This ensures that the bear was present until recently in South America and surely throughout the Pleistocene. Obviously those popu;ations have collapsed and subspecoes have gone extinct. As with the cave bear, i am inclined to blame humanity and leave it at that. After all, all bears are vulnerable during hibernization.
Hunters would soon know all such dens and soon enough they will take advantage of this natural vulnerability.
It is only where man is thin on the ground that this can be avoided. After all we leave ours aloni in mountain fastnesses and essentially no where else.