Signs of Bear Activity
One evidence of ... bear activity is evidence of digging for roots, bulbs, corms, tubers, or small mammals. ... If you see diggings, try to estimate how old they are. Remove the soil that the bear in digging has thrown on top of nearby plants and grasses. Is the vegetation that you have uncovered still as fresh looking as nearby vegetation that was not covered? If so, you ought to be looking over your shoulder....
from Bear Attacks - Their Causes and Avoidance