Distribution and chronology of brownbear (Ursus arctos L.) in the Iberian peninsula during Upper Pleistocene and Holocene

In this paper we present 13 new radiocarbon datings of brown bear (Ursus arctos L.) remains from caves of the western half of the Cantabrian Mountains (Galicia, Asturias, Cantabria). This dates, as well as other previously reported, range from more than 40,000 years BP to 2,442 ± 61 years cal BP, belonging mostly to the early Holocene. From a whole of 26 datings, only 3 are of Pleistocene age. In order to complete the distribution in space and time in the Iberian peninsula, we review the literature on this species presence and its chronology by radiocarbon dating or archaeological culture when it exists. The presence of the brown bear has been observed in at least 143 sites. Oldest mentions are from Middle Pleistocene from the south of the Iberian peninsula. In Upper Pleistocene, sites cover the whole peninsula, with only 5 radiocarbon dates. Sites with Pleistocene fossils are a few more than the Holocene ones. There are several problems with the observed distribution. Firstly, as for the vast majority of terrestrial biocenosis, even if the species was present there are not preserv ed remains. An example of this is the lack of Holoeene remains in places we know it was present according to the historical literature. In general, there are gaps in the distribution that coincide with no limestone lithology. Furthermore, there is a bias related to the intensity of research in certain areas. It was suggested that brown bear population increased when cave bear (Ursus spelaeus ROSENMÙLLER) wiped out, but only in 12.5 % of the places in which both species are present is possible to see a substitution. The number of brown bears in every site is low before and after the extinction of its alleged competitor. Our results suggest that the denning ecology was different from the cave bear and, like nowadays, brown bears used different types of dens, like holes in the ground, inside trees or smaller natural caves. In the XVI century the population begins to decrease, till reaching its minimum in the XX century, with two surviving populations in Cantabrian Mountains and Pyrenees, but population began to drop since the Neolithic, probably due to the pressure caused by the expansion of human activities.