They were the tracks of the grizzly bear.

There could be no doubt of this, for there were the prints of the long plantigrade feet, the tubercules of the toes, and the holes where the curving claws had sunk several inches into the mud.

No other animal could have made such marks--not even the black or brown bear, whose claws are short in comparison with those of the grizzly monster of the mountains.
For some moments our hunters hesitated under feelings of alarm; but, as the animal that had made the tracks was not in sight, their fears gradually subsided to some extent, and they began to consider what was best to be done.

Should they go up the ravine, and endeavour to reach the summit?
This would only be carrying out their original intention, and they would have started upward without hesitation, had they not discovered the bear-tracks.

Seeing these, however, had put a new aspect on the matter.