Holocene brown bear (Ursus arctos L.) from Norwegian caves

Norwegian caves contain stratigraphical information regarding the historical faunal composition valuable in the assessment of postglacial colonization and phylogeographical structure. In some of these limestone caves, brown bear ( Ursus arctos L.) remains have been excavated and radiometrically dated. We present osteology (95 traits defined) from 29 brown bears found within 22 Norwegian caves above 658N. Our data span the time interval 6210–420 ¹⁴C yr BP. The sex of individuals was based on dimorphic canines, while age was determined by cementum analysis and body size estimated from regressions between morphological traits compared to a contemporary reference collection. Five females and 14 males were recognized, while the remaining bears could not be sexed because of their small size, low age or lack of canines. The ages of 26 bears (tooth cementum age and estimates) ranged from juveniles (<0.5 year) to adults (23 years), the majority being old animals. Both sexes have used these caves for over-wintering lairs, as seen in several caves, where denning is also suggested based on the observations of adult females and cubs. There were no signs of predator or human transported bear remains, suggesting natural mortality. The age of the bears suggests that young or old bears may have died from insufficient nutrient storage, environmental harshness, or may have drowned in spring or autumnal flooding. We conclude that Norwegian brown bears have used these caves sporadically for thousands of years, which suggests that caves are not a preferred site for the brown bear during hibernation or denning.