Crows are very smart!! While hunting deer in the mountains of Virginia, I once heard a single crow early in the morning as it tried to mimic a Canada Goose as it honked away leaving a pond near my tree stand. The ole crow did a good job of trying to sound like the goose.
Crows never cease to amaze me, if the crows are calling in the woods, everything is normal, and deer still move about freely. Crows can live to be 75 years of age and older and they can mimic over 1100 sounds!!!!!