Source

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