The brown bear, Ursus arctos, is the only species common in Europe, and therefore was most likely the typical bear seen in the Westlands of Middle-earth. This identification is complicated slightly by the fact that Beorn was said to take the form of a black bear, whereas black bears are (at least in modern times) not found in Europe. Despite their name, however, brown bears can have extremely dark fur, and so this may explain the colour of Beorn's fur in his bear form.

Alternatively, there may have been some other kind of bear at large in Middle-earth that is no longer known today. Indeed, Gandalf speaks of a race of 'great and ancient bears of the mountains' (The Hobbit 7, Queer Lodgings). Whether this represents an entirely different kind of bear is unclear, though it seems at least possible. The long-extinct cave bear, Ursus spelaeus, ranged across Europe thousands of years ago, and was much larger than the modern brown bear; it may be that a remnant of such creatures (or something similar) survived in the Misty Mountains into the Third Age.